|High Resolution Animal Imaging|
In Vivo Tracking of Mesenchymal Stem Cells in
the Injured Mouse Spinal Cord
Laura Elizabeth Gonzalez-Lara1, Xiaoyun Xu1, Klara Hofstetrova1, Soha S. Ramadan1, Nicole Geremia1, Anna Pniak1, Yuhua Chen1, Lynne C. Weaver1, Brian K. Rutt1, Arthur Brown1, Paula J. Foster1
1Robarts Research Institute, London, Canada
To the best of our knowledge, this is the first report of in vivo stem cell tracking in a mouse model of spinal cord injury (SCI). Mesenchymal stem cells (MSCs) can be induced to differentiate into neural cells and MRI provides the opportunity to track the fate of MSCs transplanted into an injured spinal cord. Here we show, for the first time, the ability to monitor transplanted MSCs in mice with a clip compression spinal cord injury over 4 weeks using a fast 3D imaging sequence with a custom high-performance gradient coil insert at 3T.
Use of an OVS-FAIR Based ASL Technique for High
Spatial Resolution Mouse Cervical Spinal Cord Blood Flow (SCBF) Mapping
Guillaume Duhamel1, Virginie Callot1, Yann Le Fur1, Patrick J. Cozzone1, Frank Kober1
1CRMBM, CNRS 6612, Faculté de Médecine, Université de la Méditerranée, Marseille, France
A recent work has demonstrated the feasibility of mouse SC blood flow (SCBF) measurement with arterial spin labeling (ASL) using a flow-sensitive alternating inversion recovery (FAIR) technique at the cervical level. Although the achieved spatial resolution (130x130 μm2/pixel) permitted accurate measurements of SCBF within gray matter structures, higher spatial resolutions would be required for visualization and validation of longitudinal pathological changes in lesioned rodent SC. The combined use of a small volumic coil adapted to the SC imaging with an outer volume suppressed FAIR ASL technique was investigated for high spatial SCBF imaging (<100x100 μm2/pixel).
The First in Vivo Mouse Proton and Sodium
MR Imaging at 21 T
Victor D. Schepkin1, William W. Brey1, Nathaniel D. Falconer1, Samuel C. Grant1, 2, Petr L. Gor'kov1, Kiran K. Shetty1, Timothy A. Cross1, 2
1National High Magnetic Field Laboratory/FSU, Tallahassee, Florida, USA; 2The Florida State University, Tallahassee, Florida, USA
High magnetic fields expand our ability to investigate biomedical processes. Yet, the highest magnetic fields bring challenges in probe design and animal adaptability. The first in vivo images of a mouse brain were acquired at the unique field of 21.1 T built at the NHMFL. These images were achieved by overcoming multiple obstacles in experimental in vivo design. Normal mice (C57BL/6J) images were acquired using proton (900 MHz) and sodium (237 MHz) MRI. The unique sodium MR images of mouse brain with resolution of 0.125 µL were obtained using a custom-designed 3D back-projection sequence.
Phase Imaging of the in Vivo Rat Brain at 14.1
José P. Marques1, 2, Cristina Cudalbu1, Carol Poitry-Yamate1, Vladimir Mlynarik1, Rolf Gruetter1, 3
1Ecole Polytechnique Federale de Lausanne, Lausanne, Switzerland; 2University of Lausanne, Lausanne, Switzerland; 3University of Lausanne and Geneva, Switzerland
Gradient-recalled echo (GRE) imaging at 14.1 Tesla (TE=15ms) was used to assess contrast in brain tissue both from the T2* weighted magnitude and from the phase image. In 4 min, a spatial resolution of 33µm was achieved. In addition to the excellent depiction of veins in the magnitude images, phase images suggest that susceptibility variations in rat brain are within ±0.01ppm of that of gray matter. The phase was inverted in structures ascribed to high myelination content (white matter-like) such as external capsules, anterior and posterior caudate, compared to that in vessels, hitherto not readily accessible using standard MRI techniques.
