Hall D Monday 14:00-16:00
14:00
2825.
Flow Sensitive MRI in a Realistic Model System of the Thoracic Aorta
with Aortic Coarctation
Computer 1
Ramona
Lorenz1, Aurélien F. Stalder1, Jelena Bock1,
Dominic Klausmann2, Christoph Benk1, Jürgen Hennig1,
Michael Markl1
1University
Hospital Freiburg, Freiburg, Germany; 2University Freiburg,
Freiburg, Germany
The
purpose of this study was to establish a realistic model system for the
evaluation of hemodynamics consequences of aortic coarctation with different
stenosis grades. Flow sensitive 4D MRI was performed within a realistic rapid
prototyping vascular model of the thoracic aorta with attached flexible
stenosis in the descending aorta which was integrated into a pulsatile flow
circuit. A novel approach for generating realistic pulsatile waveforms was
realized by a pneumatically driven VAD (ventricular assistant device) pump
system. The study presents an evaluation of the impact of stenosis grade on
local and global flow dynamics.
14:30
2826.
Flow Sensitive 4D MRI: Descending Aortic Retrograde Flow and
Embolization Risk in Acute Stroke Patients
Computer 1
Michael
Markl1, Christoph Strecker2, Patrick Dudler2,
Andrea Nußbaumer2, Jelena Bock1, Aurelien F. Stalder1,
Alex Frydrychowicz1, Anna L. Stroh3, Cornelius Weiller2,
Jürgen Hennig1, Andreas Harloff2
1Dept.
of Diagnostic Radiology, Medical Physics, University Hospital, Freiburg,
Germany; 2Dept. of Neurology, University Hospital, Freiburg,
Germany; 3Dept. of Cardiology, University Hospital, Freiburg,
Germany
Flow-sensitive
4D MRI allows the detailed visualization of both physiological and pathological
3D aortic blood flow characteristics and was used to determine the role of
retrograde flow in the descending aorta (DAo) in patients with acute embolic
stroke. Our findings demonstrate a high incidence of retrograde flow in the
proximal DAo suggesting that complex DAo plaques should be considered as a
novel high-risk embolic source in patients with undetermined stroke etiology.
15:00
2827.
Analysis of 3D Flow Dynamics in a Ventricular Assist Device by Flow
Sensitive 4D MRI
Computer 1
Michael
Markl1, Ramona Lorenz1, Jelena Bock1,
Christoph Benk2, Dominic Klausmann2, Alex Frydrychowicz1,
Jürgen Hennig1, Friedhelm Beyersdorf2
1Dept.
of Diagnostic Radiology, Medical Physics, University Hospital, Freiburg,
Germany; 2Dept. of Cardiovascular Surgery, University Hospital,
Freiburg, Germany
The
assessment of flow characteristics inside ventricular assist devices (VADs)
using MRI techniques may provide insight into the mechanisms underlying the
high rate of thrombo-embolic events after VAD implantation. These
investigations may form the basis to optimize the device’s design and its need
for anticoagulation. The purpose of this study was to integrate a clinical routine
VAD into a flow circuit with realistic geometric and pulsatile inflow
conditions. Flow sensitive Magnetic Resonance Imaging (MRI) at 3 Tesla
permitted the detailed analysis of local and global 3D flow dynamics in a
realistic environment.
15:30
2828.
Diameter-Dependence of Aortic Hemodynamics: Does Size Matter?
Computer 1
Alex
Frydrychowicz1, Alexander Berger1, Aurélien F. Stalder1,
Maximilian F. Russe1, Andreas Harloff1, Mathias Langer1,
Jürgen Hennig1, Michael Markl1
1University
Hospital Freiburg, Freiburg, Germany
It
was the aim of this study based on flow-sensitive 4D MRI to analyze the
diameter dependence of aortic hemodynamics with respect to characteristic blood
flow patterns such as time to maximum arterial flow, duration of backward flow,
number of vortices, and the presence of helical flow, which can be correlated
to wall shear stress (WSS) and oscillatory shear index (OSI). The results of
this study indicate the method¡¯s potential to identify characteristic,
diameter dependent, aortic flow patterns. In a cohort of 62 individuals which
were subgrouped by the diameter of the ascending aorta (SAD-group ¡Ü 3.5cm <
LAD-group) we showed that the size of the aorta influences the hemodynamic
properties.
14:00
2829.
Multi-Dimensional Velocity Field Reconstruction from Sparsely Sampled 3D
Phase Contrast MRI
Computer 2
Kartik
Sivaram Sundareswaran1, Dave Harold Frakes1, Mark Fogel2,
Oskar Skrinjar1, Ajit P. Yoganathan1
1Georgia
Institute of Technology, Atlanta, Georgia, USA; 2Children's Hospital
of Philadelphia, Philadelphia, Pennsylvania, USA
A
new technique for velocity field reconstruction is presented in this paper that
utilizes blood flow incompressibility as a property for estimating continuous
flow field representation in blood vessels using a stack of contiguous phase
contrast MRI. The methodology has been tested on 15 in vivo datasets of
patients with a single ventricle circulation, and the results indicate superior
qualitative and quantitative velocity reconstruction compared to other traditional
techniques for flow reconstruction from PC MRI. This opens up new avenues for
higher order analysis (vortex structures, energy loss) of PC MRI flow fields.
14:30
2830.
In Vivo MR Determination of Flow Fields in Patients with Intracranial
Aneurysms Using 7D PC-MRI
Computer 2
Gabriel
Acevedo-Bolton1, Alastair Martin1, Vitaliy Rayz1,
Loic Boussel1, David Saloner1,2
1UCSF,
San Francisco, California , USA; 2VAMC San Francisco, San Francisco,
California , USA
7D
PC-MRI was used to measure and map the blood flow within intracranial aneurysms
in vivo. These flow results were compared
with in vitro reproductions and with the predictions of computational
fluid dynamics(CFD) models. It was found to be essential to determine all three
components of the velocity to adequately visualize the complex flow structures
15:00
2831.
Patient-Specific Hemodynamics of the Descending Aorta: Combination of
CFD and 4D Flow-Sensitive MRI
Computer 2
Aurélien
F. Stalder1, Zhenyu Liu2, Michael Markl1,
Jürgen Hennig1, Jan Korvink2
1University
Hospital Freiburg, Freiburg, Germany; 2University of Freiburg,
Freiburg, Germany
Flow-sensitive
4D MRI allows in vivo 3D blood flow
visualization and flow parameter estimation but is limited by spatio-temporal
resolution and measurement errors. In contrast, Computational Fluid Dynamics
(CFD) can compute very accurate flow fields from modeled arteries but depends
on the validity of the hemodynamic model and boundary conditions. We show for
the first time an integration of 4D flow-sensitive MRI and CFD into a single
framework. A combination of those 2 complementary approaches offers reciprocal
validation possibilities and has the potential to refine flow measurements
which may result in more accurate quantification of complex in vivo hemodynamic phenomena.
15:30
2832.
4D Flow of the Whole Heart and Great Vessels at 3T Using Real Time Self
Respiratory Gating
Computer 2
Sergio
Andres Uribe1, Philipp Beerbaum1, Allan Rasmusson2,
Thomas Sangild Sørensen2, Reza Razavi1, Tobias Schaeffter1
1Kings
College London, London, UK; 2University of Aarhus, Aarhus, Denmark
We
present an extension of a self-respiratory technique to acquire 4D flow data.
Self-navigation is obtained from k-space center profiles and the breathing
signal is used in real time to gate the scan. The method allows us to acquire
an isotropic non-angulated volume, 4D flow encoded, of the whole heart and
great vessel in a single free-breathing scan. Results showed a strong
correspondence between flow patterns obtained using this technique and with 2D
flow. This approach represents an important advance for the characterization of
the flow hemodynamics in the whole heart and a step forward to simplify cardiac
MR examinations.
Hall D Monday 14:00-16:00
14:00
2833.
A New Methodology for Determining Aortic Pulse Wave Velocity Using 2D
PCMR Velocity Data
Computer 3
Samuel
Fielden1,2, Brandon Fornwalt2, Michael
Jerosch-Herold3, Robert Eisner1, Arthur Stillman1,
John Oshinski1,2
1Emory
University, Atlanta, USA; 2Georgia Institute of Technology/Emory
University, Atlanta, USA; 3Oregon Health & Science University,
Portland, USA
A
novel method for estimating aortic pulse wave velocity is presented. This method uses 2D PCMR data to construct
blood velocity magnitude images in order to determine multiple flow waveforms
in the ascending, transverse, and descending sections of aorta. The waveform at each location is compared to
the most proximal waveform via cross correlation to determine the time delay of
the wave at that location and thus the pulse wave velocity. This method is more reproducible than either
of two more established methods examined.
14:30
2834.
Measurement of Aortic Pulse Wave Velocity in Volunteers
Computer 3
Neva
Hiten Patel1, Mark Butlin2, Richard T. Black1,
Martin J. Graves,13, Stacey Hickson4, Carmel McEniery4,
Ian B. Wilkinson4, David J. Lomas3
1Addenbrooke's
Hospital NHS Trust, Cambridge, UK; 2Macquarie University, Sydney,
Australia; 3University of Cambridge, UK; 4University of
Cambridge, Cambridge, UK
Aortic
pulse wave velocity (PWV) can be used as an index of the increased risk of
cardiovascular disease which is associated with aortic wall stiffness. A number
of groups have looked at measuring PWV using MRI, however we are not aware of
any reported studies addressing the best method of obtaining the transit-time
used to calculate the PWV, and the reproducibility of PWV measurement. We have
performed repeated MRI PWV measurements in healthy volunteers and investigated
several different methods of transit-time calculations.
15:00
2835.
The Effect of Wall Compliance on Aortic Hemodynamics in the Mouse:
Implications for AAA Pathogenesis
Computer 3
Smbat
Amirbekian1, Robert C. Long1, Jin Suo2, W
Robert Taylor1,2, Don P. Giddens2, John N.
Oshinski1,2
1Emory
University, Atlanta, Georgia, USA; 2Georgia Tech, Atlanta, Georgia,
USA
MRA
and PC-MRI were used to provide geometric and flow boundary conditions for a
computational study of the hemodynamics of the mouse aorta. The study showed that incorporating vessel
compliance changes the flow patterns seen in the aorta and that a rigid vessel
creates areas of oscillatory wall shear stress.
15:30
2836.
Measurement of Common Carotid Artery Lumen Dynamics During Cardiac Cycle
Using TrueFISP Cine MR Imaging
Computer 3
Tracy
Yee Mau Chow1,2, Jerry S. Cheung1, Yin Wu1,
Ed X. Wu1
1The
University of Hong Kong, Pokfulam, Hong Kong
Vascular
MR imaging provides detailed anatomical information of blood vessels, yielding
lumen size and wall thickness measurements. However, many of the studies often
specify the morphology and composition of vessel walls without examining the
dynamic pulsatile properties of these vessels. In this study, the vascular
dynamics of the right and left common carotid arteries throughout the whole
cardiac cycle was investigated using TrueFISP cine cardiac imaging. Consistent
results and area waveform patterns were observed among the normal subjects.
This lumen dynamics can better describe physiological behaviour correlated with
other vascular parameters, therefore has potential clinical importance in
differentiating abnormalities. Furthermore, TrueFISP cine MRI produces high
contrast images, allowing high accuracy in area measurements and thus waveform
tracing.
Hall D Monday 14:00-16:00
14:00
2837.
Spiral T2 Quality Evaluation in Patients with Coronary Artery Disease
Computer 4
Warren
Foltz1, Kim Alexander Connelly1, Ram Vijayaraghavan1,
Venkat Ramanan, Gideon Paul1, Graham Wright1, Alexander
Dick1
1Sunnybrook
Health Sciences Centre, Toronto, Canada
T2
has proven to be a valuable contrast mechanism for myocardial characterization
because it is a quantitative biomarker of acute and sub-acute inflammatory
processes. Clinical integration of T2 relies on T2-weighted black-blood fast-spin echo (FSE) imaging because
cardiac-gated imaging is achievable in breath-hold scan times and with useful
spatial resolutions. However the
information is semi-qualitative and the echo-train readout compromises T2
contrast. A magnetization-prepared spiral imaging method, termed T2prep, should
improve reproducibility in clinical quantification of myocardial T2 relaxation
because variability associated with coil shading is removed. In the absence of gross relaxation
fluctuations, current clinical myocardial FSE scanning is useful only to
delineate cardiac margins. Quantitative T2prep mapping reduces variability
towards physiological noise levels, providing more reproducible measurements
with the potential for faster scan times at minor cost to spatial resolution
and ROImin.
14:30
2838.
Using T2*-Maps as a Quantitative Indicator for Myocarditis
Computer 4
Karl-Heinz
Herrmann1, Diane Renz1, Pascal Baltzer1, Ines
Krumbein1, Jürgen R. Reichenbach1
1Friedrich-Schiller-University,
Jena, Germany
Diagnosis
of myocarditis with standard sequences like late enhancement, T2 TSE or
T2-weighted TIRM is not always conclusive because any through plane motion of
the myocardium causes inhomogeneous signal due to the repeated slice selective
inversion and excitation pulses. A quantitative T2*-map may be helpful in
quantifying, delineating and detecting edema associated with myocarditis.
15:00
2839.
Retrospective Correction for Induced Magnetic Field Inhomogeneity in
Measurements of Large-Vessel Hemoglobin
Oxygen Saturation by MR Susceptometry
Computer 4
Michael
Langham1, Tom Floyd2, Jeremy Magland1, Felix
W. Wehrli1
1University
of Pennsylvania School of Medicine, Philadelphia, Pennsylvania, USA; 2Univesity
of Pennsylvania School of Medicine, Philadelphia, Pennsylvania, USA
The
main source of error in MR susceptometry is the static field inhomogeneity that
is characterized by low spatial-frequency modulation on the phase image.
High-pass filtering has previously been used in conjunction with shimming. We
propose an alternative method which acquires data without scanner-implemented
default shimming, and fit, after appropriate weighting and masking, the static
field inhomogeneity to a second-order polynomial. Compared to shimming, the
retrospective correction technique improved agreement between hemoglobin
saturations measured in different segments of a vessel (femoral versus
popliteal artery and vein) from three standard errors to less than one.
Computer 4
Vincenzo
Positano1, Alessia Pepe1, Anna Ramazzotti1,
Daniele De Marchi1, Brunella Favilli1, Eliana Cracolici2,
Maria Gabriella Brizi3, Maria Filomena Santarelli1,
Massimo Lombardi1, Luigi Landini4
1Institute
of Clinical Physiology, Pisa, Italy; 2University of Palermo,
Palermo, Italy; 3A. Gemelli University Hospital, Roma, Italy; 4University
of Pisa, Pisa, Italy
In
this study we investigate the relationship between segmental R2* heterogeneity
assessed by multi-slice multi-echo MRI and iron overload progression in a large
thalassemia major patient population. Real data were compared with a surrogate
data sets obtained stating that the inhomogeneous segmental distribution of R2*
would be generated by susceptibility artefacts. Inhomogeneities in R2*
myocardial distribution in iron overloaded subjects cannot be explained by the
effect of susceptibility artefacts, that are additive in the R2* domain and
should vanish at high iron overload levels. A possible interpretation is that a
true heterogeneity in iron overload distribution in TM patients exists.
Hall D Monday 14:00-16:00
Computer 5
David
C. Zhu1, J Kevin DeMarco1, Anthony T. Vu2
1Michigan
State University, East Lansing, Michigan, USA; 2GE Healthcare,
Waukesha, Wisconsin, USA
An
optimized 3D inversion recovery prepared fast spoiled gradient recalled
sequence with multiple echoes (IR FSPGR ME) on a 3T scanner for carotid plaque
imaging is presented. It maintains the
ability of its single-echo counterpart in blood and fat signal suppression at
the carotid region as well as the benefits of high-resolution volumetric
visualization and hemorrhage detection. The IR FSPGR ME sequence can
potentially further characterizes hemorrhage types through the generated T8* maps. In addition,
combining images from the individual echoes provides a higher signal-to-noise
ratio and thus improve image visualization.
Computer 5
Makoto
Obara1,2, Masatoshi Honda3, Rie Nozaki2,
Marc Van Cauteren1, Kagayaki Kuroda2
1Philips
Medical Systems, Minato-ku, Japan; 2Tokai University, Hiratsuka-shi,
Japan; 3Tokai University Hospital, Isehara-shi, Japan
3D
turbo field echo (TFE) sequence prepared by motion sensitized driven equilibrium
(3D-MSDE-TFE) was optimized for T1W and T2W carotid artery wall imaging and
compared to the conventional 2D double inversion recovery (DIR) turbo spin echo
(TSE). T1 and T2 contrasts of 3D-MSDE-TFE were controlled by adjusting the MSDE
preparation time, shot interval and acquisition flip angle. MSDE optimization
was achieved by changing the number of refocusing pulses from 1 to 4 using MLEV
scheme. Achieved T1 and T2 contrasts of the optimized 3D-MSDE-TFE were similar
to those of conventional 2D-DIR while scan time was 2 times faster. Therefore,
this approach may be appropriate for vessel wall screening.
Computer 5
Haiyue
Ju1, Xian Xu1, Lin Ma1, Zulong Cai1,
Youquan Cai1, Xinjiang Wang1, Jianming Cai1
1Chinese
PLA General Hospital, Beijing, People's Republic of China
We
aim to evaluate the relationship between the shape and location of superficial
calcification and intraplaque hemorrhage in the atherosclerotic carotid plaque.
One hundred and eighty three slices with superficial calcification in 51
patients were enrolled in this study. All the patients underwent 3T MRI
examination with a contrast-enhanced multi-contrast weighted protocol. This
study showed that the nodular type of superficial calcification in the
atherosclerotic carotid plague has higher possibility of simultaneous
occurrence with intraplaque hemorrhage than that of patchy type, whereas, in
hemorrhage group, the percentage of either marginal or central type of
superficial calcification is not significantly different from that in
non-hemorrhage group.
15:30
2844.
Gadolinium Contrast Enhancement of Carotid Atherosclerotic Plaque is
Associated with Symptomatic Status
Computer 5
Jianming
Cai1, Niranjan Balu2, Dongxiang Xu2, Haiyue Ju1,
Xian Xu1, Xihai Zhao1, Chun Yuan2
1Chinese
PLA General Hospital, Beijing, People's Republic of China; 2University
of Washington, Seattle, USA
Symptomatic
carotid atherosclerosis is known to be associated with plaque neovasculature
and inflammation. An increase in vasa vasorum accompanies the increased
inflammation and plaque neovasculature of advanced atheorsclerosis. The
increased blood supply from the vasa vasorum plexus surrounding the carotid
artery may be reflected in contrast enhancement (CE) patterns of the outerwall.
The association between outerwall CE on black-blood contrast-enhanced MRI
(CE-MRI) and symptomatic status was investigated in 24 patients. Outerwall CE
was clearly visualized by CE-MRI. Symptomatic status was found to be associated
with a more homogenous outerwall CE compared to asymptomatic arteries.
14:00
2845.
DSCT and 3T MR for Characterization of Carotid Plaque in Patients
Computer 6
John
J. Sheehan1, Natasha Berg2, Timothy Carroll2,
Peter J. Weale3, Renate Jerecic3, James C. Carr2
1Northwestern
University, Chicago, Ireland; 2Northwestern University, Chicago,
Illinois, USA; 3Siemens Medical Solutions, Chicago, Illinois, USA
Atherosclerotic
disease is a significant cause of morbidity and mortality. Recent studies have suggested that plaque
composition is an important prognostic factor and may be more predictive of
adverse outcomes than overall degree of stenosis. Previous studies have attempted to
characterize carotid plaque components using various imaging modalities. In this small patient study, we looked at the
relative efficacy of two new technologies, 3 Tesla (3T) MR and Dual Source CT
(DSCT) to evaluate plaque components. We
hypothesized that these modalities could provide improved depiction of plaque
components, which may have important diagnostic and therapeutic implications.
14:30
2846.
Single-Shot DENSE MRI of the Carotid Arteries
Computer 6
Alexander
Peter Lin1,2, Eric Bennett2, Yuan Le2,
Scott Fraser1, Han Wen2
1California
Institute of Technology, Pasadena, California , USA; 2National
Institutes of Health, Bethesda, Maryland, USA
DENSE
strain mapping of the carotid artery wall systolic distension provides regional
stiffness measures. However, the scan lasts several minutes, and segmented
k-space acquisition suffers from artifacts due to head-neck motion and
turbulent in-plane blood flow. This problem is solved with a single-shot
imaging sequence and rigid body image registration in postprocessing.
15:00
2847.
MRI-Based
Biomechanical Imaging: Role of Hemodynamic Forces on the Early Plaque Remodeling
Computer 6
Jie
Zheng1, Dana Abendschein1, Ruth J. Okamoto2,
Deshan Yang1, Kyle McCommis1, Bernd Misselwitz3,
Robert J. Gropler1, Dalin Tang4
1Washington
University School of Medicine, Saint Louis, USA; 2Washinton
University, Saint Louis, USA; 3Bayler Schering Pharma AG, Berlin,
Germany; 4Worcester Polytechnic Institute, Worcester, Massachusetts,
USA
Local
hemodynamic forces play important roles in the regulation of early
atherosclerosis progression and vessel remodeling. A MRI-based biomechanical
imaging technique was developed and evaluated in vivo in a porcine
atherosclerotic plaque model. A plaque targeted contrast-enhanced MR images
provided plaque structure for the computational modeling in this technique.
Progression and regression of the early plaques were observed and flow shear
stress show consistent findings with other reports. Furthermore, structures stress
and strain also demonstrated strong correlations with plaque progression and
regression, indicating multi-factors of hemodynamic effect to the early
atherogenesis.
15:30
2848.
Characterization of Ex Vivo Carotid Plaque with 3T MRI: A Comparison
with Histology
Computer 6
Natasha
Berg1, John Joseph Sheehan1, Peter J. Weale2,
Mark Morasch1, Nicole Mascheri1, James C. Carr1,
Timothy Carroll1
1Northwestern
University, Chicago, Illinois, USA; 2Siemens Medical Solutions,
Chicago, Illinois, USA
Atherosclerotic
disease of the carotid artery is a significant cause of morbidity and
mortality. Previous imaging techniques
have focused on quantifying stenosis in the vessel, but recent research
suggests that composition of plaque may be a more important prognostic factor. Ex vivo studies of carotid plaques have
attempted to characterize plaque using 1.5 T MR and have shown that 2D PDW, T1W
and T2W sequences on MRI may have some utility in demonstrating areas of
fibrous matrix and necrotic core. Here, we perform an intial evaluation of 3T
MRI in the characterization of ex-vivo carotid plaque specimens.
14:00
2849.
High-Resolution Multi-Contrast MRI Characterization of Rabbit
Atherosclerosis Using Clinical Pulse Sequences
Computer 7
Andre
Jean-Louis Belisle1,2, John A. Ronald,12, Kem
A. Rogers1, Brian K. Rutt,12
1University
of Western Ontario, London, Canada; 2Robarts Research Institute,
London, Canada
We
used multi-contrast ex vivo 3T MRI of aortic specimens from defined regions of
a low-level long-term cholesterol-fed rabbit model of atherosclerosis. The
objective was to collect high-resolution images using clinically available
pulse sequences to resolve the structural components of plaques and to provide
histological verification. The most complex regions of plaque appear to be in
the descending aortic arch which was demonstrated by all sequences and is
especially evident when compared to T2w controls. Eventually this research
could be used for visualizing the vulnerable plaque and direct further in vivo
research by specifying imaging target regions in the aorta.
Computer 7
Daohai
Xie1,2, Bensheng Qiu1, Jiangyang Zhang3,
Xiaoming Yang1
1University
of Washington, Seattle, Washington, USA; 2Suzhou University School
of Medicine, Suzhou, People's Republic of China; 3Johns Hopkins
University School of Medicine, Baltimore, Maryland, USA
Atherosclerotic
cardiovascular disease remains the leading cause of death in the developed
countries. Continuous efforts are warranted to understand more about the
pathogenesis and management of atherosclerotic cardiovascular disease.
High-field micro-MR technology offers both high spatial resolution and
whole-body coverage. This study focused on evaluation of capability using in
vivo and ex vivo micro-MRI to detect mouse atherosclerotic plaques, which was
correlated with histopathology. The
results of the current study may encourage the continued efforts to develop high-field
MR imaging techniques to characterize atherosclerotic plaques in vivo,
so-called ¡°in-vivo plaque pathology,¡± which should become an essential
imaging tool for early diagnosis and efficient treatment of atherosclerotic
cardiovascular disease.
15:00
2851.
in vivo MRI and MRA Assessment of Patency in a Novel Model of Vascular
Remodelling Using Patent Aortic Grafts
Computer 7
King
Kenneth Cheung1,2, Andrew R. Thompson3, H
Hafez4, Andrew M. Taylor2, Roger J. Ordidge1,
Stephen E. Humphries3, Mark F. Lythgoe2
1University
College London (UCL), London, UK; 2UCL, London, UK; 3Royal
Free & University College London Medical School, London, UK; 4St
Richards Hospital, Chichester, UK
Fibulin-5
(fbln-5) is an extracellular matrix protein that is central to elastic fibre
maturation and vessel development. A novel model has been devised to
investigate the role of fbln-5 in vascular remodelling in a patent vessel. As
sustained graft patency is central to this model, we evaluated the accuracy of
MRI and MRA for determining graft patency in
vivo. MRI and MRA correctly identified all patent (n=8) and non-patent
(n=3) grafts. The non-invasive and robust nature of MRI and MRA offers an
excellent alternative to traditional assessment through repeated invasive
surgery, thus improving survival and reducing animal usage.
