Traditional Posters: Diffusion & Perfusion - ismrm

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1701. Characterization of White Matter Maturation in Cats: Diffusion Spectrum Imaging Tractography Qin Chen 1,2 , Emi Takahashi 3 , Guangping Dai 1 , Ellen Grant, 1,3 1 Department of Radiology, Massachusetts General Hospital, Harvard Medical School, Martinos Center for Biomedical Imaging, Charlestown, MA, United States; 2 Department of Neurology, West China Hospital of Sichuan Univeristy, Chengdu, Sichuan, China; 3 Divison of Newborn Medicine, Department of Medicine and Department of Radiology, Children¡¯s Hospital Boston, Harvard Medical School, Boston, MA, United States We have shown that at postnatal day (P) 35 kittens, the degrees of myelination varied in white matters in different brain areas (Takahashi et al., 2009). Our purpose of current study was to quantify the FA and ADC values on different fiber tracts in this specific developmental phase of juvenile kitten to characterize regional difference in degrees of maturation, and to compare these values between P35 (pediatric). Using high-resolution diffusion spectrum imaging (DSI) tractography, we successfully imaged the 3- dimensional structure of the cortical and subcortical pathways in P35 cats. 1702. DTI Study of Development and Aging of the Optic Nerve in Rhesus Monkeys Yumei Yan 1 , Longchuan Li 2 , Govind Nair 2 , Todd Preuss 3 , Mar Sanchez 4,5 , Mark Wilson 3 , Xiaoping Hu 2 , James Herndon 3 , Xiaodong Zhang 1 1 Yerkes Imaging Center, Yerkes National Primate Research Center, Emory University, Atlanta, GA, United States; 2 biomedical engineering, Emory University and Georgia Institute of Technology, Atlanta, GA, United States; 3 Neuroscience Division, Yerkes National Primate Research Center, Emory University, Atlanta, GA, United States; 4 Psychiatry & Behavioral Sciences, School of Medicine, Emory University, Atlanta, GA, United States; 5 Psychobiology Division, Yerkes National Primate Research Center, Emory University, Atlanta, GA, United States Non-human primate model was employed to access the optic nerve (ON) development and aging with Diffusion tension imaging (DTI). ADC and FA evolution in the ON of monkeys was investigated systematically. Significant changes were found between 21 months with 6 years of age, but not observed in the ON in early development. Furthermore, DTI revealed age-related changes in older rhesus monkeys that may represent axonal and myelin degeneration. DTI may provide a means to evaluate ON disorders or injury. 1703. Astrocytic Aquaporin-4 Contributes Significantly to Water Mobility in the Rat Brain Andre Obenaus 1,2 , Stephan Ashwal 3 , Jerome Badaut Badaut 3 1 Radiation Medicine, Loma Linda University, Loma Linda, CA, United States; 2 Radiology, Loma Linda University, Loma Linda , CA, United States; 3 Pediatrics, Loma Linda University, Loma Linda, CA, United States Diffusion weighted MRI is widely used in clinical diagnosis. To date the underlying molecular mechanism responsible for changes in the apparent diffusion coefficient (ADC) are poorly understood. Using small interference RNA directed against the astrocytic water channel, acqueporin-4 (AQP4), we were able to demonstrate a 50% decrease in ADC values when AQP4 expression was silenced (25%). Thus, astrocytic AQP4 contributes significantly to the ADC values in normal rodent brain. These results suggest new possibilities for interpreting ADC values in normal brain and under pathological conditions. 1704. Anatomical Phenotyping of a Mouse Model with Known White Matter Abnormalities Jacob Ellegood 1 , Ameet S. Sengar 2 , M W. Salter 2 , S E. Egan 3 , Jason P. Lerch 1 , R M. Henkelman 1 1 Mouse Imaging Centre, Hospital for Sick Children, Toronto, Ontario, Canada; 2 Neuroscience and Mental Health, Hospital for Sick Children, Toronto, Ontario, Canada; 3 Developmental Biology, Hospital for Sick Children, Toronto, Ontario, Canada Anatomical phenotyping in mouse has shown to be useful for determining small changes in volume. Similarly, Diffusion Tensor Imaging (DTI) of fixed mouse brain has been useful in assessing development and genetic differences in wild type and knockout mouse models. The purpose of this study was to determine both the volume and white matter structural changes in a mouse model with known white matter abnormalities. While some of the fractional anisotropy changes can be attributed to corresponding decreases in the volume, some structures and regions have changes that would go unnoticed if only volume or fractional anisotropy was measured. 1705. Fractional Anisotropy Changes Following Blood Brain Barrier Disruption Ashley D. Harris 1,2 , Linda B. Andersen, 2,3 , Henry Chen, 2,4 , Pranshu Sharma 2 , Richard Frayne, 2,3 1 School of Psychology, CUBRIC, Cardiff University, Cardiff, United Kingdom; 2 Seaman Family MR Research Centre, Foothills Medical Centre, Calgary, Alberta, Canada; 3 Clinical Neurosciences and Radiology, Univerisity of Calgary, Calgary, Alberta, Canada; 4 Physics, Univerisity of Calgary, Calgary, Alberta, Canada The evolution of FA is examined in a canine model following blood brain barrier disruption with hypertonic mannitol solution. White matter and grey matter show different FA responses to blood brain barrier disruption. White matter decreases, while grey matter showed significant increases. With additional understanding, FA may assist in determining the integrity of the blood brain barrier.
