PURPOSE: To optimize pseudo-continuous arterial spin labeling (PCASL) parameters to maximize SNR efficiency for RF power constrained whole brain perfusion imaging at 7 T. METHODS: We used Bloch simulations of pulsatile laminar flow to optimize the PCASL parameters for maximum SNR efficiency, balancing labeling efficiency and total RF power. The optimization included adjusting the inter-RF pulse spacing (TRPCASL), mean B1 + (B1 + ave), slice-selective gradient amplitude (Gmax), and mean gradient amplitude (Gave). In vivo data were acquired from six volunteers at 7 T to validate the optimized parameters. Dynamic B0-shimming and flip angle adjustments were used to avoid needing to make the PCASL parameters robust to B0/B1 + variations. RESULTS: The optimized PCASL parameters achieved a significant (3.3×) reduction in RF power while maintaining high labeling efficiency. This allowed for longer label durations and minimized deadtime, resulting in a 118% improvement in SNR efficiency in vivo compared to a previously proposed protocol. Additionally, the static tissue response was improved, reducing the required distance between labeling plane and imaging volume. CONCLUSION: These optimized PCASL parameters provide a robust and efficient approach for whole brain perfusion imaging at 7 T, with significant improvements in SNR efficiency and reduced specific absorption rate burden.
Journal article
2025-09-01T00:00:00+00:00
94
965 - 981
16
7 Tesla, SNR efficiency, perfusion, pseudo‐continuous arterial spin labeling (PCASL), ultra‐high field, Humans, Spin Labels, Brain, Signal-To-Noise Ratio, Adult, Male, Cerebrovascular Circulation, Image Processing, Computer-Assisted, Female, Algorithms, Magnetic Resonance Imaging, Healthy Volunteers, Computer Simulation, Perfusion Imaging, Magnetic Resonance Angiography