Wen-Ming Luh1, Eric C. Wong2, S. Lalith Talagala3, Peter A. Bandettini1
1Functional MRI Facility, NIMH, National Institutes of Health, Bethesda, MD, United States; 2Departments of Radiology & Psychiatry, University of California, San Diego, La Jolla, CA, United States; 3NMRF, NINDS, National Institutes of Health, Bethesda, MD, United States
In conventional pseudo-continuous arterial spin labeling (PCASL) techniques, a train of short RF pulses with constant amplitude are played out over entire labeling period. However, changes in velocity throughout the cardiac cycle can compromise tagging efficiency especially during systolic phases with high velocity and volume throughput. To minimize mismatch between RF amplitude increase and systolic phase, here we employed ECG triggering and short labeling period to be within a typical cardiac cycle. Moreover, RF B1 modulation was implemented in a pair-wise interleaved fashion to minimize run-to-run differences.