title: Reduced microvascular volume and hemispherically deficient vasoreactivity to hypercapnia in acute ischemia: MRI study using permanent middle cerebral artery occlusion rat model.
abstract: Vasoreactivity to hypercapnia has been used for assessing cerebrovascular tone and control altered by ischemic stroke. Despite the high prognostic potential, traits of hypercapnia-induced hemodynamic changes have not been fully characterized in relation with baseline vascular states and brain tissue damage. To monitor cerebrovascular responses, T2- and T2*-weighted magnetic resonance imaging (MRI) images were acquired alternatively using spin- and gradient-echo echo plannar imaging (GESE EPI) sequence with 5% CO2 gas inhalation in normal (n=5) and acute stroke rats (n=10). Dynamic relative changes in cerebrovascular volume (CBV), microvascular volume (MVV), and vascular size index (VSI) were assessed from regions of interest (ROIs) delineated by the percent decrease of apparent diffusion coefficient (ADC). The baseline CBV was not affected by middle cerebral artery occlusion (MCAO) whereas the baseline MVV in ischemic areas was significantly lower than that in the rest of the brain and correlated with ADC. Vasoreactivity to hypercapnic challenge was considerably attenuated in the entire ipsilesional hemisphere including normal ADC regions, in which unsolicited, spreading depression-associated increases of CBV and MVV were observed. The lesion-dependent inhomogeneity in baseline MVV indicates the effective perfusion reserve for accurately delineating the true ischemic damage while the cascade of neuronal depolarization is probably responsible for the hemispherically lateralized changes in overall neurovascular physiology.
authors.affiliation: 1] Department of Radiology, Athinoula A. Martinos Center for Biomedical Imaging, Massachusetts General Hospital, Harvard Medical School, Charlestown, Massachusetts, USA [2] Division of Magnetic Resonance Research, Korea Basic Science Institute, Cheongwon, Chungbuk, The Republic of Korea.
authors.forename: J Y
authors.initials: JY
authors.lastname: Suh
authors.affiliation: 1] Department of Radiology, Athinoula A. Martinos Center for Biomedical Imaging, Massachusetts General Hospital, Harvard Medical School, Charlestown, Massachusetts, USA [2] Department of Radiology, Research Institute of Radiology, Asan Medical Center, University of Ulsan College of Medicine, Seoul, The Republic of Korea.
authors.forename: Woo H
authors.initials: WH
authors.lastname: Shim
authors.affiliation: Division of Magnetic Resonance Research, Korea Basic Science Institute, Cheongwon, Chungbuk, The Republic of Korea.
authors.forename: Gyunggoo
authors.initials: G
authors.lastname: Cho
authors.affiliation: Neuroprotection Research Laboratory, Department of Radiology and Neurology, Massachusetts General Hospital, Harvard Medical School, Charlestown, Massachusetts, USA.
authors.forename: Xiang
authors.initials: X
authors.lastname: Fan
authors.affiliation: 1] Department of Radiology, Athinoula A. Martinos Center for Biomedical Imaging, Massachusetts General Hospital, Harvard Medical School, Charlestown, Massachusetts, USA [2] Department of Neurology, Kang's Medical Center, Pocheon, The Republic of Korea.
authors.forename: Seon J
authors.initials: SJ
authors.lastname: Kwon
authors.affiliation: 1] Department of Radiology, Athinoula A. Martinos Center for Biomedical Imaging, Massachusetts General Hospital, Harvard Medical School, Charlestown, Massachusetts, USA [2] Department of Radiology, Research Institute of Radiology, Asan Medical Center, University of Ulsan College of Medicine, Seoul, The Republic of Korea.
authors.forename: Jeong K
authors.initials: JK
authors.lastname: Kim
authors.affiliation: Department of Radiology, Athinoula A. Martinos Center for Biomedical Imaging, Massachusetts General Hospital, Harvard Medical School, Charlestown, Massachusetts, USA.
authors.forename: George
authors.initials: G
authors.lastname: Dai
authors.affiliation: Neuroprotection Research Laboratory, Department of Radiology and Neurology, Massachusetts General Hospital, Harvard Medical School, Charlestown, Massachusetts, USA.
authors.forename: Xiaoying
authors.initials: X
authors.lastname: Wang
authors.affiliation: 1] Department of Radiology, Athinoula A. Martinos Center for Biomedical Imaging, Massachusetts General Hospital, Harvard Medical School, Charlestown, Massachusetts, USA [2] School of Nano-Bioscience and Chemical Engineering, UNIST (Ulsan National Institute of Science and Technology), Ulsan, The Republic of Korea.
authors.forename: Young R
authors.initials: YR
authors.lastname: Kim
mesh_terms: D000208:Acute Disease; D000818:Animals; D001810:Blood Volume; D001921:Brain / Q000098:blood supply* / Q000473:pathology* / Q000503:physiopathology; D002560:Cerebrovascular Circulation; D004195:Disease Models, Animal; D006935:Hypercapnia / Q000150:complications* / Q000473:pathology / Q000503:physiopathology; D020244:Infarction, Middle Cerebral Artery / Q000150:complications* / Q000473:pathology / Q000503:physiopathology; D008279:Magnetic Resonance Imaging; D008297:Male; D051381:Rats; D017208:Rats, Wistar