Novel Sampling Schemes of Spin-locking Times to Improve Reproducibility of Quantitative 3D T1rho Mapping

Motivation: Reproducibility of T1rho measurements is crucial for longitudinal studies, as highly reproducible measurements are needed to detect treatment-induced changes in tissue properties. Goal(s): To evaluate two novel sampling schemes of spin-locking times (TSLs) to improve the reproducibility of T1rho quantification in inhomogeneous fields (B1/B0) compared to previously reported TSL-sampling schemes. Approach: T1rho sequences with three different T1rho preparation modules and four TSL-sampling schemes were used for repeated scans of phantom and volunteers to evaluate reproducibility in each case. Results: The proposed TSL-sampling schemes produced significantly better reproducibility (i.e., lower coefficient of variation) than the previously reported TSL-sampling schemes. Impact: The proposed novel TSL-sampling schemes may enable T1rho relaxation parameter as a robust biomarker of imaging tissues with a slow-motional process despite B1/B0 inhomogeneities.