[MR diagnosis of internal derangement of the knee by SE T1 and GRE T2* weighted images: evaluation of 300 arthroscopically proven knees].

To evaluate whether or not the combination of sagittal and coronal spin-echo (SE) T1 and sagittal gradient echo (GRE) T2* weighted imaging is adequate to diagnose internal derangement of the knee, a study was done in 300 knees of 293 consecutive patients who underwent both MR imaging of the knee and arthroscopy. In prospective analysis, the MR imaging had an accuracy, sensitivity and specificity of more than 90% in the evaluation of medial meniscus (MM) and of 97% in the evaluation of anterior cruciate ligament (ACL). In the evaluation of lateral meniscus (LM), accuracy was 83%, sensitivity 76%, and specificity 88%. In a review of false-negative MR diagnoses (n = 42) of menisci, the most significant lesion was not in the meniscus but in the ACL in 32 knees (76%). Conservative treatment was selected in 25 knees (60%), rather than partial meniscectomy (n = 13) or meniscoresis (n = 4). There were 21 false-positive MR diagnoses of menisci even in retrospective analysis, and 17 of them (81%) had findings of tear in the posterior zone, which is known to be a difficult area for arthroscopic examination. The results were similar to those of other authors' with SE T1 and/or proton density and T2 weighted images. The combination of sagittal and coronal SE T1 and sagittal GRE T2* weighted images could be sufficient as a routine MR protocol for diagnosing the internal derangement of the knee.