1706. Early Diffusion Changes Following Controlled Cortical Impact Injury on a Rat Model Jiachen Zhuo 1,2 , Su Xu 1,2 , Jennifer Racz 3 , Da Shi 1,2 , Gary Fiskum 3 , Rao Gullapalli 1,2 1 Radiology, University of Maryland School of Medicine, Baltimore, MD, United States; 2 Core for Translational Research in Imaging at Maryland (C-TRIM), University of Maryland School of Medicine, Baltimore, MD, United States; 3 Anesthesiology and the Center for Shock Trauma and Anesthesiology Research, University of Maryland School of Medicine, Baltimore, MD, United States The understanding of tissue alterations at an early stage following traumatic brain injury (TBI) is critical for injury management and prevention of more severe secondary damage. In this study, we investigated the early changes in tissue water diffusion at 2 hours and 4 hours following mild to moderate controlled cortical impact injury on a rat model. Our study indicates a distance effect from the site of injury and suggests a therapeutic window of about 2-3 hours to limit the cascade of events that may lead to secondary injury. 1707. A Longitudinal Study of DTI in a Nonhuman Primate Model of Neuro-AIDS Chun-xia Li 1 , Xiaodong Zhang 1 , Yingxia Li 1 , Amelia Komery 2 , Francis J. Novembre 3 , James G. Herndon 2 1 Yerkes Imaging Center, Yerkes National Primate Research Center, Emory University, Atlanta, GA,30329, United States; 2 Divisions of Microbiology and Immunology, Yerkes National Primate Research Center, Emory University, Atlanta, GA,30322; 3 Divisions of Neuroscience, Yerkes National Primate Research Center, Emory University, Atlanta, GA,30322 DTI has been proposed as a quantitative marker of the neurological status of HIV+ patients. In this study, DTI imaging was used to longitudinally detect white matter abnormalities in whole brain and specific regions of Simian immunodeficiency virus (SIV)-infected monkeys, a reduction in FA and an increase in MD were observed evidently after viral inoculation and whole-brain FA changes correlated significantly with CD4 depletion. Findings from this investigation support the use of DTI for measurement of HIV associated neuropathologic changes. Further longitudinal study is needed to investigate the validation of DTI measures as a marker for disease progression. 1708. Hyperammonemia and Edema: A DTI Study in the Adult Rat Brain Nicolas Kunz 1,2 , Cristina Cudalbu 1 , Yohan Van de Looij 1,2 , Petra Hüppi 2 , Stephane Sizonenko 2 , Rolf Gruetter 1,3 1 Laboratory of functional and metabolic imaging (LIFMET), Ecole Polytechnique Fédérale de Lausanne, Lausanne, Switzerland; 2 Division of Child Growth &Development, University of Geneva, Geneva, Switzerland; 3 Department of Radiology, University of Geneva & Lausanne, Geneva & Lausanne, Switzerland Ammonia is a neurotoxin that is implicated in the pathogenesis of hepatic encephalophaty, which is reported to be responsible for brain edema. It is not yet clear whether brain edema is mostly vasogenic or cytotoxic. The aim of this study was to assess the effects of hyperammonemia on the rat brain by using DTI at 9.4T. This study shows a rapid increase of the ventricle size during the three first hours of infusion along with a decrease in ADC. As the ventricle size gets stabilized after 6h, the ADC keeps on decreasing, indicating the formation of mild cytotoxic edema. 1709. Comparison of ADC Values Using Pulsed Field Gradient and Correlation Time Diffusion Techniques in a Murine Model of Steatohepatitis at 11.7T Stephan William Anderson 1 , Jorge A. Soto 1 , Holly N. Milch 1 , Hernan Jara 1 1 Radiology, Boston University Medical Center, Boston, MA, United States The purpose of this study was to compare the ADC values obtained using pulsed field gradient (PFG) and correlation time diffusion (CT-D) techniques in a mouse model of steatohepatitis at 11.7T. C57BL/6 mice fed a methionine-deficient choline-deficient (MCD) diet to induce steatohepatitis were sacrificed intermittently throughout this period for ex vivo liver imaging. A comparison of the parametric maps and whole sample histograms generated by the PFG and CTD techniques shows excellent agreement between the two diffusion techniques. In all cases CT-D parametric maps had significantly higher SNR and the histogram width was narrower than those generated using PFG technique. Blood Flow in Animal Models Hall B Tuesday 13:30-15:30 1710. Blood-Flow MRI of Non-Human Primate (Baboon) Retina Hsiao-Ying Wey 1 , Jinqi Li 1 , Jiongjiong Wang 2 , Sung-Hong Park 1 , Timothy Q. Duong 1 1 Research Imaging Institute, UT Health Science Center at San Antonio, San Antonio, TX, United States; 2 Radiology, University of Pennsylvania, Philadelphia, PA, United States Quantitative blood flow measurement of the retina is critically important as many retinal diseases could perturb basal blood flow and blood flow responses to stimulations. In this study, we developed and applied the pseudo-continuous ASL to improve ASL contrast, and systematically explored blood-flow MRI of the retina in anesthetized baboon on a human clinical scanner. Anesthetized baboons were used to exclude movement artifacts such that we could focus on evaluating hardware feasibility and imaging parameters for high-resolution quantitative BF imaging of the retina as a first step toward evaluating potential human applications.
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