T1rho MRI relaxation in knee OA subjects with varying sizes of cartilage lesions

Abstract

BackgroundThe purpose of this investigation is to evaluate the T1ρ relaxation times of articular cartilage surrounding focal defects in the tibiofemoral joint. MethodsQuantitative cartilage assessment was performed using 3T MRI with T1ρ mapping in 19 healthy individuals and 44 OA patients. Sagittal T2-weighted fast spin echo (FSE) images were acquired for lesion assessment. Differences were determined using analysis of variance (ANOVA). ResultsCartilage lesions were found in 37% of controls, and 93% of OA patients. Meniscal tears were found in 16% of controls and 57% of OA patients. We observed no difference in T1ρ relaxation times when comparing cartilage immediately surrounding a focal defect, and the remaining cartilage within that compartment. The medial femoral condyle (MFC) had the highest incidence of cartilage defects. MFC and medial meniscus posterior horn T1ρ were higher in subjects having multiple focal lesions (p=0.048, pb0.001 respectively) and extensive full thickness lesions (p=0.009, pb0.001 respectively) compared to subjects with no MFC defects. Significant elevations in T1ρ of the adjacent compartment (medial tibia) and medial meniscus were observed in subjects with MFC lesions. ConclusionIncreased relaxation times in the involved compartment as well as the adjacent compartment and associated meniscus underscore the interdependence of these structures at bearing load. However, no differences in cartilage composition immediately surrounding a defect were noted. Finally, an association was observed between cartilage defects and meniscal damage in advanced disease. Clinical RelevanceCartilage defects were not associated with degeneration in the immediately adjacent cartilage.