title: Differentiation of the Infarct Core from Ischemic Penumbra within the First 4.5 Hours, Using Diffusion Tensor Imaging-Derived Metrics: A Rat Model.
abstract: To investigate whether the diffusion tensor imaging-derived metrics are capable of differentiating the ischemic penumbra (IP) from the infarct core (IC), and determining stroke onset within the first 4.5 hours.
  
  
  
  All procedures were approved by the local animal care committee. Eight of the eleven rats having permanent middle cerebral artery occlusion were included for analyses. Using a 7 tesla magnetic resonance system, the relative cerebral blood flow and apparent diffusion coefficient maps were generated to define IP and IC, half hour after surgery and then every hour, up to 6.5 hours. Relative fractional anisotropy, pure anisotropy (rq) and diffusion magnitude (rL) maps were obtained. One-way analysis of variance, receiver operating characteristic curve and nonlinear regression analyses were performed.
  
  
  
  The evolutions of tensor metrics were different in ischemic regions (IC and IP) and topographic subtypes (cortical, subcortical gray matter, and white matter). The rL had a significant drop of 40% at 0.5 hour, and remained stagnant up to 6.5 hours. Significant differences (p< 0.05) in rL values were found between IP, IC, and normal tissue for all topographic subtypes. Optimal rL threshold in discriminating IP from IC was about -29%. The evolution of rq showed an exponential decrease in cortical IC, from -26.9% to -47.6%; an rq reduction smaller than 44.6% can be used to predict an acute stroke onset in less than 4.5 hours.
  
  
  
  Diffusion tensor metrics may potentially help discriminate IP from IC and determine the acute stroke age within the therapeutic time window.
authors.affiliation: Department of Electrical Engineering, National Taiwan University, Taipei 10617, Taiwan.; Department of Radiology, Taoyuan Armed Forces General Hospital, Taoyuan 32551, Taiwan.
authors.forename: Duen-Pang
authors.initials: DP
authors.lastname: Kuo
authors.affiliation: Research Center of Translational Imaging, College of Medicine, Taipei Medical University, Taipei 11031, Taiwan.; Department of Radiology, School of Medicine, College of Medicine, Taipei Medical University, Taipei 11031, Taiwan.; Department of Biomedical Imaging and Radiological Sciences, National Yang-Ming University, Taipei 112, Taiwan.; Department of Physical Therapy and Assistive Technology, National Yang-Ming University, Taipei 112, Taiwan.
authors.forename: Chia-Feng
authors.initials: CF
authors.lastname: Lu
authors.affiliation: Institute of Statistical Science, Academia Sinica, Taipei 11529, Taiwan.
authors.forename: Michelle
authors.initials: M
authors.lastname: Liou
authors.affiliation: Department of Biomedical Imaging and Radiological Sciences, National Yang-Ming University, Taipei 112, Taiwan.
authors.forename: Yung-Chieh
authors.initials: YC
authors.lastname: Chen
authors.affiliation: Graduate Institute of Biomedical Electrics and Bioinformatics, National Taiwan University, Taipei 10617, Taiwan.
authors.forename: Hsiao-Wen
authors.initials: HW
authors.lastname: Chung
authors.affiliation: Research Center of Translational Imaging, College of Medicine, Taipei Medical University, Taipei 11031, Taiwan.; Department of Radiology, School of Medicine, College of Medicine, Taipei Medical University, Taipei 11031, Taiwan.; Department of Medical Imaging and Imaging Research Center, Taipei Medical University Hospital, Taipei Medical University, Taipei 11031, Taiwan.; Department of Radiology, Tri-Service General Hospital, Taipei 114, Taiwan.; Department of Radiology, National Defense Medical Center, Taipei 114, Taiwan.
authors.forename: Cheng-Yu
authors.initials: CY
authors.lastname: Chen
mesh_terms: D000818:Animals; D019540:Area Under Curve; D002545:Brain Ischemia / Q000175:diagnosis* / Q000000981:diagnostic imaging; D001931:Brain Mapping; D002560:Cerebrovascular Circulation / Q000502:physiology; D056324:Diffusion Tensor Imaging; D004195:Disease Models, Animal; D066128:Gray Matter / Q000000981:diagnostic imaging; D020244:Infarction, Middle Cerebral Artery / Q000175:diagnosis* / Q000000981:diagnostic imaging; D008279:Magnetic Resonance Imaging; D008297:Male; D012372:ROC Curve; D051381:Rats; D017207:Rats, Sprague-Dawley; D013997:Time Factors; D066127:White Matter / Q000000981:diagnostic imaging
keywords: Diffusion magnitude; Diffusion tensor imaging; Infarct core; Ischemic penumbra; Pure anisotropy