Labeling Efficiency Is Critical in Pseudo-Continuous ASL

Sina Aslan¹, Feng Xu¹, Peiying L. Wang¹, Jinsoo Uh¹, Uma Yezhuvath¹, Matthias van Osch², Hanzhang Lu¹

Pseudo-Continuous Arterial Spin Labeling (pCASL) is a new ASL technique that has the potential of combining advantages of continuous ASL and pulse ASL. One of the most critical parameters in flow quantification using pCASL is the labeling efficiency. Here, we empirically determined the optimal labeling location to be 84mm distal to the AC-PC line. We then experimentally estimated the labeling efficiency using phase-contrast MRI as a normalization factor and found it to be 8710%. Finally, we demonstrated that labeling efficiency may change with physiologic state and should be estimated for each physiologic condition.