Knee joint hyaline cartilage defects: a comparative study of MR and anatomic sections

The value of routinely used MR sequences in the detection of focal changes of femorotibial articular cartilage was studied. T1-weighted, proton density, and T2-weighted SE as well as gradient echo images were acquired in 20 cadaveric knees (56-88 years old, mean 73.8 years). Three hundred five coronal and sagittal (3 mm) anatomic sections were prepared, and 82 areas of cartilage defects were identified. Initially, in an unblinded fashion, correlation of MR scans and anatomic sections was performed. Fifty-nine lesions (72.0%) were detectable on T1-weighted images, 57 (70.0%) with meniscal windowing, 49 (60.0%) on proton density images, 56 (68.3%) on T2-weighted images, and 54 (65.9%) on gradient echo images. Sixty-eight (83.0%) were visible on at least one type of imaging sequence. Most defects presented as a focus of abnormal signal. Subsequently, images of a subset of 35 pathologic and 35 normal cartilage surfaces were blindly evaluated by two osteoradiology fellows. Sensitivity was 71.4% for the detection of focal cartilage changes, specificity was 68.6%, and accuracy was 70.0%. We conclude that the value of those MR sequences that are routinely used in the analysis of internal derangements of the knee in the detection of focal defects of the hyaline cartilage is limited.