Optimization of 3D PCASL perfusion SNR efficiency at 7T

Motivation: 3D-PCASL is a well-established perfusion MRI technique at 3T. Nonetheless, its effectiveness is hampered by increased RF power deposition at 7T limiting the SNR efficiency and labeling duration. Goal(s): This work investigates the relationship between gray matter perfusion signal and labeling duration aiming to optimize 3D-PCASL SNR efficiency while taking into consideration the increased RF power constraints of 7T MRI. Approach: SNR efficiency was measured at various labeling durations maintaining scan time to ~6 min and SAR to ~90% of first-level mode limit at 7T. Results: Optimal SNR efficiency was obtained at labeling duration of ~3 s. Impact: The result of this work provides optimal labeling duration for 7T 3D PCASL studies with maximum SNR per unit time taking into account first-level mode RF power limits.