Characterization of white matter reorganization in neonatal hypoxic-ischemic cerebral injury using diffusion tensor imaging

Animal Models of Ischemia: Characterization - Poster presentationThis study employs in vivo diffusion tensor imaging (DTI) to understand the late changes in white matter (WM) injury and reorganization in the rat brain upon neonatal hypoxic-ischemic cerebral injury. In particular, detailed inspection of the color-encoded fractional anisotropy (FA) map of the principal eigenvector was performed to compare the orientations of the high FA fibers at the perilesional areas with the WM microstructures in the contralateral hemisphere. In addition to the differences in DTI parameters in the microstructures between both hemispheres, results showed that the perilesional areas had similar fiber orientations as the contralateral external capsule in the anterior section of the brain, and as the internal capsule and the fimbria of hippocampus in the posterior section. We demonstrated that DTI can detect the microstructure and orientations of WM fiber changes at the perilesional areas in vivo, and can be used for non-invasive evaluation of HI brain injuries and reorganization.published_or_final_versionThe 17th Scientific Meeting & Exhibition of the International Society of Magnetic Resonance in Medicine (ISMRM), Honolulu, HI., 18-24 April 2009. In Proceedings of ISMRM 17th Scientific Meeting & Exhibition, 2009, p. 327

Characterization of cortex and white matter injury in a mild hypoxic-ischemic neonatal rat mode by diffusion tensor MR imaging

Animal Studies: Diffusion & Perfusion - Poster presentationWe evaluated hypoxic-ischemic (HI) induced cortex and white matter (WM) damage in a mild HI neonatal rat model at 24h post HI by diffusion tensor MR imaging (DTI) and correlated the DTI indices with histological evaluations. Results showed that significantly decreased FA and ¦Ë// reflected HI induced astrogliosis in the injured cortex, whereas significantly decreased FA with increased ¦Ë¡Í indicated dysmyelination in the WM. Our results demonstrated that early mild HI induced cortex and WM damage could be reflected by DTI indices and these may be potentially useful biomarkers to non-invasively monitor mild HI induced neonatal brain damage.published_or_final_versionThe 17th Scientific Meeting & Exhibition of the International Society of Magnetic Resonance in Medicine (ISMRM), Honolulu, HI., 18-24 April 2009. In Proceedings of ISMRM 17th Scientific Meeting & Exhibition, 2009, p. 359

Mild hypoxic-ischemic injury in the neonatal rat brain: longitudinal evaluation of the white matter using diffusion tensor MR imaging

Session 75: Perfusion & Diffusion: Animal Models - Oral presentationWe evaluated longitudinally mild hypoxic-ischemic (HI) induced white matter (WM) damage in a neonatal rat model using DTI and correlated the DTI indices with histological evaluations. Results showed significantly decreased FA and increased ¦Ë¡Í in the injured WM reflected dysmyelination. The longitudinal changes of increasing FA, decreasing ¦Ë¡Í, and no change in ¦Ë// in both injured and control WM suggests continued myelination. Furthermore, differences in FA and ¦Ë¡Í between injured and control WM decreased longitudinally. Our results demonstrated that mild HI induced WM damage continues to mature with partial recovery post-HI, and this could be reflected by DTI in vivo.published_or_final_versionThe 17th Scientific Meeting & Exhibition of the International Society of Magnetic Resonance in Medicine (ISMRM), Honolulu, HI., 18-24 April 2009. In Proceedings of ISMRM 17th Scientific Meeting & Exhibition, 2009, p. 74

Mild hypoxic-ischemic injury in the neonatal rat brain: longitudinal evaluation of the white matter using diffusion tensor MR imaging

