Test–retest reliability of arterial spin labeling with common labeling strategies

Abstract

Purpose To compare the test–retest reproducibility of three variants of arterial spin labeling (ASL): pseudo‐continuous (pCASL), pulsed (PASL) and continuous (CASL). Materials and Methods Twelve healthy subjects were scanned on a 3.0T scanner with PASL, CASL, and pCASL. Scans were repeated within‐session, after 1 hour, and after 1 week to assess reproducibility at different scan intervals. Results Comparison of within‐subject coefficients of variation (wsCV) demonstrated high within‐session reproducibility (ie, low wsCV) for CASL‐based methods (gray matter [GM] wsCV for pCASL: 3.5% ± 0.02%, CASL: 4.1% ± 0.07%) compared to PASL (wsCV: 7.5% ± 0.06%), due to the higher signal‐to‐noise ratio (SNR) associated with continuous labeling, evident in the 20% gain in temporal SNR and 58% gain in raw SNR for pCASL relative to PASL. At the 1‐week scan interval, comparable reproducibility between PASL (GM wsCV 9.2% ± 0.12%) and pCASL (GM wsCV 8.5% ± 0.14%) was observed, indicating the dominance of physiological fluctuations. Conclusion Although all three approaches are capable of measuring cerebral blood flow within a few minutes of scanning, the high precision and SNR of pCASL, with its insensitivity to vessel geometry, make it an appealing method for future ASL application studies. J. Magn. Reson. Imaging 2011;33:940–949.