Computer 7
King
Kenneth Cheung*1,2, Manfred Junemann-Ramirez*2,
Pauliina Lehtolainen2, Alan Rudiger2, Mark Turmaine,
David Sanz2, Roger J. Ordidge1, John F. Martin2,
Mark F. Lythgoe2
1University
College London (UCL), London, UK; 2UCL, London, UK
The
vascular endothelium is crucial in regulating biological functions such as
haemostasis. However this layer is often impaired in cardiovascular diseases.
Understanding the evolution of vascular remodelling is therefore of great
importance and may provide insights for the development of novel interventions.
Here we present the use of in vivo
MRI and vascular ultrasound in combination with ex vivo electron microscopy for extensive characterisation of the
events involved in vascular remodelling following balloon angioplasty of the
rat carotid artery over a 28 day follow-up period.
14:00
2853.
New Insights Into Ruptured Plaques: Enhanced Detection of Neovasculature
and Fibrous Tissue by MRI
Computer 8
Alkystis
Phinikaridou1, Kevin J. Hallock1, Ye Qiao1,
James A. Hamilton1
1Boston
University, Boston, Massachusetts, USA
We
used the Constantinides New Zealand White rabbit model to study atherosclerosis
and controlled plaque rupture associated with thrombosis. We combined contrast
enhanced (Gd-DTPA) in vivo (3T) and magnetization transfer (MT) ex vivo (11.7T)
MRI coupled to histology to identify features associated with vulnerable
plaques. In vivo, Gd-DTPA uptake was associated with plaque regions rich in
neovasculature as well as fibrous tissue. Ex vivo MT identified the location of
fibrous cap rupture and fibrosis seen within organized thrombi. Further studies
about the kinetics of Gd-DTPA within plaques together with the in vivo
application of MT will provide insights about plaque vulnerability.
14:30
2854.
Enhancement of the Atherosclerotic Plaque and the Vessel Wall of the
Carotid Artery After Injection of a Blood-Pool Contrast Agent
[Not Available]
Computer 8
Sietske
Rozie1, Piotr A. Wielopolski1, Mohamed Ouhlous1,
Wiro Niessen, Theo van Walsum, Aad van der Lugt1
1Erasmus
Medical Center, Rotterdam, Netherlands
Purpose:
We hypothesized that a blood-pool agent enhances the outer wall of the carotid
artery and specific parts of the atherosclerotic carotid plaque
Methods:
We studied 26 atherosclerotic plaques of 15 consecutive patients with severe
carotid stenosis. On a 3.0T scanner a 3DT1-weighted scan was performed before
injection and 20 minutes after injection.
Results:
The mean enhancement on the 20 minute delay scan was 40.9% ± 32.5% in the
non-calcified part of the plaque and 60.0% ± 21.7% in the vessel wall of the
symptomatic carotid arteries.
Conclusions:
Images obtained before and after contrast injection with Vasovist® may improve
atherosclerotic plaque characterisation and quantification.
15:00
2855.
In Vivo and ex Vivo plaque
Characterisation in the Aortic Arch of ApoE -/- Mice with High-Resolution
Multi-Parametric Magnetic Resonance Imaging at 17.6 Tesla
Computer 8
Gert
Klug1, Volker Herold1, Marco Parczyk1,
Elisabeth Bauer1, Thomas Schulze-Till1, Eberhard Rommel1,
Peter Jakob1, Wolfgang Bauer1
1University
of Wuerzburg, Wuerzburg, Germany
High-Resolution
plaque imaging in atherosclerotic apoE knock-out (-/-) mice has been recently
shown to correlate closely with histology. However these results are limited to
the aortic-root. We intended to further enhance the ability of high-field
magnetic resonance (MR) to characterize plaque formation in murine models of
atherosclerosis at microscopic levels. Our results demonstrate that high
resolution multi-parametric plaque imaging at 17.6 Tesla is feasible with good
correlation to HE histology but further studies are necessary to distinguish
plaque components compared to a more comprehensive histology protocol.
15:30
2856.
Molecular Imaging of Atherosclerosis Using Paramagnetic Cy5.5-Labeled
PEG-Micelles
Computer 8
Sjoerd
Hak1, Geralda A.F. van Tilborg1, Esad Vucice2,
Gustav J. Strijkers1, Klaas Nicolay1, Zahi A. Fayad2,
Willem Jan Menno Mulder2
1Eindhoven
University of Technology, Eindhoven, Netherlands; 2Mount Sinai
School of Medicine, New York, New York, USA
In
this study a new contrast agent for molecular imaging of atherosclerosis was
used, paramagnetic Cy5.5-labeled PEG-micelles. The targeting ligand used was
the RGD-peptide. In vivo MRI and ex vivo fluorescence techniques demonstrated
active uptake of RGD-PEG-micelles into atherosclerotic plaque in apoE-knockout
mice. The near infrared Cy5.5 fluorophore proofed to be very valuable for ex
vivo fluorescence imaging as there is less autofluorescence and better
penetration at higher wavelengths. The non-specific uptake of bare PEG-micelles
in mouse plaques was very limited. This makes this contrast agent very
attractive for molecular imaging of atherosclerosis, also when directed to
other targets.
Hall D Tuesday 13:30-15:30
13:30
2857.
Real-Time Cardiovascular Imaging Using a Combination of HYPR,
McKinnon-Bates, and COM Gating Algorithms
Computer 1
Lauren
A. Keith1, Dana C. Peters, Julia V. Velikina1
1University
of Wisconsin - Madison, Madison, Wisconsin, USA
We
use a combination of the HYPR and McKinnon-Bates algorithms along with center
of mass self-gating in order to improve spatial resolution, signal-to-noise
ratio and reduce artifact levels in real-time cardiovascular imaging.
Computer 1
Yu
Ding1, Yiu-Cho Chung2, Subha V. Raman3,
Orlando P. Simonetti3
1The
Ohio State University, Columbus, Ohio, USA; 2Siemens Medical
Solutions, Inc., Columbus, Ohio, USA; 3The Ohio State University,
Columbus, Ohio, USA
We
describe the characteristics and performance of a new temporal filter based on
the optimal linear transform, the Karhunen-Loeve Transform. The filter is
designed to suppress noise in dynamic cardiac MR images without compromising
the sharpness of stationary or moving edges or other structures. We derive a
simple mathematical formula for the noise reduction effect of this filter, and
then verify it in real-time cardiac cine MRI with TSENSE acceleration factor 4
in normal volunteers. A SNR gain of 144%
was achieved after filtering without edge blurring or other artifacts.
14:30
2859.
Dyadic Wavelet-Based Image Noise Suppression and Enhancement in
High-Speed Cardiac MR Parallel Acquisition
Computer 1
Qi
Duan1, Jian Chen1, Andrew Francis Laine1,
Vinay M. Pai2
1Columbia
University, New York, New York, USA; 2SUNY Upstate Medical
University, Syracuse, New York, USA
An
automated integrated denoising/enhancing approach was applied to images
acquired by parallel acquisition techniques in cardiac imaging. In comparison
with previous denoising only framework, this new proposed method could future
increase the CNR of the denoised images. Quantitative evaluation on phantom and
clinical data confirmed the benefit of this new method in terms of improving
CNR on parallel MR images. Preliminary results suggested that this new
integrated denoising/enhancing framework could further push the limits on the
temporal resolution by improving the SNR and CNR simultaneously.
15:00
2860.
3D Right Ventricular Strain and Geometry in Pulmonary Hypertension and
Normals
Computer 1
Bharath
Ambale1, Steven Lloyd2, Thomas Stewart Denney Jr.1,
Louis Dell'Italia2, Raymond Benza2, Himanshu Gupta2
1Auburn
University, Auburn, Alabama, USA; 2University of Alabama at Birmingham,
Birmingham, Alabama, USA
Accurate
assessment of right ventricular (RV) function is clinically important –
particularly in pulmonary hypertension (PHTN).
Compared to the left ventricle (LV), however, analysis of RV function is
relatively difficult. Unlike the LV, the
RV does not have geometric symmetry, precluding use of simple geometric models
to calculate RV volumes and wall stress.
Also, in PHTN, higher systolic blood pressure in the RV can cause
excursion of the interventricular septum into the LV cavity. As a result, the LV cavity can also lose its
geometric symmetry. This abstract
presents methods for reconstructing three-dimensional biventricular geometry
and strain in both normal volunteers and PTN patients.
Computer 2
Khaled
Zakarya Abd-Elmoniem1, Matthias Stuber1, Amr A. Youssef1,
Tetsuo Sasano1, Theodore P. Abraham1, Xiaofeng Lui1,
Sandeep Mullur1, Evert-Jan P. A. Vonken1, M. Roselle
Abraham1, Jerry L. Prince1
1The
Johns Hopkins University, Baltimore, Maryland, USA
We
present afast algorithm for direct and complete characterization of 3-D
time-course of principle strain orientations using data acquired with zHARP
imaging protocol from SA slices without the need for LA data. Using this
scheme, two or more SA slices are acquired and processed using zHARP and the
3-D strain tensor and principal strain angles are calculated. Results from infarct swine model shows that
strain orientations time-course can provide more information about heart
dynamics, especially when combined with efficient 3-D motion imaging.
Computer 2
Wei
Li1, Jia Zhong2, Xin Yu2
1Case
Western Reserve University, Cleveland , Ohio, USA; 2Case Western
Reserve University, Cleveland, Ohio, USA
Current
MRI tagging analysis often employs the first tagging image as the reference
frame. However, for a mouse heart, the first tagging image is frequently
acquired at early systole with significant tag line deformation due to fast
heart rate. In this study, a HARP-based method was develop to generate an
undeformed tagging grids. Myocardial deformation at early systole was analyzed
using this method.
14:30
2863.
Noise Measurement in Real-Time Cardiac Cine MRI Using Eigenvalues of
Karhunen-Loeve Transform
Computer 2
Yu
Ding1, Yiu-Cho Chung2, Subha V. Raman3, Orlando
P. Simonetti3
1The
Ohio State University, Columbus, Ohio, USA; 2Siemens Medical
Solutions, Inc., Columbus, Ohio, USA; 3The Ohio State University,
Columbus, Ohio, USA
Noise
measurement is difficult in real-time cine MRI using parallel acquisition
techniques because of cardiac and respiratory motion and the spatially variant
nature of both signal and noise. In this
work, we investigate using eigenvalues derived from the Karhunen-Loeve
Transform to assess mean noise standard deviation in dynamic MR cardiac images.
This method may have general application in the evaluation of dynamic imaging
methods, and other situations other methods of noise measurement are difficult
to apply.
15:00
2864.
DENSE-MR-Elastography for Cardiac Application
Computer 2
Benjamin
Robert1, Ralph Sinkus1, Jean-Luc Gennisson1,
Mathias Fink1
1Laboratoire
Ondes et Acoustique, Paris, France
Imaging
of mechanical shear waves via MR-Elastography (MRE) allows the assessment of
inherent viscoelastic tissue parameters. Cardiac MRE poses several technical
challenges: small relaxation times, time dependant viscoelastic properties
during the heart beat, respiratory motion. To overcome the short relaxation
time and the externally induced mechanical wave problems, a MRE sequence has
been adapted from a DENSE sequence.
Hall D Tuesday 13:30-15:30
Computer 3
Darren
Lum1, Reed Busse2, Christopher Francois1, Anja
Brau3, Philip Beatty3, Joshua Huff1, Jean
Brittain2, Scott Reeder1
1University
of Wisconsin - Madison, Madison, Wisconsin, USA; 2GE Healthcare,
Madison, Wisconsin, USA; 3GE Healthcare, Menlo Park, California ,
USA
We
utilize a 2D parallel imaging method (Autocalibrating Reconstruction for
Cartesian sampling - ARC) with 3D contrast enhanced MRA for complete abdominal
coverage within a breath hold. An
intra-individual comparison study between both parallel imaging accelerated and
non-accelerated exams was performed in 6 healthy volunteers. In addition 8 consecutive patients were
evaluated with 2D-ARC MRA. We find that
the subjective image quality of exams with 2D-ARC to be essentially equivalent
to those acquired without parallel imaging.
However, the 2D-ARC sequence provided a 3.5 fold increase in imaging
volume and a 30% reduction in voxel size in the same acquisition time.
Computer 3
Harald
Kramer1, Konstantin Nikolaou1, Henrik J. Michaely2,
Christian Glaser1, Maximilian F. Reiser1
1University
Hospitals Munich - Grosshadern Campus, Munich, Germany; 2University
Hospital Mannheim, Mannheim, Germany
Atherosclerosis
is a systemic vessel disease. MRI offers the possibility of whole body MRA with
excellent image quality and without ionizing radiation. First attempts to WB
MRA suffered from MR system Hardware restrictions, recent developments in MR
Hard- and Software like parallel imaging, dedicated coil systems and higher
field strength helped to increase image quality of WB MRA exams significantly.
Computer 3
Xiaohai
Ma1,2, Zhaoqi Zhang1, Yi He1,
Zhanming Fan1
1Beijing
Anzhen Hospital, Beijing, People's Republic of China; 2Michigan
State University, East Lansing, USA
Compared
to conventional CE-MRA, EZ-STEP is a timesaving method for thoracic aorta
imaging in 3T MR scanner, and also provides comparable image quality.
15:00
2868.
Calculating Peripheral MRA Bolus Timing Using Cine-Phase Contrast Flow
Measurements
Computer 3
Grace
Choi1, Ryan Brown1, Minh Chao1, Yi Wang1,
Martin R. Prince1
1Cornell
University - Weill Cornell Medical College, New York, USA
Total
Gadolinium dose can be reduced on whole body and peripheral MRA by using 2D
cine phase contrast MRA to calculate bolus velocity at 7 locations along the
arterial tree. Accuracy of this approach
was confirmed by comparison to bolus transit measurements from 1.8s temporal
resolution time-resolved MRA. Example
cases show diagnostic peripheral MRA with single dose gadolinium based contrast
agent. These data also show a 2-fold reduction in bolus transit time with
venous compression applied to thighs.
Hall D Tuesday 13:30-15:30
Computer 4
Florian
M. Vogt1, Stefan Maderwald1, Knut Kroeger1,
Gerhard Laub2, Randall Kroeker3, Joerg Barkhausen1,
Harald H. Quick1
1University
Hospital, Essen, Germany; 2University of California Los Angeles, Los
Angeles, California , USA; 3Siemens Medical Solutions, USA
Purpose
was to develop a triple injection scan protocol for dynamic, high-resolution,
isotropic MRA of the entire peripheral vascular system applying a recently
developed time-resolved 3D MRA sequence (TWIST). Ten patients with PAD
underwent contrast-enhanced MRA collecting dynamic 3D data sets at three
consecutive stations. Catheter-based DSA served as standard of reference. For
corresponding segments, the number of visible segments was equal to DSA. TWIST
MRA provided identical functional information in regions with reduced arterial
blood flow or increased venous enhancement. TWIST-MRA is a robust technique
that combines functional with high spatial morphological information of the
entire peripheral vascular system.
14:00
2870.
Leg MR Angiography with Cuff-Compression: Quantitative Dynamic Analysis
Computer 4
Marcel
Koenigkam Santos1, Puneet Sharma1, Bobby Kalb1,
John Oshinski1, Diego Martin1
1Emory
University, Atlanta, USA
The
purpose of this study is to evaluate quantitatively the effect of mid-femoral
cuff compression on arterial inflow and venous outflow kinetics using high
temporal resolution 3D CE-MRA of the calves. The arterial in-flow time was
significantly reduced on the pressure cuff side in comparison to the control
side and, in 2 of 4 subjects, no increased signal (above background) was
observed in the veins with the pressure cuff after 300 seconds. Our findings
quantitatively evaluate the delay in venous filling and indirectly show that
this results from multi-factorial events that occur subsequent to
supravenous-subarterial blood pressure cuff inflation.
Computer 4
Clifton
R. Haider1, Houchun Harry Hu2, Nobert G. Campeau1,
John Huston1, Stephen J. Riederer1
1Mayo
Clinic, Rochester, Minnesota, USA; 2Univ. of Southern California,
California , USA
In
time-resolved acquisitions there is a need for both high temporal and spatial
resolution. The purpose of this work is to describe the incorporation of 2D
SENSE acceleration into a view-shared CArtesian Projection Reconstruction-like
(CAPR) acquisition, yielding a time-resolved sequence which has high SNR
robustness, a high level of consistency, and high temporal fidelity. The
sequence is capable of 1 mm3 isotropic resolution with sufficient temporal
resolution to distinguish intracranial arterial and venous phases of contrast
passage in whole-brain angiography.
15:00
2872.
Comprehensive Magnetic Resonance Imaging of Hands Vasculature at 3
Tesla: Preliminary Clinical Results
Computer 4
Ugur
Bozlar1,2, Patrick T. Norton1, Ahmed Mohamed
Housseini1,3, Thomas Huerta1, Hendricks E.
Daniel1, Bobby Chhabra1, David B. Drake1,
Peter B. Arnold1, Klaus D. Hagspiel1
1University
of Virginia Health System, Charlottesville, USA; 2Gulhane Military
Medical Academy, Ankara, Turkey; 3Suez Canal University, Ismailia ,
Egypt
Comprehensive
MR evaluation of the vasculature of the hand employing high resolution time
resolved contrast enhance MRA (tr-ceMRA) and volume interpolated breath-hold
examination (VIBE) was performed in patients with clinical symptoms
attributable to vascular etiologies. This combine complimentary approach
requires a single 20ml administration of contrast agent and utilizes the power
of arterial-venous separation provided by the tr-ceMRA and high contrast to
noise ratio of the VIBE sequence to allow for assessment of both proximal and
distal arterial vessels of the hand. To the best of our knowledge, there is no
published study which evaluates the hand vasculature at 3T in such a
population.
Computer 5
Robert
C. Gilkeson1,2, Martin Blaimer3, Randall
Kroeker4, Gerhard Laub4, Jeffrey L. Duerk1,2,
Jeffrey L. Sunshine1,2, Robert O. Schilz2,
Mark A. Griswold1,2
1Case
Western Reserve University, Cleveland, Ohio, USA; 2University
Hopitals of Cleveland, Cleveland, Ohio, USA; 3University of
Wuerzburg, Wuerzburg, Germany; 4Siemens Medical Solutions, Germany
Computer 5
Alex
Frydrychowicz1, Maximilian F. Russe1, Aurélien F. Stalder1,
Alexander Berger1, Andreas Harloff1, Raoul Arnold1,
Mathias Langer1, Jürgen Hennig1, Michael Markl1
1University
Hospital Freiburg, Freiburg, Germany
Gadofosveset
trisodium has reached approval for diagnostic purposes in Europe as the first
gadolinium-based blood-pool contrast agent. Its imaging characteristics have
not been fully evaluated with respect to imaging at 3T and during time-resolved
3D MR-angiography. Therefore, it was the purpose of this study to compare the
first-pass imaging characteristics of a blood-pool contrast agent (BPA) to a
low albumin-binding standard contrast agent (SCA) in time-resolved
contrast-enhanced 3-dimensional MR angiography (tr-CE-MRA) at 3T. Results show
that first-pass imaging characteristics of the blood-pool agent are equally
well suited for tr-CE-MRA at 3T.
Computer 5
Jiang
Du1, Nick Pinto1, Michael S. Middleton1,
Claude Sirlin1, Graeme M. Bydder1
1University
of California, San Diego, San Diego, California , USA
Contrast-enhanced
three-dimensional (3D) magnetic resonance angiography (CE-MRA) is a useful
noninvasive method for evaluating the vascular system. Time-resolved imaging is
of great importance in providing contrast dynamics and eliminating contrast timing.
Here we present a novel technique called time-resolved interleaved projection
sampling along the 3D Cartesian phase and slice encodings (TRIPPS), which is
robust and provides high spatial and temporal resolution 3D images with minimal
undersampling artifact.
Computer 5
Ting
Song1, Pippa Storey2, Qun Chen2, Henry Rusinek2,
Ruth Lim2, Andrew F. Laine1, Vivian S. Lee2
1Columbia
University, New York, New York, USA; 2NYU School of Medicine, New
York, New York, USA
We
have analyzed k-space sampling strategies for time-resolved MRA by studying the
effects of varying (a) the center area of k-space assumed to be fully sampled
and (b) the sampling density of k-space periphery. Outcome measures consist of
vessel ringing artifacts and diameter measurement accuracy. Overall, we
observed that for smaller vessels, higher sampling density of k-space periphery
is more important than the size of the fully sampled center area, while for
larger vessels, larger center areas gave better accuracy of diameter resolving
ability.
13:30
2877.
Controlled Experimental Study Depicting Moving Objects in View-Shared
Time-Resolved 3D MRA
Computer 6
Petrice
Marie Mostardi1, Clifton R. Haider1, Phil J. Rossman1,
Stephen J. Riederer1
1Mayo
Clinic, Rochester, Minnesota, USA
The
purpose of this work was to develop and use a computer-controlled motion
phantom for study of the fidelity with which 3D time-resolved sequences with
view-sharing can portray dynamic phenomena.
This allowed determination not only of such properties as ghosting,
blurring, and undesired vascular enhancement, but also the fidelity of
portraying a rapid influx of contrast into a vessel as well as the smooth
passage of contrast across an extended field of view. These studies helped to identify desirable
characteristics of a pulse sequence used for time-resolved studies.
14:00
2878.
Three-Dimensional Time-Resolved Flow Quantification with Balanced SSFP
Computer 6
Francesco
Santini1, Stephan G. Wetzel2, Klaus Scheffler1
1University
of Basel/University Hospital, Basel, Switzerland; 2Basel University
Hospital, Basel, Switzerland
Balanced
SSFP sequences do not suffer from spin saturation effects that result in signal
loss for tissues with long T1. Their contrast is therefore optimal for the
imaging of fluids (blood and CSF) and flow quantification, especially when
inflow enhancement effects cannot be exploited, as in three-dimensional
sequences. In this work, a three-dimensional, three-directional time-resolved
phase contrast bSSFP sequence is presented, along with methods to minimize the
artifacts commonly associated with bSSFP sequences, and the application to the
study of cerebro-spinal fluid circulation is demonstrated.
14:30
2879.
Femoral Artery Compression in the Adductor Canal During Isometric Thigh
Contraction Using a Rapid 3D Steady-State Free Precession Acquisition
Computer 6
Ryan
Brown1,2, Thanh Nguyen1, Martin R. Prince1,
Yi Wang1,2
1Weill
Medical College of Cornell University, New York, USA; 2Weill
Graduate School of Medical Sciences of Cornell University, New York, USA
A
rapid 3D steady-state free precession (SSFP) sequence was implemented to image
the femoral artery. A long section (15-20 cm) of artery was imaged during
isometric thigh contraction to analyze artery compression. Sufficient
resolution and contrast to visualize the artery lumen were achieved in a short
scan time (approximately 22 sec), which was required for minimal motion artifacts
during thigh contraction. Significant artery compression was observed in the
adductor canal region, while the artery was less disturbed inferior and
superior to the adductor canal.
Computer 6
Andrea
Seba Les1, Carlos Alberto Figueroa1, Mary Therese Draney
Blomme1, Maureen M. Tedesco1, Jinha M. Park1,
Adrianne Thompson1, Ronald L. Dalman1, Robert J. Herfkens1,
Charles A. Taylor1
1Stanford
University, Stanford, California , USA
We
hypothesize that exercise may slow the growth of abdominal aortic aneurysms
(AAAs). A gadolinium-enhanced magnetic resonance angiography sequence (MRA) was
used to image the aortas of three males with small AAAs using a 1.5T scanner.
Infrarenal and supraceliac aortic blood velocities were also measured using a
cardiac-gated phase contrast (PC-MRI) sequence. Blood flow was simulated by
solving the Navier-Stokes equations on finite-element meshes generated from the
MRA and using rest and exercise boundary conditions specified from the PC-MRI
data. Mean wall shear stress was calculated at four locations. Infrarenal
volumetric flow waveforms obtained from simulation and PC-MRI were compared.
Hall D Tuesday 13:30-15:30
13:30
2881.
Multiple-Mouse Self-Gated Cardiac Cine MRI with Multiple Arrays of
Receive Coils (MARCs)
Computer 7
Emilio
Esparza-Coss1, Marc Stephen Ramirez1, James Andrew
Bankson1
1The
University of Texas M. D. Anderson Cancer Center, Houston, Texas, USA
Simultaneous
multiple-animal, self-gated cardiac cine MRI has been shown to drastically
improve the imaging efficiency in small animal models of cardiac disease. Here
we propose that further improvements can be achieved by dedicating a
phased-array coil to each animal to increased SNR and achieve parallel imaging
acceleration. Self-gated cardiac cine data was acquired with a four-channel
spoiled gradient echo pulse sequence developed to acquire navigator information
before application of readout gradients.
Preliminary results indicate that accelerated self-gated cardiac cine
MRI using phased-array coils is both feasible and desirable since SNR enhancement
can be achieved by averaging oversampled data.
Computer 7
Marcus
Carlsson1, Alastair J. Martin1, Mark Wilson1,
Loi Do1, David Saloner1, Maythem Saeed1
1University
of California San Francisco, San Francisco, California , USA
Microembolization
causes microinfarction in patients with unstable angina pectoris and following
PCI and CABG. It thought to explain part of decreased ejection fraction in
patients. In this study, microembolization was simulated by selective injection
of embolic agents in LAD. Cine and tagging MR imaging was used to assess the
acute and subacute effects of microembolization on LV volumes, ejection
fraction, systolic wall thickening and strain. Cine MRI showed persistent
decline in wall thickening and strain associated with increased LV volumes and
decreased EF; markers of LV remodeling. Thus, microembolization could be the
cause of LV dysfunction in patients.
14:30
2883.
