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Purpose To demonstrate the repeatability of fast 3D T 1 mapping using Magnetization‐Prepared Golden‐angle RAdial Sparse Parallel (MP‐GRASP) MRI and its robustness to variation of imaging parameters including flip angle and spatial resolution in phantoms and the brain. Theory and Methods Multiple imaging experiments were performed to (1) assess the robustness of MP‐GRASP T 1 mapping to B 1 inhomogeneity using a single tube phantom filled with uniform MnCl 2 liquid; (2) compare the repeatability of T 1 mapping between MP‐GRASP and inversion recovery‐based spin‐echo (IR‐SE; over 12 scans), using a commercial T1MES phantom; (3) evaluate the longitudinal variation of T 1 estimation using MP‐GRASP with varying imaging parameters, including spatial resolution, flip angle, TR/TE, and acceleration rate, using the T1MES phantom (106 scans performed over a period of 12 months); and (4) evaluate the variation of T 1 estimation using MP‐GRASP with varying imaging parameters in the brain (24 scans in a single visit). In addition, the accuracy of MP‐GRASP T 1 mapping was also validated against IR‐SE by performing linear correlation and calculating the Lin's concordance correlation coefficient (CCC). Results MP‐GRASP demonstrates good robustness to B 1 inhomogeneity, with intra‐slice variability below 1% in the single tube phantom experiment. The longitudinal variability is good both in the phantom (below 2.5%) and in the brain (below 2%) with varying imaging parameters. The T 1 values estimated from MP‐GRASP are accurate compared to that from the IR‐SE imaging (R 2 = 0.997, Lin’s CCC = 0.996). Conclusion MP‐GRASP shows excellent repeatability of T 1 estimation over time, and it is also robust to variation of different imaging parameters evaluated in this study.
Li et al. (Fri,) studied this question.