Quantitative assessment of articular cartilage degeneration using 3D ultrashort echo time cones adiabatic T_1ρ (3D UTE-Cones-AdiabT_1ρ) imaging

Objectives: To evaluate articular cartilage degeneration using quantitative three-dimensional ultrashort-echo-time cones adiabatic-T_1ρ (3D UTE-Cones-AdiabT_1ρ) imaging.

Methods: Sixty-six human subjects were recruited for this study. Kellgren-Lawrence (KL) grade and Whole-Organ Magnetic-Resonance-Imaging Score (WORMS) were evaluated by two musculoskeletal radiologists. The human subjects were categorized into three groups, namely normal controls (KL0), doubtful-minimal osteoarthritis (OA) (KL1-2), and moderate-severe OA (KL3-4). WORMS were regrouped to encompass the extent of lesions and the depth of lesions. The UTE-Cones-AdiabT_1ρ values were obtained using 3D UTE-Cones data acquisitions preceded by seven paired adiabatic full passage pulses that corresponded to seven spin-locking times (TSLs) of 0, 12, 24, 36, 48, 72, and 96 ms. The performance of the UTE-Cones-AdiabT_1ρ technique in evaluating the degeneration of knee cartilage was assessed via the ANOVA comparisons with subregional analysis and Spearman's correlation coefficient as well as the receiver-operating-characteristic (ROC) curve.

Results: UTE-Cones-AdiabT_1ρ showed significant positive correlations with KL grade (r = 0.15, p < 0.05) and WORMS (r = 0.57, p < 0.05). Higher UTE-Cones-AdiabT_1ρ values were observed in both larger and deeper lesions in the cartilage. The differences in UTE-Cones-AdiabT_1ρ values among different extent and depth groups of cartilage lesions were all statistically significant (p < 0.05). Subregional analyses showed that the correlations between UTE-Cones-AdiabT_1ρ and WORMS varied with the location of cartilage. The AUC value of UTE-Cones-AdiabT_1ρ for mild cartilage degeneration (WORMS=1) was 0.8. The diagnostic threshold value of UTE-Cones-AdiabT_1ρ for mild cartilage degeneration was 39.4 ms with 80.8% sensitivity.

Conclusions: The 3D UTE-Cones-AdiabT_1ρ sequence can be useful in quantitative evaluation of articular cartilage degeneration.

Key points: • The 3D UTE-Cones-AdiabT_1ρ sequence can distinguish mild cartilage degeneration from normal cartilage with a diagnostic threshold value of 39.4 ms for mild cartilage degeneration with 80.8% sensitivity. • Higher UTE-Cones-AdiabT_1ρ values were observed in both larger and deeper lesions in the articular cartilage. • UTE-Cones-AdiabT_1ρ is a promising biomarker for quantitative evaluation of early cartilage degeneration.