Optimized inversion-time schedules for quantitative T1 measurements based on high-resolution multi-inversion EPI

PurposeDemonstrate an optimized multi-inversion echo-planar imaging technique to accelerate quantitative T-1 mapping by judicious selection of inversion times for each slice. MethodsSlice ordering is optimized to maximize discrimination between tissues with different T-1 values. The optimized slice orderings are tested in the International Society for Magnetic Resonance in Medicine/National Institute of Standards and Technology phantom and compared with an unoptimized 21-measurement acquisition. The utility of the method is demonstrated in a healthy subject in vivo at 3T and validated with a gold-standard inversion-recovery sequence. The in vivo precision of our technique was tested by repeated scans of the same subject within a scan session and across scan sessions, occurring 28 days apart. ResultsPhantom measurements yielded good agreement (R-2=0.99) between the T-1 estimates from the proposed optimized protocol, reference values from the National Institute of Standards and Technology phantom and gold-standard inversion-recovery values, as well as a negligible estimation bias that was slightly lower than that from the unoptimized 21-measurement protocol (0.74 versus 19 ms). The range of values for the scan-rescan coefficient of variation was 0.86 to 0.93 (within session) and 0.83 to 0.92 (across sessions) across all scan durations tested. ConclusionsOptimized slice orderings allow faster quantitative T-1 mapping. The optimized sequence yielded accurate and precise T-1 maps. Magn Reson Med 79:2101-2112, 2018. (c) 2017 International Society for Magnetic Resonance in Medicine.