Correlation Between T1 Rho Value of Magnetic Resonance and Clinical Characteristics of Patients with Knee Osteoarthritis and Analysis of Related Factors of T1 Rho Value.

Purpose: To investigate the correlation between magnetic resonance spin-lattice relaxation time (T1 rho) value and clinical characteristics of patients with knee osteoarthritis, and to analyze the related factors of T1 rho value. Methods: This study was a cross-sectional study. Sixty patients with knee osteoarthritis diagnosed and treated in our hospital from October 2020 to March 2022 were selected as the arthritis group. Sixty patients with non-knee osteoarthritis detected in our hospital during the same period were selected as non-arthritis group. The clinical data of the subjects were collected and all of them were examined by magnetic resonance imaging (MRI). The mixed-effects model was used to control the correlation of multiple compartments in the knee joint, and the nonlinear relationship of T1 rho value (continuous variable) was treated by restricted cubic spline function. The relationship between T1 rho value and clinical characteristics was analyzed by mixed-effects linear regression, and the relationship between T1 rho value and WORMS score and ICRS grade was analyzed by mixed-effects ordinal logistic regression. The multiple comparisons were corrected by Holm-Bonferroni method. Results: Compared with the non-arthritis group, the arthritis group had significantly higher T1 rho values on magnetic resonance imaging of the patella, femur, and tibia (P < 0.05). Mixed-effects linear regression showed that proteoglycans < 41% (β = 5.82, 95% CI: 3.76-7.88, Padj < 0.001), disordered collagen fiber arrangement (β = 4.93, 95% CI: 2.89-6.97, Padj < 0.001), overloading exercise (β = 6.17, 95% CI: 3.52-8.82, Padj < 0.001), and femoral septum (vs patella, β = 2.31, 95% CI: 0.98-3.64, Padj = 0.002) were significantly correlated with increased T1 rho values. Mixed-effects ordinal logistic regression showed that for every 1ms increase in T1 rho value, the OR for upgrading WORMS score was 1.18 (95% CI: 1.03-1.35, Padj = 0.021), and the OR for upgrading ICRS grading was 1.23 (95% CI: 1.05-1.44, Padj = 0.015). Moreover, the correlation strength of T1 rho values was higher in patients with WORMS ≥ II and ICRS ≥ II (all Padj < 0.001). Multivariate mixed-effects linear regression confirmed that proteoglycans < 41%, disordered collagen fiber arrangement, overload exercise, increased WORMS score, increased ICRS grading, age increase (every 10 years, β = 0.82, 95% CI: 0.21-1.43, Padj = 0.019), and BMI ≥ 24 kg/m Conclusion: This cross-sectional study showed that the higher T1 rho value was significantly related to the lower proteoglycan content (< 41%), disordered collagen fiber arrangement, self-reported overload exercise history and higher WORMS and ICRS scores, which can provide a basis for understanding the pathophysiological background reflected by T1 rho value.