title: Precision of the CASL-perfusion MRI technique for the measurement of cerebral blood flow in whole brain and vascular territories.
abstract: OBJECTIVE
  To analyze the precision of cerebral blood flow (CBF) measurements made with continuous arterial spin labeling(CASL) perfusion magnetic resonance imaging (MRI) over experimentally relevant intervals.
  
  
  METHODS
  CASL perfusion MRI measurements of CBF on a 1.5-T GE Signa magnet were repeated in young healthy male and female subjects at one hour and one week. Precision of the measurement was evaluated at both time intervals.
  
  
  RESULTS
  CASL perfusion MRI measurements of CBF yielded within-subject coefficients of variation (wsCV) of 5.8% for global and 13% for individual vascular regions when measurements were repeated within one hour. Differences in these values represent the error in post-processing. Global and regional CBF measurements over one week yielded wsCVs of 13% and 14%, respectively. At one week, error secondary to physiologic variability affected global and regional measurements to the same degree and masked the software post-processing error seen at one hour. The magnitude of the difference in repeated measures correlated with the magnitude of the measurement.
  
  
  CONCLUSIONS
  CASL perfusion MRI CBF measurements are accurate and precise. Variability over longer periods of time appears attributable to physiologic factors. Repeatability of the CASL measurement is sensitive to the magnitude of the measurement. This should be taken into account when studies requiring repeated measures involve subjects with significant variability in CBF.
authors.affiliation: University of Pennsylvania School of Medicine, Philadelphia, Pennsylvania 19104, USA. floydt@uphs.upenn.edu
authors.forename: Thomas F
authors.initials: TF
authors.lastname: Floyd
authors.forename: Sarah J
authors.initials: SJ
authors.lastname: Ratcliffe
authors.forename: Jiongjiong
authors.initials: J
authors.lastname: Wang
authors.forename: Brooke
authors.initials: B
authors.lastname: Resch
authors.forename: John A
authors.initials: JA
authors.lastname: Detre
mesh_terms: D000328:Adult; D000704:Analysis of Variance; D001921:Brain / Q000098:blood supply* / Q000502:physiology*; D002560:Cerebrovascular Circulation / Q000502:physiology; D005260:Female; D006801:Humans; D018810:Magnetic Resonance Angiography / Q000379:methods*; D008297:Male; D012039:Regional Blood Flow / Q000502:physiology; D012680:Sensitivity and Specificity; D013997:Time Factors