title: Technical Note: Development of a cranial phantom for assessing perfusion, diffusion, and biomechanics.
abstract: OBJECTIVE
  A novel cranial phantom was developed to simulate the relationships among factors such as blood perfusion, water diffusion, and biomechanics in intracranial tissue.
  
  
  METHODS
  The cranial phantom consisted of a high-density polypropylene filter (mimicking brain parenchyma) with intra- and extrafilter spaces (mimicking cerebral artery and vein, respectively), and a capacitor space (mimicking the cerebrospinal fluid space). Pulsatile and steady flow with different flow rates were applied to the cranial phantom using a programmable pump. On 3.0-T MRI, the measurements of the internal pressure in the phantom, apparent diffusion coefficient (ADC) with monoexponential analysis in the filter, and total simulated cerebral blood flow (tSCBF) into the phantom were synchronized with the pulsatile flow. We obtained their maximum changes during the pulsation period (ΔP, ΔADC, and ΔtSCBF, respectively). Then, the compliance index (CI) was calculated by dividing the volume change (ΔV) by the ΔP in the phantom. Moreover, the same measurements were repeated after the compliance of the phantom was reduced by increasing the water volume in the capacitor space. Under steady flow conditions, we determined the regional SCBF (rSCBF) and perfusion-related and restricted diffusion coefficients (D* and D, respectively) with biexponential analysis in the filter.
  
  
  RESULTS
  The internal pressure, ADC, and tSCBF varied over the pulsation period depending on the input flow. Moreover, the ΔP, ΔADC, ΔtSCBF, and rSCBF increased with the input flow rate. Compared to the high compliance condition, in the low compliance condition, the ΔP and ΔADC were higher by factors of 2.5 and 1.3, respectively, and the CI was smaller by a factor of 2.7, whereas the ΔV was almost unchanged. The D* was strongly affected by the input flow.
  
  
  CONCLUSIONS
  Our original phantom models the relationships among the blood perfusion, water diffusion, and biomechanics of the intracranial tissue, potentially facilitating the validation of novel MRI techniques and optimization of imaging parameters.
authors.affiliation: Faculty of Health Sciences, Institute of Medical, Pharmaceutical and Health Sciences, Kanazawa University, 5-11-80 Kodatsuno, Kanazawa, Ishikawa, 9200942, Japan.
authors.forename: Naoki
authors.initials: N
authors.lastname: Ohno
authors.affiliation: Faculty of Health Sciences, Institute of Medical, Pharmaceutical and Health Sciences, Kanazawa University, 5-11-80 Kodatsuno, Kanazawa, Ishikawa, 9200942, Japan.
authors.forename: Tosiaki
authors.initials: T
authors.lastname: Miyati
authors.affiliation: Department of Radiology, Okazaki City Hospital, 3-1 Goshoai, Koryuji-cho, Okazaki, Aichi, 4448553, Japan.
authors.forename: Tomohiro
authors.initials: T
authors.lastname: Chigusa
authors.affiliation: Department of Radiology, Yokohama City University Hospital, 3-9 Fuku-ura, Kanazawa-ku, Yokohama, Kanagawa, 2360004, Japan.
authors.forename: Hikari
authors.initials: H
authors.lastname: Usui
authors.affiliation: Faculty of Health Sciences, Institute of Medical, Pharmaceutical and Health Sciences, Kanazawa University, 5-11-80 Kodatsuno, Kanazawa, Ishikawa, 9200942, Japan.
authors.forename: Shota
authors.initials: S
authors.lastname: Ishida
authors.affiliation: Faculty of Health Sciences, Institute of Medical, Pharmaceutical and Health Sciences, Kanazawa University, 5-11-80 Kodatsuno, Kanazawa, Ishikawa, 9200942, Japan.
authors.forename: Yuki
authors.initials: Y
authors.lastname: Hiramatsu
authors.affiliation: Faculty of Health Sciences, Institute of Medical, Pharmaceutical and Health Sciences, Kanazawa University, 5-11-80 Kodatsuno, Kanazawa, Ishikawa, 9200942, Japan.
authors.forename: Satoshi
authors.initials: S
authors.lastname: Kobayashi
authors.affiliation: Department of Radiology, Kanazawa University, 13-1 Takara-machi, Kanazawa, Ishikawa, 9208641, Japan.
authors.forename: Toshifumi
authors.initials: T
authors.lastname: Gabata
authors.affiliation: Department of Radiology, University of Miami, 1150 NW 14th Street, Suite 713, FL, 33146, USA.
authors.forename: Noam
authors.initials: N
authors.lastname: Alperin
mesh_terms: D001921:Brain / Q000098:blood supply / Q000000981:diagnostic imaging*; D002560:Cerebrovascular Circulation; D004058:Diffusion; D006801:Humans; D008279:Magnetic Resonance Imaging; D010477:Perfusion; D019047:Phantoms, Imaging
keywords: apparent diffusion coefficient; cerebral blood flow; cranial phantom; intracranial compliance