Feasibility of Knee MR Fingerprinting at 0.55T and comparison with 3.0T MAPSS: Hip-OA cohort with probable early knee cartilage-loss

Motivation: Low-cost 0.55T-scanners pose an excellent opportunity to formulate efficient, fast, and quantitative T2 mapping methods that could enhance the reach of early OA-diagnosis. Goal(s): To analyze the feasibility of a novel, fast, and high-resolution MRF-scanning technique to quantify knee cartilage-T2 overcoming the low SNR and inefficient gradient systems at 0.55T and compare against the MAPSS approach at 3.0T. Approach: A suite of techniques was leveraged for MRF, including an optimized-sampling-trajectory, subspace-reconstruction, locally-low-rank-constraint, gradient-waveform-correction, Cramer-Rao-Lower-Bound (CRLB)-optimization for flip-angle-patterns, motion-correction, and deep-learning-based-denoising. Results: The average T2 increase at 0.55T compared to 3.0T provides a wider range for the depiction of granular regions of elevated cartilage-T2 Impact: In this study, advanced techniques including CRLB-optimization, gradient trajectory correction, subspace reconstruction, attention-based denoising, and motion correction were included to demonstrate the feasibility and benefits of a faster, higher-resolution Knee MRF acquisition on a cost-effective 0.55T scanner compare with 3.0T MAPSS.