• Felipe B Tancredi, Claudine J Gauthier, Cécile Madjar, Divya S Bolar, Joseph A Fisher, Danny J J Wang, and Richard D Hoge.
• Institut de génie biomédical, Département de physiologie, Université de Montréal, Montreal, Quebec, Canada. felipe.tancredi@umontreal.ca
• J Magn Reson Imaging. 2012 Aug 1; 36 (2): 312-21.

PurposeTo compare the performance of pulsed and pseudocontinuous arterial spin-labeling (PASL and pCASL) methods in measuring CO(2) -induced cerebrovascular reactivity (CVR).Materials And MethodsSubjects were scanned using both ASL sequences during a controlled hypercapnia procedure and visual stimulation. CVR was computed as the percent CO(2) -induced increase in cerebral blood flow (Δ%CBF) per mmHg increase in end-tidal PCO(2) . Visually evoked responses were expressed as Δ%CBF. Resting CBF and temporal signal-to-noise ratio were also computed. Regionally averaged values for the different quantities were compared in gray matter (GM) and visual cortex (VC) using t-tests.ResultsBoth PASL and pCASL yielded comparable respective values for resting CBF (56 ± 3 and 56 ± 4 mL/min/100g) and visually evoked responses (75 ± 5% and 81 ± 4%). Values of CVR determined using pCASL (GM 4.4 ± 0.2, VC 8 ± 1 Δ%CBF/mmHg), however, were significantly higher than those measured using PASL (GM 3.0 ± 0.6, VC 5 ± 1 Δ%CBF/mmHg) in both GM and VC. The percentage of GM voxels in which statistically significant hypercapnia responses were detected was also higher for pCASL (27 ± 5% vs. 16 ± 3% for PASL).ConclusionpCASL may be less prone to underestimation of CO(2) -induced flow changes due to improved label timing control.Copyright © 2012 Wiley Periodicals, Inc.

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