Low-rank reconstruction of variable-density random undersampled data for low-field MRI: accelerated T1 mapping at 46 mT

Motivation: Limited access to medical equipment makes low-field MRI an interesting option in many settings. One challenge is the prolonged scan time, especially for quantitative imaging. However, parallel imaging is typically not used due to the very high sensitivity of a single solenoid receive coil. Goal(s): This study aims to accelerate T1 mapping (used for estimating brain myelination) on a Halbach low-field system. Approach: A locally low-rank reconstruction was applied to diminish undersampling artifacts from the variable-density random sampling trajectory. Results: The study highlights the potential for both, fast lower-resolution (2.5mm2 in-plane) and higher-resolution (1.5mm2 in-plane) T1 mapping with an acceleration factor of R=4. Impact: Our study's advanced low-rank reconstruction approach for low-field MRI could transform imaging methods in regions where high-field MRI is inaccessible, enabling precise and fast T1 brain mapping, which is critical for assessing myelination-related diseases with newfound speed and reliability.