Low-rank reconstruction for simultaneous Double-Half-Echo 23Na and undersampled 23Na Multi-Quantum Coherences MRI

Motivation: Sodium (23Na) Multi-Quantum Coherences (MQC) MRI potentially provides richer tissue information. However, 3D 23Na multi-quantum coherences imaging lacks conventional 23Na MRI resolution and requires multiple radiofrequency phase-cycling limiting spatial resolution. Goal(s): We propose an efficient sequence to simultaneously acquire Cartesian double-half echo (DHE) 23Na and accelerated 23Na MQC MRI. Approach: Leveraging advanced low-rank matrix completion frameworks to enable simultaneous DHE 23Na and 23Na MQC MRI were tested on numerical simulations, retro- and prospectively undersampled phantom and in vivo brain data acquired at 7T. Results: Simultaneous Cartesian 23Na and higher resolution 3-fold prospectively undersampled 23Na MQC brain MRI of 4 volunteers were obtained. Impact: The new sequence, in combination with the low-rank reconstruction frameworks, enables efficient 23Na and higher resolution 23Na MQC MRI while supporting conventional 1H-based acceleration techniques and offers, therefore, a convenient sequence for the sodium MRI community.