Diagnosis of internal derangement of the knee at 3.0-T MR imaging: 3D isotropic intermediate-weighted versus 2D sequences.

PURPOSE To compare three-dimensional (3D) isotropic fast spin-echo (SE) intermediate-weighted magnetic resonance (MR) imaging with two-dimensional (2D) fast SE MR imaging-both performed at 3.0 T-for performance in the diagnosis of internal derangements of the knee. MATERIALS AND METHODS The institutional review board approved this HIPAA-compliant study, and the requirement for informed consent was waived. The authors retrospectively reviewed 87 knee MR images obtained in 85 patients who had undergone both 3D isotropic and 2D MR examinations of the knee at 3.0 T and subsequent arthroscopic surgery. The 2D MR images included intermediate-weighted coronal and sagittal images, intermediate-weighted axial images with fat saturation, and T2-weighted sagittal images. The 3D isotropic MR images were obtained with multiplanar reformation (MPR), a fast SE intermediate-weighted sequence, and a reconstruction voxel size of 0.5 x 0.5 x 0.5 mm. Two radiologists retrospectively and independently evaluated the 2D and 3D data sets, at different sessions, for the presence of medial meniscus (MM), lateral meniscus (LM), anterior cruciate ligament (ACL), and posterior cruciate ligament (PCL) tears. These interpretations were compared with the arthroscopic surgery findings. The statistical differences between the sensitivities, specificities, and accuracies of the two methods were determined at McNemar testing, with surgical findings serving as the reference standard. Interobserver agreement was calculated by using kappa coefficients. RESULTS For both reviewers, the sensitivity, specificity, and accuracy of both MR techniques were higher than 95% for the diagnosis of ACL and PCL tears, higher than 85% for the diagnosis of MM tears, and higher than 80% for the diagnosis of LM tears. There were no significant differences in sensitivity, specificity, or accuracy between the two methods. Interobserver agreement for evaluation of all lesions was excellent and ranged from 0.81 (LM tears evaluated with 3D and 2D sequences) to 0.93 (ACL tears evaluated with 3D and 2D sequences, PCL tears evaluated with 2D sequence, and MM tears evaluated with 3D sequence). CONCLUSION The performance of 3D isotropic fast SE intermediate-weighted MR imaging with MPR was not significantly different from that of 2D MR imaging in the diagnosis of cruciate ligament and meniscal tears of the knee.