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Abstract: Objective: The purpose of this study was to clarify the detectability of the International Cartilage Repair Society (ICRS) grade 1 cartilage lesions in anterior cruciate ligament (ACL)–injured knees using T1ρ and T2 mapping. Materials and Methods: We performed preoperative T1ρ and T2 mapping and 3D gradient–echo with water–selective excitation (WATS) sequences on 37 subjects with ACL injuries. We determined the detectability on 3D WATS based on arthroscopic findings. The T1ρ and T2 values (ms) were measured in the regions of interest that were placed on the weight–bearing cartilage of the femoral condyle. The receiver operating characteristic (ROC) curve based on these values was constructed using the arthroscopic findings as a reference standard. The evaluation of cartilage was carried out only in the weight–bearing cartilage. The cut–off values for determining the presence of a cartilage injury were determined using each ROC curve, and the detectability was calculated for the T1ρ and T2 mapping. Results: The cut–off values for the T1ρ and T2 were 41.6 and 41.2, respectively. The sensitivity and specificity of T1ρ were 91.2% and 89.5%, respectively, while those of T2 were 76.5% and 81.6%, respectively. For the 3D WATS images, the same values were 58.8% and 78.9%, respectively. Conclusions: Our study demonstrated that the T1ρ and T2 values were significantly higher for ICRS grade 1 cartilage lesions than for normal cartilage and that the two mappings were able to non–invasively detect ICRS grade 1 cartilage lesions in the ACL–injured knee with a higher detectability than were 3D WATS images. [Copyright &y& Elsevier]

Abstract: Objective: To study the effects of aging and cartilage degeneration of the proximal tibiofibular- and femorotibial joint (PTFJ, FTJ) on the cartilage of the PTFJ using T 1 ρ and T 2 mapping. Materials and methods: We performed sagittal T 1 ρ and T 2 mapping of the PTFJ and FTJ on 55 subjects with knee disorders. We placed 3 regions of interest (ROIs) on images of the cartilage in the PTFJ, medial femoral condyle (MFC), and medial tibia plateau (MTP). Correlation analysis was performed for the T 1 ρ and T 2 values of each ROI and the patient age and the osteoarthritic grade of the PTFJ and FTJ. Results: The T 1 ρ and T 2 values of the PTFJ were affected neither by aging nor the osteoarthritic grade of the FTJ. Values of the FTJ normalized to PTFJ values were correlated with the osteoarthritic grade of the FTJ in the MFC (r =0.851 and 0.779, respectively) and the MTP (r =0.635 and 0.762, respectively). There was a significant difference in the T 1 ρ but not the T 2 value of the PTFJ and MFC between normal and mildly osteoarthritic cartilage of each joint. Conclusion: We document that the T 1 ρ and T 2 values of PTFJ cartilage were not affected by aging or cartilage degeneration in the FTJ. The T 1 ρ value of the PTFJ may represent a useful internal standard reference for evaluating early degeneration of the FTJ. [Copyright &y& Elsevier]