T2 Mapping And Delayed Gadolinium-enhanced Magnetic Resonance Imaging (dGEMRIC) Reveal The Extracellular Matrix Of Articular Cartilage In Osteoarthritis Of The Knee At 7T

Object:To determine the T2 values and the delta relaxation rate ΔR1{ΔR1= (1/T1Gd-1/T1pre), which presents dGEMRIC index} in human knee osteoarthritic cartilage and to quantify the correlation between T2 values, ΔRlvalues, biochemical composition and histology in human knee osteoarthritic cartilage.Method:Sagittal T2 maps, T1mapping and T1Gd mapping were postoperatively obtained from 20 knee osteoarthritis patients. Osteochondral samples harvested from the resected medial/lateral Femoral condyle and tibial plateaus during total knee arthroplasty were consistent with the MRIs of the patients’ knees. Parameters that included water content, glycosaminoglycan (GAGs) content (which constitutes PGs), Collagen content, histological grading of cartilage degeneration, presence of collagen anisotropy were evaluated along with T2 values, ΔR1, and statistical analysis was performed using univariate analysis and multiple regression analysis.Result:T2 values and AR1 values were significantly correlated with the degree of cartilage degeneration (p=0.53 and 0.77, respectively) and the GAG content (p=0.43 and p=-0.84, respectively). Moreover, in univariate and multiple regression analysis, the T2 values both correlated with water content (r=0.69, p=0.28) and PLM grade (r=0.47, p=0.19), but not with collagen content (r=-0.02, p=0.110).Conclusion: The present study demonstrated that T2 values and dGEMRIC index correlated with histological degeneration, reflected the change of extracellular matrix components content of human knee cartilage and can indicate cartilage degeneration. Use of these parameters can facilitate the noninvasive diagnosis and evaluation of cartilage degeneration.