Diagnostic value of MRI for detection of knee cartilage lesions vs. weight-bearing CT arthrography (WBCTa).

objectiveUsing WBCT arthrography (WBCTa) as the referent standard, this study evaluated the diagnostic performance of MRI for visualizing cartilage lesions and determined the rates at which WBCTa detects cartilage lesions that were missed or scored as more severe compared to MRI. MATERIALS AND

methodsThis cross-sectional, level II evidence, prospective observational study included 65 participants undergoing MRI for evaluation of suspected cartilage damage. WBCTa images were acquired following MRI. Knee cartilage morphology was semi-quantitatively assessed using the MRI Osteoarthritis Knee Score (MOAKS) on both imaging modalities. Sensitivity, specificity, accuracy, PPV, and NPV were calculated. The frequencies for cartilage severity detected on WBCT versus MRI in patellar, femoral, and tibial subregions were summarized.

resultsMRI visualization of cartilage lesions had a sensitivity ranging from 0-79% for lesions detected on WBCT, specificity of 84-100%, and accuracy of 71-92%. Excluding the posterolateral tibia, cartilage lesion severity was greater on WBCTa than on MRI in all other subregions (3.1-33.8% of knees) where lesions were detected by both modalities.

conclusionMRI did not visualize a significant proportion of cartilage lesions that were visualized with WBCTa. In all subregions, excluding the posterolateral tibia, cartilage lesion severity was found to be greater on WBCTa than on MRI. Reasons for lower performance of MRI compared to WBCTa are likely multifactorial, potentially relating to scanning configurations, inferior conspicuity of the articular surfaces due to a lack of intraarticular contrast or fluid, and technical reasons such as inferior resolution and type of MRI sequence used.