title: Evaluation of glymphatic system activity with the diffusion MR technique: diffusion tensor image analysis along the perivascular space (DTI-ALPS) in Alzheimer's disease cases.
abstract: OBJECTIVE
  The activity of the glymphatic system is impaired in animal models of Alzheimer's disease (AD). We evaluated the activity of the human glymphatic system in cases of AD with a diffusion-based technique called diffusion tensor image analysis along the perivascular space (DTI-ALPS).
  
  
  METHODS
  Diffusion tensor images were acquired to calculate diffusivities in the x, y, and z axes of the plane of the lateral ventricle body in 31 patients. We evaluated the diffusivity along the perivascular spaces as well as projection fibers and association fibers separately, to acquire an index for diffusivity along the perivascular space (ALPS-index) and correlated them with the mini mental state examinations (MMSE) score.
  
  
  RESULTS
  We found a significant negative correlation between diffusivity along the projection fibers and association fibers. We also observed a significant positive correlation between diffusivity along perivascular spaces shown as ALPS-index and the MMSE score, indicating lower water diffusivity along the perivascular space in relation to AD severity.
  
  
  CONCLUSIONS
  Activity of the glymphatic system may be evaluated with diffusion images. Lower diffusivity along the perivascular space on DTI-APLS seems to reflect impairment of the glymphatic system. This method may be useful for evaluating the activity of the glymphatic system.
authors.affiliation: Department of Radiology, Nagoya University, 65 Tsurumai-cho, Showa-ku, Nagoya, Aichi, 466-8550, Japan. ttaoka@med.nagoya-u.ac.jp.
authors.forename: Toshiaki
authors.identifier: http://orcid.org/0000-0001-9227-0240
authors.initials: T
authors.lastname: Taoka
authors.affiliation: Department of Biomedical Information Sciences, Graduate School of Information Sciences, Hiroshima City University, 3-4-1, Ozuka-Higashi, Asa-Minami-Ku, Hiroshima, 731-3194, Japan.
authors.forename: Yoshitaka
authors.initials: Y
authors.lastname: Masutani
authors.affiliation: Department of Radiology, Nagoya University, 65 Tsurumai-cho, Showa-ku, Nagoya, Aichi, 466-8550, Japan.
authors.forename: Hisashi
authors.initials: H
authors.lastname: Kawai
authors.affiliation: Department of Radiology, Nagoya University, 65 Tsurumai-cho, Showa-ku, Nagoya, Aichi, 466-8550, Japan.
authors.forename: Toshiki
authors.initials: T
authors.lastname: Nakane
authors.affiliation: Department of Psychiatry, Nara Medical University, 840 Shijo-cho, Kashihara, Nara, 634-8522, Japan.
authors.forename: Kiwamu
authors.initials: K
authors.lastname: Matsuoka
authors.affiliation: Department of Psychiatry, Nara Medical University, 840 Shijo-cho, Kashihara, Nara, 634-8522, Japan.
authors.forename: Fumihiko
authors.initials: F
authors.lastname: Yasuno
authors.affiliation: Department of Psychiatry, Nara Medical University, 840 Shijo-cho, Kashihara, Nara, 634-8522, Japan.
authors.forename: Toshifumi
authors.initials: T
authors.lastname: Kishimoto
authors.affiliation: Department of Radiology, Nagoya University, 65 Tsurumai-cho, Showa-ku, Nagoya, Aichi, 466-8550, Japan.
authors.forename: Shinji
authors.initials: S
authors.lastname: Naganawa
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D000544:Alzheimer Disease / Q000134:cerebrospinal fluid / Q000000981:diagnostic imaging* / Q000503:physiopathology; D001921:Brain / Q000000981:diagnostic imaging / Q000503:physiopathology; D060825:Cognitive Dysfunction / Q000134:cerebrospinal fluid / Q000000981:diagnostic imaging / Q000503:physiopathology; D056324:Diffusion Tensor Imaging / Q000379:methods; D005260:Female; D006801:Humans; D008208:Lymphatic System / Q000000981:diagnostic imaging* / Q000503:physiopathology; D008297:Male; D008875:Middle Aged
keywords: Alzheimer’s disease; Diffusion tensor; Glymphatic system; MRI; Perivascular space