Usefulness of T2-weighted Oblique Coronal MR Imaging In Anterior Cruciate Ligament Injury

ABSTRACT

PURPOSE: To evaluate the usefulness of T2-weighted oblique coronal imaging in the diagnosis of anteriorcruciate ligament (ACL) injury. MATERIALS AND METHODS: The MRI findings of 12 patients with ACL injury and a groupof 12 with normal ACL were respectively reviewed in terms of nonvisualization or focal defect, morphologic changeand increased signal intensity of ACL. Diagnostic accuracy in the conventional sagittal or coronal plane and inthe T2-weighted oblique coronal plane was also compared. T2-weighted oblique coronal scanning was performed, withthe imaging plane parallel to the direction of the intercondylar roof. RESULTS: In the ACL injury group,conventional MR imaging showed nonvisualization or focal defect (10/12), morphologic change (7/12), displacement(4/12), and increased signal intensity (9/12). T2-weighted oblique coronal imaging showed nonvisualization orfocal defect (11/12), morphologic change (5/12), and increased signal intensity(9/12). In the normal ACL group,conventional MR imaging demonstrated false-positive findings, i.e. these mimicked ACL injuries. Nonvisualizationor focal defect (2/12), and morphologic change (1/12), and increased signal intensity (5/12) were seen.T2-weighted oblique coronal imaging demonstrated normal ACL as an anteromedial and posterolateral band ; therewere no false-positive cases. On T2-weighted oblique coronal scan, no normal ACL showed increased signal intersity; compared with conventional MR imaging, this difference was statistically significant(P < 0.005). Overall, thesensitivity, specificity, and accuracy of conventional sagittal or coronal plane and T2-weighted oblique coronalplane imaging were, respectively 92% and 92%, 58% and 100%, and 75% and 96%. CONCLUSION: On T2-weighted obliquecoronal scans, the visualization of all normal anterior cruciate ligaments was better than on conventional MRimages. When ACL injury is vague on conventional MR imaging, T2-weighted oblique coronal imaging is considered tobe useful for the differentiation of ACL injury and normal ACL.