| Molecules & Cells: Novel Imaging Methods |
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Friday 24 April 2009 |
| Room 323ABC |
10:30-12:30 |
Moderators: |
Jeff W. M. Bulte and Peter M. Jakob |
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10:30 |
802. |
SWIFT Detection of SPIO
Labeled Stem Cells Grafted in the Myocardium |
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Rong Zhou1,
Djaudat Idiyatullin2, Steen Moeller2,
Curt Corum2, Hualei Zhang1,
Michael Garwood2
1Labotories of Molecular Imaging, Department
of Radiology, University of Pennsylvania,
Philadelphia, PA, USA; 2Center for
Magnetic Resonance Research , University of
Minnesota, Minneapolis, MN, USA |
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We demonstrate the
feasibility of (SWIFT) based detection of
superparamagnetic iron-oxide (SPIO) labeled stem
cells in the heart. We show that SWIFT allows
3-dimensional imaging of SPIO labeled cells while
simultaneously presenting T1-weighted signal of
myocardial wall. Compared to T2*W GRE images, SWIFT
magnitude images suppress the susceptibility
artifacts leading to better delineation of stem cell
distribution while SWFT imaginary images present an
enhanced (positive) boundary between regions
containing high concentration of SPIOs and the
surrounding myocardium. |
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10:42 |
803. |
Fast Positive-Contrast Imaging
of SPIO-Labeled Cells with Low-Angle Alternating-TR
SSFP |
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Tolga Çukur1,
Mayumi Yamada2, William R. Overall1,
Phillip Yang2, Dwight G. Nishimura1
1Electrical Engineering, Stanford University,
Stanford, CA, USA; 2School of Medicine,
Stanford University, Stanford, CA, USA |
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There has been recent
interest in positive-contrast MRI methods for
tracking cells labeled with super paramagnetic iron
oxide (SPIO) nanoparticles. High off-resonant signal
can be generated by utilizing the low-angle SSFP
response to achieve fast high-resolution imaging.
However, the positive contrast is compromised by the
limited suppression of on-resonant and fat signals.
In this work, we investigate an improved technique
based on alternating-TR SSFP to achieve reliable
background suppression. Sensitivity measurements are
performed, and phantom and in vivo data are
presented to demonstrate the reliability of the
generated contrast. |
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10:54 |
804. |
UTE Imaging for Single Cell
Detection with Positive Contrast |
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Clemens Diwoky1,
Andreas Reinisch2, Dieter Gross3,
Volker Lehmann3, Dirk Strunk2,
Rudolf Stollberger1
1Inst. of Medical Engineering, TU Graz, Graz,
Austria; 2Stem Cell Research Unit, Dept.
of Hematology, Univ. Clinic of Internal Medicine,
Medical University of Graz, Graz, Austria; 3Dept.
of Microimaging, Bruker BioSpin GmbH, Rheinstetten,
Germany |
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For the detection of
single SPIO loaded cells 3D GRE sequences with small
isotropic imaging volumes are essential.
