title: Time Course of Diffusion Kurtosis in Cerebral Infarctions of Transient Middle Cerebral Artery Occlusion Rat Model.
abstract: OBJECTIVE
  To evaluate the relationship between fiber bundle direction and changes in diffusion kurtosis, we evaluated the apparent diffusion kurtosis coefficients (AKCs) that were perpendicular to and parallel to the principal diffusion tensor eigenvector.
  
  
  METHODS
  Adult male Wistar rats were subjected to 30 or 60 minutes of middle cerebral artery occlusion and imaged with a 7T Magnetic Resonance Imager System (Varian MRI System 7T/210: Agilent Technologies, CA). Diffusion kurtosis images were obtained before middle cerebral artery (MCA) reperfusion and 3, 6, and 24 hours after reperfusion to generate the apparent diffusion coefficient (ADC), fractional anisotropy (FA), mean apparent diffusion kurtosis coefficient (mAKC), AKC axial to the eigenvector (axAKC), and AKC radial to the eigenvector (radAKC) images. The time course of the region/normal ratio was evaluated for the above parameters in the caudoputamen and white matter.
  
  
  RESULTS
  Relative FA and relative ADC values decreased 3 hours after MCA reperfusion and remained decreased until 24 hours. Relative mAKC, axAKC, and radAKC values were increased 3 hours after MCA reperfusion, peaked after 6 hours, and slightly decreased after 24 hours. In the white matter, axAKC showed larger changes than radAKC.
  
  
  CONCLUSIONS
  The time course of the diffusion kurtosis value showed earlier pseudonormalization than the ADC value of the lesions. For white matter lesions, the increase in axAKC was larger than that in radAKC, suggesting that the tissue changes after infarction mainly produce reduced diffusivity along the fibers and lead to increased inhomogeneity of the diffusion.
authors.affiliation: Department of Radiology, Nagoya University, Nagoya, Japan. Electronic address: ttaoka@med.nagoya-u.ac.jp.
authors.forename: Toshiaki
authors.initials: T
authors.lastname: Taoka
authors.affiliation: Emergency and Critical Care Medical Center, Nara Medical University, Nara, Japan; Department of Neurosurgery, Osaka Saiseikai Senri Hospital, Osaka, Japan.
authors.forename: Masayuki
authors.initials: M
authors.lastname: Fujioka
authors.affiliation: Department of Drug Metabolism & Pharmacokinetics, Research Laboratory for Development, Shionogi & Co., Ltd, Osaka, Japan.
authors.forename: Yuto
authors.initials: Y
authors.lastname: Kashiwagi
authors.affiliation: Department of Drug Metabolism & Pharmacokinetics, Research Laboratory for Development, Shionogi & Co., Ltd, Osaka, Japan.
authors.forename: Atsushi
authors.initials: A
authors.lastname: Obata
authors.affiliation: Department of Drug Metabolism & Pharmacokinetics, Research Laboratory for Development, Shionogi & Co., Ltd, Osaka, Japan.
authors.forename: Takemi
authors.initials: T
authors.lastname: Rokugawa
authors.affiliation: Department of Radiology, Juntendo University, Tokyo, Japan.
authors.forename: Masaaki
authors.initials: M
authors.lastname: Hori
authors.affiliation: Department of Intelligent Systems, Graduate School of Information Sciences, Hiroshima City University, Hiroshima, Japan.
authors.forename: Yoshitaka
authors.initials: Y
authors.lastname: Masutani
authors.affiliation: Department of Radiology, Juntendo University, Tokyo, Japan.
authors.forename: Shigeki
authors.initials: S
authors.lastname: Aoki
authors.affiliation: Department of Radiology, Nagoya University, Nagoya, Japan.
authors.forename: Shinji
authors.initials: S
authors.lastname: Naganawa
authors.affiliation: Department of Drug Metabolism & Pharmacokinetics, Research Laboratory for Development, Shionogi & Co., Ltd, Osaka, Japan.
authors.forename: Kohji
authors.initials: K
authors.lastname: Abe
mesh_terms: D000704:Analysis of Variance; D000818:Animals; D016880:Anisotropy; D002544:Cerebral Infarction / Q000000981:diagnostic imaging / Q000209:etiology*; D038524:Diffusion Magnetic Resonance Imaging; D004195:Disease Models, Animal; D007091:Image Processing, Computer-Assisted; D020244:Infarction, Middle Cerebral Artery / Q000150:complications* / Q000000981:diagnostic imaging; D008279:Magnetic Resonance Imaging; D008297:Male; D051381:Rats; D017208:Rats, Wistar; D013997:Time Factors
keywords: MRI; Rat; diffusion; infarction; kurtosis; middle cerebral artery occulusion