Virtual Mapping of Cyto-Architectonic
Distinct Structures with MRI
Daniel Barazany1, Ory Levy1, Tamar Blumenfeld-Katzir1, Yossi Yovel1, Yaniv Assaf1
1Tel Aviv University, Tel Aviv, Israel
Cytoarchitecture and myeloarchitecture are histological features that are used to segment the brain into neuroanatomical regions. In this work we used a multi-parametric MRI acquisition and analysis framework (virtual.com imaging) to compare the rat’s thalamus MRI segmentation with cyto-architecture mapping of the same sample. We found good correspondence between the MRI clusters and cyto-architectonic arrangement of the thalamus nuclei. In addition, the MRI contrast profile interpretation followed the cellular composition of the tissue. Cluster of multi-parametric MRI can evolve into an in-vivo cyto-architectonic mapping procedure that can be applied on the single subject level.
Magnetization-Prepared Segmented FLASH Sequences for
High-Field Anatomical Brain Imaging in Animals
Nicholas Adam Bock1, Frank Ye1, Afonso C. Silva1
1National Institutes of Health, Bethesda, USA
We compare three magnetization-prepared segmented FLASH sequences for high resolution 3D animal brain imaging at high field: MP-RAGE, MDEFT, and a segmented FLASH sequence with a delay between the segments. In simulations, the MP-RAGE sequence produces the best gray/white matter contrast, but little signal where the contrast is maximized. The segmented FLASH sequence produces the best signal, with proton density-weighted contrast that becomes good at longer delay times. We compare the MP-RAGE and segmented FLASH sequences in a marmoset at 7 Tesla. The segmented FLASH sequence proves advantageous because it produces a higher signal for SNR-limited high resolution 3D imaging.
In Vivo Visualization of Cerebro-Microvasculature
Using 3D δR2-Based Microscopic MR Angiography (3D MMRA)
Chien-Yuan Lin1, 2, Jyh-Hong Chen1, Ming-Huang Lin2, Wai-Mui Cheung2, Teng-Nan Lin2, Chen Chang2
1National Taiwan University, Taipei, Taiwan; 2Academia Sinica, Taipei, Taiwan
3D ŁGR2-Based Microscopic MR Angiography (3D mMRA) method is proposed and validated in order to evaluate the cerebro-microvasculature. The results demonstrate that 3D mMRA is a promising technique in monitoring and quantitatively evaluating microvascular remodeling in cerebro-microvascular disease.
Decreased Mean Diffusivity and Changes in Proton
Spectra in the Brain of Aged Rats with Learning Deficits
Ivan Vorisek1, Daniel Jirak2, Katerina Namestkova3, Milan Hajek2, Eva Sykova1
1Institute of Experimental Medicine ASCR, Prague, Czech Republic; 2Institute for Clinical and Experimental Medicine, Prague, Czech Republic; 3Charles University, 2nd Medical Faculty, Prague, Czech Republic
Cognitive decline in old age has been linked to changes in brain anatomy, morphology, volume, and functional deficits. Degenerative processes could also affect extrasynaptic transmission, mediated by the diffusion of transmitters through the extracellular space. Therefore, we studied diffusivity and changes in proton spectra in the brain tissue of aged rats with and without a learning deficit. Superior and inferior learners were selected according to their performance in a Morris water maze. Decreased mean diffusivity and changes in metabolite concentrations were found in aged inferior learners but not in aged superior learners.
|17:36||814.||MRI Can Detect Brain Shape Changes in Mice Caused by
Five Days of Learning
Jason P. Lerch1, Adelaide P. Yiu1, Veronique D. Bohbot2, R Mark Henkelman1, Sheena A. Josselyn1, John G. Sled1
1Hospital for Sick Children, Toronto, Canada; 2McGill University, Verdun, Canada
Mice were trained for five days on the Morris Water Maze, scanned at 32µm at 7T, and resulting MRIs analyzed for brain shape differences using deformation based morphometry. Significant results were found in multiple regions of the brain relating to the cogntive strategy used.
Evidences of Learning and Memory Related Brain
Plasticity from Diffusion Tensor Imaging in the Rat
Tamar Blumenfeld-Katzir1, Ofer Pasternak2, Yaniv Assaf2
1Tel-Aviv University, Tel Aviv , Israel; 2Tel-Aviv University, Tel-Aviv, Israel
Brain Plasticity is defined as the ability of the brain region to re-organize following the demand for specific cognitive function. In this work we used DTI to follow morphological brain plasticity induced by learning and memory experience. Using a voxel-based analysis routine we compared the FA maps of rat brains before and after a learning and memory task. Following a 5-days learning and memory task, the FA in specific brain regions increased (hippocampus, septum and posterior part of the corpus callosum). This demonstrates that plasticity can be studied on morphological level and not only on the functional level.