title: Reproducibility of pulmonary blood flow measurements by phase-contrast MRI using different 1.5 T MR scanners at two institutions.
abstract: BACKGROUND
  Magnetic resonance imaging (MRI) can be beneficial for diagnosis of disease by offering quantitative information. However, reproducibility can be a major problem when there is a numerical threshold in multi-institution, multi-vendor situations.
  
  
  OBJECTIVE
  To measure pulmonary blood flow with phase-contrast (PC) imaging using two different MR scanners (1.5 T) at different institutions in the same participants and to examine the reproducibility of the measurements.
  
  
  METHODS
  Participants were 10 healthy volunteers (5 men; age range, 27-36 years). The measurements included the mean and maximal blood velocities, the mean blood flow volume, and the acceleration time and volume (AT and AV), derived from the time-flow curve of the PC-MRI. Simultaneously obtained maximal, minimal, and mean areas from regions of interest set in the pulmonary artery were also calculated. In order to calculate the reproducibility of the quantitative variables, intra-class correlation coefficients (ICCs) were employed. When an adequate ICC was obtained, Bland-Altman analysis was conducted to identify any systematic bias.
  
  
  RESULTS
  The ICCs were almost perfect for the mean blood flow volume and the AV (r = 0.82 and 0.80), and were substantial in the mean and maximal areas, and the AT (r = 0.63, 0.74, and 0.64, respectively). However, there was a fixed bias in the area measurement between the two scanners. Also, the AV had a proportional bias.
  
  
  CONCLUSIONS
  Our results reveal that various indices derived from PC-MRI on different MR scanners are promising as common indices for pulmonary flow assessment. Research and clinical use of PC-MRI for the pulmonary artery is expected to extend to multi-institution situations.
authors.affiliation: Department of Radiology, Graduate School of Medical Science, University of the Ryukyus, Okinawa, Japan.
authors.forename: Rin
authors.initials: R
authors.lastname: Iraha
authors.affiliation: Department of Radiology, Graduate School of Medical Science, University of the Ryukyus, Okinawa, Japan.
authors.forename: Nanae
authors.initials: N
authors.lastname: Tsuchiya
authors.affiliation: Department of Radiology, Graduate School of Medical Science, University of the Ryukyus, Okinawa, Japan.
authors.forename: Tsuneo
authors.initials: T
authors.lastname: Yamashiro
authors.affiliation: Department of Radiology, Kanagawa Cardiovascular and Respiratory Center, Kanagawa, Japan.
authors.forename: Tae
authors.initials: T
authors.lastname: Iwasawa
authors.affiliation: Department of Radiology, Graduate School of Medical Science, University of the Ryukyus, Okinawa, Japan.
authors.forename: Sadayuki
authors.initials: S
authors.lastname: Murayama
keywords: Magnetic resonance imaging (MRI); flow measurement; multi-vendor; phase-contrast MRI; pulmonary artery; reproducibility