Session 75: Perfusion & Diffusion: Animal Models - Oral presentationWe evaluated longitudinally mild hypoxic-ischemic (HI) induced white matter (WM) damage in a neonatal rat model using DTI and correlated the DTI indices with histological evaluations. Results showed significantly decreased FA and increased ¦Ë¡Í in the injured WM reflected dysmyelination. The longitudinal changes of increasing FA, decreasing ¦Ë¡Í, and no change in ¦Ë// in both injured and control WM suggests continued myelination. Furthermore, differences in FA and ¦Ë¡Í between injured and control WM decreased longitudinally. Our results demonstrated that mild HI induced WM damage continues to mature with partial recovery post-HI, and this could be reflected by DTI in vivo.published_or_final_versionThe 17th Scientific Meeting & Exhibition of the International Society of Magnetic Resonance in Medicine (ISMRM), Honolulu, HI., 18-24 April 2009. In Proceedings of ISMRM 17th Scientific Meeting & Exhibition, 2009, p. 74

Spin-echo BOLD temporal dynamics in the rat superior colliculus and lateral geniculate nucleus

Session - fMRI Neuroscience Methods & Applications I: Computer 57 (Wednesday)INTRODUCTION: The superior colliculus (SC) and lateral geniculate nucleus (LGN) are important subcortical components of the visual system[1]. The majority of fMRI studies to date focus on higher visual processing centers in the cortex. fMRI studies in rats have examined visual responses in the subcortex using long stimulus duration block-design paradigms[2-4]. These studies focused on locating responsive regions and measuring differences in BOLD responses for different stimulation frequencies. Relatively little attention has been given to BOLD temporal dynamics in the rat subcortex. In this study, we apply …published_or_final_versionThe 19th Annual Meeting and Exhibition of the International Society for Magnetic Resonance in Medicine (ISMRM 2011), Montreal, QC., 7-13 May 2011.In Proceedings of the 19th ISMRM, 2011, v. 19, p. 365

Noninvasive fMRI investigation of interaural level difference processing the rat auditory subcortex

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Detection of ipsilateral and contralateral activation components in unilateral fingers-tapping using spinal BOLD fMR

Ipsilateral activation component has been reported in brain fMRI studies using unilateral finger motion. However, the ipsilateral component is usually taskdependent and sparsely distributed. In this study, spinal BOLD fMRI has been performed on 4 healthy right-handed volunteers performing unilateral fingerstapping to investigate the ipsilateral and contralateral activation inside the cervical spinal cord. Our results showed that more activation were found at the spinal level C5-C6/C7. Bilateral activation was observed in all subjects both in left/right hand fingers-tapping. Spinal fMRI was sensitive to detect bilateral firing in fingers-tapping using dominant or non-dominant hands.published_or_final_versio

BOLD fMRI study of the rat superior colliculus responding to a moving visual stimulus

Session - Animal fMRI: Computer 59 (Tuesday)INTRODUCTION: The superior colliculus (SC), or tectum, is a midbrain structure in vertebrates critical for directing eye movements[1]. It possesses neurons that are highly sensitive to moving stimuli[2]. To date, functional imaging has only been used to study the SC’s response to a stimulus moving at one speed[3]. Few fMRI studies have been conducted on the human SC because of technical challenges[4-5]. The rat SC occupies a significantly larger portion of the brain and receives a greater fraction of retinal projections. Thus, the rat is more suitable for studying SC function. In this study, we apply …published_or_final_versionThe 19th Annual Meeting and Exhibition of the International Society for Magnetic Resonance in Medicine (ISMRM 2011), Montreal, QC., 7-13 May 2011. In Proceedings of the 19th ISMRM, 2011, v. 19, p. 367

Myocardial fiber length mapping with MR diffusion tensor imaging

Diffusion tensor MRI is emerging as a rapid, nondestructive method to map myocardial fiber organization. A precise biological description of myocardial fiber performance requires knowledge of four variables: length, force, velocity and time. However, study of quantification of myocardial fiber length is lacking. The current study aims to show myocardial fiber length maps of formalin-fixed heats. Diffusion tensor MRI with medium diffusion resolution (15 directions) was performed in one isolated pig heart. Fiber length maps were investigated in multiple short-axis slices. The results provide supplementary information of myocardial fiber organization. To our knowledge, the present study is the first report of the myocardial fiber length mapping. © 2005 IEEE.published_or_final_versio

Longitudinal diffusion tensor MR imaging study of radiation induced white matter damage in a rat model

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