Highly efficient simultaneous joint T1-T2 mapping for isotropic resolution 3D knee imaging at 0.55 T

Motivation: Low-field 0.55T knee imaging promises to provide more accessible assessment of injuries. Anatomic imaging has been evaluated, however quantitative knee imaging at 0.55T has not been demonstrated. Goal(s): To investigate the feasibility of 3D joint T1-T2 mapping for evaluation of the articular cartilage at 0.55T. Approach: A free-running, 3D-radial sequence with golden-angle and spoiled gradient echo readout and 1mm3 isotropic resolution was implemented using Pulseq for T1-T2 mapping. Bloch simulations were used for dictionary matching. Results: The sequence was tested with a standardized phantom, showing good agreement with reference values, and promising results for in-vivo images in healthy subjects in a ~4min scan. Impact: 3D joint T1-T2 mapping of knee articular cartilage with low-field MRI could provide a fast, more accessible and comprehensive test to assess knee injuries and chronic knee disease.