title: Noninvasive MRI assessment of intracranial compliance in idiopathic normal pressure hydrocephalus.
abstract: OBJECTIVE
  To assess the state and dynamics of the intracranial system in idiopathic normal-pressure hydrocephalus (I-NPH), we determined intracranial compliance using magnetic resonance imaging (MRI).
  
  
  METHODS
  The intracranial compliance index (ICCI), which was defined as the ratio of the peak-to-peak intracranial volume change (ICVC(p-p)) to the peak-to-peak cerebrospinal fluid (CSF) pressure gradient (PG(p-p)) during the cardiac cycle, was obtained from the net transcranial blood and CSF flow measured with phase-contrast (PC) cine MRI. ICCI was determined in patients with I-NPH (N = 7), brain atrophy, or asymptomatic ventricular dilation (VD) (N = 6), and in healthy volunteers (control group; N = 11). The changes in ICCI indices were also analyzed after a CSF tap test (N = 2).
  
  
  RESULTS
  The ICCI in the I-NPH group was significantly lower than in the control and VD groups, whereas no difference was found between the control and VD groups. The ICVC(p-p) was also lower than in the control and VD groups. However, no significant difference was found in the PG(p-p) between groups. The ICCI increased after the tap test.
  
  
  CONCLUSIONS
  Intracranial compliance analysis with MRI makes it possible to noninvasively obtain more detailed information of intracranial biomechanics in the I-NPH and to assist in the diagnosis of I-NPH.
authors.affiliation: Division of Health Sciences, Graduate School of Medical Science, Kanazawa University, Kanazawa, Ishikawa, Japan. ramiyati@mhs.mp.kanazawa-u.ac.jp
authors.forename: Tosiaki
authors.initials: T
authors.lastname: Miyati
authors.forename: Mitsuhito
authors.initials: M
authors.lastname: Mase
authors.forename: Harumasa
authors.initials: H
authors.lastname: Kasai
authors.forename: Masaki
authors.initials: M
authors.lastname: Hara
authors.forename: Kazuo
authors.initials: K
authors.lastname: Yamada
authors.forename: Yuta
authors.initials: Y
authors.lastname: Shibamoto
authors.forename: Michaela
authors.initials: M
authors.lastname: Soellinger
authors.forename: Christof
authors.initials: C
authors.lastname: Baltes
authors.forename: Roger
authors.initials: R
authors.lastname: Luechinger
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001696:Biomechanical Phenomena; D001921:Brain / Q000473:pathology*; D016022:Case-Control Studies; D005260:Female; D006801:Humans; D006850:Hydrocephalus, Normal Pressure / Q000175:diagnosis* / Q000473:pathology*; D007091:Image Processing, Computer-Assisted; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008297:Male; D008875:Middle Aged; D012016:Reference Values; D015203:Reproducibility of Results