Lesions of the menisci of the knee: Value of MR imaging criteria for recognition of unstable lesions

OBJECTIVE. This study aimed to determine the value of four MR imaging crite ria for evaluating unstable meniscal lesions. MATERIALS AND METHODS. Criteria for unstable meniscal lesions were the pres ence of a displaced meniscal fragment, visibility on more than three 3-mm-t hick coronal and two 4-mm-thick sagittal images, having more than one orien tation plane or more than one pattern (contour irregularity, peripheral sep aration. tear), and having intrameniscal high signal intensity on T2-weight ed spin-echo images. Sensitivity, specificity, and positive and negative pr edictive values for recognition of instability among all meniscal lesions w ere determined for the presence of each individual criterion and for the pr esence of at least one criterion in 50 consecutive patients (mean age, 46 y ears) who underwent MR imaging and subsequent arthroscopy. RESULTS, Sensitivities and specificities of these four criteria ranged betw een 18% and 54% and between 94% and 100%. respectively, Positive and negati ve predictive values ranged between 92% and 100% and between 39% and 52%, r espectively. The presence of at least one criterion enabled recognition of unstable lesions with a sensitivity and specificity of 82% and with positiv e and negative predictive values of 90% and 70%. respectively. CONCLUSION, The four MR imaging criteria have high specificities and positi ve predictive values and low sensitivities and negative predictive values w hen evaluating unstable meniscal lesions.