MAGNETIC-RESONANCE-IMAGING OF ARTICULAR-CARTILAGE IN THE KNEE - AN EVALUATION WITH USE OF FAST-SPIN-ECHO IMAGING

The purpose of this study was to demonstrate that specialized magnetic resonance imaging provides an accurate assessment of lesions of the a rticular cartilage of the knee, Arthroscopy was used as the comparativ e standard, Eighty-eight patients who had an average age of thirty-eig ht Sears were evaluated with magnetic resonance imaging and subsequent arthroscopy because of a suspected meniscal or ligamentous injury. Th e magnetic resonance imaging was performed with a specialized sequence in the sagittal, coronal, and axial planes. Seven articular surfaces (the patellar facets, the trochlea, the femoral condyles, and the tibi al plateaus) were graded prospectively on the magnetic resonance image s by two independent readers with use of the 5-point classification sy stem of Outerbridge, which was also used at arthroscopy. Six hundred a nd sixteen articular surfaces were assessed, and 248 lesions, were ide ntified at arthroscopy, Eighty-two surfaces had chondral softening; se venty-five, mild ulceration; fifty-three, deep ulceration, fibrillatio n, or a nap without exposure of subchondral bone; and thirty-eight, fu ll-thickness wear. To simplify the statistical analysis, grades 0 and 1 were regarded as disease-negative status and grades 2, 3, and 4 were regarded as disease-positive status. When the grades that had been as signed by readier 1 were used for the analysis, magnetic resonance ima ging had a sensitivity of 87 per cent (144 of 166), a specificity of 9 4 per cent (424 of 450), an accuracy of 92 per cent (568 of 616), a po sitive predictive value of 85 per cent (144 of 170), and a negative pr edictive value of 95 per cent (424 of 446) for the detection of a chon dral lesion, Interobserver variability was minimum, as indicated by a weighted kappa statistic of 0.93 (almost perfect agreement). With use of this readily available modified magnetic resonance imaging sequence , it is possible 40 assess all articular surfaces of the knee accurate ly and thereby identify lesions that are amenable to arthroscopic trea tment.