Fast and Reproducible 3D T1ρ Mapping Using Unpaired Phase Cycling and Optimal Sampling of Spin-Lock Times

Motivation: Fast and reproducible T1ρ imaging would be beneficial in longitudinal studies for evaluating treatment responses in radiotherapy. Goal(s): To enhance reproducibility and accelerate MAPSS T1ρ imaging using unpaired phase cycling combined with reproducibility-guided optimal sampling (ROS) of spin-lock times (TSLs). Approach: 3D T1ρ imaging was performed with eight pairs of TSLs on a phantom over ten different days. The coefficient of variation and changes in T1ρ values were evaluated for paired and unpaired MAPSS. Results: The ROS scheme significantly improved the performance of the unpaired MAPSS sequence while reducing scan time by 75% compared to paired MAPSS for T1ρ imaging. Impact: 3D T1ρ imaging, utilizing optimal spin-lock time (TSL) sampling in combination with unpaired MAPSS, enables rapid and highly reproducible T1ρ measurements. This advancement facilitates longitudinal studies, such as assessing treatment response in radiotherapy.