title: Transfer characteristics of arterial pulsatile force in regional intracranial tissue using dynamic diffusion MRI: a phantom study.
abstract: BACKGROUND
  To clarify the mechanism underlying apparent diffusion coefficient (ADC) changes in regional intracranial tissue during the cardiac cycle, we investigated relationships among ADC changes, volume loading, and intracranial pressure using a hemodialyzer phantom in magnetic resonance imaging (MRI).
  
  
  METHODS
  The hemodialyzer phantom consisted of hollow fibers (HF), the external space of HFs (ES), and a gateway of dialysis solution, filled with syrup solution and air. The high-volume and low-volume loadings were periodically applied to HFs by a to-and-fro flow pump, and syrup solution was permitted to enter or leave HFs during the volume loading cycles. ADC maps at each volume loading phase were obtained using ECG-triggered single-shot diffusion echo-planar imaging. Dynamic phase contrast MRI was also used to measure volume loading to the phantom. We compared the ADC changes, volume loading, and intracranial pressure in the phantom during the cardiac cycle.
  
  
  RESULTS
  ADC changes synchronized significantly with absolute volumetric flow rate change. The maximum ADC change was higher in high-volume loading cycles than in low-volume loading cycles. Results showed that the water molecules in ES fluctuated according to the force transferred from HF to ES. ADC changes were dependent upon the volumetric flow rate during the cardiac cycle.
  
  
  CONCLUSIONS
  Our original phantom allowed us to clarify the mechanism underlying water fluctuations in intracranial tissues. Measurement of maximum changes in ADC is an effective method to define the transfer characteristics of the arterial pulsatile force in regional intracranial tissue.
authors.affiliation: Department of Radiology, Nagoya City University Hospital, 1-Kawasumi, Mizuho-cho Mizuho-ku, Nagoya City, Aichi, 4678602, Japan; Division of Health Sciences, Graduate School of Medical Science, Kanazawa University, 5-11-80 Kodatsuno, Kanazawa, Ishikawa, 9200942, Japan. Electronic address: gpx246@yahoo.co.jp.
authors.forename: Hirohito
authors.initials: H
authors.lastname: Kan
authors.affiliation: Division of Health Sciences, Graduate School of Medical Science, Kanazawa University, 5-11-80 Kodatsuno, Kanazawa, Ishikawa, 9200942, Japan. Electronic address: ramiyati@mhs.mp.kanazawa-u.ac.jp.
authors.forename: Tosiaki
authors.initials: T
authors.lastname: Miyati
authors.affiliation: Department of Radiology, Nagoya City University Hospital, 1-Kawasumi, Mizuho-cho Mizuho-ku, Nagoya City, Aichi, 4678602, Japan. Electronic address: hhkasai@gmail.com.
authors.forename: Harumasa
authors.initials: H
authors.lastname: Kasai
authors.affiliation: Department of Radiology, Nagoya City University Hospital, 1-Kawasumi, Mizuho-cho Mizuho-ku, Nagoya City, Aichi, 4678602, Japan. Electronic address: rarai51@med.nagoya-cu.ac.jp.
authors.forename: Nobuyuki
authors.initials: N
authors.lastname: Arai
authors.affiliation: Division of Health Sciences, Graduate School of Medical Science, Kanazawa University, 5-11-80 Kodatsuno, Kanazawa, Ishikawa, 9200942, Japan. Electronic address: nohno@med.kanazawa-u.ac.jp.
authors.forename: Naoki
authors.initials: N
authors.lastname: Ohno
authors.affiliation: Department of Neurosurgery, Nagoya City University Hospital, 1-Kawasumi, Mizuho-cho Mizuho-ku, Nagoya City, Aichi, 4678602, Japan. Electronic address: mitmase@med.nagoya-cu.ac.jp.
authors.forename: Mitsuhito
authors.initials: M
authors.lastname: Mase
authors.affiliation: Department of Radiology, Nagoya City University Hospital, 1-Kawasumi, Mizuho-cho Mizuho-ku, Nagoya City, Aichi, 4678602, Japan. Electronic address: yshiba@med.nagoya-cu.ac.jp.
authors.forename: Yuta
authors.initials: Y
authors.lastname: Shibamoto
mesh_terms: D001158:Arteries / Q000473:pathology*; D001921:Brain / Q000098:blood supply / Q000473:pathology*; D038524:Diffusion Magnetic Resonance Imaging / Q000379:methods*; D017352:Echo-Planar Imaging / Q000379:methods*; D004562:Electrocardiography / Q000379:methods; D006321:Heart / Q000502:physiology; D006801:Humans; D007427:Intracranial Pressure; D019028:Magnetic Resonance Imaging, Cine / Q000379:methods; D019047:Phantoms, Imaging; D011312:Pressure; D011673:Pulsatile Flow
keywords: Apparent diffusion coefficient; Diffusion weighted imaging; Magnetic resonance imaging; Water molecular fluctuation