Robust water-only liver T1 mapping with Look-Locker spiral out-in-out-in imaging at 0.55T

Motivation: Evaluation of patients with fatty liver disease can benefit from low-field scanners due to their larger bore size and reduced cost. However, fat is a cofounding factor for liver T1 mapping, and there is currently no reliable water-only T1 mapping method for low B0 field strengths. Goal(s): To develop a practical water-only liver T1 mapping method at 0.55T. Approach: Inversion recovery preparation combined with a 3-echo bSSFP spiral out-in-out-in (OIOI) readout was used to obtain water/fat separated images and quantify water-only T1. Results: The proposed water-only T1 mapping method is insensitive to liver PDFF, compared to Cartesian MOLLI and water-fat in-phase T1 values. Impact: For patients with fatty liver disease, this new method provides reliable water-only T1 mapping at low field strength (0.55T). This method may be incorporated into clinical protocols as an indicator of liver inflammation, fibrosis, and stiffness.