Diagnostic value of T1ρ and T2 mapping sequences of 3D fat-suppressed spoiled gradient (FS SPGR-3D) 3.0-T magnetic resonance imaging for osteoarthritis.

Three-dimensional fat-suppressed spoiled gradient magnetic resonance imaging can be used to observe cartilages with high resolution. To quantify and compare the T1 rho and T2 relaxation times of the knee articular cartilage between healthy asymptomatic adults and patients with osteoarthritis (OA). This was a retrospective study of 53 patients with symptomatic OA (6 males and 47 females; aged 57.6 +/- 10.0 years) and 26 healthy adults (11 males and 15 females; aged 31.7 +/- 12.2 years) from the Ruijin Hospital. T1 rho and T2 relaxation times of knee cartilage were quantified using sagittal multi-echo T1 rho and T2 mapping sequences (3.0-T scanner) and analyzed by receiver operating characteristic (ROC) curve. T1 rho and T2 relaxation times in the OA group were higher than in controls (both P < .01). The sensitivity, specificity, and critical value for differentiating normal from OA cartilage were respectively 92%, 85.6%, and 45.90 ms for T1 rho, and 93.6%, 93.3%, and 50.42 ms for T2. T2 mapping sequence showed a higher area under the ROC curve (AUC) than T1 rho (0.965 vs 0.927, P = .02). The AUC for differentiating normal from Noyes IIA cartilage was 0.922 for T1 rho (cut-off: 46.0; sensitivity: 87.7%; specificity: 89.7%) and 0.954 for T2 (cut-off: 49.5; sensitivity: 91.2%; specificity: 92.3%), with no significant difference between them (P = .08). Both T1 rho and T2 mapping sequences could be used to assess OA cartilage lesions, with T2 mapping sequence demonstrating significant sensitivity for cartilage degeneration. These 2 sequences could also identify early-stage OA cartilage.