David D. Shin1, Ho-Ling Liu2, Thomas T. Liu1
1Center for Functional MRI, University of California, San Diego, La Jolla, CA, United States; 2Chang Gung University, Taoyuan, Taiwan
We present a novel PCASL technique for correcting compromised inversion efficiency resulting from off-resonance effects and gradient imperfections at the tagging plane. The implemented sequence acquires the ASL signal using 8 RF phase offsets during the first 32 reps then switches to the regular tag/control mode to acquire the conventional PCASL signal. The inversion response curves from the first mode is used to estimate the tagging efficiencies for the main feeding arteries, which are in turn used during the quantification step to correct for underestimated CBFs associated with regular PCASL. The gray matter CBFs calculated from alpha-corrected PCASL are compared to those from OptPCASL which restores inversion efficiency but requires additional calibration scans.