Quantitative Ultrashort T2 Components Imaging using Variable Flip Angle Balanced Steady State Free Precession Ultrashort Echo Time MRI

Motivation: The current UTE-based myelin quantification method requires multiple TEs acquisitions, which has disadvantages include long scan time, complicated fitting models with too many unknown parameters to be fit. Goal(s): To propose a simplified fitting model to quantify myelin fraction. Approach: Previously developed dual-echo bSSFP UTE sequence with variable flip angles was applied. The difference of the signal curve along flip angles between first and second TE was used to quantify T1 and fraction values of myelin. Multiple sclerosis patients were recruited and tested. Results: The overall myelin T1 values are around 80 to 200 ms, and the uT2 fraction is around 10-20%. Impact: This new UTE-based method used simplified model to provide reliable fitting results of uT2 fraction, which was also tested on multiple sclerosis patients, could aid in future multiple sclerosis diagnosis and evaluation of re-myelination during treatment.