Application of the power independent of number of slices presaturated ultrashort echo time (PINS-UTE) sequence to sodium MRI

Motivation: Sodium (23Na) MRI produces images with complimentary information about tissue viability; however time-consuming ultrashort echo time (UTE) sequences are required. Simultaneous multi-slice techniques reduce scan times, but were not compatible with UTE sequences until the PINS-UTE sequence was developed. Goal(s): To translate the PINS-UTE sequence to 23Na MRI. Approach: We investigate the effects of prepulse flip angle, spoiler gradient area, and maximum prepulse B1 on in-vivo 23Na PINS-UTE slice profiles and implement the sequence for in-vivo 23Na imaging. Results: The 23Na PINS-UTE sequence was optimized with a 115°, 40μT prepulse and 14.1ms·mT/m spoiler gradients. In-vivo 23Na images from three simultaneous slices were obtained. Impact: We translate the PINS-UTE sequence to 23Na MRI for the simultaneous acquisition of multiple slices. The PINS-UTE sequence is expected to reduce 23Na MRI scan times by a factor of 2.5, while achieving the same echo time as current sequences.