| Ultrahigh Field & High Resolution Neuroimaging |
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Monday 20 April 2009 |
| Room 316BC |
11:00-13:00 |
Moderators: |
Joseph J. H. Ackerman and Kamil Ugurbil |
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11:00 |
42. |
Investigating the Sources of Phase Contrast: Iron
Oxide Nanoparticle Study to Exclude Deoxyhemoglobin
as a Major Source for the Gray/white Matter Phase
Contrast |
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Jongho Lee1, Yoshiyuki Hirano, Masaki
Fukunaga1, Afonso Silva, Jeff H. Duyn1
1Advanced MRI/LFMI/NINDS, National Institute
of Health, Bethesda, MD, USA |
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An
intravascular contrast agent (iron oxide
nanoparticle) was used to investigate the sources of
phase contrast. The result indicates that deoxy-hemoglobin
is not a major source for the white and gray matter
contrast. |
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11:12 |
43. |
Susceptibility Weighted Imaging of the Human Brain
at 9.4T |
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Juliane Sabine Budde1,
Rolf Pohmann1, Gunamony Shajan1,
Kâmil Ugurbil2
1Magnetic Resonance Center, Max Planck
Institute for Biological Cybernetics, Tuebingen,
Germany; 2Center for Magnetic Resonance
Research, University of Minnesota, Minneapolis, MN,
USA |
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Susceptibility weighted
imaging benefits from ultra-high field in terms of
increased contrast-to-noise ratio and SNR. High
resolution phase images with up to 0.175mm x 0.175mm
in-plane resolution were acquired at a 9.4T scanner
using a 3D velocity compensated gradient echo
sequence. The images, covering almost the whole
brain area, show excellent susceptibility weighted
contrast and SNR. Compared to 3T images with an
in-plane resolution of 0.45mm x 0.50mm acquired in
about the same scan time, a qualitative improvement
can be observed and a greatly increased number of
small veins can be visualized at 9.4T. |
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11:24 |
44. |
Presurgical Visualization of Cerebral Surface Veins
with Susceptibility Weighted Imaging |
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Zeinab
Al-Rekabi1,2, Kelly McPhee3,
Kevin Fitzpatrick3,4, Bruce Bjornson3,5,
Alexander Rauscher3,6
1University of British Columbia , Vancouver,
BC, Canada; 2University of Ottawa,
Ottawa, Ontario, Canada; 3University of
British Columbia, Vancouver, BC, Canada; 4Children's
Brain Mapping Centre, BC Children's Hospital; 5Children's
Brain Mapping Centre, BC Children's Hospital and
Child & Family Research Institute; 6UBC
MRI Research Centre |
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Susceptibility Weighted
Imaging combines magnitude and phase of a high
resolution fully flow-compensated 3D gradient echo
scan, from which detailed images of the cerebral
venous vasculature can be obtained without using a
contrast agent. Due to the required high pass
filtering of the phase, visualization of veins at
the brain's surface has been poor. We used bilateral
filtering to preserve vein related phase information
at the brain's surface, by minimizing blurring
across boundaries between brain and noise. A
combination of resulting surface venograms with a
structural scan provides images of the brains
surface with venous vessels as landmarks for
surgery. |
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11:36 |
45. |
Susceptibility and T2/T1 Weighted Contrast
Enhancements in Rat Brain Using BSSFP at 9.4T |
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Joseph S. Gati1, L Martyn Klassen1,
Robert Bartha1, Ravi S. Menon1
1CFMM, Robarts Research Institute, London,
Ontario, Canada |
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Balanced steady-state
free precession (bSSFP) pulse sequences have found
widespread use at clinical field strengths,
particularly for cardiac applications, because of
short acquisition times, high contrast and increased
signal to noise characteristics compared to
similarly acquired gradient echo (GRE) methods. We
have previously demonstrated there to be a greater
than 3 times signal to noise advantage, per unit
time, using a fully optimized bSSFP sequence over a
similarly matched gradient echo acquisitions. The
current study demonstrates unique image contrast at
high magnetic field strength observed in both high
resolution ex vivo and in vivo rat brain
images. |
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11:48 |
46. |
Cortical Layers Imaging with Inversion Recovery MRI |
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Daniel Barazany1, Ory Levy1,
Yaniv Assaf1
1Department of Neurobiology, Tel Aviv
University, Tel Aviv, Israel |
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Cyto-architecture is a
histological features that delineate the neuronal
morphology of the tissue in general and layers in
cortex in particular. Currently there is no
in-vivo imaging modality that enables accurate
and robust visualization of neuronal cell
structures. In this work we use a multi-parametric
MRI and clustering approach to segment the cortex
into a laminar pattern based on multi-spectral
inversion recovery dataset. This approach was
implemented on the rat brain and compared with cyto-architectonic
analysis; there is a good agreement between the MRI
layers and histological identification of the
layers. Similar results were also obtained on the
human brain. |
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12:00 |
47. |
Within Gray and White Mater R2*
Variations Correlate Histochemical Iron Stain of the
Human Brain |
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Masaki Fukunaga1,
Jongho Lee1, Tie-Qiang Li, Kant K.
