title: Regional reliability of quantitative signal targeting with alternating radiofrequency (STAR) labeling of arterial regions (QUASAR).
abstract: OBJECTIVE
  Quantitative signal targeting with alternating radiofrequency labeling of arterial regions (QUASAR) is a recent spin labeling technique that could improve the reliability of brain perfusion measurements. Although it is considered reliable for measuring gray matter as a whole, it has never been evaluated regionally. Here we assessed this regional reliability.
  
  
  METHODS
  Using a 3-Tesla Philips Achieva whole-body system, we scanned four times 10 healthy volunteers, in two sessions 2 weeks apart, to obtain QUASAR images. We computed perfusion images and ran a voxel-based analysis within all brain structures. We also calculated mean regional cerebral blood flow (rCBF) within regions of interest configured for each arterial territory distribution.
  
  
  RESULTS
  The mean CBF over whole gray matter was 37.74 with intraclass correlation coefficient (ICC) of .70. In white matter, it was 13.94 with an ICC of .30. Voxel-wise ICC and coefficient-of-variation maps showed relatively lower reliability in watershed areas and white matter especially in deeper white matter. The absolute mean rCBF values were consistent with the ones reported from PET, as was the relatively low variability in different feeding arteries.
  
  
  CONCLUSIONS
  Thus, QUASAR reliability for regional perfusion is high within gray matter, but uncertain within white matter.
authors.affiliation: Department of Diagnostic Radiology, Tohoku University Graduate School of Medicine, Miyagi, Japan.
authors.forename: Yasuko
authors.initials: Y
authors.lastname: Tatewaki
authors.affiliation: Department of Diagnostic Radiology, Tohoku University Graduate School of Medicine, Miyagi, Japan.
authors.forename: Shuichi
authors.initials: S
authors.lastname: Higano
authors.affiliation: Division of Developmental Cognitive Neuroscience Institute of Development, Aging and Cancer, Tohoku University, Miyagi, Japan.|Division of Medical Image Analysis, Department of Community Medical Megabank, Tohoku Medical Megabank Organization, Tohoku University, Miyagi, Japan.|Depatment of Nuclear Medicine & Radiology, Institute of Development, Aging and Cancer, Tohoku University, Miyagi, Japan.
authors.forename: Yasuyuki
authors.initials: Y
authors.lastname: Taki
authors.affiliation: Division of Developmental Cognitive Neuroscience Institute of Development, Aging and Cancer, Tohoku University, Miyagi, Japan.
authors.forename: Benjamin
authors.initials: B
authors.lastname: Thyreau
authors.affiliation: Department of Diagnostic Radiology, Tohoku University Graduate School of Medicine, Miyagi, Japan.
authors.forename: Takaki
authors.initials: T
authors.lastname: Murata
authors.affiliation: Department of Diagnostic Radiology, Tohoku University Graduate School of Medicine, Miyagi, Japan.
authors.forename: Shunji
authors.initials: S
authors.lastname: Mugikura
authors.affiliation: Division of Radiology, Tohoku University Hospital, Miyagi, Japan.
authors.forename: Daisuke
authors.initials: D
authors.lastname: Ito
authors.affiliation: Department of Diagnostic Radiology, Tohoku University Graduate School of Medicine, Miyagi, Japan.
authors.forename: Kei
authors.initials: K
authors.lastname: Takase
authors.affiliation: Department of Diagnostic Radiology, Tohoku University Graduate School of Medicine, Miyagi, Japan.
authors.forename: Shoki
authors.initials: S
authors.lastname: Takahashi
mesh_terms: D000328:Adult; D001783:Blood Flow Velocity / Q000502:physiology*; D001921:Brain / Q000033:anatomy & histology / Q000502:physiology*; D002560:Cerebrovascular Circulation / Q000502:physiology*; D005260:Female; D066128:Gray Matter / Q000098:blood supply / Q000502:physiology*; D006801:Humans; D007089:Image Enhancement / Q000379:methods; D007090:Image Interpretation, Computer-Assisted / Q000379:methods*; D021621:Imaging, Three-Dimensional / Q000379:methods; D018810:Magnetic Resonance Angiography / Q000379:methods*; D008297:Male; D011846:Radio Waves; D012016:Reference Values; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D013113:Spin Labels; D066127:White Matter / Q000098:blood supply / Q000502:physiology*; D055815:Young Adult
chemical_list: D013113:Spin Labels
keywords: ASL; QUASAR; regional cerebral blood flow; regional reliability