Self-Gated MR Cardiac Imaging of Developing Chick Embryos in the Egg
Computer 7
William
Matthew Holmes1, Christopher McCabe1, Barrie Condon1,
Jim M. Mullin1, Maureen M. Bain1
1University
of Glasgow, Glasgow, UK
The
chick embryo is a well-known animal model for cardiovascular research. The lack of MRI application to chick embryos
is partly due to the difficultly of monitoring chick ECG and respiration
signals, which are conventionally essential in acquiring images free of motion
artefact. In this study we remove these obstacles by employing a self-gated
multi-slice CINE MRI protocol that incorporates a navigator-based retrospective
gating technique, making possible for the first time cardiac MRI images of a
chick embryo inside the egg.
15:00
2884.
Retrospective Gating Strategies for Small Animal MR Imaging at 9.4 Tesla
Computer 7
S
David Smith1,2, Shams Rashid3, Mark Wagshul3,
Mei Yu1, Helene Benveniste1,3
1Brookhaven
National Laboratory, Upton, New York, USA; 2SA Instruments, Inc,
Stony Brook, New York, USA; 3SUNY at Stony Brook, Stony Brook, New
York, USA
A
Data acquistion system with application software has been developed allowing
the retrospective reodering of acquired MR data prior to reconstruction, and is
used for the Cardiac Imaging of mice on a 9.4 T Bruker MRI system. Waveforms for respiratory, Electrocardiogram,
Blood pressure and Peripheral pulse measurements were acquired simultaneously
to the MRI acquisiton, thereby allowing the same MRI dataset to be reconstructed
using reodering schemes based upon each of the different physiological
waveforms. Quantitative evaluation of
the cine images made using each of the monitoring waveforms is presented.
Advanced strategies refining the reordering using data from multiple waveforms
is also presented.
Computer 8
Wei
Li1,2, Wei Liu3, Allen Ye4,
Priyanajana Chaudhuri4, Suhanti Banerjee4, Xin Yu,24
1Case
Western Reserve University, Cleveland , Ohio, USA; 2Cleveland, Ohio,
USA; 3Philips Research North America, Bariarcliff Manor, New York,
USA; 4Case Western Reserve University, Cleveland, Ohio, USA
Dystrophin-glycoprotein
complex (DGC) maintains the structural integrity of myocardium. It also plays
important signaling roles through nNOS. α-Dystrobrevin
deficiency leads to nNOS displacement from DGC, leading to the development of
cardiac lesions at an older age. In the current study, the impact of impaired
DGC signaling and the development of cardiac lesions on in vivo ventricular
function was examined with MRI tagging in α-dystrobrevin knockout mice.
Potential mechanisms responsible for altered ventricular function were explored
by histological and cellular studies.
14:00
2886.
Functional Cardiac Phenotyping of Vasoactive Intestinal Peptide (VIP)
Deficient Mice by MR Microscopy
Computer 8
S.
David Smith1, Anthony Szema2, Sami I. Said2,
Helene Benveniste1,2
1Brookhaven
National Laboratory, Upton, New York, USA; 2Stony Brook University,
Stony Brook, New York, USA
Mice
with deletion of the gene for VIP exhibit spontaneous pulmonary arterial
hypertension (PAH) and vessel remodeling in the absence of hypoxemia with
pathology showing thickened pulmonary vessels. We hypothesized that VIP
deficient mice with known spontaneous PAH would also develop a decreased
functional capacity of their right ventricle. We tested this hypothesis using
MR microscopy. Quantitative analysis of cardiac MR microscopy images of VIP
deficient mice revealed dilated right ventricles and reduced ejection
fractions.
14:30
2887.
Effect of Iron Oxides on Tag MRI at 1.5T in a Rat Myocardial Infarct
Model
Computer 8
Jean-Luc
Daire1, Jean-Noel Hyacinthe1, Karin Montet-Abou1,
Jean-Pascal Jacob1, Denis Morel1, Jean-Paul Vallée1,
Xavier Montet1
1Geneva
University Hospital, Geneva, Switzerland
This
paper proves that despite high accumulation of iron oxides in myocardium
infarct, Tag MRI at 1.5T can be realized and analysed in small rodent. The
observed defect of contraction in circumferential strains corresponds to the
hypointense region containing iron oxides.
Computer 8
Robert
L. Janiczek1, Brett R. Blackman1, R. Jack Roy1,
Scott T. Acton1, Craig H. Meyer1, Frederick H. Epstein1
1University
of Virginia, Charlottesville, Virginia , USA
Conventional
rectilinear k-space trajectories can result in displacement artifacts due to
movement of spins between excitation and data acquisition, and signal loss due
to phase dispersion. Spiral trajectories have long been used for human MRI due
to their desirable flow characteristics caused by their short echo-times and
low gradient moments. However, these methods have yet to be applied to imaging
small animals on high-field small-bore MRI systems. We present phase-contrast
data at 7T in the mouse aorta and demonstrates these advantages allow PC data
to be obtained in more regions of the mouse vasculature than a rectilinear
trajectory.
13:30
2889.
Effect of SEA0400 on Cardiac Mn2+ Efflux Rates, Using T1-Mapping
Manganese-Enhanced MRI (MEMRI) in a Murine Model
Computer 9
Ben
Waghorn1,2, Yuhui Yang2, Brianna Klein2,
Akemichi Baba3, Toshio Matsuda3, Nathan Yanasak2,
Tom Hu2
1Georgia
Institute of Technology, Augusta, Georgia, USA; 2Medical College of
Georgia, Augusta, Georgia, USA; 3Osaka University, Osaka, Japan
The
Na+/Ca2+ exchanger (NCX) is an important transporter for
the regulation of intracellular Ca2+ concentration. This study uses T1-mapping of
murine cardiac Manganese-Enhanced MRI to quantitatively assess the rate of
signal decay post Mn2+ infusion. A 50% attenuation of the signal in
the left ventricular free wall, normally enhanced by Mn2+, is
observed within approximately 2.5 hours post infusion. By inhibiting the NCX with
SEA0400, we can proceed to characterize a trend of Mn2+ efflux
modulation. Future work to study the actions of the NCX in detail will be
undertaken using various pharmaceutical agents.
Hall D Wednesday 13:30-15:30
Computer 1
Kotaro
Shimada1, Hiroyoshi Isoda2, Tomohisa Okada2,
Yoji Maetani2, Shigeki Arizono2, Yuusuke Hirokawa2,
Toshikazu Kamae2, Kaori Togashi2
1Kyoto
University Graduate School of Medicine , Kyoto, Japan; 2Kyoto
University Graduate School of Medicine, Kyoto, Japan
Our
purpose is to delineate the hepatic arteries selectively by using
respiratory-triggered three-dimensional true steady-state free-precession with
time spatial labeling inversion pulse (T-SLIP). T-SLIP is a kind of arterial
spin labeling which can provide quantitative and selective inflow information
by placing the inversion pulse at any place independent of the imaging area
before data acquisition and suppress background signal. 21 healthy volunteers
were examined. As a result, selective and high contrast visualization of the
hepatic arteries was acquired in 20 cases without exogenous contrast agent. We
report our initial experience and describe the optimization of this protocol.
Computer 1
Darren
Lum1, Christopher Francois1, Kevin Johnson1,
Scott Reeder1, Oliver Wieben1, Thomas Grist1
1University
of Wisconsin - Madison, Madison, Wisconsin, USA
In
this study, we present our initial clinical experience with
respiratory-triggered, non-contrast enhanced PC-VIPR MRA of the abdominal
vessels at 3.0T. We demonstrate
comparable image quality between PC-VIPR and 3D contrast enhanced MRA. Furthermore, PC-VIPR provides improved
conspicuity of the segmental renal arteries due to the subtraction of
stationary background tissues. Finally,
we find good agreement between the two techniques for measurements of vessel
diameter. In patients who cannot receive
contrast secondary to the risk of nephrogenic systemic fibrosis, PC-VIPR may
serve as an alternative to abdominal 3D contrast enhanced MRA. Further
validation and optimization of this technique is ongoing.
14:30
2892.
ECG Triggered Acquisition Non-Contrast Enhanced (TRANCE) MRA at 3.0Tesla
in Peripheral MRA
Computer 1
Takeshi
Ishimoto1, Takayuki Ikeda1, Naomi Yamamoto1,
momoe Kawakami1, Masaru Ishihara2, Eiji Okamoto3,
Tomoyuki Okuaki4
1Hyogo
Brain and Heart Center, Himeji, Japan; 2Hyogo Prefectural Kakogawa
Hospital, Kakogawa, Japan; 3Philips Electronics Japan, LTD., Osaka,
Japan; 4Philips Electronics Japan, LTD., Minato-ku, Japan
Recently,
non-contrast enhanced MRA techniques were clinically useful and widely use in
routine examination, rapidly gaining in clinical importance. The purpose of
this study was to evaluation the technical feasibility and clinical utility of
ECG triggered acquisition Non-Contrast Enhanced (TRANCE) MRA at 3.0Tesla in
patients with peripheral vascular disease. In peripheral MRA, TRANCE MRA at
3.0Tesla provided diagnostic images comparable with those of CTA and DSA
without the administration of contrast agent. This technique will be
noninvasive standard examination in the diagnosis of peripheral vascular
disease as well as 1.5Tesla.
15:00
2893.
Visualization of the Lenticulostriate Artery with Flow-Sensitive
Black-Blood Imaging in Comparison with Time-Of-Flight MR Angiography
Computer 1
K.
Gotoh1, T. Okada1, Y. Miki1, M. Ikedo2,
A. Ninomiya2, T. Kamae1, K. Togashi1
1Kyoto
University Graduate School of Medicine, Kyoto, Japan; 2Toshiba
Medical Systems, Ohtawara, Japan
We
visualized lenticulostriate arteries (LSAs) by using Flow-sensitive Black Blood
(FSBB) method, which is a variant of 3D-FE (field echo) and make it possible to
attenuate the signal of arteries by applying very weak motion probing gradients
to disturb refocusing of moving spins only. We compared FSBB with TOF on
visualzed LSAs of 19 volunteers and had good results.
13:30
2894.
Non-Contrast-Enhanced MR Portography Using 3D Inversion Recovery-In Flow
Iterative Spatial Saturation Pulses (IR-IFIS) Steady-State Free Precession
(FIESTA)
Computer 2
Motoyuki
Katayama1, Takayuki Masui1, Kimihiko Sato1,
Hidekazu Seo1, Megumi Ishii1, Masayoshi Sugimura1,
Kazuhiko Ito1, Mitsuharu Miyoshi2, Naoyuki Takei2,
Tetsuji Tsukamoto2
1Seirei
Hamamatsu General Hospital, Hamamatsu, Japan; 2GE Yokogawa Medical
Systems. Ltd, Hino, Japan
We
optimized the parameters of IFIS FIESTA technique in normal volunteer, and
applied this technique to the MR examinations in patients with hepatobiliary
disorder. The non-contrast-enhanced 3D IR-IFIS FIESTA technique provides good
image quality MR portography. When gadolinium is not usable, this sequence
might be an alternative choice of method.
14:00
2895.
T1 Insensitive Background Saturation by Two Inversion Pulses for
Flow-Prep Non-Contrast-Agent MR Angiography
Computer 2
Mitsuharu
Miyoshi1, Naoyuki Takei1, Tetsuji Tsukamoto1
1GE
Yokogawa Medical Systems, Hino, Japan
Flow-Preparation-pulse
(Flow-Prep) is a preparation pulse that enhances flow signal and suppresses
stationary signal. This is used for Non-Contrast-Agent MRA in this study.
However, the stationary background signals remain because of T1 relaxation
between the Flow-Prep preparation and the data acquisition. Although T2-Prep
and Spectral IR can suppress the kidney and the fat signals, short-T1
intestinal contents remain high signal background. We developed Flow-Prep with
two IR pulses, which enabled T1 insensitive background suppression. Aorta and
renal artery signals were depicted in high contrast. Intestinal contents,
kidney and fat signals were suppressed homogeneously.
14:30
2896.
Using Phase Contrast MRA for the Diagnosis of Pelvic Congestion Syndrome
Computer 2
Luis
Andres Meneses1,2, Cristian Tejos1,3,
Mario Fava1, Marcelo Andia1,3, Moshe Pincu4,
Jorge Cifuentes4, Pablo Irarrazaval1,3
1Pontificia
Universidad Catolica de Chile, Santiago, Chile; 2Biomedical Imaging
Center, Santiago, Chile; 3Biomedical Imaging Center, Santiago,
Chile; 4Hospital Sotero del Rio, Santiago, Chile
In
Pelvic congestion syndrome (PCS) ovarian veins (OV) is characterized by
abnormal blood flow. We evaluated the accuracy of flow velocity (measured with
PC-MRA) as a diagnostic criterion. We studied 16 OV with PC-MRA and with direct
venography (DV) as a reference test. PC-MRA showed the same results as DV for
the 12 pathological veins. PC-MRA correctly identified 2 of the 4 normal veins.
We believe that in the 2 cases with discrepancy, PC-MRA could to detect an
early stage of the PCS which DV could
not to identify. PC-MRA provides useful diagnostic tools for the diagnosis of
PCS.
15:00
2897.
Non-Contrast MRA Using ECG-Triggered 3D Valuable Flip Angle Fast Spin
Echo for the Vessels of the Pelvis and Legs with Total Imaging Matrix Coil
Computer 2
Satoru
Kitano1, Shinji Hirohashi2, Nagaaki Marugami1,
Junko Takahama1, wataru higashiura1, Toshiaki Taoka1,
Kimihiko Kichikawa1
1Nara
Mediacl University, Kashihara, Japan; 2Osaka gyoumeikan Hospital,
Osaka, Japan
The
purpose of this study is to clearly 3D valuable flip angle TSE with Tim (Total
imaging matrix) array coil system can be applied to 3D non contrast body MRA. 5
patients underwent 3D non contrast body MRA in a three step table feed
technique. Pelvic, femoral and lower leg MRA were obtained ECG-triggered 3D
valuable flip angle TSE (space). 3D
non-contrast MRA with Tim coil system is a promising technique in the diagnosis
of the arterial vascular system of the vessels of the pelvis and legs.
13:30
2898.
Non-Contrast MRA with FIESTA Using IR-IFIS for Selective Visualization
the Renal Arteries
Computer 3
Takayuki
Masui1, Motoyuki Katayama1, Kimihiko Sato1,
Hidekazu Seo1, Kazuhiko Ito1, Hiroki Ikuma1,
Masayoshi Sugimura1, Naoyuki Takei2, Mitsuaharu Miyoshi2,
Tetsuji Tsukamoto2, Megumi Ishii1, Akihiko Kutsuna1
1Seirei
Hamamatsu General Hospital, Hamamatsu, Japan; 2GEYMS, Hino, Japan
Non-contrast
MRA for the aorta and renal arteries was obtained using respiratory-triggered
peripheral-gated 3D FIESTA with Inversion recovery-In Flow Iterative Spatial
Saturation pulse (IR-IFIS), based on tagging of the blood in the heart and
thoracic aorta, which is running through the abdominal aorta, with background
suppression by non-selective inversion pulse. The optimal parameters for normal
volunteers were evaluated and the abdominal aorta and renal arteries were
successfully visualized. In the patients with suspected renal tumors, contrast
MRA provide still better information of the aorta and renal arteries, non
contrast MRA has potentials to visualize the selected arteries of interest.
14:00
2899.
Non-Enhanced MR Angiography of the Uterine Vessels; Optimization of the
Sequence Parameters
Computer 3
Takashi
Koyama1, Tomohisa Okada2, Koji Fujimoto2,
Toshikazu Kamae2, Ayako Niyomiya3, Saori Satou3,
Nobuyasu Ichinose3, Kaori Togashi2
1Kyoto
University Hospital, Kyoto, Japan; 2Kyoto University, graduate
school of medicine, Kyoto, Japan; 3Toshiba Medical Systems, Tokyo,
Japan
The
purpose of this study is to evaluate the difference of depiction and contrast
of the uterine vessels in different inversion time in non-enhanced MRA
utilizing Time-SLIP. Nonenhanced Time-SLIP MRA was performed in eight healthy
volunteers combining separately with SSFP and FASE at different TI times. With
FASE, images the difference of contrast between arteries and veins dose not
significantly differ, although images with longer TI tend to show better
depiction of the uterine veins. With SSFP, TI of 1800ms provides best depiction
of the both arteries and veins, and best contrast between them.
14:30
2900.
Non-Contrast Time-Resolved 2D Fresh Blood Imaging (FBI)
Computer 3
Mitsue
Miyazaki1,2, Toshiro Fukuta2, Girish
Srinivasan1, Robert Anderson3, nobuyasu Ichinose2,
Shinichi Kitane4
1Toshiba
Medical Research Institute, Vernon Hills, USA; 2Toshiba Medical Systems
Corp., Otawara, Japan; 3Toshiba Medical Research Institute, Ohio,
USA; 4Toshiba Medical Engineering Co., Japan
With
the recent association of gadolinium contrast agent and nephrogenic systemic
fibrosis (NSF) disease, there is growing interest in using non-contrast MRA
techniques as alternatives for contrast enhanced (CE) MRA. As a result, there
have been many non-contrast MRA techniques reported. However, many of studies were limited to the
morphology of the vessel lumen. In this
study, a new non-contrast time-resolved MRA technique, using a keyhole
technique and parallel imaging, is proposed to shorten scan time. Furthermore,
assessment of the proposed technique was investigated to obtain the peripheral
arterial hemodynamic information.
15:00
2901.
Non-Contrast MRA of the Toes Using Time-Spatial Labeling Inversion Pulse
(Time-SLIP) and Optimization of Flow-Spoiled Gradient Pulses for the Assessment
of Foot Arteries in Flow-Spoiled Fresh Blood Imaging (FBI)
Computer 3
Jun
Isogai1, Mitsue Miyazaki2, Takeshi Shimada1,
Hideo Hatakeyama1, Takashi Yamada1, Naoto Matsuo1,
Shizuaki Maejima1, Kenji Yodo3, Tomoko Miyata3
1Hasuda
Hospital, Hasuda, Japan; 2Toshiba Medical Research Institute USA,
Illinois, USA; 3Toshiba Medical Systems Corporation, Japan
Visualization
of small arteries of the foot and toes is quite difficult in using conventional
non-contrast MR angiography (MRA) techniques, including time-of-flight (TOF)
and phase contrast MRA, due to tortuous vessels out of plane and slow velocity.
In addition, Gadolinium-enhanced MRA has also several problems on an injection
rate or the amount of contrast materials. Due to the recent concerns of
Gadolinium-related Nephrogenic Systemic Fibrosis (NSF), non-contrast MRA
solutions have gained interest. Non-contrast flow-spoiled fresh blood imaging
(FBI) and time-spatial labeling inversion pulse (time-SLIP) were investigated
for visualization of small arteries of the foot and toes.
13:30
2902.
FBI-Navi for Easy Determination of Diastolic and Systolic Triggering Phases
in Non-Contrast Fresh Blood Imaging (FBI)
Computer 4
Naoyuki
Furudate1, Mitsue Miyazaki,12
1Toshiba
Medical Systems, Otawara, Japan; 2Toshiba Medical Research Institute
USA, Vernon Hills, USA
Due
to the recent association of gadolinium contrast agent dose and nephrogenic
systemic fibrosis (NSF) disease, there have been increasing interests in MRA
examination using non-contrast MRA techniques as alternatives. Cardiac gated
FSE-based flow-spoiled fresh blood imaging (FS-FBI), allows separation of
arteries from veins in peripheral MRA. To find the suitable systolic and
diastolic delays, single-slice multiple phases (ECG-prep) images are acquired.
However, the determination of systolic and diastolic triggering delays can be
problematic. In this study, we propose a new software algorithm, (FBI-Navi), to
determine the diastolic and systolic trigger delays to reduce the operational
burden.
14:00
2903.
Optimization of Non-Contrast Renal MRA Using a TI-Prep Scan for
Time-Spatial Labeling Pulse (Time-SLIP) in 3D Balanced SSFP
Computer 4
Junji
Takahashi1, Yoshinori Tsuji1, Yusuke Hamada1,
Takashi Yoshida1, Sachiko Isono2, Ayako Ninomiya2,
Yoshimori Kassai3, Mitsue Miyazaki,34
1Toranomon
Hospital, Tokyo, Japan; 2Toshiba Medical Systems, Tokyo, Japan; 3Toshiba
Medical Systems Corp., Otawara, Japan; 4Toshiba Medical Research
Institute USA, Vernon Hills, USA
Non-contrast-enhanced
renal 3D MRA using time-spatial labeling inversion pulse (time-SLIP) is
presented to depict the renal arteries. The contrast between the renal arteries
and background signals was best visualized with a black blood inversion time
(BBTI) of around 1100 msec. However, the depiction of the smaller renal
branches depends on the flow speed in patients. We have applied a 2D BBTI
preparation scan, which provides a series of single shot images with different
BBTI times, prior to the 3D scan. Good correlation was obtained between the 2D
BBTI preparation scan and 3D scan in both volunteers and patients.
14:30
2904.
The Value of CINE Bright Blood Sequences in the Evaluation of
Cryptogenic Stroke
Computer 4
Larry
Allen Kramer1, Eduardo J. Matta2, Anuradha T. Rao2,
Durga K. Pai2, Khader M. Hasan2
1University
of Texas-Houston, Houston, USA; 2UT-Houston, Houston, USA
Magnetic
Resonance Venography (MRV) of the pelvic venous system is utilized to evaluate
for occult pelvic venous thrombosis in patients with crytogenic stroke. Echocardiographic evidence of a right to left
shunt and negative clinical exam or lower extremity venous doppler study
results in investigation of the pelvic venous system with MRV. Because of tortuosity of the pelvic venous
system and valves flow artifacts are common.
To improve specificity CINE bright blood sequences were utilized to
evaluate flow defects seen on the conventional 2D time-of-Flight gradient-echo
sequences. Our results show that CINE sequences readily distinguishes clot from
flow artifact.
15:00
2905.
Accelerated 3D Phase-Contrast MR Angiography Using Time-Interleaved
Autocalibration (TCAL)
Computer 4
Anja
C.S. Brau1, Wei Sun2, Philip J. Beatty1
1GE
Healthcare, Menlo Park, California , USA; 2GE Healthcare, Waukesha,
Wisconsin, USA
This
work demonstrates the feasibility of time-interleaved autocalibration (TCAL)
for improving the imaging efficiency of accelerated 3D PC MRA. By sharing the
calibration burden across velocity-encoding measurements, TCAL reduces the
calibration time penalty by 4x while retaining robustness to motion and
compatibility with PC reconstruction.
Computer 5
Jessica
L. Klaers1, Kevin M. Johnson1, Christopher Francois1,
Ethan K. Brodsky1, Youngkyoo Jung1, Oliver Wieben1,
Walter F. Block1
1University
of Wisconsin - Madison, Madison, USA
An
ultrashort TR dual-echo 3D radial Linear Combination SSFP (LCSSFP) sequence is
used in conjunction with a novel real-time adaptive expiratory respiratory
gating method for high resolution renal non-contrast enhanced MRA. This is especially applicable for use in
patients with renal insufficiency in the wake of the recent discovery of the
link between Nephrogenic Systemic Fibrosis (NSF) and Gd based contrast
agents. The promising initial results
give excellent depiction of the renal arteries, including branch vessels, not
typically seen in contrast enhanced exams.
14:00
2907.
Phase Contrast Stack of Stars Imaging
Computer 5
Steven
Kecskemeti1,2, Kevin M. Johnson1, Oliver
Wieben1, Charles Mistretta1,2
1University
of Wisconsin , Madison, Wisconsin, USA; 2University of Wisconsin -
Madison, Madison, Wisconsin, USA
A
hybrid radial-Cartesian “stack of stars”(SOS) phase contrast (PC)method has
been developed to overcome some of the limitations of conventional Cartesian
based PC acquisitions, such as long scan times and artifacts from cardiac
pulsatility and intravoxel dephasing.
The PC SOS method can be undersampled without aliasing artifact or a
loss of resolution as in the Cartesian method, thereby reducing scan times. In addition, the distributed nature and low
frequency over sampling of this sequence reduces cardiac pulsatility
artifacts. We present results comparing
the PC SOS images to those obtained with a clinical Cartesian PC sequence.
14:30
2908.
Non Contrast MRA of Renal Transplant Vasculature Using 3D TrueFISP
Computer 5
Natasha
Berg1, John Joseph Sheehan1, Xiaoming Bi2,
Peter J. Weale2, Randall Ramsay1, Renate Jerecic2,
James C. Carr1
1Northwestern
University, Chicago, Illinois, USA; 2Siemens Medical Solutions,
Chicago, Illinois, USA
Contrast
enhanced Magnetic Resonance Angiography (CEMRA) has previously been considered
a safe alternative to CTA or conventional angiography in the assessment of the
renal transplant patient. However, non contrast techniques may be more
desirable in this population due to renal impairment. We examined a novel non
contrast MRA (NCMRA) technique using a 3D True FISP sequence with selective
inversion pulse to assess the renal vasculature in post-transplant
patients. The NCMRA technique
demonstrated equivalent and superior imaging of post-transplant vasculature
compared to CEMRA. This technique may be
clinically advantageous for renal transplant patients who are unsuitable
candidates for contrast administration.
Computer 5
Peter
J. Weale1, Natasha Berg2, John Sheehan2,
Randall Ramsay2, James Carr2, Renate Jerecic1,
Xiaoming Bi1
1Siemens
Medical Solutions, Chicago, Illinois, USA; 2Northwestern University,
Chicago, Illinois, USA
A
qualitative and quantitative comparison in patients referred for MRA of a
non-contrast approach to abdominal angiography using a 3D IR prepared TrueFISP
sequence with a selective IR preparation with spatial localization independent
from the imaging volume.
Myocardial Function: Human Studies
Hall D Wednesday 13:30-15:30
13:30
2910.
