title: Spatiotemporal microstructural white matter changes in diffusion tensor imaging after transient focal ischemic stroke in rats.
abstract: Structural reorganization in white matter (WM) after stroke is a potential contributor to substitute or to newly establish the functional field on the injured brain in nature. Diffusion tensor imaging (DTI) is an imaging modality that can be used to evaluate damage and recovery within the brain. This method of imaging allows for in vivo assessment of the restricted movements of water molecules in WM and provides a detailed look at structural connectivity in the brain. For longitudinal DTI studies after a stroke, the conventional region of interest method and voxel-based analysis are highly dependent on the user-hypothesis and parameter settings for implementation. In contrast, tract-based spatial statistics (TBSS) allows for reliable voxel-wise analysis via the projection of diffusion-derived parameters onto an alignment-invariant WM skeleton. In this study, spatiotemporal WM changes were examined with DTI-derived parameters (fractional anisotropy, FA; mean diffusivity, MD; axial diffusivity, DA; radial diffusivity, RD) using TBSS 2 h to 6 weeks after experimental focal ischemic stroke in rats (N = 6). FA values remained unchanged 2-4 h after the stroke, followed by a continuous decrease in the ipsilesional hemisphere from 24 h to 2 weeks post-stroke and gradual recovery from the ipsilesional corpus callosum to the external capsule until 6 weeks post-stroke. In particular, the fibers in these areas were extended toward the striatum of the ischemic boundary region at 6 weeks on tractography. The alterations of the other parameters in the ipsilesional hemisphere showed patterns of a decrease at the early stage, a subsequent pseudo-normalization of MD and DA, a rapid reduction of RD, and a progressive increase in MD, DA and RD with a decreased extent in the injured area at later stages. The findings of this study may reflect the ongoing processes on tissue damage and spontaneous recovery after stroke.
authors.affiliation: Department of Radiology, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul, Korea.|Center for NeuroScience Imaging Research, Institute for Basic Science (IBS), Suwon, Korea.
authors.forename: Won-Beom
authors.initials: WB
authors.lastname: Jung
authors.affiliation: Department of Radiology, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul, Korea.
authors.forename: Yong Hee
authors.initials: YH
authors.lastname: Han
authors.affiliation: Department of Radiology, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul, Korea.|Center for NeuroScience Imaging Research, Institute for Basic Science (IBS), Suwon, Korea.|Samsung Advanced Institute of Health Science and Technology, Sungkyunkwan University, Seoul, Korea.
authors.forename: Julius Juhyun
authors.initials: JJ
authors.lastname: Chung
authors.affiliation: Department of Radiology, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul, Korea.|Center for NeuroScience Imaging Research, Institute for Basic Science (IBS), Suwon, Korea.|Samsung Advanced Institute of Health Science and Technology, Sungkyunkwan University, Seoul, Korea.
authors.forename: Sun Young
authors.initials: SY
authors.lastname: Chae
authors.affiliation: Department of Medicine, Kyungpook National University, School of Medicine, Daegu, Korea.|Center for Molecular and Cellular Imaging, Samsung Biomedical Research Institute, Seoul, Korea.
authors.forename: Sung Hoon
authors.initials: SH
authors.lastname: Lee
authors.affiliation: Center for Molecular and Cellular Imaging, Samsung Biomedical Research Institute, Seoul, Korea.
authors.forename: Geun Ho
authors.initials: GH
authors.lastname: Im
authors.affiliation: Department of Radiology, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul, Korea.
authors.forename: JiHoon
authors.initials: J
authors.lastname: Cha
authors.affiliation: Department of Radiology, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul, Korea.|Center for NeuroScience Imaging Research, Institute for Basic Science (IBS), Suwon, Korea.|Samsung Advanced Institute of Health Science and Technology, Sungkyunkwan University, Seoul, Korea.
authors.forename: Jung Hee
authors.initials: JH
authors.lastname: Lee
mesh_terms: D000818:Animals; D016880:Anisotropy; D002545:Brain Ischemia / Q000473:pathology*; D056324:Diffusion Tensor Imaging / Q000379:methods*; D017207:Rats, Sprague-Dawley; D020521:Stroke / Q000473:pathology*; D013997:Time Factors; D066127:White Matter / Q000473:pathology*
keywords: diffusion tensor imaging (DTI); stroke; structural reorganization; tract-based spatial statistics (TBSS)