Towards synthetic T2-weighted imaging based on multiple acquisition bSSFP at 0.55T

Motivation: Low-field MRI systems offer excellent image quality and SNR-efficiency with balanced-SSFP. T2 contrast remains a major unmet need when using bSSFP. Goal(s): To develop a multi-acquisition bSSFP-based method for synthetic T2-weighted imaging suitable for mid- and low-field strengths including 0.55T. Approach: We leverage the geometric properties of the bSSFP signal, with six phase-cycles and two flip angles, to estimate T2,T1,M0 on a voxel-wise basis. We evaluate performance through simulations, ISMRM/NIST phantom experiments, and T2-weighted brain imaging at 0.55T. Results: The proposed method demonstrates negligible-bias in T2-estimation for GM(<8 ms) and WM(<4 ms) in MC simulations when SNR>50, and enables synthetic T2-weighted images. Impact: We demonstrate synthetic T2-weighted imaging based on multiple bSSFP acquisitions, and voxel-wise estimation of NMR parameters. This could be useful for relaxometry and synthetic imaging at mid and low-field strengths where bSSFP performance is favorable.