Simultaneous bilateral T1, T2, and T1ρ relaxation mapping of the hip joint with magnetic resonance fingerprinting

Quantitative MRI can detect early biochemical changes in cartilage, but its bilateral use in clinical routines is challenging. The aim of this prospective study was to demonstrate the feasibility of magnetic resonance fingerprinting for bilateral simultaneous T-1, T-2, and T-1 rho mapping of the hip joint. The study population consisted of six healthy volunteers with no known trauma or pain in the hip. Monoexponential T-1, T-2, and T-1 rho relaxation components were assessed in femoral lateral, superolateral, and superomedial, and inferior, as well as acetabular, superolateral, and superomedial subregions in left and right hip cartilage. Aligned ranked nonparametric factorial analysis was used to assess the side's impact on the subregions. Kruskal-Wallis and Wilcoxon tests were used to compare subregions, and coefficient of variation to assess repeatability. Global averages of T-1 (676.0 +/- 45.4 and 687.6 +/- 44.5 ms), T-2 (22.5 +/- 2.6 and 22.1 +/- 2.5 ms), and T-1 rho (38.2 +/- 5.5 and 38.2 +/- 5.5 ms) were measured in the left and right hip, and articular cartilage, respectively. The Kruskal-Wallis test showed a significant difference between different subregions' relaxation times regardless of the hip side (p < 0.001 for T-1, p = 0.012 for T-2, and p < 0.001 for T-1 rho). The Wilcoxon test showed that T-1 of femoral layers was significantly (p < 0.003) higher than that for acetabular cartilage. The experiments showed excellent repeatability with CVrms of 1%, 2%, and 4% for T-1, T-2, and T-1 rho,T- respectively. It was concluded that bilateral T-1, T-2, and T-1 rho relaxation times, as well as B-1(+) maps, can be acquired simultaneously from hip joints using the proposed MRF sequence.

Automated summary

This prospective study demonstrated the feasibility of magnetic resonance fingerprinting for bilateral simultaneous T-1, T-2, and T-1 rho mapping of the hip joint. The results showed differences in relaxation times between different subregions in the left and right hip, with excellent repeatability in the experiments.