Comparison of weight-bearing CT arthrography with MRI to evaluate knee meniscal tears

Magnetic Resonance Imaging (MRI) is considered the imaging modality of choice for identifying meniscal pathology. However, it can be challenging to differentiate intrameniscal signal changes from tears. Given that meniscal tears may be more conspicuous when loaded, weight-bearing imaging may better visualize tears. We hypothesized that weight-bearing CT arthrography (WBCTa) would demonstrate meniscal pathology not visualized on MRI.

This cross-sectional, observational study compared WBCTa with MRI to evaluate rates of detection of meniscal pathology. Sixty-five subjects (age >18) who underwent clinical MRI to evaluate suspected meniscal pathology received WBCTa of the knee an average of 6 days later. Meniscal tears, extrusion, and cysts were semi-quantitatively scored using the MOAKS scoring system.

65 participants (mean age, 48.4 ± 13.9 years, 45 women) were evaluated. Medial meniscal body tears were detected by WBCTa for 45% of the 40 knees that were visually normal or demonstrated only non-specific signal abnormality on MRI. WBCTa identified medial extrusion of the medial meniscus in 53.3% of 30 knees that did not have this finding on MRI. Scoring of lateral meniscal tears and extrusion as well as meniscal root tears, and cysts generally agreed between WBCTa and MRI.

WBCTa detected a higher rate of medial meniscal tears (complete/partial maceration; complex, partial, and horizontal tears) and a higher rate of medial meniscal extrusions than were visualized on MRI in this study. Visualization of lateral meniscal tears, meniscal root tears, and cysts did not differ between WBCTa and MRI.