Strain Encoding MRI (SENC) for the Quantification of Regional
Ventricular Function in Pulmonary Arterial Hypertension
Computer 6
Monda
L. Shehata1,2, Lynette Brown1, Dirk Lossnitzer3,
Jens Vogel-Claussen1, Joao A. C. Lima1, Reda E. Girgis1,
Paul M. Hassoun1, David A. Bluemke1, Nael F. Osman1
1Johns
Hopkins University, Baltimore, USA; 2Ain Shams University, Cairo,
Egypt; 3Universty of Heidelberg, Heidelberg, Germany
Right
ventricular function evaluation and monitoring are considered important
prognostic factors in many cardiac and/or pulmonary disorders especially
pulmonary arterial hypertension (PAH)which eventually leads to RV dysfunction
and failure. CMR is a versatile tool for global and regional ventricular
function evaluation. Tagging has been used for LV function quantification .
However, in RV, this technique is limited by thin wall. Strain encoding
(SENC)MR is a technique that applies tags parellel to the imaging plane with
narrow tag spacing yielding high spatial resolution images. Using 3T MRI, 5 PAH
patients were imaged using SENC to quatify regional longitudinal strain (ELL)
in RV and interventricular septum and we compared them to 6 healthy controls.
Reduced ELL was noted at anterior RV free wall and septum (p<0.05). SENC MR
can provide a rapid tool for RV function quantification and monitoring in PAH
patients.
14:00
2911.
Imaging Cardiac Motion and Flow Simultaneously During Exercise Stress
Studies Using SPAMM N' EGGS
Computer 6
Smita
Sampath1, John Andrew Derbyshire1, Maria J.
Ledesma-Carbayo, Elliot R. McVeigh1
1National
Institutes of Health, Bethesda, Maryland, USA
Detecting
myocardial mechanical dysfunctions and trans-valvular flow abnormalities during
the stress of exercise provides early diagnostic indicators in patients with
valvular diseases. Since these events
are transient in nature, the ability to acquire these measurements simultaneously
is important. In this study, we apply a
new MR imaging technique called SPAMM n’ EGGS (spatial modulation of
magnetization acquisitions with encoded gradients for gauging speed), that
combines tagging and phase-contrast imaging principles to provide simultaneous
measurements of longitudinal left ventricular compression and trans-mitral
chamber blood velocity during exercise stress studies in normal volunteers.
14:30
2912.
Evaluation of CSPAMM with Steady State Free Precession for Myocardial
Tagging at 3T
Computer 6
Jean-Noel
Hyacinthe1, Jean-Luc Daire, Joost P.A. Kuijer2, Magalie
Viallon1, Pierre-Frederic Keller1, Pierre Croisille3,
Jean-Paul Vallée1
1Geneva
University Hospital, Geneva, Switzerland; 2VU University Medical
Center, Amsterdam, Netherlands; 3Université Claude Bernard lyon 1,
Lyon, France
Imaging
at 3T, using CSPAMM and/or SSFP are efficient means to improve myocardial
tagging. In this study we evaluate the combination of all of them in 6
volunteers and 10 patients. CSPAMM with balanced SSFP at 3T combines gain of
absolute CNR from the field strength with improved relative tag contrast,
easing thus the post processing, and sensitivity to typical SSFP banding
artefacts is drastically reduced. Moreover, the technique shows no loss of
accuracy in strain measurements, and an accurate diagnosis was performed in
patients.
Computer 6
Mihaela
Jekic1,2, Yu Ding2, Eric Foster1,3,
Subha V. Raman1,2, Orlando P. Simonetti1,2
1The
Ohio State University, Columbus, USA; 2Dorothy M. Davis Heart and
Lung Research Institute, Columbus, USA; 3Dorothy M. Davis Heart and
Lung Research Institiute, Columbus, USA
Rapid
heart rates and heavy breathing associated with exercise stress testing demand
higher temporal resolution than is attainable by current methods. Our standard
exercise stress protocol utilizes a 12-channel coil and parallel acceleration
rate 4, resulting in temporal resolution of approximately 52 msec, but further
gain in temporal resolution is desired. We investigated the performance of
real-time cardiac imaging immediately after maximal treadmill exercise by the
combined application of a 32-channel cardiac array coil, TGRAPPA rate 5
acceleration, and KLT filtering, and quantitatively compared SNR to our
standard method. We successfully increased temporal resolution to 43.7 msec
without compromising spatial resolution or SNR.
13:30
2914.
Image Based Real-Time Monitoring of Cardiac Parameters for Stress
Testing or Interventions
Computer 7
Corinna
S. Maier1,2, Peter Kellman3, Michael Bock2,
Wolfhard Semmler2, Christine H. Lorenz4
1Siemens
Corporate Research, Princeton, New Jersey, USA; 2German Cancer
Research Center (dkfz), Heidelberg, Germany; 3National Institutes of
Health, Bethesda, Maryland, USA; 4Siemens Corporate Research,
Baltimor
The
proposed framework provides a method for real-time monitoring and detecting
changes for regional and global ejection fraction (EF) and heart rate (HR)
during a cardiovascular intervention or dobutamine stress test under MRI.
Basal, mid and apical MRI left ventricular (LV) short axis images are acquired.
End systolic and end diastolic volumes are estimated in each heart cycle based
on the results of an Expectation-Maximization segmentation algorithm. EF and HR
are calculated continuously, are corrected and smoothed and a change detection
algorithm is applied. Estimated EF and HR are compared to the offline
calculated EF and the recorded ECG, respectively.
14:00
2915.
Left Ventricular Internal Flow in Patients with Dyssynchronous Heart
Failure: Quantification by Cine MRI
Computer 7
Brandon
K. Fornwalt1,2, Patrick C. Gonzales1, Jana G.
Delfino1,2, Robert L. Eisner1,3,
Angel R. León1,3, John N. Oshinski1,2
1Emory
University, Atlanta, Georgia, USA; 2Emory/Georgia Institute of
Technology, Atlanta, Georgia, USA; 3The Carlyle Fraser Heart Center,
Atlanta, Georgia, USA
Better
methods to quantify left ventricular dyssynchrony are needed to identify
candidates for cardiac resynchronization therapy (CRT). Dyssynchrony creates
abnormal displacement of blood within
the left ventricle, and this “internal flow” may represent the most direct
measure of dyssynchrony. We hypothesized
that internal flow could be quantified from cine-MRI and would be increased in
patients undergoing CRT compared to controls. Systolic internal flow was 21±10%
in 10 patients and 2±2% in 10 controls (p<0.001). A threshold systolic
internal flow of 6% discriminated patients from controls with 100% accuracy.
MRI-based quantification of ventricular internal flow may be useful in
diagnosing dyssynchrony.
14:30
2916.
Saturation-Band Cine MRI Improves Detection of Intracardiac Shunt
Computer 7
Wiphada
Patricia Bandettini1, Andrew Ernest Arai1
1National
Institutes of Health, Bethesda, Maryland, USA
Saturation-bands
interleaved with gradient echo cine MRI provides “tagged” blood, but its use in
the assessment of congenital intracardiac shunt has been limited. The technique
is easily implemented and can be added to a standard congenital imaging
protocol. The purpose of this study was
to demonstrate the utility of adding a saturation pulse to gradient recalled
echo cine MRI to assist in the identification and anatomic delineation of intracardiac shunts.
15:00
2917.
Assessment of Left Ventricular Volume and Mass at 3.0T Using SSFP and
FLASH Cine Imaging
Computer 7
Neil
Woodhouse1, Dan Hagger1, Jim M. Wild1
1University
of Sheffield, Sheffield, UK
SSFP
is the accepted standard for cine imaging of cardiac function at 1.5 T. Recent
work at 3T suggests SSFP offers increased contrast to noise ratio (CNR) over
spoiled gradient echo methods (FLASH). Left ventricular (LV) measurements were
evaluated at 3.0T using SSFP and FLASH sequences in 6 healthy volunteers.
Significant differences in both mass and volume were demonstrated between both
imaging methods. FLASH systematically overestimated mass and underestimated
volume (p<0.05) when compared to SSFP although it was significantly lees
affected by magnetic susceptibility artefact. FLASH appears to be the more
robust sequence at 3.0T despite having a lower CNR.
Hall D Wednesday 13:30-15:30
Computer 8
Egbert
Gedat1, Rainer Kirsch2, Mojgan Mohajer1,
Bernhard Meyer1, Bernd Frericks1
1Charité
Universitätsmedizin Berlin, Berlin, Germany; 2Siemens Medical
Solutions, Erlangen, Germany
High
resolution CE MRAs of the lower limb were acquired in the steady state phase
after administration of bloodpool contrast agent gadofosveset trisodium. To
remove the veins and facilitate the assessment of the arteries they were
computationally combined with first pass image volumes by replacing central
k-space. 18 patients were examined yielding resulting MIPs of the lower limbs’
arteries of good quality for 8 patients. The veins were mostly removed and the
high resolution was preserved. For the other patients either the distribution
of the contrast agent was inappropriate or patient motion had occurred.
14:00
2919.
MR Phlebography with a Blood Pool Contrast Agent in Patients with
Peripheral Arterial Occlusive Disease
Computer 8
Guido
Matthias Kukuk1, Dariusch Reza Hadizadeh1, Markus
Moehlenbruch1, Kai Wilhelm1, Arne Koscielny1,
Frauke Verrel1, Hans Heinz Schild1, Winfried Albert
Willinek1
1University
of Bonn, Bonn, Germany
Contrast-enhanced
MR angiography is routinely used for evaluation of peripheral arterial
occlusive disease (PAOD). The introduction of the intravascular contrast agent
Gadofosveset Trisodium allows for longer acquisition times with high T1
relaxivity resulting in higher spatial resolution imaging of both arteries and
veins during the steady state phase. 139 patients were referred to MRA for
evaluation of PAOD at 1.5T. In 46/139 patients (33%) we incidentally found
clinically relevant venous diseases including deep vein thrombosis, varicosis
or arteriovenous fistula. In conclusion, the combination of MRA and MR
phlebography appears to be a promising clinical application for blood pool
contrast agents.
14:30
2920.
Gadofosveset-Enhanced Steady State MRA of the Peripheral Vessels with
Dixon Fat-Saturation
Computer 8
Henrik
Jakob Michaely1, Ulrike I. Attenberger2, Harald Kramer2,
Maximilian F. Reiser2, Stefan O. Schoenberg1
1University
Hosptial Mannheim, Mannheim, Germany; 2University of Munich, Munich,
Germany
In
this study the feasibility and image quality of a two-point Dixon MRA during
the steady state after the injection of gadofosveset was compared to a MRA with
conventional spectral fat-saturation. Using the Dixon technique a significantly
higher SNR and CNR were achieved due to a more homogenous fat-suppression than
with spectral fat-suppression.
15:00
2921.
Comparison of Renal MRA and Angiography Data in the CORAL Study
Computer 8
Honglei
Zhang1, Alan Matsumoto2, Timothy Murphy, Don Cutlip3,
Katie Wade3, Christopher J. Cooper4, Lance Dworkin5,
Martin R. Prince1
1Weill
Medical College of Cornell University, New York, New York, USA; 2Virginia
University, USA; 3Harvard Clinical Research Institute, USA; 4University
of Toledo College of Medicine, Toledo, Ohio, USA
Fifty-five
renal MRAs were reviewed by MRA core lab for randomization in to CORAL study,
of which 26 (47%) were diagnosed as having > 60% stenosis. For the 7 randomized to balloon angioplasty
and stent therapy, angiography confirmed that MRA correctly identified 8
lesions as hemodynamically significant with an accuracy of 100%. In 35 MRAs with local reports, MRA readings
by coral lab were consistent with the readings by local radiologist in 19
patients (54%). These included 15
positive studies and 4 negative studies.
In the remaining 16 patients, local radiologists overestimated the
severity of renal artery stenoses.
Hall D Thursday 13:30-15:30
Computer 1
Motonori
Nagata1, Hajime Sakuma1, Nanaka Ishida1, Tairo
Kurita1, Yoko Mikami1, Hiroshi Nakajima1,
Katsuya Onishi1, Masaaki Ito1, Kan Takeda1
1Mie
university hospital, Tsu, Japan
Use
of 32 channel coils allows for acquisition of whole heart coronary MRA in a
reduced imaging time and with high study success rate, which resulted in
considerably improved overall detection rate of CAD in subjects who underwent
coronary MRA.
14:00
2923.
Signal-To-Noise Ratio Enhancement in Coronary MRA Using Parallel Imaging
Computer 1
Jing
Yu1, Michael Schär1, Evert-jan P.A. Vonken1,
Sebastian Kelle1, Matthias Stuber1
1Johns
Hopkins University, Baltimore, Maryland, USA
Coronary
MRA with short acquisition windows is limited by SNR. We propose a method to
enhance SNR based on parallel imaging in conjunction with a reduced number of
radiofrequency excitations while the scanning time remains unchanged. A
practical method to quantify SNR on images obtained with parallel imaging was
developed as well. Numerical simulations predict that the SNR gain using the
proposed method is greatest for very short acquisition windows. These
theoretical findings are in good agreement with in vitro and in vivo results
obtained in this study.
14:30
2924.
Contrast-Enhanced MR Angiography: A Helpful Methodology to Detect
Coronary Atherosclerotic Plaque
Computer 1
Xihai
Zhao1,2, Xin Liu3, Liuquan Cheng2,
Li Yang2, Zulong Cai2, Chun Yuan1
1Vascular
imaging lab. , Seattle, Washington, USA; 2deparment of radiology,
Beijing, People's Republic of China; 3Departments of Radiology,
Chicago, Illinois, USA
This
study focus on using contrast-enhanced MR angiography to improve the SNR and
CNR of MR images and to increase the detection rate of coronary atherosclerotic
plaque.
15:00
2925.
Contrast-Kinetics-Resolved Whole-Heart Coronary MRA Using 3DPR
Computer 1
Peng
Lai1, Feng Huang2, Sonia Nielles-Vallespin3,
Xiaoming Bi4, Andrew C. Larson1, Renate Jerecic4,
Debiao Li1
1Northwestern
University, Chicago, Illinois, USA; 2Invivo Corporation,
Gainesville, Florida, USA; 3Siemens AG Medical Solutions, Erlangen,
Germany; 4Siemens Medical Solutions, Chicago, Illinois, USA
In
contrast-enhanced coronary MRA, a bolus scan is usually necessary to estimate
the transit time from contrast injection to peak arterial enhancement. However,
optimal timing of data acquisition often remains elusive due to variations of
heart rates and respiratory gating efficiency as well as simultaneous
myocardial enhancement. In this work a contrast-kinetics-resolved technique
using 3DPR was developed which eliminates the tedious planning task and enables
retrospective selection of the optimal coronary artery visualization for
different coronary artery segments. Also, the center-k-space magnitude change
could be used to approximate contrast kinetics during a scan, enabling
automatic selection of optimal time frames.
13:30
2926.
Contrast-Enhanced Coronary MR Angiography with Gd-DTPA Slow Infusion
Computer 2
Liuquan
Cheng1, Tao Li1, Haiyue Ju1, Xihai Zhao1,2,
Yuangui Gao1, Yi Wang3
1Chinese
PLA General Hospital, Beijing, People's Republic of China; 2Northwestern
University Medical School, Chicago, USA; 3Weill Medical College of
Cornell University, New York, USA
The
navigator-gated FIESTA coronary MRA was acquired during the slow infusion of
Gd-DTPA. The SNR and image quality could be improved and it is more accurate
than the non-contrast study in stenosis detection.
14:00
2927.
Breath-Hold Whole-Heart Coronary MR Angiography (CMRA) by 2D-Parallel
Acquisition Compared with Respiration-Gated CMRA Using a Multi-Element Body
Coil
Computer 2
Tomohisa
Okada1, Shotaro Kanao1, Shigehide Kuhara2,
Ikuo Aoki2, Ayako Ninomiya2, Saori Satou2,
Toshikazu Kamae1, kimio Gotoh1, Kaori Togashi1
1Kyoto
University Graduate School of Medicine, Kyoto, Japan; 2Toshiba
Medical Systems Corporation, Ohtawara, Japan
The
multi-element phased-array body coil is now widely available in clinical
practice. It has capability of 2D-parallel imaging, which may largely reduce
scan time. This study investigated the attainable quality of coronary MRA in
breath-hold (BH) compared with respiration-gated (RG) CMRA. Examination of 14
healthy subjects resulted in scan time reduction approximately from 12 minutes
to 34 seconds. The average quality score of visualization (0-4) was reduced by
0.93, however, proximal segments (#1-2, #5-7, #11) showed average scores over
2, which was considered usable for clinical evaluation.
14:30
2928.
Whole Heart Coronary Vein Imaging
Computer 2
Christian
Stoeck1,2, Dana C. Peters2, Yuchi Han2,
Beth Goddu2, Warren J. Manning2, Sebastian Kozerke3,
Reza Nezafat2
1ETH
Zurich, Zurich, Switzerland; 2Beth Israel Deaconess Medical Center
Harvard Medical School, Boston, Massachusetts, USA; 3Institute for
Biomedical Engineering, University and ETH Zurich, Zurich, Switzerland
Transvenous
BiV lead implantation in cardiac resynchronization (CRT) therapy is preferred
to surgical placement. However, for the transvenous approach, knowledge of the
coronary vein anatomy is needed prior or during the implantation procedure.
Recent studies showed the strength of cardiovascular MR in assessing coronary
vein anatomy. In this study we investigated the use of MT-SSFP whole heart
imaging to assess coronary vein anatomy.
15:00
2929.
2D Spin-Labeling Coronary MR-Angiography with Cartesian and Radial
K-Space Sampling
Computer 2
Marcus
Katoh1,2, Matthias Stuber3, Arno Buecker1,
Rolf W. Gunther2, Elmar Spuentrup2,4
1University
Hospital Saarland, Homburg, Germany; 2RWTH Aachen University
Hospital, Aachen, Germany; 3Johns Hopkins University Medical School,
Baltimore, Maryland, USA; 4University Hospital Köln, Köln, Germany
3D
spin-labeling coronary MR-angiography (cMRA) allows selective visualization of
the coronary arteries. This technique is limited by a long scanning time as two
3D data sets must be subtracted. In this study, the value of a 2D approach was
investigated. The coronary arteries of 8 volunteers were imaged on a 1.5 T
MR-system using a navigator-gated and cardiac-triggered 2D SSFP cMRA sequence
with Cartesian and radial k-space sampling. 2D spin-labeling cMRA allowed for
selective visualization of the left and right coronary system within a minute.
Radial k-space sampling proved to be superior with respect to artifact
suppression, SNR, CNR and vessel border definition.
Contrast-Enhanced Myocardial Perfusion Imaging
Hall D Thursday 13:30-15:30
13:30
2930.
Free Breathing Myocardial Perfusion Using Navigator Slice Tracking and
TSENSE
Computer 3
Bryan
Kressler1, Pascal Spincemaille2, Thanh D. Nguyen2,
Jonathan W. Weinsaft2, Martin R. Prince2, Yi Wang1
1Cornell
University, Ithaca, USA; 2Weill-Cornell Medical College, New York,
USA
Conventional
contrast enhanced myocardial perfusion imaging relies on a prolonged breath
hold to eliminate respiratory motion.
However, the contrast enhancement time course may be too long for
patients to successfully suspend respiration, resulting in breathing motion and
rendering image analysis difficult. In
this work, navigator slice tracking is applied to myocardial perfusion,
eliminating the need to perform breath holding and enabling acquisition of the
entire contrast enhancement time course with minimal breathing motion. TSENSE acquisition and processing are applied
to increase the number of slices that can be acquired. The technique is demonstrated in healthy
volunteers and patients.
14:00
2931.
Dual Bolus Myocardial Stress Perfusion Quantification in Normals
Computer 3
Yi
Wang1,2, Raphael Hazel1, Bin Luo1,
Marguerite Roth1, Jing Han1, Nathaniel Reichek1,2
1St.
Francis Hospital, Roslyn, New York, USA; 2SUNY, Stony Brook, New
York, USA
We
studied Fermi model-based quantitative perfusion quantification methods in dual
bolus myocardial adenosine stress perfusion and evaluated their absolute
perfusion values at different dose in 16 normal volunteers. The results showed significant difference in
average perfusion values both under stress (5.64 ml/min/g) and at rest (2.30
ml/min/g) at 0.05mM/kg standard contrast dose versus stress perfusion (2.07
ml/min/g) and rest perfusion (0.69 ml/min/g) when 0.005mM/kg contrast dose
blood signal was used as the arterial input function. However, their flow
reserves both dual bolus or standard dose only were significantly associated
and their means were close (2.49 at SD versus 2.31 at DB). The flow reserve
values showed good correlation with subject age and are consistent with PET
findings in normals.
14:30
2932.
First-Pass Myocardial Perfusion: Comparison Between Full-Dose Hybrid-EPI
and Half-Dose Balanced-SSFP
Computer 3
Peter
D. Gatehouse1, Chiara Bucciarelli-Ducci, Jonathan C. Lyne, David N.
Firmin, Dudley J. Pennell
1Royal
Brompton Hospital, London, UK
Comparisons
of these sequences at the same dose have shown abundant myocardial SNR for
myocardial perfusion balanced SSFP compared to hybrid-EPI, but with more
dark-rim subendocardial artefact in bSSFP. This study compared the two
sequences for stress perfusion in 8 subjects, using reduced contrast agent dose
for bSSFP to reduce one potential source of artefact (B0 distortion). While
myocardial SNR with bSSFP remained equivalent or superior to hEPI, dark-rim
artefact also occurred in normal segments more frequently in half-dose bSSFP
than full-dose hEPI.
15:00
2933.
Myocardial Magnetic Resonance Stress Perfusion Imaging at 3T Using a
1-Molar Contrast Agent
Computer 3
Bernhard
Daniel Klumpp1, Christina Doesch1, Achim Seeger1,
Joerg Doering1, Tobias Hoevelborn1, Ulrich Kramer1,
Michael Fenchel1, Andreas May1, Claus D. Claussen1,
Stephan Miller1
1Eberhard-Karls-University
of Tuebingen, Tuebingen, Germany
Myocardial
stress perfusion MR imaging (MRSPI) at 1.5T is limited by low SNR. This can be
compensated by an increase of field strength and contrast agent concentration.
Aim of our study was the evaluation of MRSPI at 3T using a 1-molar contrast
agent. MRSPI was assessed in 57 patients with suspected coronary artery disease
(CAD) using a 2D sr GRE sequence (0.1 mmol Gadobutrol / kg BW). Standard of
reference was invasive coronary angiography. Sensitivity for coronary artery
stenoses >70% was 97%, specificity 81%, diagnostic accuracy 93%. MRSPI under
such optimized conditions provides increased sensitivity / specificity for CAD.
13:30
2934.
Myocardial Perfusion Quantification: Effects from Contrast Dose, Imaging
Plane and Sequence
Computer 4
Yi
Wang1,2, Raphael Hazel1, Bin Luo1,
Marguerite Roth1, Jie Jane Cao1, Nathaniel Reichek1,2
1St.
Francis Hospital, Roslyn, New York, USA; 2SUNY, Stony Brook, New
York, USA
The
quantification of myocardial perfusion using MRI is an important research and
clinical tool for evaluating ischemia. However, its dependence to contrast
dosages, imaging sequences and imaging orientation has not been thoroughly
investigated. We studied 14 normal volunteers using a dual bolus approach with
3 different sequences to acquire perfusion images in both long and short axis,
and evaluated the regional absolute perfusion values. The objective of this
study was to determine whether the resting perfusion quantification using the
dual bolus approach is dependent on the MRI pulse sequence or imaging plane
orientation.
Computer 4
Marcus
Carlsson1, David Saloner1, Alastair J. Martin1,
Loi Do1, Juha Koskenvuo1, Maythem Saeed1
1University
of California San Francisco, San Francisco, California , USA
Coronary
microembolization is a frequent complication of coronary interventions. We
determined the effects of microembolization on perfusion and visualization of
microinfarction 1hr and 1week after delivery of embolic agents. First pass
perfusion and delayed contrast enhanced (CE) MR imaging was used to
non-invasively monitor the serial changes in regional perfusion and viability.
Histopathology was used to confirm the presence of microinfarction. The embolic
agents were visualized in coronary tree surrounded by microinfarction. Acute
and subacute microinfarction showed perfusion deficit. CE-MR imaging delineated
subacute microinfarction due to the loss of membrane integrity of ischemic
myocytes, but not all discrete acute microinfarction.
14:30
2936.
Multislice Single Shot Spin Echo EPI Perfusion Imaging with
Zone-Selection and Parallel Imaging
Computer 4
Pedro
Ferreira1, Peter Gatehouse2, David Firmin1,
Chiara Bucciarelli-Ducci1, Ricardo Wage2
1Imperial
College, London, UK; 2Royal Brompton Hospital, UK
Myocardial
perfusion images are often affected by a subendocardial Dark Rim Artifact
(DRA). A sequence has been designed with the underlying ethos of greater
robustness against the DRA, by reducing the echo train length and nulling the
signal in the left ventricle blood pool. The sequence is a single-shot
spin-echo EPI with zonal excitation and parallel imaging techniques.
Preliminary
results show no evidence of myocardial dephasing, or distortion by cardiac
motion or field nonuniformity during first pass of contrast agent; although
TSENSE is proving challenging to include with saturation recovery due to low
SNR.
15:00
2937.
Compressed Sensing Cardiac Perfusion Imaging
Computer 4
Viton
Vitanis1, Robert Manka1,2, Urs Gamper1,
Peter Boesiger1, Sebastian Kozerke1
1ETH
Zurich, Zurich, Switzerland; 2German Heart Institute Berlin, Berlin,
Germany
This
work demonstrates the feasibility of accelerating perfusion imaging using
Compressed Sensing and compares the method to k-t SENSE. Based on computer
simulations and actual in-vivo measurements it is shown that Compressed Sensing
yields lower reconstruction errors up to a net acceleration factor of three.
