title: Regional perfusion imaging using pTILT.
abstract: OBJECTIVE
  To demonstrate the feasibility that the pseudo-continuous transfer insensitive labeling technique (pTILT) sequence can be modified to achieve regional perfusion imaging by either vessel-encoded or vessel-selective pTILT, similar to the regional perfusion imaging sequences using pseudo-continuous arterial spin labeling (pCASL).
  
  
  METHODS
  Static phantom experiments were carried out to investigate the selectivity and efficiency of region-specific labeling by pTILT. The ability of the modified pTILT sequences to separate perfusion territories was also examined at two levels of the arterial tree on four healthy subjects: (i) the left and right internal carotid arteries (ICAs) and (ii) individual vascular territories of arteries above the circle of Willis (anterior cerebral artery [ACA], left and right middle cerebral arteries [MCAs]).
  
  
  RESULTS
  In the phantom study, compared with non-region-specific pTILT, a labeling efficiency of 0.92 and 0.88 was measured at the target vessels using vessel-encoded and vessel-selective pTILT, respectively. In human studies, the perfusion territories of ACA, left and right MCA branches with estimated CBF of 74.5 ± 26.1, 65.9 ± 7.2, and 72.3 ± 14.5 mL/100 g/min, respectively, as well as more general left/right end territories (76.8 ± 12.7 and 72.8 ± 7.2 mL/100 g/min), were clearly delineated by the modified pTILT sequences for regional perfusion imaging.
  
  
  CONCLUSIONS
  Two regional perfusion imaging modules (vessel-encoded and vessel-selective) used in pCASL can also be adapted into the pTILT sequence, and our results confirmed that the region-specific pTILT sequence is capable of regional perfusion imaging to separate perfusion territories of major cerebral arteries.
authors.affiliation: Toshiba Medical Research Institute USA, Inc., Vernon Hills, Illinois, USA.
authors.forename: Cheng
authors.initials: C
authors.lastname: Ouyang
authors.forename: Bradley P
authors.initials: BP
authors.lastname: Sutton
mesh_terms: D000465:Algorithms; D001783:Blood Flow Velocity / Q000502:physiology; D002536:Cerebral Arteries / Q000033:anatomy & histology / Q000502:physiology*; D002560:Cerebrovascular Circulation / Q000502:physiology*; D006801:Humans; D007089:Image Enhancement / Q000379:methods; D007090:Image Interpretation, Computer-Assisted / Q000379:methods*; D018810:Magnetic Resonance Angiography / Q000295:instrumentation / Q000379:methods*; D055420:Perfusion Imaging / Q000379:methods*; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity
keywords: arterial spin labeling; labeling pattern; pTILT; regional perfusion imaging; vascular territory imaging