title: Nonenhanced extracranial carotid MR angiography using arterial spin labeling: improved performance with pseudocontinuous tagging.
abstract: OBJECTIVE
  To compare pulsed arterial spin labeling (PASL) and pseudocontinuous arterial spin labeling (PCASL) for nonenhanced extracranial carotid MR angiography (MRA).
  
  
  METHODS
  Parametric signal equations for PASL and PCASL MRA were formulated and compared. Volunteer imaging (n=7) at 1.5 Tesla was performed to compare the methods over a broad range of repetition and labeling times. Empirical results were compared with theoretical predictions. The feasibility of the optimal method was investigated in patients (n=2) with sonographically documented carotid artery disease.
  
  
  RESULTS
  In volunteers, PCASL provided significantly improved signal than PASL (range: 32-255% improvement; P<0.01), and better supported the use of long labeling times and short repetition times. Excellent agreement between theory and experiment was found (intraclass correlation coefficient=0.966; P<0.001). PCASL provided excellent depiction of the carotid arteries in initial patient studies.
  
  
  CONCLUSIONS
  Compared with pulsed tagging, pseudocontinuous tagging provides improved performance for nonenhanced extracranial carotid MRA and warrants further clinical investigation.
authors.affiliation: Department of Radiology, NorthShore University HealthSystem, Evanston, Illinois 60201, USA. ikoktzoglou@northshore.org
authors.forename: Ioannis
authors.initials: I
authors.lastname: Koktzoglou
authors.forename: NavYash
authors.initials: N
authors.lastname: Gupta
authors.forename: Robert R
authors.initials: RR
authors.lastname: Edelman
mesh_terms: D000328:Adult; D000792:Angiography / Q000379:methods*; D001158:Arteries / Q000473:pathology*; D002339:Carotid Arteries / Q000473:pathology*; D003952:Diagnostic Imaging / Q000379:methods; D005260:Female; D006801:Humans; D007091:Image Processing, Computer-Assisted / Q000379:methods; D018810:Magnetic Resonance Angiography / Q000379:methods*; D008297:Male; D008875:Middle Aged; D015233:Models, Statistical; D015203:Reproducibility of Results; D013113:Spin Labels
chemical_list: D013113:Spin Labels