Unfortunately they are highly time consuming and not
applicable in a clinical setup. An alternative are
2D GRE acquisitions with enlarged slices. However,
signal variations caused by global SPIO induced
field inhomogeneities reduce their usefulness for
cell detection. To enhance detectability, we propose
the use of 2D UTE sequences with positive SPIO
contrast. As a visual benchmark, the outstanding
performance of UTE compared to 2D GRE is shown on a
new in-vitro model consisting of cell networks build
by endothelial progenitor cells. |
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11:06 |
805. |
3D Radial
UTE Imaging for Quantification of Transplanted Iron
Oxide Labelled Islet Cells |
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Lindsey
Alexandra Crowe1, Frederic Ris2,
Sonia Nielles-Vallespin3, Peter Speier3,
Solange Masson2, Mathieu Armanet2,
Domenico Bosco22, Thierry Berney2,
Jean-Paul Vallée1,4
1Faculty of Medicine , University of
Geneva, Geneva, Switzerland; 2Cell
Isolation and Transplant Center, Department of
Surgery, Geneva University Hospital, Geneva,
Switzerland; 3Siemens AG Medical
Solutions, Erlangen, Germany; 4Work
supported in part by the Center for Biomedical
Imaging (CIBM), Geneva and Lausanne, Switzerland |
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Monitoring the fate of
transplanted pancreatic Islets of Langerhans into
the liver is vital for improvement of treatment for
type 1 diabetes. MR provides quantitative,
non-invasive imaging for serial examination of iron
oxide labelled cells. In-vivo 3D difference
ultra-short echo time (dUTE) imaging gives positive,
quantifiable contrast from iron labelled islets in
rat. Between the ultra-short and ‘long’ echo times
the islet cell signal changes but the small vessels
and liver constant. Coverage of the whole liver in
the absence of cardiac and respiratory motion
artifact, and isotropic resolution provides
improvement over 2D GRE. |
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11:18 |
806. |
Multi-Color 19F
CSI: Simultaneous Detection of Differently Labeled
Cells in Vivo |
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Thomas Christian
Basse-Lüsebrink1,2, Gesa Ladewig1,
Thomas Kampf2,3, Gerd Melkus2,
Daniel Haddad4, Wolfgang Rudolf Bauer3,
Peter M. Jakob2,4, Guido Stoll1
1Neurology, University of Würzburg, Würzburg,
Germany; 2Department of Experimental
Physics 5, University of Würzburg, Würzburg,
Germany; 3Medical Clinic and Polyclinic
I, University of Würzburg, Würzburg, Germany; 4Research
Center for Magnetic Resonance Bavaria (MRB),
Würzburg, Germany |
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19F markers
provide unambiguous signal in vivo due to the
low natural abundance of fluorine in living
organisms. A further advantage of 19F molecular MRI
is that fluorine markers possess a unique spectral
signal. Therefore, chemical shift imaging (CSI)
methods can be used to distinguish between cells
labeled with different fluorine markers.
This pilot study
demonstrates the feasibility of distinguishing
between differently labeled cells in vivo in
a PT mouse model. This is possible by using fast and
specific multi-color CSI methods. |
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11:30 |
807. |
Dynamic
Manganese-Enhanced MRI Reveals Dominant Modulation
of Myocardial L-Type Calcium Channel Flux by
Neuronal, Not Endothelial Nitric Oxide Synthase in
Mice |
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Moriel H. Vandsburger1,
Brent A. French1,2, Christopher M. Kramer2,3,
Frederick H. Epstein1,2
1Biomedical Engineering, University of
Virginia, Charlottesville, VA, USA; 2Radiology,
University of Virginia, Charlottesville, VA, USA;
3Medicine, University of Virginia,
Charlottesville, VA, USA |
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Modulation of L-Type
Calcium Channel (LTCC) flux plays an important role
in calcium cycling and cardiomyocyte contractility.
Manganese (Mn2+) enters cardiomyocytes through the
LTCC and shorterns T1 proportionatly. Modulation of
LTCC flux by neuronal (nNOS) and endothelial (eNOS)
isoforms of nitric oxide synthase is unclear. The
uptake of Mn2+ was examined in wild type (WT), nNOS-/-,
and eNOS-/- mice at baseline and with dobutamine
using an ECG-gated saturation recovery pulse
sequence with constant repetition time (TR) of
200ms. Whereas baseline LTCC flux was higher in nNOS-/-
mice and unchanged with dobutamine, LTCCI increased
with dobutamine in WT and eNOS-/- mice. |
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11:42 |
808. |
Assessment
of Myocardial Ca2+ Dysregulation Using Mn
Enhanced MRI |
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Janaka
Wansapura1, Doug Millay1, Jeff
Molkentin1, Woody Benson1
1Cincinnati Children's Hospital Medical
Center, Cincinnati, OH, USA |
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Accumulated Mn2+ within the myocardial
tissue causes signal enhancement. In this study, we
infused delta-sarcoglycan null mice, a model for
muscular dystrophy with highly purified 20mM,
MnCl2.4H2O while TrueFISP images were being obtained
in the short axis. Compared to WT, these mice showed
significantly low rate of enhancement in the
myocardium. It is widely accepted that dystrophic
cardiomyocytes show altered Ca2+ influx.
