SNR-efficient acquisition strategies for 2D phase contrast CMR at 0.55T

Motivation: Phase-contrast (PC) flow sequences are routinely used to assess hemodynamics in the heart and great vessels. At 0.55T, the use of SNR efficient acquisition strategies (spiral sampling, bSSFP) may have a role. Goal(s): We implement and compare the SNR efficiency of cartesian GRE, spiral GRE, cartesian bSSFP, and spiral bSSFP for ECG-gated PC flow measurements at 0.55T. Approach: In three healthy-volunteers, measurements of peak velocity, flow, and SNR efficiency are compared in the ascending aorta. Results: All sequences comparably measure flow rate and peak velocity. bSSFP acquisitions offer 2-fold higher SNR efficiency than GRE acquisitions and spiral sampling offers 30-40% finer temporal resolution. Impact: Flow dynamics are comparably captured by all four sequences. bSSFP PC sequences were more SNR efficient than GRE counterparts by roughly a factor of two. bSSFP Spiral acquisitions incurred unresolved flow-related artifacts.