Beyond this factor k-t SENSE outperforms with respect to root-mean-square
reconstruction error. The lower error is, however, associated with some
temporal low pass filtering of signal-intensity curves. In conclusion, both
methods tested seem suitable to accelerate cardiac perfusion imaging up to net
acceleration factors of five without compromising signal-intensity perfusion
curves significantly.
13:30
2938.
First-Pass Cardiac Perfusion MRI with 50%-Reduced Contrast Agent Dosage
Computer 5
Daniel
Kim1
1New
York University, New York, New York, USA
While
first-pass cardiac perfusion MRI is a promising modality for the assessment of
coronary artery disease, there are safety concerns associated with
Gadolinium-based MRI contrast agents, especially in patients with renal
insufficiency. One strategy to reduce the contrast agent dosage is to achieve
maximal myocardial contrast-to-noise ratio (CNR) through pulse sequence
optimization and trade off a portion of CNR to reduce the dosage. The purpose
of this study is to optimize the pulse sequence with optimal k-space trajectory
and variable flip angles to achieve comparable image quality at 50%-reduced
dosage to that produced by a convention sequence at standard dosage.
14:00
2939.
Perfusion Phantom for Quantitative Imaging
Computer 5
Behzad
Ebrahimi1,2, Scott D. Swanson, Timothy E. Chupp,2
1University
of Michigan, Ann Arbor, USA; 2Focus Center, Ann Arbor, USA
A
perfusion phantom with unique features and a wide variety of applications in MR
and other imaging modalities is presented. The phantom is especially suited to
tissue perfusion simulation with diffusible and non-diffusible MR tracers. A
network of micro-channels in the scale of actual capillaries replicates the
blood flow in tissues. Using microfabrication technique, networks with any
desired pattern can be generated. Since the geometry of networks is known, flow
rate, delay, dispersion and other fluid parameters can be exactly calculated,
using finite elements numerical methods. These calculated results can be used
to investigate the accuracy of experimental measurements and the precision of
mathematical models.
Computer 5
Raphael
Delano Hazel1, Nathaniel Reichek1, Yi Wang1
1St
Francis Hospital, Roslyn, New York, USA
Dark
Rim Artifact (DRA) in Gadolinium enhanced saturation recovery TrueFISP cardiac
first pass perfusion images from normal volunteers collected during stress and
rest, show similar frequency affecting 12.5% of the rest and 10.2% of stress
images, with comparable severity represented by signal loss of 32.9 % (rest)
and 31.5 % (stress) in the endocardium. The duration and severity of the DRA
coincides with the maximum contrast agent concentration and susceptibility
difference between LV and myocardium. A comparison of three pulse sequences shows
that TrueFISP is most affected by the DRA, followed by TFL while EPI shows no
artifact.
Computer 5
Daniel
C. Lee1,2, Nils P. Johnson1, Kathleen R.
Harris1
1Northwestern
University, Chicago, Illinois, USA
Calculation
of absolute myocardial blood flow from magnetic resonance first-pass perfusion
studies by deconvolution requires a linear relationship between signal
intensity (SI) and gadolinium concentration [Gd] in both the blood pool and the
myocardium. We measured this relationship in canine myocardium for three common
perfusion pulse sequences. Inversion recovery-prepared single-shot steady-state
free-precession demonstrates excellent myocardial signal enhancement and a
linear SI-[Gd] relationship. Saturation recovery-prepared segmented
echo-planar-imaging and saturation recovery-prepared turbo fast low-angle shot
exhibit less robust myocardial signal enhancement and a curvilinear SI-[Gd]
relationship. This nonlinear signal response may result in underestimation of
absolute myocardial blood flow.
Cardiac Diffusion Tensor Imaging
Hall D Thursday 13:30-15:30
13:30
2942.
Myofiber Developmental Plasticity in Fetal Hearts Delineated with
Diffusion Tensor MRI
Computer 6
Lei
Zhang1, Junjie Chen1, Allyson Gibson1, Mark R.
Holland1, Gregory M. Lanza1, Samuel A. Wickline1
1Washington
University in St. Louis, St. Louis, Missouri, USA
Cardiac
functions in prenatal and postnatal phases are different. We hypothesized that
myocardial fiber structures in fetal hearts may also differ from that of the
adult hearts. Diffusion tensor MRI was used to delineate myocardial fiber
structures in fetal pig hearts. Balanced contributions from both left ventricle
and right ventricles to the septal myofibers and a thick right ventricle free
wall (RVFW) in fetal hearts were observed. In contrast, adult hearts showed
thinner RVFW and a dominant contribution to the septal fibers from left
ventricle. These structural differences may reflect the plasticity of
myocardial fiber development in response to the programmed differential
contractile functions before and after birth.
14:00
2943.
A Study of Variability of the Mouse Myocardial Fiber Structure Obtained
by MR Diffusion Tensor Imaging
Computer 6
Yi
Jiang1, Sarang Joshi2, Kumar Pandya3, Oliver
Smithies3, Edward W. Hsu2
1Duke
University, Durham, North Carolina, USA; 2University of Utah, Salt
Lake City, Utah, USA; 3University of North Carolina, Chapel Hill,
North Carolina, USA
Principal
component analysis (PCA) was used to assess the variability of the mouse
myocardial fiber helix angle and fractional anisotropy obtained by MR diffusion
tensor imaging (DTI). Leave-one-out tests indicate that structural variability
of the normal mouse hearts can be represented by as few as 6 DTI datasets.
Moreover, PCA successfully distinguished hypertrophic hearts from the normal
group. These findings suggest a rather low degree of intra-group variability
and lend validity to atlas-based representation and modeling of the myocardial
fiber structure.
14:30
2944.
Diffusion Tensor MRI Reflects Age-Associated Changes in Normal and
Cardiomyopathic Syrian Hamsters
Computer 6
Wen
Li1,2, Allen Ye1, Ming Lu1, Suhanti
Banerjee1, Xin Yu1
1Case
Western Reserve University, Cleveland, Ohio, USA
The
purpose of this study is to explore the potential of diffusion tensor MRI
(DTMRI) in evaluating aging and cardiomyopathy (CM)-associated myocardial
remodeling in Syrian hamsters. DTMRI
were performed on formalin-fixed hearts of both normal and CM hamsters. Our
results suggest that DTMRI is sensitive to microscopic structural changes
associated with aging and disease progression.
15:00
2945.
Interspecies Variability in the Myocardial Fiber Structure Acquired
Using MR Diffusion Tensor Imaging
Computer 6
Lindsey
Healy1, Sarang Joshi1,2, Yi Jiang3,
Edward Hsu1
1University
of Utah, Salt Lake City, Utah, USA; 2Salt Lake City, USA; 3Duke
University, Durham, North Carolina, USA
The
variability in the fiber helix angle of mouse, rabbit, and sheep, obtained
using MR diffusion tensor imaging (DTI), was assessed using principal component
analysis (PCA). A significant difference
was found between each of the rabbit and sheep hearts compared to the mouse
hearts. The sheep and rabbit hearts were
not significantly different. The
significant difference between the rabbit and mouse and sheep and mouse hearts
suggest that larger hearts cannot be directly scaled down to replace the
structure of smaller animals.
Hall D Thursday 13:30-15:30
13:30
2946.
Quantitative Assessment for Late Gadolinium Enhancement in Normal
Myocardium
Computer 7
Atsushi
Kono1,2, Naoaki Yamada1, Masahiro Higashi1,
Suzu Kanzaki1, Teruo Noguchi1, Kazuro Sugimura2,
Hiroaki Naito1
1National
Cardiovascular Center, Suita, Japan; 2Kobe University Graduate
School of Medicine, Kobe, Japan
Current
assessment of delayed gadolinium enhancement in myocardium has limitation in detection
of diffuse myocardial disease as based on relative signal intensity to the
apparently non-enhanced myocardium. Normalization of myocardial signals by
lumen signals in delayed enhancement (M/L) is useful to cancel out sensitivity
inhomogeneity of surface coil. We demonstrate that normal M/L is invariable in
a wide range of time after gadolinium administration, heart rate, hematocrit,
and renal function (serum creatinine). On the basis of the results, M/L can
detect abnormality of diffuse myocardial disease such as cardiac amyloidosis
and Fabry disease.
Computer 7
Aya
Kino1, John Sheehan1, Sven Zuehlsdorff2, Peter
Weale2, Xin Liu1, Randal Ramsey1, Renate
Jerecic2, James Carr1
1Northwestern
University, Chicago, Illinois, USA; 2Siemens Medical Solutions,
Chicago, Illinois, USA
Delay
enhanced (DE) imaging is a well-established method for detection of myocardial
scar. 2D PSIR TurboFLASH is a widely accepted viability imaging technique and a
3D viability strategy, incorporating respiratory gating, have been shown to
detect small myocardial scars compared to 2D approaches. The purpose of this
study was to assess a 3D PSIR TurboFLASH imaging technique for detecting left
ventricular myocardial scar and compare it to a conventional 2D PSIR
TurboFLASH. This study demonstrated the navigator-gated 3D PSIR sequence shows
equivalent results for the assessment of myocardial scar, quantitatively and
qualitatively compared to routine segmented 2D-PSIR techniques
Computer 7
Thanh
D. Nguyen1, Matthew D. Cham1, Pascal Spincemaille1,
Martin R. Prince1, Jonathan W. Weinsaft1, Yi Wang1
1Weill
Medical College of Cornell University, New York, New York, USA
The
objective of this study was to prospectively compare a recently developed free-breathing
navigator-gated 3D (3DNAV) delayed enhancement MRI (DE-MRI) with routine
breath-hold (2DBH) DE-MRI in patients with confirmed myocardial infarction. 23
patients were imaged with both techniques at 1.5T. Compared to 2DBH imaging,
3DNAV imaging provided significantly better image quality in 33% less scan
time. 2DBH and 3DNAV imaging identified 90 and 91 involved segments and 22 and
24 transmural segments, respectively. There were a strong correlation and
narrow limits of agreement between the two techniques with respect to detected
infarct volumes.
15:00
2949.
LV Infarct Size and Peri-Infarct Zone Measurements: A Comparison of High
Resolution 3D and Conventional 2D Late Gadolinium Enhancement Imaging
Computer 7
Dana
C. Peters1, Evan A. Appelbaum1, Reza Nezafat1,
Yuchi Han1, Kraig V. Kissinger1, Beth Goddu1,
Warren J. Manning1
1Beth
Israel Deaconess Medical Center, Boston, Massachusetts, USA
A
high spatial resolution 3D late gadolinium enhancement sequence was used to
image seven patients with prior myocardial infarction. The results show a clearer picture of scar
morphology compared to 2D images, demonstrating features such as islands of
viability, subendocardial infarcts not visualized on the 2D images, and
improved papillary muscle scar detection.
The scar volume by 3D correlated well with 2D measurement, but the
peri-infarct zone was larger by 2D. This
3D higher spatial resolution imaging may be a step towards correlating infarct
morphology with arrhythmias.
Computer 8
Raquel
Espregueira Themudo1,2, Lars Johansson1,3,
Charlotte Ebeling Barbier1, Lars Lind1, Håkan Ahlström1,
Tomas Bjerner1
1Uppsala
University Hospital, Uppsala, Sweden; 2Hospital Geral Santo António,
Porto, Portugal; 3AstraZeneca, Gothenburg, Sweden
This
study comprised signal intensity analysis of myocardial scars in
delayed-enhancement Magnetic Resonance Imaging aiming to investigate if there
was any difference between clinically recognized myocardial infarctions and
clinically unrecognized myocardial scars. There was a significant difference
between the signal intensity ratio between these 2 groups, suggesting that it might
represent a difference in the scar tissue composition.
Computer 8
Anne
Elizabeth Scott1, Scott Ian Semple1, Thomas Redpath1,
Graham Hillis1
1Aberdeen
University, Aberdeen, UK
The
development of left ventricular dilatation in the months following acute
myocardial infarction (AMI) is known as ‘adverse remodelling’ and confers a
poor prognosis. Adverse remodelling is
measured as changes in left ventricular end diastolic volume (LVEDV). We examined the relative utility of delayed
enhancement (DE) and low dose dobutamine (LDD) CMR parameters, recorded 2 to 6
days post AMI, as predictors of changes in LVEDV six months later. LDD
parameters added incremental value to DE parameters and were independently
predictive of adverse remodelling.
14:30
2952.
Cardiac Phase-Resolved Acute Myocardial Infarct Imaging in Swines
Computer 8
Rohan
Dharmakumar1, Nirat Beohar1, Jain Mangalathu Arumana1,
Zhouli Zhang1, Debiao Li1,2
1Northwestern
University, Chicago, Illinois, USA; 2Evanston, Illinois, USA
This
work examines the feasibility of cardiac phase-resolved acute myocardial
infarct imaging.
Computer 8
Li-Yueh
Hsu1, Erik B. Schelbert1, Stasia A. Anderson1,
Bibhu D. Mohanty1, Syed M. Karim1, Peter Kellman1,
Anthony H. Aletras1, Andrew E. Arai1
1National
Institutes of Health, Bethesda, USA
We
hypothesized that the intermediate signal intensity in the peri-infarct border
zone between normal and infarcted myocardium maybe explained by partial volume
averaging. Using 3D ex vivo rat heart MRI at an isotropic voxel resolution
equivalent to 3 cardiomyocytes, we quantified the volume of peri-infarction on
the acquired isotropic 3D high resolution images and on post-hoc slab averaged
low resolution images.
13:30
2954.
Detection of Recent Myocardial Infarction Using CINE SSFP Imaging
Computer 9
James
William Goldfarb1, Lenore Barhak1, Jing Han1
1Saint
Francis Hospital, Roslyn, USA
In
this study, use of conventional CINE SSFP imaging for the detection of
myocardial edema resulting from recent MI was investigated. The signal behavior
of infarcted and viable myocardium as well as the LV bloodpool was investigated
as a function of cardiac phase to determine the image parameters for optimal
imaging of myocardial edema. In CINE SSFP images, the LV bloodpool and
myocardial signal intensities vary normally with cardiac phase. Myocardial
edema can be best detected at the end of systole when its contrast with
adjacent myocardium is the greatest.
14:00
2955.
Fat/Water Separated Delayed Hyperenhanced (DHE) Myocardial Infarct
Imaging
Computer 9
James
William Goldfarb1
1Saint
Francis Hospital, Roslyn, USA
A
three-point DIXON acquisition and reconstruction was combined with an inversion
recovery gradient-echo pulse sequence.
This allowed fat/water separation along with contrast-enhanced T1
sensitive delayed hyperenhanced myocardial infarct imaging. The technique was demonstrated in phantom
experiments and subjects with chronic myocardial infarctions. Areas of
infarction were well defined as conventional hyperenhancement in water images. Fatty deposition of myocardial infarction
detected using this novel sequence was confirmed by precontrast opposed phase
imaging.
Computer 9
Andreas
Kumar1, Rohan Dharmakumar2, Jordin D. Green3,
Jacqueline Flewitt1, Matthias G. Friedrich1
1University
of Calgary, Calgary, Canada; 2Northwestern University, Chicago,
Illinois, USA; 3Siemens Canada, Calgary, Canada
T2
spin echo sequences are commonly used to detect edema in acute myocardial
infarction. Here, we show that the inherent T2 weighting of cine SSFP sequences
used for functional imaging of the heart may be sufficient to detect edema.
This may abolish the need for a dedicated T2 spin echo sequence in the imaging
protocol for acute myocardial infarction.
15:00
2957.
Improved Myocardial Viability Imaging with T2-Prepared Inversion
Recovery (T2PREP-IR)
Computer 9
Chia-Ying
Liu1, Oliver Wieben1, Jean H. Brittain2, Scott
Brian Reeder1
1University
of Wisconsin-Madison, Madison, Wisconsin, USA; 2GE Healthcare,
Madison, Wisconsin, USA
The
clinical applications of delay-enhanced (DE) MRI using inversion recovery (IR)
preparation are increasingly important for evaluation of myocardial viability.
However, due to the similar T1 values of blood and infarcted tissue (MI), the
contrast between the ventricular blood and subendocardial MI is often limited,
adversely impacting the detection and evaluation of infarcted tissue.
Exploiting differences between blood and myocardial T2, we propose a method
that combines IR and T2 preparation into a single magnetization-prepared
sequence (T2Prep-IR) to achieve T1 and T2 contrast within a single imaging
acquisition to improve differentiation of enhancing subendocardial infarction
and blood.
Computer 10
Yasuo
Amano1, Morimasa Takayama2, Yoshio Matsumura3,
Yuriko Suzuki4, Shinichiro Kumita1
1Nippon
Medical School, Tokyo, Japan; 2Sakakibara Memorial Hospital, Tokyo,
Japan; 3Nippon Medical Schhol, Tokyo, Japan; 4Philips
Medical Systems, Tokyo, Japan
Free-breathing
delayed contrast-enhanced three-dimensional (3D) viability imaging of the
myocardium at three-tesla (3T) magnetic resonance was compared with breath-hold
two-dimensional (2D) viability imaging for assessments of CNR and extensions of
damaged myocardium. A k-space weighted navigator and cardiac gating were used.
This 3D imaging technique depicted 83.8 % of hyperenhancing myocardia with high
CNR between hyperenhancing myocardium and blood and excellent agreement for
transmural extension of the damaged myocardia (k = 0.875). Free-breathing
delayed contrast-enhanced 3D viability imaging was feasible for the evaluation
of the hyperenhancing myocardium at 3T.
Computer 10
Amol
S. Pednekar1
1Philips
Medical Systems, Bothell, Washington, USA
An
artificial mid-spetal hyperenhancement often appears on the inversion recovery
prepared interleaved segmented gradient recalled echo (IRISGRE) sequence with a
low-high phase encoding order. In this simulation we studied the imaging
artifacts resulting due to the signal modulation across the phase encode
direction in the IRISGRE sequence. These hyperenhancement artifacts capable of
leading to the spurious diagnosis of myocardial scarring, can be avoided by
using liner phase encoding order.
14:30
2960.
T1 Pulse Sequence Optimization in a Diabetic Cohort
Computer 10
Warren
Foltz1, Kim Alexander Connelly1,2, Venkat
Ramanan, Gideon Paul1, Graham Wright1, Alexander Dick1
1Sunnybrook
Health Sciences Centre, Toronto, Canada; 2St Michael's Hospital,
Toronto, Canada
Quantitative
MRI measurements of left ventricular remodeling have the potential to
facilitate earlier diagnosis and allow therapeutic monitoring of patients with
diabetic cardiomyopathy. The Gd-DTPA partition coefficient or λ, defined
as the tissue-to-blood ratio of extra-cellular volume fractions, should be
valuable because changes in λ from control values of 0.3 reflect
alterations in the extra-cellular volume, such as that seen in pathological
ventricular remodeling. We performed
quantitative λ measurements within a diabetic cohort using a cardiac-gated
but free-breathing single-point spiral T1prep strategy. Mean λ appears to be elevated to 0.44
from control levels. The spiral methodology appears to provide reproducibility
in global λ quantification which is on the order of 10%, which is the
sensitivity target for monitoring diabetic remodeling.
15:00 2961.
Myocardial T1ρ Mapping at 3T
Using a Novel Spin-Locking Technique
Computer 10
Benjamin
Edward Northrup1,2, Xiang He1, Kyle Stephan
McCommis1, Jie Zheng1
1Washington
University School of Medicine, St. Louis, USA; 2Dartmouth Medical
School, Hanover / Lebanon, USA
A
new spin-locking technique was used in conjunction with segmented
gradient-recalled echo and TrueFISP acquisitions on a 3T MRI system to acquire
cardiac T1-weighted images in a single (~20 second) breath-hold. This facilitated the calculation of
single-section myocardial T1ρ maps with minimal
intra-scan motion artifacts. No
significant difference between GRE and TrueFISP myocardial T1ρ signal values was observed. No difference in T1ρ values among the three spin-locking frequencies was
observed. This study provided baseline
myocardial T1ρ mapping data in normal
subjects, which will be useful for the evaluation of myocardial function with T1ρ techniques in the future.
Hall D Monday 14:00-16:00
14:00
2962.
Experimental Reduction of Acoustic Noise Through Cancellation of
Impulsive Forces
Computer 9
Xin
Chen1, Xingxian Shou1, Jamal J. Derakhshan1,
Shmaryu M. Shvartsman,12, Jeffrey L. Duerk1,3,
Robert W. Brown1
1Case
Western Reserve University, Cleveland, Ohio, USA; 2Hitach Medical
Systems, Twinsburg, Ohio, USA; 3University Hospitals, Cleveland,
Ohio, USA
MRI
acoustic noise is a long-standing problem exacerbated by higher field strengths
and faster imaging. We investigate the
idea of using the impulsive forces produced by gradient ramping to cancel each other. Guided by string simulations, we conduct
experiments to test pulse sequences incorporating these cancellations. As examples of appropriate timings,
combinations of trapezoid or “quadratic” pulses or pairs of trapezoids are
shown to cancel three frequencies and their harmonics. All results are in good agreement with the
simulations and Fourier theory. A rich
variety of possibilities in sequence design, including the TR freedom, may be
optimized for noise control.
14:30
2963.
Analysis of Acoustic Noise Transfer Function in MRI: Multi-Center Trial
Computer 9
Takashi
Hamaguchi1, Tosiaki Miyati2, Masaya Hirano3,
Yasuhiro Fuziwara4, Hirohiko Kimura4, Hiroyasu Takeda5,
Yasuo Takehara5, Kenro Nagashima6, Yuriko Suzuki6,
Jousei Ueda2
1Kanazawa
University Hospital, Kanazawa, Japan; 2Kanazawa University,
Kanazawa, Japan; 3GE Medical Systems, Hino, Japan; 4University
of Fukui Hospital, Japan; 5Hamamatsu University School of Medicine,
We
determined a gradient-pulse-to-acoustic-noise transfer function (GPAN-TF) at
various MRI centers. We measured sound pressure levels in the frequency domain
in six clinical super-conducting MRI systems, and calculated a GPAN-TF in each
gradient coil. GPAN-TF at a high frequency range was larger than that at low
frequency for all MR scanners. For high frequency, the 3.0-T MR scanner had a
larger GPAN-TF than that of 1.5-T. MR scanner with a vacuum chamber reduced
GPAN-TF at a lower frequency. GPAN-TF analysis enables to obtain more detailed
information on acoustic noise properties independent of pulse sequences or
imaging parameter in MR scanner.
15:00
2964.
Experimental Study of Active Acoustic Noise Control with MRI Compatible
Headphones and Microphones in a 4T MRI Scanner
Computer 9
Jing-Huei
Lee1, Brent W. Rudd1, Mingfeng Li1, Jeffrey
Osterhage1, Teik C. Lim1
1University
of Cincinnati, Cincinnati, USA
Typical
speakers and microphones utilizing magnetic components are unable to be used in
the vicinity of the MRI scanner. In this
study, we reproduced MRI noise in a sound quality chamber while measuring SPL
and running a feed-forward control system targeting one of the dominant
frequencies. The noise reduction performance of a high fidelity
headphone/microphone containing magnetic components is compared with an MRI
compatible combination utilizing piezoelectric speakers and an optical
microphone. In this report, the results
from the sound quality chamber show that the MRI compatible system produces
results that are comparable to that of the high fidelity system.
15:30
2965.
Sound Pressure Level Prediction of Arbitrary Sequences
Computer 9
Sebastian
Schmitter1, Lothar Rudi Schad2
1German
Cancer Research Center, Heidelberg, Germany; 2University of
Heidelberg, Mannheim, Germany
During
MR image acquisition huge sound pressure levels are generated, which can tamper
the results of auditory fMRI experiments. A prediction of the generated
acoustic noise and its spectrum is necessary in order to adapt auditory stimuli
to the scanning sequence. In this work the linearity between gradient amplitude
and sound pressure is verified in a wide range between 60 and 115dB. This
linearity is exploited in a simulation program which predicts the SPL of an
arbitrary sequence.
A
loud and a silent sequence were exemplarily simulated, the results deviate only
1.8dB from the measured values.
Hall D Tuesday 13:30-15:30
13:30
2966.
An Evaluation of the Potential Extent of Catheter Heating During MR
Imaging
Computer 10
Alastair
Martin1, Bryant Baek2, Gabriel Acevedo-Bolton2,
Randall Higashida1, John Comstock2, David Saloner1,2
1University
of California, San Francisco, California , USA; 2San Francisco VA
Medical Center, San Francisco, California , USA
An
obstacle to the incorporation of MR methods in endovascular procedures is the
potential for focal heating near catheters and guidewires. This study investigated the magnitude of
heating near endovascular devices in a tissue mimicking phantom. A fiber-optic temperature sensing system was
used to measure temperature changes in an assortment of geometric conditions
and with SAR levels up to 4W/kg. Heating
was found to be amplified near these devices and was a function of immersed
device length, position within the bore, and SAR. SAR limits are proposed as sufficient for
safely imaging catheterized patients without concern for thermal injury.
14:00
2967.
MR Safety and Compatibility of Cardiac and Peripheral Stents at 7T
Computer 10
Ivan
Emilov Dimitrov1,2, Aman Haider3, Emmanouil
Brilakis2, Subhash Banerjee3, Craig Malloy2,3
1Philips
Medical Systems, Cleveland, Ohio, USA; 2University of Texas
Southwestern, Dallas, Texas, USA; 3Dallas VA Medical Center, Dallas,
Texas, USA
We
investigated the magnetic interactions (translational attraction, torque), RF
heating, and artifact levels for five coronary and four peripheral stents
(Express, Cypher, Ultra, Palmaz are made of stainless steel; Vision,
Driver -
cobalt chromium; Sentinol, Precise -
nitinol) at 7T. With the exception of Palmaz, all stents showed
deflection less than 45 degrees. All stents exhibited no torque and
insignificant RF heating (0.1 – 0.2 0C). Artifact levels were different for the
different stents, all of them creating a void few times their geometrical
sizes. All stents, with the exception of the large stainless steel Palmaz, are
MR safe at 7T.