Increased [Ca2+] cause decreased Mn2+
uptake by the heart. Thus our results demonstrate
the feasibility of assessing Ca2+
dysregulation in the dystrophic heart using Mn
enhancement. |
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11:54 |
809. |
High
Throughput MRI Method for in Vitro CEST Agent
Screening |
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Guanshu
Liu1, Assaf A. Gilad2, Jeff
W.M. Bulte2, Peter C.M. van Zijl1,
Michael T. McMahon1
1F.M. Kirby Center, Kennedy Krieger
Institute, Baltimore, MD, USA; 2Russell
H. Morgan Department of Radiology and Radiological
Science, The Johns Hopkins University School of
Medicine, Baltimore, MD, USA |
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We
developed a high throughput MRI method for screening
Chemical Exchange Saturation Transfer (CEST) agents.
This approach allows simultaneous evaluation of
multiple samples in presence of B0 inhomogeneity.
Data with and without shimming were comparable in
quality. As a first example, we screened a library
of 16 samples and were able to obtain high quality
CEST spectra with an average acquisition time of 2.6
minutes, which implies the great potential of this
method in developing CEST MRI reporter agents. |
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12:06 |
810. |
High
Resolution MR Imaging of Brain Lactate Using
Selective Saturation Transfer |
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Christopher Lascola1,2, Talignair
Venkatraman1, Sean Snodgress1,
Haichen Wang3
1Radiology, Duke University Medical
Center, Durham, NC, USA; 2Brain Imaging
and Analysis Center, Durham, NC, USA; 3Anesthesiology,
Duke University Medical Center, Durham, NC, USA |
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Lactate
is an important metabolic biomarker for a variety of
neurological disease states, and is now also
recognized as an essential substrate of neuronal
metabolism [1]. An improved MR method for mapping
brain lactate would aid the study of this important
metabolite in physiologic and pathologic conditions,
and provide a clinically relevant diagnostic tool.
13C and 1H MR spectroscopic (MRS) methods have been
used previously to measure brain lactate
concentrations but have limited temporal and spatial
resolution. The purpose of this study is to
investigate whether magnetic coupling between
lactate methyl and water protons previously reported
in MRS studies [2] and in phantoms [3] can be
exploited to generate MRI contrast specific
localized lactate accumulations. Our initial
findings show that selective radiofrequency
saturation of lactate methyl protons results in
cumulative saturation of dominant water protons via
immobilized macromolecules in both protein phantoms
and in vivo, increasing the sensitivity of
lactate detection in vivo as compared to MRS,
and enabling high resolution mapping of subtle
lactate changes in brain. |
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12:18 |
811. |
Delta
Relaxation Enhanced MR: Experimental Validation |
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Jamu K.
Alford1, Brian K. Rutt1,2,
Timothy J. Scholl1, William B. Handler1,
Blaine A. Chronik1
1Physics and Astronomy, The University of
Western Ontario, London, Ontario, Canada; 2Imaging,
Robarts Research Institute, London, Ontario, Canada |
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Herein
the first experimental validation of a new approach
to MRI molecular imaging is described. This method,
delta relaxation enhanced MRI (dreMR) uses induced
magnetic field perturbations as a means of measuring
the binding of molecule-specific MR probes such as
Vasovist and EP-2104R to their respective target
molecules. It is shown that this approach results in
unprecedented specificity to the binding state of
the contrast agent and therefore clearly
distinguishes samples containing the target molecule
from all other samples. This method has significant
implications in the areas of molecular imaging,
tumor physiology, and detection of disease. |
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