title: Comparison of long-labeled pseudo-continuous arterial spin labeling (ASL) features between young and elderly adults: special reference to parameter selection.
abstract: BACKGROUND
  The signal intensity obtained by arterial spin labeling (ASL) depends not only on perfusion signal, but also on arterial transit time (ATT). Although ATT has a more significant effect on accurate regional cerebral blood flow (CBF) calculations, the multiple post-labeling delay (PLD) approach is difficult to use in routine examinations.
  
  
  OBJECTIVE
  To optimize imaging parameters for labeling duration (LD) and PLD and to confirm their validity in long-labeled pseudo-continuous ASL.
  
  
  METHODS
  The perfusion signal was simulated in four LDs and theoretical signal-to-noise ratio efficiency (SNReff) was calculated. In vivo studies were performed on a 3.0 T magnetic resonance imaging (MRI) scanner and 15 volunteers were categorized into either the young or elderly adult groups. We compared the differences in CBF values with or without ATT correction.
  
  
  RESULTS
  Regarding signal simulation, perfusion signal increased with the length of LD. SNReffalso improved with LD, but SNReffplateaued at an LD of 3.0 s. As for the in vivo study, SNR linearly increased along with the LD. The CBF differences with the correction of ATT were larger in the elderly adult group. This trend was most prominent in the longer ATT area in the occipital cortical region.
  
  
  CONCLUSIONS
  A combination of imaging settings of LD = 3.5 s and PLD = 2.0 s were suggested as optimal imaging parameters for allowing acceptable CBF quantification and sufficient SNR in both young and elderly individuals.
authors.affiliation: Department of Medical Imaging, Faculty of Life Sciences, Kumamoto University, Kumamoto, Japan.
authors.forename: Yasuhiro
authors.initials: Y
authors.lastname: Fujiwara
authors.affiliation: Global MR Applications and Workflow, GE Healthcare Japan, Japan.
authors.forename: Tsuyoshi
authors.initials: T
authors.lastname: Matsuda
authors.affiliation: Radiological Center, University of Fukui Hospital, Fukui, Japan.
authors.forename: Masayuki
authors.initials: M
authors.lastname: Kanamoto
authors.affiliation: Department of Radiology, Faculty of Medical Sciences, University of Fukui, Fukui, Japan.
authors.forename: Tatsuro
authors.initials: T
authors.lastname: Tsuchida
authors.affiliation: Department of Radiology, Faculty of Medical Sciences, University of Fukui, Fukui, Japan.
authors.forename: Kazunobu
authors.initials: K
authors.lastname: Tsuji
authors.affiliation: Department of Radiology, Faculty of Medical Sciences, University of Fukui, Fukui, Japan.
authors.forename: Nobuyuki
authors.initials: N
authors.lastname: Kosaka
authors.affiliation: Radiological Center, University of Fukui Hospital, Fukui, Japan.
authors.forename: Toshiki
authors.initials: T
authors.lastname: Adachi
authors.affiliation: Department of Radiology, Faculty of Medical Sciences, University of Fukui, Fukui, Japan kimura@u-fukui.ac.jp.
authors.forename: Hirohiko
authors.initials: H
authors.lastname: Kimura
mesh_terms: D000328:Adult; D000368:Aged; D000375:Aging / Q000502:physiology*; D000465:Algorithms; D001783:Blood Flow Velocity; D002533:Cerebral Angiography / Q000379:methods*; D002536:Cerebral Arteries / Q000502:physiology*; D002560:Cerebrovascular Circulation / Q000502:physiology*; D005260:Female; D006801:Humans; D007089:Image Enhancement / Q000379:methods*; D007090:Image Interpretation, Computer-Assisted / Q000379:methods; D018810:Magnetic Resonance Angiography / Q000379:methods*; D008297:Male; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D013113:Spin Labels
chemical_list: D013113:Spin Labels
keywords: Magnetic resonance imaging (MRI); arterial spin labeling (ASL); arterial transit time (ATT); cerebral blood flow; perfusion