Computer 10
Fabio
Settecase1, Timothy P. L. Roberts2, Walter Kucharczyk3,
Steven Hetts1, Mark Wilson1, Ron Arenson1
1University
of California San Francisco, San Francisco, California , USA; 2Children's
Hospital of Philadelphia, Philadelphia, Pennsylvania, USA; 3University
of Toronto, Toronto, Canada
Catheters
can be steered in interventional MRI using magnetic moments induced by applying
current to orthogonally arranged wire coils at a catheter tip. Nonferromagnetic conducting wires, however,
can cause significant radiofrequency (RF) heating in MRI. This study
demonstrates, in a worst case scenario without convective blood flow,
RF-induced temperature increases using a MARC-steered catheter are less than
1ºC after 15 min of real-time MRI. Physiologically significant resistive
heating (greater than 4ºC) occurs only above 200 mA for 30 s in multiple coils.
MARC steering may be an attractive alternative to catheter navigation with
heating safety concerns arising only at higher currents using this prototype.
15:00
2969.
MR-Safety and Compatibility of Silver Based Wound Dressings at 7T
Computer 10
Steffen
Sammet1, Zaid Chaudhry1, William TC Yuh1,
Rebecca Coffey1, Andrew Crockett1, Sidney Miller1,
Michael Vincent Knopp1
1The
Ohio State University, Columbus, USA
The
purpose of this study was to determine whether silver based wound dressings are
compatible with MRI imaging by investigating if ultra high field MRI and silver
based dressings produce either increased body surface temperature and/or caused
distortions in the resulting MR image. All tested silver containing wound
dressings are both safe and compatible with MRI at 7T.
Hall D Wednesday 13:30-15:30
13:30
2970.
Reduction of SNR Losses Due to RF Coil Coupling Via Coil Current Sensing
Computer 9
Randy
Duensing1
1Invivo
Corporation, Gainesville, Florida, USA
This
method employs a new paradigm in multi-channel RF coils in which coupling (in
moderate amounts) is not detrimental as long as it is measurable, thus
permitting algebraic inversion. Two preamplifiers are utilized in each loop,
one preamplifier with the impedance mismatched used to provide inductive
decoupling, but the other matched to produce minimal impact on the loop
impedance. This second non-damping
preamplifier measures the residual current in the loop and therefore a model of
voltage coupled in other nearby coils.
Utilization of this additional signal improves the SNR over standard
methods when the coupling is moderate.
14:00
2971.
Transmission Line Effects on the Noise Correlation Matrix for Multiple
RF Coils
Computer 9
Ryan
Brown1,2, Yi Wang1,2
1Weill
Medical College of Cornell University, New York, USA; 2Weill
Graduate School of Medical Sciences of Cornell University, New York, USA
The
original noise correlation formula derived by Redpath showed correlation
depends on the real part of the impedance matrix. In this work, we introduce a more generalized
formula to include effects from transmission lines and preamplifier impedance
mismatch. This formula is used to
calculate correlation between two-channel circuits connected to preamplifiers
using several transmission line lengths.
The calculated correlation matches well with that measured on the MR
scanner and suggests transmission line length can be utilized as an additional
degree of freedom for coil decoupling, and can be adjusted to achieve zero
noise correlation.
14:30
2972.
An Eigenvalue/eigenvector Analysis of Decoupling Methods and Its
Application at 7T MR Imaging
Computer 9
Zhentian
Xie1, Xiaoliang Zhang1,2
1UC
San Francisco, San Francisco, California , USA; 2UCSF/UC Berkeley
Joint Graduate Group in Bioengineering, San Francisco & Berkeley,
California , USA
this
work, we report an eigenvalue/eigenvector analysis method for designing
non-overlapped coil arrays and one of its immediate applications as a novel
decoupling method. The proposed microstrip array coil for 7T MRI, consisted of
2 microstrip resonators and one microstrip decoupling line, was built on a
Teflon cylinder. Bench test and preliminary imaging results show that the
proposed design provides a robust approach to design of parallel imaging arrays
at ultrahigh fields.
Computer 9
Zhentian
Xie1, Xiaoliang Zhang1,2
1UC
San Francisco, San Francisco, California , USA; 2UCSF/UC Berkeley
Joint Graduate Group in Bioengineering, San Francisco & Berkeley,
California , USA
We
present an 8-channel microstrip array coil for mouse studies at 7T. The
decoupling strategy of using microstrip resonators was employed as adjustable
magnetic walls in order to block couplings between coil elements. Different
from some decoupling methods for non-overlapping design, the magnetic wall
method has no physical connection between the coil elements and the decoupling
elements, theoretically this method is not frequency-sensitive. Therefore the
decoupling performance can be maintained in a broad frequency range. The
Preliminary MR images indicate the effectiveness of the proposed magnetic wall
decoupling technique at the ultrahigh field of 7T. The proposed coil array
provides a robust approach to design of parallel imaging arrays at ultrahigh
fields.
13:30
2974.
An 8-Channel Non-Overlapped Spinal Cord Array Coil for 7T MR Imaging
Computer 10
Zhentian
Xie1, Xiaoliang Zhang1,2
1UC
San Francisco, San Francisco, California , USA; 2UCSF/UC Berkeley
Joint Graduate Group in Bioengineering, San Francisco & Berkeley,
California , USA
In
this report, we designed and constructed an 8-channel non-overlapped surface
coil array using with strong decoupling performance and good coverage for spine
parallel imaging. Different from conventional decoupling methods for
non-overlapping design such as the method using lumped L/C decoupling circuits
, we use a new magnetic-wall decoupling method to decouple the resonant elements.
The magnetic wall is generated by the microstrip circuits positioned between
two adjacent surface coil elements. Without physical connection between the
decoupling microstrip and array elements, theoretically this method is not
frequency-sensitive. Therefore the decoupling performance can be maintained in
a broad frequency range. Bench test and preliminary imaging results are shown
using the proposed coil array at 7T.
14:00
2975.
Investigation of Liquid Nitrogen Cooled Coils for Low Field MR Imaging
Computer 10
Hoon-Sin
Cheong1, Ivo Volkov2, Eugeny Krjukov1, Neil
Alford3, Chris Randell4, Jim Wild1, Martyn
Paley1
1University
of Sheffield, Sheffield, UK; 2London South Bank University, London,
UK; 3Imperial College London, London, UK; 4Pulseteq Ltd.,
Gloucester, UK
Images
have been acquired using a specially designed cryostat and a liquid nitrogen
cooled copper coil on a dedicated 0.17T neonatal/orthopedic imaging system. A
factor of 1.4 improvement in SNR was obtained. Future work will compare the
cooled copper coil with an identical geometry HTSC coil.
14:30
2976.
Double Loop-Asymmetric Saddle Coil Arrays Optimized for Spine and Torso
Imaging
Computer 10
Pei
H. Chan1, Dan Spence2, Vincent Chen1, Piero
Ghedin2
1GE
Healthcare Coils, Aurora, USA; 2GE Healthcare, Milwaukee, USA
In
this abstract we present a double loop-asymmetric saddle (DLAS) coil array
configuration which has two highly overlapped asymmetric saddle coils in the
middle and two loop coils on the sides. The overlap and quadrature nature
between the two asymmetric saddle coils result in significant SNR improvement
at the spine region. A 3.0T posterior array coil built with multiple DLAS
blocks has demonstrated better SNR than a 3.0T 8-channel
cervical-thoracic-lumber coil for spine imaging as well as good parallel
imaging capability for torso imaging.
15:00
2977.
A Modular Approach to Large Arrays Using Stacked Segments
Computer 10
Wolfgang
Driesel1, Harald E. Möller2
1Max
Planck Institute for Human Cognitive and Brain Sciences , Leipzig, Germany; 2Max
Planck Institute for Human Cognitive and Brain Sciences, Leipzig, Germany
We
propose a stacked combination of loop coils and microstrip transmission-line
elements (MTL), which are intrinsically orthogonal, to obtain a large number of
coil segments. In a first prototype a 32-channel array based on 16 stacked
segments was tested. Experimental results indicate, that array coils with a
large number of segments and excellent decoupling between segements can be
designed from stacks of MTLs plus one or more loop-structures consisting of one
or more loops. Simulations indicate a potential for parallel imaging with
acceleration in z-direction.
RF Transmit Coils & Calculations
Hall D Wednesday 13:30-15:30
Computer 11
Achim
Bahr1, Stefan Orzada1, Thomas Bolz1
1IMST
GmbH, Kamp-Lintfort, Germany
Microstrip
resonators are interesting basic elements for the design of RF volume coils at
high frequencies. In this work we describe a novel 8 channel microstrip array
at 7 T which provides good B1-Field homogeneity in combination with decreased
mutual coupling. The novelty implemented in this coil is the use of meander
line structures at both ends of the coil elements. Low mutual coupling is
verified by S-parameter measurements. In addition simulation and measurement
results of the B1-Field and SAR are shown.
14:00
2979.
A Novel 7 T Microstrip Element Using Meanders to Enhance Decoupling
Computer 11
Stephan
Orzada1, Achim Bahr1, Thomas Bolz1
1IMST
GmbH, Kamp-Lintfort, Germany
In
this work we describe a novel method to distinctly increase the decoupling of
neighbouring microstip elements at 7 T. The novelty implemented in these coil
elements is the use of meanders at both ends.
Symmetrically
fed elements with different numbers of meanders are compared to a symmetrically
fed stripline element without meanders via simulation and measurement.
While
longitudinal homogeneity remains the same, decoupling between neighbouring
elements is increased by up to 10 dB. Penetration depth, absolute field
strength and separation between neighbouring sensitivities are improved.
Therefore meander elements are superior compared to standard microstrip lines
concerning the use of parallel transmit and receive techniques.
14:30
2980.
Worst Case SAR Scenario as a New Metric for SAR Analysis in B1 Phase
Shim
Computer 11
Xiaoping
Wu1, Tsung-Hui Chang1, Zhi-Quan Luo1, Can
Akgun1, J. Thomas Vaughan1, Kamil Ugurbil1,2,
Pierre-Francois Van de Moortele1
1University
of Minnesota, Minneapolis, Minnesota, USA; 2Max Planck Institute for
Biological Cybernetics, Tübingen, Germany
It
has been shown numerically and experimentally that B1 shim can efficiently
address transmit B1 (B1+) inhomogeneity (1). However, the risk of increasing
specific absorption rate (SAR) deposition with RF manipulation is a major
concern especially at very high magnetic field. The impact of B1 shim on SAR
has been considered but it remains difficult to compare SAR maps obtained with
multi-transmit RF coils with a variety of phase and amplitude inputs. Here we
propose a new metric, "pixel-wise worst case SAR scenario", to be
used as a reference when comparing SAR for different B1 shim solutions. Computing
this reference, based on electromagnetic models, consists of finding the
maximum E2 value for each pixel for all of possible B1 input complex values. We
propose a fast computational solution for solving this nonconvex optimization
problem, and we apply this method to generate E2 maps for 16-channel RF coils
at 7 T.
15:00
2981.
An Inexpensive and Programmable Separated Coil CASL System
Computer 11
Qin
Xu1, Lei Zhou1, Christopher Glielmi1, Kisueng
Choi, Xiaoping Hu1
1Georgia
Institute of Technology/Emory University, Atlanta, Georgia, USA
A
low-cost and programmable design for two-coil continuous arterial spin
labelling system with minimal scanner hardware modifications is presented. A
system-on-chip direct digital frequency synthesizer is chosen to generate the RF
without sacrificing signal performance. This system offers remote control and
programmable capabilities for easy setup and debugging of the perfusion.
Performance of this system for CASL is demonstrated experimentally.
RF Receive Coils: Dual Tuned & Microstrip
Hall D Wednesday 13:30-15:30
13:30
2982.
A Theoretical Study on the Frequency Modes Separation of Double Tuned
TEM Resonators
Computer 12
Assunta
Vitacolonna1, Marcello Alecci1
1University
of L'Aquila, L'Aquila, Italy
The
poor high field mode separation in double tuned TEM Resonators, can produce
shading artifacts when the TEM is loaded with human tissue. In this work we
show theoretically that a suitable design and geometrical disposition of the
coaxial elements allows a significant increase of the high frequency resonant
modes splitting.
14:00
2983.
A Novel Double-Tuned Head Coil with 16 Double-Tuned Elements for 7T
MRI/S
Computer 12
Chunsheng
Wang1, Bing Wu1, Duan Xu1, Xiaoliang Zhang1
1University
of California San Francisco, San Francisco, USA
A
Novel double-tuned head coil with 16 double-tuned elements was designed and
tested successfully at 7T. Resonant modes at both low frequency and high
frequency are well-defined at bench test. This kind of structure can provide
almost identical B1 field distribution for both 13C MRS and 1H MRI because of
identical symmetric of elements for both nuclei.
14:30
2984.
Design of Quadrature Microstrip Transmission Line (MTL) Volume Coil for
Cat MRI/fMRI Application at 9.4T
Computer 12
Ye
Li1,2, Xiaohong Zhu2, Yi Zhang2,
Xiaohua Jiang1, Wei Chen2
1Tsinghua
University, Beijing, People's Republic of China; 2University of
Minnesota, Minneapolis, USA
The
ability to scan entire cat brain is important to investigate large-scale neural
networks. A new design of MTL volume coil integrated with head holder for the
whole cat brain MR imaging has been presented. A prototype coil was developed
and constructed using 16 MTL resonant elements. The mineral oil images and
in-vivo cat brain images were acquired for coil test and validation. The
preliminary images suggest that the MTL volume coil provides good homogeneity
and sensitivity in the entire cat brain. Moreover, the coil is superior for
investigating brain functions, in particular, in deep brain regions, showing a
clear thalamocortical visual network connecting LGNs and V1 in the cat brain.
15:00
2985.
A Novel Dual-Frequency Volume Coil Using Common Mode/differential Mode
(CMDM) Resonators at 7T
Computer 12
Zhentian
Xie1, Xiaoliang Zhang1,2
1UC
San Francisco, San Francisco, California , USA; 2UCSF/UC Berkeley
Joint Graduate Group in Bioengineering, San Francisco & Berkeley,
California , USA
In
this work, we applied common mode and differential mode concepts to design dual
frequency volume coil designs. Common
mode and differential mode (CMDM) exist within two coupled parallel
transmission lines, yielding two current distributions and magnetic radiation
fields. At the common mode, the two currents on a resonator are identical. At
the differential mode, the currents are opposite to form a loop on that
resonator. Both currents and magnetic fields in a CMDM resonator are isolated
between two modes. Therefore, these modes could be designed independently at
two resonant frequencies without any interference. Based on CMDM algorithm, we
presents a dual tuned carbon-proton volume coil working in 7T MR system. The
volume coil had 8 CMDM elements with the 75MHz and 298.14MHz operating
frequencies for in vivo 13C/1H MRI/S studies at 7T. Preliminary results from a
corn oil phantom were acquired using the proposed coil at 7T. Based on the
preliminary results on bench test and MR scans, dual-tuned microstrip volume
coil with CMDM resonant elements is feasible, provided that sufficient radial
separation is maintained between the strip conductor and the ground to provide
sufficient coupling between corresponding elements. The proposed design may
provide a simple approach to dual-tuned volume coil design for in vivo
multinuclear MR at ultrahigh fields.
Systems, Subsystems, & Hybrid Systems
Hall D Thursday 13:30-15:30
13:30
2986.
Development of a Combined MicroPET®/MR System
Computer 11
Rob
C. Hawkes1, Alun J. Lucas1, Richard E. Ansorge1,
Stefan B. Siegel2, Robert Nutt2, John C. Clark1,
Tim D. Fryer1, T Adrian Carpenter1
1University
of Cambridge, Cambridge, UK; 2Siemens Molecular Imaging, Knoxville,
Tennessee, USA
We
have constructed a combined microPET®/MR system. This system delivers a complete PET detector
ring of diameter 15cm and axial field of view 7.8cm for simultaneous PET/MR,
with the unique facility to apply conventional PET-based attenuation correction
for validation of MR-based techniques.
We have previously reported detector module performance, and a 'dual
module' PET/MR interaction study. Here
we report on assembly and initial tests of the complete PET/MR system.
Computer 11
Sergio
Enrique Solis1, Dardo Tomasi2, Alfredo Odon Rodriguez1
1UAM
Iztapalapa, Mexico, Mexico; 2Brookhaven National Laboratory, Upton,
New York, USA
A
single imaging modality cannot provide information both structure information
and function. The combination of PET and MRI offers tantalizing opportunities,
with important challenges. Cross talk between the MRI transceiver and the PET
digital electronics can lead to interfering RF noise in both imaging
modalities. An electromagnetic shielding, decoupling the PET and MRI systems,
must be tightly located between the RF coil and the PET scintillating crystals
to minimize this interference without loosing sample space. We numerically
studied the behaviour of a 4-coil array for a PET-MRI system. This is mainly
motivated by the advantages offered by MRI parallel imaging.
14:30
2988.
Understanding Acoustic Noise Suppression with Gradient Design: a Vibrating String Model
Computer 11
Xin
Chen1, Xingxian Shou1, Timothy P. Eagan1,2,
Robert W. Brown1
1Case
Western Reserve University, Cleveland, Ohio, USA; 2Present address:
Philips Medical Systems, Highland Heights, Ohio, USA
Gradient
acoustic noise in MR scanners has long been a concern for patient comfort and,
on occasion, hearing safety. We apply a
forced damped vibrating string system to model sets of individual frequencies
found in the coil response spectrum. The general string solution accounts for
previous experiments on peak cancellation, provides a physical basis for
understanding these results, is a robust embodiment of a linear response
system, and offers a new approach to active noise suppression. The method opens up a number of different
pulse profiles and combinations that can be used to attenuate important
contributions to the acoustic spectrum.
15:00
2989.
Ultra-Short Echo Time Imaging Using an Independent Spectrometer and Coil
Insert
Computer 11
Martyn
Paley1, Eugeny Krjukov1, Michael Lamperth2,
Ian Young2
1University
of Sheffield, Sheffield, UK; 2Imperial College, London, UK
Short
echo time and repeat time sequences have been implemented and tested on an
independent spectrometer and gradient/RF coil insert. Echo times a short as 10
microseconds for a radial sequence and repeat times as short as 680
microseconds for a 2D gradient echo sequence have been demonstrated.
13:30
2990.
The Design of Planar Transverse Gradient Coils Using a Deformation
Algorithm
Computer 12
Minhua
Zhu1, Feng Liu2, Ling Xia1, Andrew Mehnert2,
Hector Sanchez Lopez2, Qing Wei2, Stuart Crozier2,
Jianfeng Zhu1, Zhaoyang Jin1
1Zhejiang
University, Zhejiang, People's Republic of China; 2University of
Queensland, Brisbane, Australia
In
this work we have proposed an efficient real-space method for the design of
bi-planar gradient coils for open MRI systems. The algorithm can be used for
complicated gradient coil design through an appropriate parameterization of the
current arcs. It represents each arc by a closed contour described by
parametric equations such that the ensemble of closed contours can be
deformed/reshaped in a simple manner controllable by just a few parameters.
These parameters are then used to define system rearrangements in the design
procedure. An iterative optimization procedure is used to adjust the control
parameters to minimize target/cost functions including gradient homogeneity,
inductance and other parameters. The given planar transverse coil example
demonstrates the capability of the proposed deformation-space methodology.
14:00
2991.
A New Shimming Approach Using the Equivalent Magnetizing Current (EMC)
Method
Computer 12
Hector
Sanchez Lopez1, Feng Liu1, Adnan Trakic1,
Ewald Weber1, Stuart Crozier1
1University
of Queensland, Brisbane, Australia
This
paper presents a new alternative shimming procedure to correct the magnetic
field inhomogeneities generated by horizontal and C-shape biplanar MRI magnets.
A magnetization map obtained through the application of the Equivalent
Magnetizing Current (EMC) method is used to define the domain where the
discrete iron shim set is placed to generate a given field harmonic [1].
Optionally, instead of iron a current pattern is used, then the magnetization is
related to the stream function (SF) and the current pattern is placed at
equally spaced contours of the SF [1]. If a set of discrete iron pieces with no
reversible magnetization direction is employed to mimic the continuous
magnetization function (MF) map, then iron shims of unit strength are placed
only in the positive domain (valid domain) of the MF map. The field source
matrix is calculated only for the discrete elements located in the valid
domain, which leads to a better conditioned matrix and superior solutions. An
LP algorithm is used to calculate the optimal thickness and location of the
discrete ferroshims to produce the target harmonics. Examples of simulated
shimming of horizontal/C-shape magnets are presented. In the case of permanent
open magnets, the magnetic coupling among the iron pieces and its influence
over the magnetic field harmonics is studied for linear and nonlinear iron
cases. The influence of the selection and arrangement of individual shim sizes
over the field source matrix conditioning is also analysed.
14:30
2992.
Generalized Two-Dimensional Orthogonal Spatial Encoding Fields
Computer 12
Gerrit
Schultz1, Anna Welz1, Jürgen Hennig1, Maxim
Zaitsev1
1University
Hospital Freiburg, Freiburg, Germany
Orthogonality
of the gradient fields is crucial to good image quality using non-bijective,
curvilinear spatial encoding fields. Often it is advantageous to apply a linear
z-gradient along with a pair of nonlinear encoding fields. We present a simple
method capable of finding all possible mutually orthogonal fields for this
actual two-dimensional encoding situation.
This
can be achieved by defining the encoding fields to be the real and the
imaginary part of any holomorphic function. The presented approach is flexible
in the design of fields for specialized applications and its simple
mathematical structure allows numerical accessibility to general optimal design
formulations.
15:00
2993.
Cardiovascular MRI in Mice in Vivo at 9.4T with a 1500 MT/m (150
Gauss/cm) Actively Shielded Gradient Coil
Computer 12
Guangping
Dai1, Kai-Ming Lo1,12,23,34,4,
Shuning Huang1,12,23,34,4,
Piotr Starewicz1,12,23,34,4,
David Sosnovik,1,2,3,45
1;
2; 3; 4; 5Martinos Center for
Biomedical Imaging, Massachusetts General Hospital, Harvard Medical School,
Charlestown, Massachusetts, USA
A
novel 1500 mT/m gradient coil has been constructed for cardiac MRI in mice at
9.4 T. Echo times of 1 ms and less can be obtained with this coil allowing fine
cardiovascular structures to be imaged with a new level of clarity and resolution.
MR-Guided Interventions (Non-Thermotherapy)
Hall D Monday 14:00-16:00
14:00
2994.
Magnetic Resonance Delivery and Monitoring of Empty MR Visible Capsules:
Long Term Follow-Up
Computer 11
David
Arthur Woodrum1, Wesley D. Gilson2, Thomas Link2,
Li Pan2, Christine H. Lorenz2, Di Qian2, Brad
P. Barnett2, Dara L. Kraitchman2, Jeff WM Bulte2,
Aravind Arepally2
1Mayo
Clinic, Rochester, Minnesota, USA; 2Johns Hopkins University School
of Medicine, Baltimore, Maryland, USA
Cell
microencapsulation provides immuno-protection where individual cells are
surrounded with a thin shell that is impermeable to antibodies but is permeable
to small molecules. However, basic questions for long-term implantation of
clinical dose of magnetocapsules (140,000) into the portal vein need to be
addressed. Therefore, in this survival
study, five swine underwent MR guided transplantation with 140,000 empty
magnetocapsules as a first step towards the goal of delivering encapsulated
cells as therapy. All animals survived the procedure and were followed for 4
weeks. Magnetocapsules were intact at four-week follow-up without disruption or
change in distribution.
14:30
2995.
Marked Microspheres Assessment Using 1.5T Scanner for Embolization
Follow Up
Computer 11
Hassan
Jassar1
1Université
de Technologie de Compiègne (UTC), Compiègne, France
Controlled
embolization with MRI remains challenging due to the abscence of effective
detection with another imaging modality. 4 sizes SPIO loaded microspheres were
injected into 8 ex vivo sheep kidneys or were embedded in a hydrogel as
different grouping. The feasibility of in vivo assessment was determined
according to coils, FOV, and sequence. Marked microspheres appeared as black
spots, a strong linear correlation between apparent and real sizes of
microspheres regardless their number, a positive visualization in in vivo
condition. Our methods demonstrate the efficiency of marked microspheres
assessment, in vitro and in vivo conditions, with MRI according to different
sizes.
15:00
2996.
MR Assessment of Vasospasm Severity and the Impact of Endovascular
Therapy
Computer 11
Alastair
Martin1, Nerrisa Ko1, Randall Higashida1,
Adrian Gelb1, Max Wintermark1, Van Halbach1,
Christopher Dowd1, David Saloner1
1University
of California, San Francisco, California , USA
An
XMR suite is used to evaluate endovascular therapies aimed at patients
suffering from cerebral vasospasm.
Vasospasm usually occurs secondary to subarachnoid hemorrhage and can
result in delayed infarction if not properly treated. Present methods for diagnosing and treating
the condition have limitations and therefore we explored the utility of
augmenting endovascular treatment with MR assays including quantitative flow
and perfusion. An increase in bulk flow
following therapy was evident even with substantially lower post-procedure mean
arterial pressure. Abnormalities in
perfusion timing maps resolved following therapy and a global increase in rCBF
was evident.
15:30 2997.
