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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.

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).

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.

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.

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.

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.

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 £GR2-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.

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.

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.

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.