title: Arterial transit time imaging with flow encoding arterial spin tagging (FEAST).
abstract: Arterial spin labeling (ASL) perfusion imaging provides direct and absolute measurement of cerebral blood flow (CBF). Arterial transit time is a related physiological parameter reflecting the duration for the labeled spins to reach the brain region of interest. Most of the existing ASL approaches to assess arterial transit time rely on multiple measurements at various postlabeling delay times, and thus are vulnerable to motion artifact as well as computational error. We describe the use of flow encoding arterial spin tagging (FEAST) technique to measure tissue transit time, which can be derived from the ratio between the ASL signals measured with and without appropriate bipolar gradients. In the present study, we provided a theoretical framework and carried out an experimental validation during steady-state imaging. The global mean tissue transit time was approximately 1100 and 1400 ms for two conditions of bipolar gradients with specific encoding velocity (Venc) of 29 and 8 mm/sec, respectively. The mean tissue transit time measured within cerebral vascular territories was shortest in the deep middle cerebral artery (MCA) territory. Application of the FEAST technique in two patients with cerebrovascular disease demonstrated prolonged tissue transit times in the affected vascular territories which were consistent with results from other MR imaging modalities.
authors.affiliation: Department of Radiology, University of Pennsylvania, Philadelphia, Pennsylvania 19104, USA. jwang@rad.upenn.edu
authors.forename: Jiongjiong
authors.initials: J
authors.lastname: Wang
authors.forename: David C
authors.initials: DC
authors.lastname: Alsop
authors.forename: Hee Kwon
authors.initials: HK
authors.lastname: Song
authors.forename: Joseph A
authors.initials: JA
authors.lastname: Maldjian
authors.forename: Kathy
authors.initials: K
authors.lastname: Tang
authors.forename: Alana E
authors.initials: AE
authors.lastname: Salvucci
authors.forename: John A
authors.initials: JA
authors.lastname: Detre
mesh_terms: D000328:Adult; D000465:Algorithms; D001158:Arteries; D001783:Blood Flow Velocity; D002560:Cerebrovascular Circulation / Q000502:physiology*; D005260:Female; D006801:Humans; D007091:Image Processing, Computer-Assisted; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008297:Male; D013113:Spin Labels
chemical_list: D013113:Spin Labels