Promising Methods and Applications for 0.55T MRI

Magnetic resonance imaging (MRI) is a powerful and widely available technology for looking within the human body to assess health and disease. The dominant configuration is based on a cylindrical superconducting magnet operating at 1.5 or 3 Tesla. However, researchers are constantly exploring different field strengths and system configurations. There has been a recent surge in interest in MRI field strengths <1.5T, resulting in several new commercial and research systems on the market. Reasons include reduced artifact (susceptibility, B0 and B1 homogeneity), patient comfort (bore size, acoustic noise), system cost (total cost of ownership), environmental sustainability (reduced He, reduced power consumption), and portability. Compared to historical work, this recent wave is enhanced by the availability of modern fast gradients, array receiver coils, and computational image reconstruction (including machine learning). My group has been an early adopter of contemporary mid-field 0.55T MRI with fast gradients. In this talk, I will explain our motivation, and will summarize our experience over the past 3+ years. I will discuss acquisition methods that are well-suited, including balanced steady-state free precession, spiral and other non-Cartesian trajectories, and real-time imaging. I will then discuss applications where 0.55T has the potential to outperform 1.5T and 3T configurations. This includes imaging around metal, pulmonary and cardiac imaging, abdominal imaging, and fetal screening.