title: Idiopathic normal-pressure hydrocephalus: temporal changes in ADC during cardiac cycle.
abstract: OBJECTIVE
  To determine whether temporal changes in apparent diffusion coefficient (ADC) over the cardiac cycle are different in patients with idiopathic normal-pressure hydrocephalus (INPH) as compared with patients with ex vacuo ventricular dilatation and healthy control subjects.
  
  
  METHODS
  This prospective study was approved by the institutional review board and was performed only after informed consent was obtained from each patient. At 1.5 T, electrocardiographically triggered single-shot diffusion echo-planar magnetic resonance imaging (b = 0 and 1000 sec/mm(2)) was performed with sensitivity encoding and half-scan techniques to minimize bulk motion. ΔADC was defined as the difference between maximum and minimum ADC on a pixel-by-pixel basis over 20 phases of the cardiac cycle. Mean ADC during the diastolic phase and ΔADC in the frontal white matter were determined in patients with INPH (n = 13), patients with ex vacuo ventricular dilatation (n = 8), and healthy volunteers (n = 10). Kruskal-Wallis tests were used to determine significance between groups.
  
  
  RESULTS
  Mean ΔADC in the INPH group was significantly higher than that in the ex vacuo ventricular dilatation and control groups (P < .01 for both). There was no significant difference in ΔADC between the ex vacuo ventricular dilatation and control groups (P = .86). There was no significant difference in mean ADC during the diastolic phase among groups (P > .05 for all). There was no significant correlation between ΔADC and mean ADC during the diastolic phase in any group.
  
  
  CONCLUSIONS
  Determination of fluctuation of ADC over the cardiac cycle may render it possible to noninvasively obtain new and more detailed information than that provided by standard ADC measurement in suspected INPH, potentially facilitating the diagnosis of this disease.
authors: Division of Health Sciences, Graduate School of Medical Science, Kanazawa University, 5-11-80, Kodatsuno, Kanazawa, Ishikawa 920-0942, Japan.
authors: Naoki
authors: N
authors: Ohno
authors: Tosiaki
authors: T
authors: Miyati
authors: Mitsuhito
authors: M
authors: Mase
authors: Tomoshi
authors: T
authors: Osawa
authors: Hirohito
authors: H
authors: Kan
authors: Harumasa
authors: H
authors: Kasai
authors: Masaki
authors: M
authors: Hara
authors: Yuta
authors: Y
authors: Shibamoto
authors: Norio
authors: N
authors: Hayashi
authors: Toshifumi
authors: T
authors: Gabata
authors: Osamu
authors: O
authors: Matsui
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D055424:Cardiac-Gated Imaging Techniques / Q000379:methods*; D016022:Case-Control Studies; D038524:Diffusion Magnetic Resonance Imaging / Q000379:methods*; D017352:Echo-Planar Imaging / Q000379:methods; D005260:Female; D006439:Hemodynamics; D006801:Humans; D006850:Hydrocephalus, Normal Pressure / Q000473:pathology*; D008297:Male; D011446:Prospective Studies; D013997:Time Factors