The effects of acute loading on T1rho and T2 relaxation times of tibiofemoral articular cartilage

SummaryObjectiveTo evaluate the effect of acute loading on healthy and osteoarthritic knee cartilage T1ρ and T2 relaxation times.DesignTwenty subjects with radiographic evidence of osteoarthritis (OA) and 10 age-matched controls were enrolled. Magnetic resonance imaging (MRI) acquisition, including T1ρ and T2 map sequences were performed unloaded and loaded at 50% body mass. Cartilage masks were segmented semi-automatically on registered high-resolution spoiled gradient-echo (SPGR) images for each compartment (medial and lateral). Cartilage lesions were identified using a modified Whole Organ Magnetic Resonance Imaging Score (WORMS) score. Statistical differences were explored using separate two-way (group×loading condition) Analysis of Variance (ANOVA) using age as a covariate to evaluate the effects of loading on T1ρ and T2 relaxation times.ResultsA significant decrease in T1ρ (44.5±3.8 vs 40.2±4.8ms for unloaded and loaded, respectively; P<0.001) and T2 (31.8±3.8 vs 30.5±4.8ms for unloaded and loaded, respectively; P