Is the quantitative Diffusion-Weighted MR Imaging and ADC mapping with b-values of 50, 400, and 800 sec/mm2 a reliable method for evaluation of meniscal tears in the knee?

BACKGROUND Our aim was to evaluate the efficacy of Diffusion-Weighted Imaging (DWI) and Apparent Diffusion Coefficient (ADC) mapping with different b-factors in visualisation of meniscal tears. MATERIAL/METHODS Seventy-four patients; 30 males and 44 females, 37 left and 37 right knees with meniscal tears were involved in this study. Eleven of them were lateral meniscal tears and 63 - medial meniscal tears. DWI was obtained by 3D-SE Echo-planar Imaging (EPI) in coronal and sagittal planes. ADC mapping was carried out in coronal planes with b-factors of 50, 400, and 800 sec/mm(2). The statistical analysis of DWI and ADC mapping results was performed with the use of the Fisher's test and the chi-square test. RESULTS 1. For both menisci and 74 tears: DWI revealed 86% sensitivity and 100% specificity (p=0.149) with a positive predictive value (PPV) of 1 and a negative predictive value (NPV) of 0.09. ADC mapping with b-value of 400 sec/mm(2) had 78% sensitivity, and 100% specificity, with PPV of 1 and NPV of 0.06 (p=0.230). 2. For the lateral meniscal tears: DWI and ADC mapping with b-value of 800, for the medial meniscal tears: DWI and ADC mapping with b-factor of 400 s/mm(2) revealed higher sensitivity and specificity than other methods. CONCLUSIONS Quantitative DWI and ADC mapping, especially with b-factor of 400 sec/mm(2), may be an alternative to routine MR imaging sequences for the visualisation of meniscal tears in the knee.