title: Apparent Diffusion Coefficient Value Is Not Dependent on Magnetic Resonance Systems and Field Strength Under Fixed Imaging Parameters in Brain.
abstract: OBJECTIVE
  The aim of the study was to investigate the causes of apparent diffusion coefficient (ADC) measurement errors and to determine the optimal scanning parameters that are independent of the field strength and vendors of the magnetic resonance (MR) system.
  
  
  METHODS
  Brain MR images of 10 healthy volunteers were scanned using 6 MR scanners of different field strengths and vendors in 2 different institutions. Ethical review board approvals were obtained for this study, and all volunteers gave their informed consents. Coefficient of variation (CV) of ADC values were compared for their differences in various MR scanners and in the scanned subjects.
  
  
  RESULTS
  The CV of ADC values for 6 different scanners of 6 brains was 3.32%. The CV for repeated measurements in 1 day (10 scans per day) and in 10 days (scan per day for 10 days) for 1 subject was 1.72% and 2.96%, respectively (n = 5, P < 0.001). The CV of measurements for 10 healthy subjects was 5.22%. The measurement errors of the ADC values for 6 different MR units in 1 subject were higher than the intrascanner variance for the same subject but were lower than the intersubject variance for the same scanner.
  
  
  CONCLUSIONS
  The variance in the ADC values for different MR scanners is reasonably small if appropriate scanning parameters (repetition time, >3000 ms; echo time, minimum; and high enough signal-to-noise ratio of high-b diffusion-weighted image) are used.
authors.affiliation: From the *Graduate School, Gunma Prefectural College of Health Sciences, Maebashi; †Department of Clinical Support, Hiroshima University Hospital, Hiroshima; ‡Division of Health Sciences, Kanazawa University Graduate School of Medical Sciences, Kanazawa; §Department of Medical Technology, Osaka University Hospital, Osaka; ∥Department of Diagnostic Imaging and Nuclear Medicine, Graduate School of Medicine, Kyoto University, Kyoto; ¶Institute of Medical, Pharmaceutical and Health Sciences, Kanazawa University, Kanazawa; #Japan Community Health Care Organization Sendai Minami Hospital, Sendai; **Department of Radiology, Kyoto City Hospital, Kyoto; and ††Department of Radiology, Yokohama Sakae Kyosai Hospital, Federation of National Public Service Personnel Mutual Associations, Yokohama, Japan.
authors.forename: Akio
authors.initials: A
authors.lastname: Ogura
authors.forename: Takayuki
authors.initials: T
authors.lastname: Tamura
authors.forename: Masanori
authors.initials: M
authors.lastname: Ozaki
authors.forename: Tsukasa
authors.initials: T
authors.lastname: Doi
authors.forename: Koji
authors.initials: K
authors.lastname: Fujimoto
authors.forename: Tosiaki
authors.initials: T
authors.lastname: Miyati
authors.forename: Yukiko
authors.initials: Y
authors.lastname: Ito
authors.forename: Fumie
authors.initials: F
authors.lastname: Maeda
authors.forename: Hiroyuki
authors.initials: H
authors.lastname: Tarewaki
authors.forename: Mitsuyuki
authors.initials: M
authors.lastname: Takahashi
mesh_terms: D000328:Adult; D001921:Brain / Q000033:anatomy & histology*; D038524:Diffusion Magnetic Resonance Imaging / Q000379:methods*; D006801:Humans; D007090:Image Interpretation, Computer-Assisted / Q000379:methods*; D008297:Male; D008875:Middle Aged; D011446:Prospective Studies; D012016:Reference Values; D059629:Signal-To-Noise Ratio