Matsuda2, Hellmut Merkle, Peter van
Gelderen1, Jacco A. de Zwart1,
Jeff H. Duyn1
1Advanced MRI/LFMI/NINDS, National Institutes
of Health, Bethesda, MD, USA; 2Laboratory
of Pathology/NCI, National Institutes of Health,
Bethesda, MD, USA |
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High resolution T2*
weighted MRI at high field strength shows
substantial contrast variation across laminae in
cortical gray matter. This contrast variation also
exist within cortical gray matter and subcortical
white matter. In this work, to assess the
contribution of non-heme iron and myelin in the R2*
variations, we investigated the similarity of R2*
map and histochemical stained image of the human
brain. The contrast variation of R2* map
highly corresponded to iron stain than myelin stain,
it demonstrates that possible main contributor of R2*
variation is non-heme iron. |
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12:12 |
48. |
Detection and Delineation of Focal Cortical Lesions
in Patients with Focal Epilepsy: Preliminary Results
at 7T and 3T with 32 Channel Phased Arrays |
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Neel Madan1, Thomas Benner2,
Elizabeth Anne Thiele3, Emad N. Eskandar4,
Lawrence L. Wald2,5, Patricia Ellen Grant1,2
1Department of Pediatric Radiology,
Massachusetts General Hospital, Boston, MA, USA;
2A.A. Martinos Center for Biomedical
Imaging, Department of Radiology, Massachusetts
General Hospital, Boston, MA, USA; 3Pediatric
Epilepsy Service, Department of Neurology,
Massachusetts General Hospital, Boston, MA, USA;
4MGH-HMS Center for Nervous System
Repair, Department of Neurosurgery, Massachusetts
General Hospital, Boston, MA, USA; 5Harvard-MIT
Division of Health Sciences and Technology,
Cambridge, MA, USA |
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Identification of focal
cortical dysplasias (FCD) on MRI is critical in the
management of patients with medically refractory
epilepsy. In this study, four patients with known or
suspected FCD were imaged at 7T and 3T with 32
channel phased array coils. High resolution imaging
allowed characterization and delineation of tissue
involvement in three of the patients. These two
technologies complemented each other in defining
lesion boundary and characterizing the involved
tissue. Both 7T and 3T with 32 channel coil hold
great promise as a problem solving tool for lesion
identification in those patients with “MR negative”
medically refractory epilepsy. |
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12:24 |
49. |
Three-Dimensional Segmentation of the Internal
Structures of the Human Hippocampus at 7 Tesla |
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Marie Chupin1,
Stephane Lehericy2,3, Olivier Colliot1,
Malgorzata Marjanska4, Ute Goerke4,
Kamil Ugurbil4, Pierre-Francois Van de
Moortele4
1CNRS UPR 640 - LENA, University Pierre and
Marie Curie - Paris 6, Paris, France; 2Center
for NeuroImaging Research, University Pierre and
Marie Curie - Paris 6, Paris, France; 3Neuroradiology,
Inserm U610, Pitie-Salpetriere Hospital, Paris,
France; 4Center for Magnetic Resonance
Research and Department of radiology, University of
Minnesota, Minneapolis, MN, USA |
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In this work, we used 7T
whole body to image and segment in three dimension
the internal structure of the human hippocampus.
Three human volunteers were included. Six subparts
of the hippocampus were clearly differentiated
including the stratum pyramidale of the cornu
ammonis (CA), more precisely the first 3 segments of
CA (CA1-3), the hilum of the dentate (corresponding
to the dentate proper and CA4), the subiculum, the
alveus and the fimbria. Segmentation of the internal
structure of the hippocampus at 7T provides new
biomarkers that can be used in brain pathologies. |
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12:36 |
50. |
Separation and Reproducibility of Touch Activations
in Areas 3b and 1 Within the Primary Somatosensory
Cortex by High Resolution FMRI at 7T |
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Elizabeth Ann Stringer1,
Robert M. Friedman2, J Chris Gatenby1,
Li Min Chen1, John C. Gore1
1Institute of Imaging Science, Vanderbilt
University, Nashville, TN, USA; 2Department
of Psychology, Vanderbilt University, Nashville, TN,
USA |
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Ultra-high field fMRI
provides greater sensitivity and increases spatial
resolution, resulting in finer scale activity maps
than at lower fields. Here, we test the feasibility
of 7T fMRI to visualize millimeter resolution
somatotopic maps in neighboring regions, Brodmann
Areas 3b and 1, within the primary somatosensory
cortex. Images were acquired using a 7T Philips
Achieva scanner while innocuous air puffs were
delivered to alternating digits. Repeated trials
within single subjects showed reproducible
topological activations within areas 3b and 1 of the
primary somatosensory cortex. The data support
findings from nonhuman primate studies. |
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