title: Arterial transit time effects in pulsed arterial spin labeling CBF mapping: insight from a PET and MR study in normal human subjects.
abstract: Arterial transit time (ATT), a key parameter required to calculate absolute cerebral blood flow in arterial spin labeling (ASL), is subject to much uncertainty. In this study, ASL ATTs were estimated on a per-voxel basis using data measured by both ASL and positron emission tomography in the same subjects. The mean ATT increased by 260 +/- 20 (standard error of the mean) ms when the imaging slab shifted downwards by 54 mm, and increased from 630 +/- 30 to 1220 +/- 30 ms for the first slice, with an increase of 610 +/- 20 ms over a four-slice slab when the gap between the imaging and labeling slab increased from 20 to 74 mm. When the per-slice ATTs were employed in ASL cerebral blood flow quantification and the in-slice ATT variations ignored, regional cerebral blood flow could be significantly different from the positron emission tomography measures. ATT also decreased with focal activation by the same amount for both visual and motor tasks (approximately 80 ms). These results provide a quantitative relationship between ATT and the ASL imaging geometry and yield an assessment of the assumptions commonly used in ASL imaging. These findings should be considered in the interpretation of, and comparisons between, different ASL-based cerebral blood flow studies. The results also provide spatially specific ATT data that may aid in optimizing the ASL imaging parameters.
authors: Department of Diagnostic Radiology, Yale University School of Medicine, New Haven, Connecticut 06520-2048, USA. maolin.qiu@yale.edu
authors: Maolin
authors: M
authors: Qiu
authors: R
authors: R
authors: Paul Maguire
authors: Jagriti
authors: J
authors: Arora
authors: Beata
authors: B
authors: Planeta-Wilson
authors: David
authors: D
authors: Weinzimmer
authors: Jinghua
authors: J
authors: Wang
authors: Yuenan
authors: Y
authors: Wang
authors: Hyeonjin
authors: H
authors: Kim
authors: Nallakkandi
authors: N
authors: Rajeevan
authors: Yiyun
authors: Y
authors: Huang
authors: Richard E
authors: RE
authors: Carson
authors: R Todd
authors: RT
authors: Constable
mesh_terms: D000328:Adult; D001783:Blood Flow Velocity / Q000502:physiology*; D002560:Cerebrovascular Circulation / Q000502:physiology*; D005260:Female; D006801:Humans; D007090:Image Interpretation, Computer-Assisted / Q000379:methods*; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008297:Male; D010104:Oxygen Radioisotopes; D055420:Perfusion Imaging / Q000379:methods*; D049268:Positron-Emission Tomography / Q000379:methods*; D019275:Radiopharmaceuticals; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D013113:Spin Labels
chemical_list: D010104:Oxygen Radioisotopes; D019275:Radiopharmaceuticals; D013113:Spin Labels