Phantom and Clinical Validation of 3T MRI for Gamma Knife® Radiosurgery Treatment Planning
Computer 11
Beibei
Zhang1, Derek MacFadden2, Andrei Z. Damyanovich1,
Marcus Rieker3, Kristy K. Brock1, Mojgan Hodaie4,
Normand Laperriere1, Michael Schwartz4, May Tsao1,
Jeffrey Stainsby5, David A. Jaffray1, Mark Bernstein4,
David Mikulis6, Cynthia Ménard1
1Princess
Margaret Hospital, Toronto, Canada; 2University of Toronto, Toronto,
Canada; 3Physikalisch-Technische Gesellschaft für Radiologie mbH,
Tübingen, Germany; 4Toronto Western Hospital, Toronto, Canada;
<su
MRI
is central to Gamma Knife® (GK) Radiosurgery (RS) treatment planning. In this
study we explored the validity of using 3T MRI for GK RS planning. Geometric
accuracy measured in fiducial reference deviations and anatomic landmark
displacements yielded comparable results for 3T and 1.5T MRI. Inter- and
intra-observer study on target volume definition and treatment isocenter
placement also yielded similar results in spatial congruency. Hence we have
demonstrated that 3T MRI is valid for GK RS planning under the imaging conditions
investigated, but did not demonstrate an improvement in observer
reproducibility despite a subjective improvement in image quality.
Computer 12
Norihiko
Ozawa1,2, Yoshihiro Muragaki1, Hirokazu
Suzukawa3, Ryoichi Nakamura1, Hiroshi Iseki1
1Tokyo
Women's Medical University, Tokyo, Japan; 2Hitachi Medical co.,
Chiba, Japan; 3Infocom co., Tokyo, Japan
In
surgical resection of brain tumor in the vicinity of the pyramidal tract,
identification and preservation of the tract is extremely important to protect
the motor function. Although DWI/DTI is useful to demonstrate the position and
the direction of the deep white matter bundles, intraoperative imaging is
essential during neurosurgical procedure which could cause brain deformation.
To our knowledge, however, there are few reports on performing both
gintraoperativeh DWI/DTI and subcortical electrical stimulation for
identification of the pyramidal tract. In this study, we identified the
pyramidal tract using neuronavigation based on intraoperative DWI in
combination with subcortical electrical stimulation.
Computer 12
Andrew
Peter King1, Redha Boubertakh1, Kawal S. Rhode1,
Ying-Liang Ma1, Phani Chinchapatnam2, Gang Gao2,
Tarinee Tangcharoen1, Matt Ginks1, David J. Hawkes2,
Reza Razavi1, Tobias Schaeffter1
1Kings
College, London, UK; 2University College, London, UK
We
describe a novel technique for respiratory motion correction of roadmaps in
XMR-guided cardiac catheterisations using a patient-specific motion model derived
from MR imaging. Validation is performed on four volunteers and three clinical
cases. We test two dynamic MR imaging sequences (low resolution 3-D and high
resolution 2-D) and two different registration approaches (full affine and
constrained affine) for forming the model. Accuracy in volunteers was 2-4mm and
in clinical cases the 2-D accuracy of the roadmap was improved from up to 13mm
to less than 4mm in all three cases.
15:00
3000.
X-Ray Fused with Magnetic Resonance (XMR) Imaging for Accessing the Portal
Vein
Computer 12
David
Arthur Woodrum1, Wesley D. Gilson2,3, Robert
Liddell2, R J. Lederman4, C Ozturk4, M Sonmez3,
Thomas Link2, V Howland2, Dara L. Kraitchman2,
Aravind Arepally2
1Mayo
Clinic, Rochester, Minnesota, USA; 2Johns Hopkins University School
of Medicine, Baltimore, Maryland, USA; 3Siemens Corporate Research,
Baltimore, Maryland, USA; 4National Institutes of Health, Bethesda,
M
We
evaluated use of real-time X-ray imaging fused with MRI (XFM) to guide
interventions targeting portal vein. This technique uses roadmaps from
MRI-derived data to provide roadmaps during conventional X-ray
fluoroscopy. Using an interventional
MRI/X-ray suite equipped Siemens Espree MRI scanner and AXIOM Artis dFC. After placement of multimodality external
fudicial markers over abdomen, 3D gradient echo images were acquired for marker
visualization and contrast-enhanced imaging was performed for portal vein
imaging. Animal was transferred to a
calibrated fluoroscopy system, while portal vein was manually segmented from MR
images. Image overlay of portal vein
with real time fluoroscopy was feasible.
15:30
3001.
Real-Time and Color-Flow Spiral MR Imaging of Peripheral Chronic Total
Occlusion (CTO)
Computer 12
Yoriyasu
Suzuki1, William R. Overall1, Juan M. Santos1,
Masahiro Terashima1, Fumiaki Ikeno1, Alan C. Yeung1,
John M. Pauly1, Stephen B. Williams1, Michael V.
McConnell1
1Stanford
University, Stanford, USA
This
study tested the feasibility of real-time spiral MRI (RT-MRI) techniques for
visualizing peripheral arteries and chronic total occlusions (CTO) lesions in
vivo in patients using RTHawk real-time system. Inflow enhancement resulted in
high, pulsatile signal in patent portions of the vessel, while CTO regions
exhibited consistently low signal. RT-color-flow-MRI showed pulsatile color
signal in the patent segment and absence of color flow in the CTO.
Post-intervention, RT-MRI confirmed vessel patency in both atherectomy and
nitinol stent cases. This study demonstrates the capability of RT-MRI to
visualize and assess peripheral CTO lesions prior to and following
interventions at 1.5 T.
14:00
3002.
A Framework for 3D Visualization of Active Catheters Using Compressed
Sensing
Computer 13
Carsten
Oliver Schirra1,2, Sascha Krueger3, Steffen
Weiss3, Reza Razavi1, Tobias Schaeffter1,
Sebastian Kozerke2
1King's
College London, London, UK; 2University and ETH Zurich, Zurich,
Switzerland; 3Philips Medical Systems, Hamburg, Germany
True
three-dimensional visualization of the full length of catheters has hitherto
been impossible given scan time constraints. Images acquired with active
interventional devices are inherently sparse therefore render Compressed
Sensing ideally suited for accelerating data acquisition.
We
propose a framework for the visualization of active catheters in 3D employing
CS to gain high undersampling factors making real-time applications feasible.
Constraints are introduced taking into account prior knowledge of catheter
geometry and catheter motion over time to improve and accelerate image reconstruction.
The potential of the method is demonstrated using computer simulations and
phantom experiments.
14:30
3003.
A New System for Passive Tracking of a Prostate Biopsy Device with
Automatic 3D Needle Position Estimation
Computer 13
Andre
de Oliveira1, Jaane Rauschenberg1, Dirk Beyersdorff2,
Wolfhard Semmler1, Michael Bock1
1Deutsches
Krebsforschungszentrum (dkfz), Heidelberg, Germany; 2Charite Campus
Mitte, Berlin, Germany
A
new passive marker system is proposed to localize the 3D needle tip position
during MR-guided prostate biopsies. Modifications to a previously existing
tracking sequence were made to allow for depth tracking of the passive marker
and to visualize the estimated position of the biopsy gun in real-time. In a
phantom experiment the error of needle tip position estimation was about 1.5
mm, with an update rate of 1 image/s. This passive concept provides a
cost-effective and simple to implement alternative that is expected to
significantly speed up and improve the precision of MR-guided prostate
biopsies.
Computer 13
Junichi
Tokuda1,2, Simon DiMaio1,2, Gregory
Fischer3, Csaba Csoma3, David Gobbi4, Gabor
Fichtinger4, Nobuhiko Hata1,2, Clare Tempany1,2
1Brigham
and Women's Hospital, Boston, Massachusetts, USA; 2Harvard Medical
School, Boston, Massachusetts, USA; 3The Johns Hopikins University,
Baltimore, Maryland, USA; 4Queen's University, Kingston, Canada
A
real-time MR imaging integrated with surgical navigation software 3D Slicer and
a MRI-compatible transperineal needle placement device using open-source
software tools is presented. The system was designed to maintain the 2D imaging
plane in parallel or perpendicular to the needle, allowing physicians to
monitor needle advancement in the tissue in real-time. The latency and
positional accuracy of the real-time image were evaluated by using a phantom in
a 3T closed-bore scanner. The study showed that it is feasible to integrate the
system using the open-source software tools, providing enough capability to
guide prostate biopsy and brachytherapy.
15:30
3005.
Control of Intravascular Catheters Using a 3D Array of Active Steering
Coils
Computer 13
Natalia
Gudino1,2, Jeremiah A. Heilman1,3,
Jamal J. Derakhshan1,3, Jeffrey L. Sunshine3,
Jeffrey L. Duerk1,3, Mark A. Griswold1,3
1Case
Western Reserve University, Cleveland, USA; 2University Hospitals
Case Medical Center, Cleveland , USA; 3University Hospitals Case
Medical Center, Cleveland, USA
One
of the challenges of endovascular procedures is directing a catheter tip into
small or complicated blood vessels. The strong magnetic field of MRI systems
provides a special environment that can be used to enable remote control of a
catheter. In the present work we propose a 3D array of steering coils as a
potential solution for remote control of catheters in an Interventional MRI
setting. We also demonstrate methods for visualization of the catheter and/or
surrounding areas.
14:00
3006.
Catheter Steering in MRI Using Longitudinal Current Loops
Computer 14
Michael
Vi-Nguyen Truong1, Kevan Anderson2, Mihaela Pop2,
Hartwig Peemoeller1, Alexander Dick3, Graham A. Wright2
1University
of Waterloo, Waterloo, Canada; 2University of Toronto, Toronto,
Canada; 3Sunnybrook Health Sciences Centre, Toronto, Canada
Electrical
mapping and RF ablation of the heart requires precise maneuvering and steering
of a catheter. We have developed a
method for steering a catheter that exploits the static magnetic field of an MR
scanner by looping a wire around the wall of a catheter (along the longitudinal
axis) and applying a DC electric current.
Lorentz forces cause a separation between the portions of the wire inside
and outside of the catheter, resulting in a deflection. Deflections of ~4 cm are achievable with 50
mA of current in the transverse plane perpendicular to the magnetic field.
14:30
3007.
A 3-DOF MR Compatible Limb Positioning Manipulator to Facilitate Magic
Angle Experiments in Vivo
Computer 14
Haytham
Elhawary1, Zion Tsz Ho Tse1, Aleksandar Zivanovic1,
Marc Rea1, Brian L. Davies1, M Paley2, G
Bydder3, Ian Young1, Michael Lamperth1
1Imperial
College London, London, UK; 2Sheffield University, Sheffield, UK; 3UCSD,
USA
Magic
angle studies provide useful clinical information about tissues such as
tendon. We describe a system which can
be used in an MRI system to orientate a patient¡¦s limb to map signal changes
with angle. So that most of the
patient¡¦s body does not have to move it uses three driven axes (using novel
air motors) for positioning. Motion is
constrained by the size of the machine DSV, the bore of the machine and the
desire to keep imaging near the machine center using a computer-based algorithm. In vivo data from an early prototype is
shown.
15:00
3008.
The Development of Bone Cement for the Interventional MRI
Computer 14
Florian
Wichlas1, Christian Seebauer1, Rene Schilling1,
Jens Rump1, jens Pinkernelle1, Florian Streitparth1,
Ioannis Papanikolaou1, Sascha Chopra1, Ulf Teichgräber1,
Hermann Joseph Bail1
1Charité
Berlin, Berlin, Germany
As
bone cement is widely used in musculoskeletal surgery but has no signal in the
MRI, it cannot be directly visualized during intervention. In order to
establish vertebroplasty and cancer surgery in the open MRI, visible cement
becomes necessary.
Several
contrast agents were added to PMMA cement in order to create a signal in the
MRI. Gd-DOTA, Gd-BOPTA, Mangafodipir and manganese were used.
PMMA
bone cement can be prepared in order to give a positive contrast in the MRI.
This cement may improve safe intervention in the open MRI, and allow early
coping of complications due to leaking.
15:30
3009.
Three-Dimensional Localization of MR-Visible Markers with Potential
Applications in Position Tracking: Feasibility, Speed, and Precision
Computer 14
Harald
Busse1, Wilfried Gründer2, Nikita Garnov2,
Michael Moche1, Thomas Kahn1
1Leipzig
University Hospital, Leipzig, Germany; 2Leipzig University, Leipzig,
Germany
The
purpose was to evaluate the performance of an image feature discrimination
based on 2D-Gaussian peak fitting for fast localization of MR-visible markers
and to determine its reliability and spatial precision using
inductively-coupled RF micro coils that were scanned over a wide range of
positions/orientations. By using a 128-matrix, half-Fourier balanced SSFP
sequence, acquisition and localization could be performed in <1.0 sec with
submillimeter precision. Therefore, that approach provides a relatively simple,
flexible, and safe way for selected applications, such as the tracking of
patient motion or interventional instruments/devices, that do not require
extremely fast position updates.
Hall D Tuesday 13:30-15:30
13:30
3010.
Clinical Use of Robot Assistance in MR Image-Guided Microwave
Thermocoagulation Therapy of Liver Tumors
Computer 11
Shigehiro
Morikawa1, Toshiro Inubushi1, Koichiro Murakami1,
Shigeyuki Naka1, Yoshimasa Kurumi1, Tohru Tani1,
Hasnine A. Haque2, Junichi Tokuda3, Nobuhiko Hata3
1Shiga
University of Medical Science, Ohtsu, Japan; 2GE Yokogawa Medical
Systems, Hino, Japan; 3Brigham and Women's Hospital, Boston,
Massachusetts, USA
We
have developed a motorized robot with a virtual remote-center-of-motion (RCM)
control to assist the choice of the puncture route in MR image-guided microwave
thermocoagulation therapy of liver tumors. After the certification of MR
compatibility, accuracy and safety, we have commenced the clinical use of this
robot and the results were feasible. Our navigation software showed the treated
and untreated areas of the tumor. We could set the target point in this
software and directly instruct this point to the robot. The robot immediately
led the surgeon to this point and the procedure completed accurately and
quickly.
Computer 11
Eric
Delabrousse1, Rares Salomir1, Alain Birer1,
Christian Paquet2, Cyril Lafon1
1Inserm,
Lyon, France; 2Ecole Nationale Veterinaire, Marcy l'Etoile, France
Contact
ultrasound permits accurate control of the spatial pattern of heat deposition,
with directive and angularly controlled beams. In this study we investigated
the feasibility of percutaneous thermoablation in liver using an MR compatible
device, delivering High Intensity Contact Ultrasound (HICU). Fast MR
thermometry was used for therapy monitoring and active feedback on the applied
power. No sonication-related RF artifacts were detected in any experiment. The
standard deviation of the MR thermometry baseline was 1°C. The temperature
controller converged to the target curve and further maintained the
steady-state regime within a standard deviation of 2°C. MR followup and post
mortem histology demonstrated that all individual sonications lead to near
identical shape of the lesion (15±2 mm depth, 3cm equivalent diameter).
14:30
3012.
MR-Guided Radiofrequency Ablation of Hepatocellular Carcinoma: Long-Term
Clinical Effectiveness
Computer 11
Stephan
Clasen1, Andreas Boss1, Christina Schraml1,
Jan Fritz1, Diethard Schmidt1, Fritz Schick1,
Claus D. Claussen1, Philippe L. Pereira1
1University
of Tübingen, Tübingen, Germany
MR-guided
radiofrequency (RF) ablation in the treatment of hepatocellular carcinoma (HCC)
was evaluated. The entire ablation procedure was performed in an interventional
0.2-Tesla open MR-system. In 20 patients 28 HCC with a mean diameter of 2.8 cm
were treated. Technique effectiveness was achieved in 27/28 HCC (96.4%)
evidenced by dynamic MR imaging at 1.5-Tesla four months after RF ablation. At
a mean follow-up of 24.2 months (range: 6 – 52 months) 26/28 HCC (92.9%) showed
a complete coagulation. In conclusion, MR-guided RF ablation is an effective
therapy option in the treatment of HCC.
15:00
3013.
MRI Monitoring and Mathematical Modeling to Predict Tissue Lesion Size
from Laser Thermal Ablation
Computer 11
Simi
Paul1, Jeong Joon Park2, Stephen R. Yutzy,12,
Ravi Patel2, Sherif G. Nour1,2, Fadi W.
Abdul-Karim1, Gerald M. Saidel2, Jeffrey L. Duerk,12
1University
Hospitals Case Medical Center, Cleveland, Ohio, USA; 2Case Western
Reserve University, Cleveland, Ohio, USA
This
study demonstrates how a mathematical model together with MR imaging can
predict lesion size from thermal ablation of a tumor in tissue. Rabbit
paraspinal muscles, with and without implanted VX-2 tumor, were thermally
ablated. Model-based computer simulations of temperature and cell death
dynamics via MR phase and magnitude images were used to follow lesion size
development. Final lesion size predicted by computational analysis correspond
closely with histopathological analysis. Since MR imaging and simulations can
be accomplished in seconds, this approach has potential for real-time prediction
of the lesion boundary during laser thermal ablation in clinical application.
13:30
3014.
MRTI Evaluation of SPIO Core Gold Coated Nanoshells for Thermal Therapy
and as T2* Contrast Agent
Computer 12
Andrew
M. Elliott1, Anil M. Shetty1, Marites P. Melancon1,
Xiaojun Ji1, Brian Taylor1, John D. Hazle Hazle1,
Chun Li1, R. Jason Stafford1
1University
of Texas M.D. Anderson Cancer Center, Houston, USA
Laser
Induced Thermal Therapy (LITT) is used in conjunction with gold-silica
nanoshells that have superpaprmagnetic iron oxide cores (SPIO). The optical properties of these nanoshells
and their high absorbance in the near infra-red make them ideal for use in
thermal therapy. The SPIO core alters
the susceptibility and therefore the T2* value in regions where the nanoshells
collect. The aim of this work is to
validate and characterize the thermal response characteristics of these
nanoparticles and to investigate their use as a T2* contrast agent.
Computer 12
Yi
Feng1, Eun-Kee Jeong2, Lyska Emerson2,
Zheng-Rong Lu
1Unviersity
of Utah, Salt Lake City, USA; 2Unviersity of Utah, USA
Biodegradable
macromolecular contrast agents (BMCA) alleviate this toxicity problem of macromolecular contrast agents by in vivo
degradation. (Gd-DTPA)-cystamine copolymers (GDCC at 40 KDa) was used to assess
the acute response from tumor and to correlate it with residual tumor.
14:30
3016.
A Fast Phase-Correction Algorithm for Improved Real-Time PRF Shift
Thermometry
Computer 12
Roger
Jason Stafford1, Roger J. McNichols2, Ashok Gowda2,
John D. Hazle1
1The
University of Texas M. D. Anderson Cancer Center, Houston, Texas, USA; 2BioTex,
Inc., Houston, Texas, USA
A
fast, simple loco-regional phase-correction algorithm for proton resonance
frequency shift based magnetic resonance temperature imaging is tested in in
vivo animal and human experiments to evaluate its potential to decrease the
artifact in PRF thermometry due to motion, tissue swelling and drift. The technique is purely post-processing based
and does not rely on specific acquisition techniques. Initial results relying on phase-correction
only and no image registration show both a qualitative and quantitative
increase in the quality of the PRF temperature map.
15:00
3017.
Absolute MR Thermometry Using Time Domain Analysis of the Multi
Gradient-Echo Modulus Signal
Computer 12
Sara
Maria Sprinkhuizen1, Chris J. Bakker1, Lambertus
Wilhelmus Bartels1
1University
Medical Center, Utrecht, Netherlands
The
modulus signal of a multi gradient-echo (mFFE) sequence contains spectral
information of the substances involved. In substances containing two components
of which only one has a temperature dependent resonance frequency, e.g. in
tissue containing water and fat, the frequency difference ∆f between
the peaks in the spectrum of the mFFE signal thus provides a measure of the
absolute temperature. To proof this principle, absolute temperature maps of
ethylene glycol are computed, using time domain analysis of multi gradient-echo
modulus signal. This technique yielded absolute temperature maps which were
insensitive to field disturbances and field drift.
13:30
3018.
Temperature Mapping with IDEAL Water-Fat Phase Differences
Computer 13
Brian
J. Soher1, Cory Wyatt1, Scott B. Reeder2,
James R. MacFall1
1Duke
University, Durham, North Carolina, USA; 2University of Wisconsin,
Madison, Wisconsin, USA
Tissues
containing both water and lipids, e.g. breast, confound standard MR phase
methods for mapping temperatures. We demonstrate temperature changes in a
water-fat phantom using an IDEAL acquisition. Active heating was applied in an
OFF-ON-OFF pattern over 60 minutes. Water-fat phase angle changes were used to
calculate temperature change. Calculated IDEAL-Temp values adjacent to the
Luxtron probe showed excellent agreement. IDEAL water-fat methods which use fat
as an internal frequency drift reference show great promise for improving MR
thermometry in fatty tissues such as breast.
14:00
3019.
A High Spatiotemporal Chemical Shift Imaging Technique for MR-Guided
Thermal Therapy with Multi-Parametric Monitoring Capabilities
Computer 13
Brian
Allen Taylor1, Ken-Pin Hwang,12, Andrew M. Elliott1,
Anil Shetty1, John D. Hazle1, Roger Jason Stafford1
1The
University of Texas M.D. Anderson Cancer Center, Houston, USA; 2GE
Healthcare Technologies, Waukesha, USA
A
chemical shift imaging (CSI) technique for magnetic resonance temperature
imaging is presented with spatiotemporal resolutions comparable to complex
phase difference (CPD) methods. This technique takes a novel approach to
frequency estimation for temperature measurements via autoregressive moving
average (ARMA) modeling to overcome limitations seen in low spectral
resolution, Fourier-based frequency estimation methods. Also, additional measurements such as T1 and
R2* can be simultaneously acquired with the PRF to facilitate a
multi-parametric approach to temperature imaging.
Computer 13
Mathieu
Burtnyk1,2, Rajiv Chopra1,2,
Michael Bronskill1,2
1Sunnybrook
Health Sciences Centre, Toronto, Canada; 2University of Toronto,
Toronto, Canada
The
goal of this work is to use numerical simulations and 3D patient-specific
models to investigate the feasibility of treating men with prostate cancer with
a transurethral ultrasound therapy device and a feedback control algorithm
based on clinically-relevant 1.5T MR thermometry temperature measurements (1°C
noise stdev, 5s sampling). For all 20
patient models, the standard deviation of the treatment error remained below
1mm, while the maximum and minimum error were usually less than 5mm,
demonstrating a high level of treatment accuracy. Treatment times are improved by a factor of
six as compared to transrectal HIFU procedures.
Computer 13
Rajiv
Chopra1,2, Kee Tang1, Aaron Boyes1,
Mathieu Burtnyk1, Laurence Klotz1, Michael Bronskill1
1Sunnybrook
Health Sciences Centre, Toronto, Canada; 2University of Toronto,
Toronto, Canada
MRI-guided
transurethral ultrasound therapy was performed in a canine model to evaluate
the accuracy (spatial and temporal) of heating using active MR temperature
feedback.
13:30
3022.
Subzero Temperature Mapping in a Cryosurgery Ice Ball by Using MR Signal
Time Course
Computer 14
Toru
Yamamoto1, Aogu Yamaguchi2, Tadashi Shimizu3
1Hokkaido
University, Sapporo, Japan; 2Hokkaido University Hospital, Sapporo,
Japan; 3Hokkaido University , Sapporo, Japan
Cryosurgery
is a technique for freezing and killing tumors by cooling the cryoprobe
inserted subcutaneously. The frozen area appears dark in MR monitoring because
the water of ice is MR-invisible. The malignant tumor becomes necrotic at
freezing temperatures below E0ºC. However, it is hard to discern the necrotic
area below E0ºC in the frozen area, so-called ice ball. To visualize the
necrotic area, we developed a method to map subzero temperatures in a black ice
ball and an agar phantom was imaged using a 0.3-T MRI every 20 s during the
cooling of the cryoprobe. The temperature at ten points around the cryoprobe
was monitored by using thermocouples and our method was confirmed.
14:00
3023.
Proton Resonant Frequency Shift and R2* in Frozen Ex Vivo Renal Tissue
at 7T
Computer 14
Elena
Kaye1,2, Stephen Lynch1, Christopher C. Caires1,
Kim Butts Pauly1
1Stanford
University, Palo Alto, USA
Image-guided
cryoablation is a minimally invasive therapy for renal cancer. Temperature
dependence of MR parameters of frozen tissue has already been studied on a low
field interventional system. In this work proton resonance frequency shift and
R2* of frozen renal tissue were studied on a 7T spectrometer. 1H frequency
changed linearly with temperature (slope -0.009 ppm/°C). Following the
transition to the solid phase, the behavior of the 1H frequency with
temperature changed from linear to exponential. R2* increased linearly with
decreasing temperature.
14:30
3024.
To Characterize the Safety Window of Focused Ultrasound When Applied to
Blood-Brain Barrier Disruption
Computer 14
HaoLi
Liu1, Po-Hong Hsu1, KoonKwan Ng, YauYau Wai, JiunJie Wang1
1ChangGung
University, KueiShan, Taiwan
High
Intensity Focused Ultrasound provided a new method for blood-brain-barrier
disruption, which might facilitate the drug delivery to the brain. However,
side effects such as hemorrhage prevent it from clinical applications. In this
study, a safety window can be characterized by the combination of
susceptibility weighted imaging and contrast enhanced T1 MRI.
15:00
3025.
SuperParamagnetic Iron-Oxide in Monitoring of Focused Ultrasound Induced
Blood-Brain Barrier Disruption
Computer 14
HaoLi
Liu1, Po-Hong Hsu1, Zeitsan Tsai1, KoonKwan Ng2,
Chia-Rui Shen1, JiunJie Wang1
1ChangGung
University, KueiShan, Taiwan; 2ChangGung Memorial Hospital, Taiwan
super
paramagnetic iron oxide particle (SPIO) was used to monitor the Blood Brain
Barrier disruption and separate it from the potentially induced brain
hemorrhage by use of susceptibility weighted imaging. SPIO-enhanced SWI
provides a T2 based approach to in vivo monitoring of the focused ultrasound
induced BBB disruption. The mismatched areas implied an area without brain
tissue damage.
Hall D Monday 14:00-16:00
14:00
3026.
Shimming Strategies for the Neck and C-Spine: a Computational Study
Computer 15
Kevin
M. Koch1, J A. Stainsby2
1GE
Healthcare, Waukesha, Wisconsin, USA; 2GE Healthcare, Toronto,
Canada
Anatomy-induced
B0 perturbations in the neck and c-spine can degrade the quality of
MR acquisitions. A computational study
is presented whereby the efficacies of different room-temperature shimming
schemes are evaluated in this anatomic region.
Static 1st-order, static 2nd-order, dynamic 1st-order, and dynamic
2nd-order shimming strategies are evaluated on a computed B0
distribution. It is shown that
slice-specific updating of only 0th and 1st-order shim terms can result in
significant improvement over static shimming scenarios in the neck and c-spine
region.
14:30
3027.
Simulating the Effect of TMS-Pulses on the Evolution of Magnetization
Computer 15
Andreas
Bungert1, Richard W. Bowtell1
1University
of Nottingham, Nottingham, UK
Transcranial
magnetic stimulation (TMS) is a method for stimulating cortical regions of the
brain using a pulsed magnetic field. In this study the influences of this field
on the evolution of nuclear magnetization have been simulated based on the
measured TMS pulse waveform and calculated spatial field variation due to the
TMS coil. The results indicate that the TMS pulse has negligible effect on the
longitudinal magnetization, but even in the case of a balanced biphasic TMS
pulse causes strong dephasing of transverse magnetization over a large region
adjacent to the coil.
15:00
3028.
Effects of the TMS Coil on MR Image Quality in Combined TMS/fMRI
Computer 15
Andreas
Bungert1, Richard W. Bowtell1
1University
of Nottingham, Nottingham, UK
By
applying MR-based field mapping to the head and simple spherical phantoms, the
passive effects of a TMS coil on the Bo- and B1-field homogeneity have been
investigated at 1.5 and 3 T, for different coil orientations. In addition
measurements of EPI time series have been used to measure the effects of the
TMS coil on the signal to noise ratio (SNR) in fMRI experiments. The results
show that the presence of the TMS coil generally has only a small effect on B1
and Bo homogeneity and global SNR.
15:30
3029.
Correcting for B0 Field Drift in MR Temperature Mapping with Oil
References
Computer 15
Brian
J. Soher1, Cory Wyatt1, Vadim Stakhursky1,
James R. MacFall1
1Duke
University, Durham, North Carolina, USA
Proton
resonance frequency shift (PRFS) temperature mapping methods are confounded by
changes in frequency not due to temperature changes, such as main B0 field
drift. We demonstrate a method that uses oil filled references that are
insensitive to temperature changes to estimate changes in B0 during hyperthermia
treatments. A minimum curvature spline surface is fitted to phase change values
in the oil references and a global B0 map is created. Phase changes not due to
temperature change are removed from the PRFS data prior to temperature
calculation. Corrections are demonstrated in both a phantom and a leg sarcoma
patient.
Hall D Monday 14:00-16:00
14:00
3030.
A Continuous Nyquist Ghost Correction for EPI-Based FMRI
Computer 16
Wietske
van der Zwaag1,2, José Marques1,2,
Tobias Kober1,2, Rolf Gruetter1,3
1Ecole
Polytechnique Federale de Lausanne, Lausanne, Switzerland; 2University
of Lausanne, Lausanne, Switzerland; 3Universities of Lausanne and
Geneva, Switzerland
The
traditional ghost correction approach based on acquiring reference k-space
lines without phase-encode gradients was supplemented with schemes based on
continually reversing read-out polarity in EPI in every other volume. Three
strategies were evaluated using fMRI data acquired at 7 Tesla, all of which
significantly reduced Nyquist ghost intensity by up to 62%, resulting in 13%
higher maximum T-scores. It is concluded that at high B0 substantial
Nyquist ghost reductions are possible by alternating the read-out gradient
amplitude every other volume, allowing continuous artefact reduction.
Computer 16
Simon
Robinson1, Jorge Jovicich1
1University
of Trento, Trento, Italy
EPI
distortions arising from local field inhomogeneities are severe at 4T (~10 mm),
but may be remedied via the field mapping and point-spread function correction
methods. We show how high quality phase images and field maps may be generated
using multi-channel data, using the multiplicity of measures of phase to
eliminate erroneous boundary pixel values. We acquired data from six subjects
over a wide range of receiver bandwidth, and corrected with the fieldmap and
point-spread function method. Using measures of boundary shape, both measures
provide excellent correction. No residual distortion was evident in the image
interior.
15:00
3032.
The Use of Three Navigator Echoes in Cartesian EPI Reconstruction
Reduces Nyquist Ghosting
Computer 16
Andrew
S. Nencka1, Andrew D. Hahn1, Daniel B. Rowe1
1Medical
College of Wisconsin, Milwaukee, Wisconsin, USA
Reconstructed
images from Cartesian echo planar imaging suffer from Nyquist ghosting because
of hardware timing errors and eddy current effects shifting the odd and even
k-space lines in opposite directions. Previous solutions to the ghosting
problem have included acquiring a reference scan with no phase encoding blips
or the omission of a phase encoding blip when the center line of k-space is
acquired. We illustrate here a method for utilizing three navigator echoes to
estimate the shifts and reduce the Nyquist ghost. This method is less
computationally intensive than the two-navigator method and yields superior
results to the reference scan methods. Like the two navigator method, this method
additionally offers the ability to measure the center frequency offset and
alternating line time shift with each image acquisition.
15:30
3033.
Reduction of Shading Artifact with Center-Out View Order for
Diffusion-Weighted PROPELLER
Computer 16
Xiaoli
Zhao1, Ajeetkumar Gaddipati1, Shaorong Chang1,
Dawei Gui1
1GE
Healthcare, Waukesha, USA
The
non-CPMG nature of diffusion-weighted PROPELLER imaging causes signal dropout
if the refocus flip angles are out of the desirable range. This is particularly
true for 3T due to B1 inhomogeneity, and shading artifact will be introduced.
In the present work, “center-out” view order is demonstrated to significantly
reduce the shading artifact. For each blade in PROPELLER acquisition, the echo
train is phase encoded in the way the early echoes are placed near the center
k-space. Center-out view order also improves the overall SNR because of the
reduced TE.
14:00
3034.
Presence and Reduction of Off-Resonance Ghosting in Magnetization
Prepared TrueFISP
Computer 17
Jamal
Jon Derakhshan1,2, Mark A. Griswold1,2,
Jeffrey L. Sunshine2, Jeffrey L. Duerk,12
1Case
Western Reserve University, Cleveland, Ohio, USA; 2University
Hospitals Case Medical Center, Cleveland, Ohio, USA
Magnetization
storage during bSSFP acquisitions has opened the door to various manipulations
of the steady state signal. First, we demonstrate that conventional periodic
magnetization preparation during TrueFISP acquisitions using α/2 at TR/2
pulses can lead to significant ghosting (>1/2 amplitude of object) of
off-resonant spins. Second, simulations and experimental results demonstrate
the amplitude of the ghosts can be reduced to near the non-prepared bSSFP
levels by partially randomizing the number of readouts collected between
magnetization preparations. Phantom and human in-vivo images demonstrate both
the ghosting in regularly prepared bSSFP acquisitions and the significant
reductions afforded by the proposed randomization scheme.
14:30
3035.
Slice Offset Frequency Adjustment (SOFA) for SSFP Imaging
Computer 17
Martin
John Graves1, Pauline Wong1, David John Lomas1
1University
of Cambridge and Addenbrooke's Hospital, Cambridge, UK
Steady
state free precession (SSFP) imaging is limited by off-resonance artifacts,
particularly away from isocenter. We have developed a simple method to
characterize the frequency offset as a function of position away from
isocenter, using a uniform phantom. This correction is then applied to the
scanner center frequency (f0) in either a multi-slice prescription or as part
of a interactive imaging study. Initial evaluation in a phantom and normal
volunteers shows a substantial reduction in artifacts when using this
pre-determined correction.
Computer 17
Leland
S. Hu1, John p. Karis1, Donglai Huo1, Zhiqiang
Li2, Eric Aboussouan1, Nabeel Farhataziz1,
Josef Debbins1, Roger Bird1, Jeff Ross1, James
Pipe1
1Barrow
Neurological Institute, Phoenix, USA; 2General Electric Corporation,
Milwaukee, USA
Conventional
Cartesian methods for T1W contrast-enhanced magnetic resonance imaging (CE-MRI)
produce flow-related phase artifacts which both obscure and simulate true
pathologic lesions. PROPELLER MRI
scanning techniques substantially diminish the perceptibility of flow-related
phase artifacts on T1W CE-MRI compared to conventional techniques. Further work is necessary to determine if
these differences result in significant changes in accuracy of lesion
detection.
Computer 17
Qi
Duan1,2, Anand S. Patel3, Andrew Francis Laine1,
Philip M. Robson3, Charles A. McKenzie4, Daniel K.
Sodickson2
1Columbia
University, New York, New York, USA; 2New York University Medical
Center, New York, New York, USA; 3Beth Israel Deaconess Medical
Center and Harvard Medical School, USA; 4University
of Western Ontario
Parallel
acquisitions involve well-known tradeoffs between acceleration and
signal-to-noise ratio (SNR). The principal component technique offers a rapid
approach to noise reduction using information about the coil sensitivity
encoding process. However, this method has in the past required an
unaccelerated reference image. We have demonstrated a method based on dyadic
wavelet expansion to adaptively derive the reference image from the accelerated
one, thereby increasing ease of use. The
new method also yielded sharper and more detailed image structures after noise
reduction. Overall, the approach is a promising candidate for adaptive and
rapid noise reduction in highly accelerated images.
Image Analysis - Parametric Mapping
Hall D Monday 14:00-16:00
14:00
3038.
A Novel Method of Combining Multi-Coil MRI Images: The Level-Weighted
Wavelet Fusion
Computer 18
Jeong
Hwan Bang1, Andy Stenger, Todd Reed
1University
of Hawaii, Honolulu, Hawaii, USA
Multi-coil
MR images are conventionally combined using a magnitude sum. A problem with
this approach is the loss of contrast due to the global lowpass filtering
operation. Wavelet methods have been shown to be useful for reducing receiver
sensitivity inhomogeneity in multi-coil applications, but not much work has
been done to alleviate the loss of resolution. We present a novel
Level-Weighted Wavelet Fusion (LWWF) scheme to address this. We show that the
method is successful improving the contrast in multi-coil brain images at 3T.
14:30
3039.
Hepatocyte Growth Factor Gene Delivered Intramyocardially Improves
Cardiac Function and Strain on MR Imaging
Computer 18
Marcus
Carlsson1, Nael Osman2, David Saloner1,
Alastair J. Martin1, Loi Do1, Maythem Saeed1
1University
of California San Francisco, San Francisco, California , USA; 2Johns
Hopkins University, Baltimore, Maryland, USA
In
animal models and patients with AMI, left ventricular (LV) remodeling is
accompanied by interstitial fibrosis in remote myocardium. Such fibrosis in
remote myocardium is considered to be a major histological landmark resulting
in cardiac dysfunction after AMI. Previous studies have shown that VEGF has a
potent effect on angiogenesis, but no effect on fibrosis, whereas the other
angiogenic growth factor bFGF stimulates fibrosis. On the other hand,
hepatocyte growth factor (HGF) has dual effects, namely angiogenic and
antifibrotic effects. In this study MR imaging has been used to determine the
effects of intramyocardial HGF gene therapy transferred by plasmid DNA on left
ventricular function and strain. Intramyocardial injection of plasmid
expressing HGF improved LV global function and prevents LV remodeling
associated with infarction. It also improved regional strain in both
peri-infarcted and infarcted regions.
15:00
3040.
Fast and Accurate Voxel-By-Voxel Perfusion Imaging Using Convolution
Models
Computer 18
Artem
Mikheev1, Henry Rusinek1
1NYU
School of Medicine, New York, New York, USA
Modeling
of the perfusion using dynamic contrast-enhanced imaging based on convolution
models is gaining increasing attention. To improve the computational speed and
be able to control the convolution error due to discrete sampling we have
developed and implemented the adaptive convolution algorithm. Algorithm was tested on the kidney perfusion
model and MR renography acquisition. It
enables fast and accurate analysis of DCE MR datasets.
15:30
3041.
ADC Histogram Derived RGB Color-Maps for Characterizing Low Grade Glioma
Subtypes
Computer 18
Inas
S. Khayal1,2, Tracy R. McKnight1, Wei Bian1,
Soonmee Cha1, Susan M. Chang1, Sarah J. Nelson1
1University
of California, San Francisco, San Francisco, California , USA
Low
grade gliomas are a heterogeneous group of brain tumors with variable prognosis
and response to therapy. Prior studies have reported that the Apparent
Diffusion Coefficient (ADC) may aid in subtyping low-grade gliomas. The goal of
this study was to use ADC histograms from patients with astrocytoma and
oligodendroglioma to generate RGB color-maps showing astrocytoma-like and
oligodendroglioma-like regions. Because biopsies are limited to a very small
piece of tissue, this technique allows for the visualization of the
biologically different regions within the whole tumor mass, which may aid in
image-guided biopsies, assessment of treatment response or prognosis of
clinical outcome.
14:00
3042.
Visceral Fat Quantification on MRI: The Impact of Partial Volume Effect
Computer 19
Qi
Peng1, Anqi Zhou1, Yao Ding2, Roderick W.
McColl2, Paul T. Weatherall2
1UT
Health Science Center at San Antonio, San Antonio, Texas, USA; 2UT
Southwestern Medical Center at Dallas, Dallas, Texas, USA
MR
images are generally known to have lower spatial resolution than CT images.
This greatly reduces the accuracy of visceral fat measurement on MRI since
partial-volume fat may contribute a significant part to the total visceral fat.
By employing a novel fat quantification strategy, we estimated the number of
full- and partial–volume fat pixels (Nf and Np,
respectively) in visceral area on 9 healthy volunteers. It is found that the
average Np is more than twice the average Nf (Np/Nf=2.1),
and fat volume from partial-volume fat voxels is 104.0% of that from
full-volume voxels. Therefore, partial volume effect is significant on MR
images with typical spatial resolution.
14:30
3043.
On Automatic Regional Analysis of Quantitative Relaxation Times Mapping
in the Brain
Computer 19
Benjamin
Segun Aribisala1, Jiabao He1, Peter E. Thelwall1,
Kieran G. Hollingsworth1, Andrew M. Blamire1
1Newcastle
University, Newcastle upon Tyne, UK
Quantitative
assessment of MR images is an important step in the analysis of many types of
scan data. A significant step in many
methods is registration of the individual brain to a standard space. Image
registration requires smoothing and re-sampling and introduces partial volume
effects, biasing analysis. Here we
propose an automatic division into ROIs and we use the inverse process whereby
regions of interest in standard space are registered to the individual, thereby
analyzing each brain in its own real space. This approach reduces partial
volume errors while taking into account variations in brain shapes and sizes.
Computer 19
Sandra
M. Meyers1, Cornelia Laule2, Irene M. Vavasour2,
Shannon H. Kolind2, Burkhard Maedler3, Roger Tam2,
Jimmy S. Lee2, Anthony L. Traboulsee2, David K.B. Li2,
Alex L. MacKay2
1University
of Alberta, Edmonton, Canada; 2University of British Columbia,
Vancouver, Canada; 3Philips Medical Systems, Vancouver, Canada
We
compared region of interest (ROI) and pixel-by-pixel (PBP) analysis methods for
myelin water fraction (MWF) determination. 20 controls were scanned twice using
multi-echo T8-relaxation. For ROI-analysis, the mean pixel intensity
within an ROI was fit using NNLS. In PBP-analysis, MWF was obtained for each
pixel and the mean value within an ROI was calculated. PBP-analysis was more
reliable among 4 different observers and gave a higher correlation, and a 3
times lower mean square difference between scans. As the PBP-method is more
reproducible and gives more options for visualization and analysis of MWF, it
is recommended over the ROI-method.
15:30
3045.
Feasibility of Rapid B1 Mapping with RF Prepulse Tagging
Computer 19
Xin
Chen1, Xingxian Shou1, Wayne R. Dannels2
1Case
Western Reserve University, Cleveland, USA; 2Toshiba Medical
Research Institute USA, Inc, Cleveland, USA
A
B1 mapping technique which is fast and tolerant of patient motion is desired
for measuring B1 field per subject due to the dependence of the B1 field
patterns upon the sample. In this work, we propose an accurate and efficient
method of 2-D B1 mapping with RF prepulse tagging. Our simulation shows that
the calculated B1 profile agrees with the pre-assumed B1 profile very well. We
also perform an error analysis to study the precision of our algorithm in the presence of noise.
14:00
3046.
Imaging and Analysing Iron Accumulations in the Human Brain Using
Magnetic Resonance Imaging
Computer 20
Guenther
Grabner1, Dietrich Haubenberger1, Eduard Auff1,
Siegfried Trattnig1
1Medical
University of Vienna, Vienna, Austria
This
work is about analyzing (phase-shift and phase-shift-symmetry) iron
accumulations in brains of patients with Parkinson's disease (PD) and healthy
controls by using susceptibility-weighted imaging phase. In order to perform
image based phase-shift-symmetry comparisons and prevent bias due to shape
differences, a symmetric phase model was build. All data-sets were non-linearly
registered to the symmetric model and 3D correlation coefficients were used to
determine symmetry (in the area of the Putamen). Phase-shift symmetry is a
possible marker for unilaterally PD and largely independent of absolute
phase-values. Phase-shift analysis show an increasing phase-shift (in anterior-
posterior direction) within the Putamen.
14:30
3047.
AnalyzeNNLS: Software Designed to Simplify Multiexponential Decay Image
Analysis
Computer 20
Thorarin
A. Bjarnason1, J Ross Mitchell1
1University
of Calgary, Calgary, Canada
Multiecho
MR studies provide unique insight into tissue microstructure. Two major hurdles
prevent scientists from applying this technique in their research: creating the
pulse program and developing the analysis technique. We provide a solution to
the latter issue by creating an easy to use, cross-platform software package,
called AnalyzeNNLS, capable of analyzing multiexponential decays. This software
allows scientists to perform region of interest analysis on multiecho,
multislice data, thus allowing them to focus on the sciences of MRI and
biology.
15:00
3048.
Accurate Estimation of T1 from SPGR Signals
Computer 20
Lin-Ching
Chang1,2, Cheng Guan Koay2, Peter J. Basser2,
Carlo Pierpaoli2
1The
Catholic University of America, Washington, District Of Columbia, USA; 2NICHD,
National Institutes of Health, Bethesda, USA
T1
can be estimated from two or more SPGR images acquired with different flip
angles and/or repetition times. However, T1 estimated by a widely-used linear
method is biased due to improper accounting for noise in the fitting. This bias
can be significant for clinical SPGR images, for example, T1 estimated in brain
tissue (800~1600ms) can be over-estimated by 10-20%. We propose a weighting
scheme that correctly accounts for the noise contribution in the fitting
procedure. Simulations of SPGR experiments are used to evaluate the accuracy of
the estimated T1 from the widely-used linear, the proposed weighted-uncertainty
linear, and the nonlinear methods.
15:30
3049.
Quantitative Estimation of Prostate Cancer Using Inner Product of
Intervoxel Eigenvector (IPIE) Method
Computer 20
Koji
Ishihara1, Mikio Suga1,2, Riwa Kishimoto2,
Susumu Kandatsu2, Hiroshi Tsuji2, Hiroo Ikehira2,
Takayuki Obata2
1Chiba
University, Chiba, Japan; 2National Institute of Radiological
Sciences, Chiba, Japan
The
apparent diffusion coefficient (ADC) provides the possibility of adding
information for an accurate diagnosis of prostate cancer. The ADC use only
eigenvalues from the DTI information. Itfs suspected that the structure will
show deformities if prostate cancer exists. Eigenvectors of the DTI might be
applicable to estimate tissue structures. We propose the quantitative
evaluation method, the inner product of intervoxel eigenvector (IPIE) method,
to assess structural tissue changes from eigenvectors. The IPIE values in the
prostate cancer region are significantly changed before and after carbon-ion
radiotherapy. These results suggest the IPIE method can quantitatively evaluate
changes of tissue structure.
14:00
3050.
Tagged Helium-3 MRI Analysis for Pulmonary Kinematic Quantitation
Computer 21
Nicholas
James Tustison1, Jing Cai2, Tally A. Altes1,
G. Wilson Miller2, Eduard E. de Lange2, John P. Mugler
III2, James C. Gee1
1University
of Pennsylvania, Philadelphia, Pennsylvania, USA; 2University Of
Virginia, Charlottesville, Virginia , USA
Tagged
helium-3 is used to quantify pulmonary kinematics. Sample results including visuals illustrate
the feasibility of our approach.
Computer 21
Arvind
Balachandrasekaran1, Nathan Allen Pack1, Edward V.R
DiBella1
1University
of Utah, Salt Lake City, USA
In
this paper,complete blind and partial blind estimation were compared for
estimating the kinetic parameters.The first method (complete blind) estimates
the Arterial Input Function (AIF) completely whereas the second method (partial
blind) estimates only the samples around the peak because
gadolinium
concentration is non-linearly proportional to the signal intensity changes near
the peak.
The
kinetic parameters estimated from partial blind estimation had a higher
correlation with the truth than those obtained from complete blind estimation.
15:00
3052.
Model Based Blind Estimation of Kinetic Parameters
Computer 21
Jacob
Fluckiger1, Matthias Schabel1, E.V.R. DiBella1
1University
of Utah, Salt Lake City, USA
This
work introduces a novel functional form for the arterial input function
consisting of two gamma variate curves and a sigmoid curve. This model is then
applied in iterative blind estimation to determine perfusion kinetic
parameters. The blind estimation technique used alternately estimates
parameters for the input function and the tissue concentration. The kinetic
parameter estimates were compared with “truth” obtained from standard
deconvolution. The average kinetic parameter variance between the two methods
was less than 10%, suggesting blind estimation may be confidently used in
situations where a directly measured AIF is not easily obtained.
15:30
3053.
Optimal Processing to Derive Static PC-MRA from Time-Resolved 3D PC-MRI
Data
Computer 21
Jelena
Bock1, Oliver Wieben2, Kevin M. Johnson2,
Juergen Hennig1, Michael Markl1
1University
Hospital, Freiburg, Germany; 2University of Wisconsin-Madison, USA
The
purpose of this study was to implement and to evaluate several algorithms for
the optimal extraction of PC-MRA data from flow-sensitive 4D MRI, since PC-MRA
has proven to be a useful alternative to contrast-enhanced MRA. All algorithms
were implemented within an interactive pre-processing tool and could be
combined with additional noise masking and static tissue-removal. Results of
all algorithms were compared and evaluated based on data sets with different
SNR.
14:00
3054.
Improved Field Map Estimation in the Presence of Multiple Spectral
Components
Computer 22
Diego
Hernando1, Peter Kellman2, Justin Haldar1,
Zhi-Pei Liang1
1University
of Illinois at Urbana-Champaign, Urbana, Illinois, USA; 2National
Institutes of Health, Bethesda, Maryland, USA
B0
field map estimation in the presence of multiple spectral components is an
important and challenging problem in MRI, e.g., for cardiac and abdominal
imaging, where the B0 field may contain large variations across the image. This
paper presents a novel method for regularized field map estimation, which
formulates the estimation of the complete field map as a joint problem (instead
of, e.g., voxel-by-voxel estimation followed by smoothing). In vivo cardiac
results demonstrate good robustness of the proposed method.
14:30
3055.
Fast Susceptibility Weighted Imaging: FSWI
Computer 22
Frederik
Testud1, Jürgen Hennig1, Maxim Zaitsev1
1University
Hospital Freiburg, Freiburg, Germany
Susceptibility
weighted imaging (SWI) show a strong contrast between gray and white matter.
SWI experiments are typically performed with a gradient recalled echo sequence.
The image phases are highly affected by B0 fluctuations and
sometimes by phase wraps which are leading to long measurement and computation
times. We propose a method to obtain phase contrast images with a standard EPI
sequence. The method has the advantage of rapid data acquisition and a fast
computation, and is referred to as fast SWI (FSWI).
15:00
3056.
A Fast and Robust Method for Quantifying Magnetic Susceptibility of
Arbitrarily Shaped Objects Using MR
Computer 22
Jaladhar
Neelavalli1, Yu-Chung Norman Cheng1, Ewart Mark Haacke1,2
1Wayne
State University, Detroit, USA; 2The Magnetic Resonance Imaging
Institute for Biomedical Research, Detroit, USA
We
present here a novel, fast and robust method for quantifying the magnetic
susceptibility of arbitrarily shaped objects using MR.
15:30
3057.
Robust and Mask Free Phase Unwrapping Technique Dedicated to B0
and T8+ Phase Imaging
Computer 22
Cyril
Poupon1,2, Christopher Wiggins1,2,
Myriam Chaumeil1, Valdis Gudmundsdottir1,2,
Fabrice Poupon1,2
1CEA
NeuroSpin, Saclay, France; 2IFR49, Saclay, France
The
phase unwrapping problem occurs in different engineering domains. It can be
applied directly into clinical practice (e.g. in MR angiography), but also, it
can be used to estimate and adjust various MR acquisition related parameters,
or to correct for some image acquisition artifacts such as susceptibility
artifacts. Existing unwrapping techniques often involves the use of masks of
the brain that are not necessarily easy to obtain.We introduced a fast and
robust technique for unwrapping phase that do not necessitate employment of
region masks and applied the technique to the phase signal of GRE data acquired
at 7T.