Combining ACL Oblique Coronal MRI with the Routine Knee MRI Protocol in the Diagnosis of ACL Bundle Lesions. Can It Add A Value?

Abstract Background: The Anterior Cruciate Ligament (ACL) is formed of two bundles. Routine MRI protocol is usually insufficient to delineate both bundles structure, so diagnosis of AM and PL bundle injury is often limited, and development of further imaging orientation and pulse sequences is key for further improving characterization of these bundles. Accurately grading the ACL tears and differentiating between complete and partial tears as well as assessing the two bundles is key in improving the clinical and surgical management. Aim of Study: The purpose of this study is to evaluate the diagnostic value of combining oblique coronal images to the routine MRI protocol for better assessment of the ACL bundles, thus improving management outcome by performing two MRI protocols and comparing them to the arthroscopic findings. Patients and Methods: This prospective study was con-ducted between January 2016 and February 2018 in Ain Shams University Hospitals and private centers. The study population has consisted of 32 patients (26 men & 6 women), ranging between 19-45 years, with mean age of 27.11 years. All patients were suspected of ACL injury referred from the outpatient clinic of orthopedic. All patients were examined by MRI examinations com-posed of sagittal T2-weighted Fast-Spin Echo (FSE), coronal T2-weighted FSE, and axial T2-weighted. The sagittal images were planned on axial localizer by 15-degree medial angling on perpendicular line to the bicondylar line and by oblique coronal MRI were the oblique coronal STIR images named were planned on midsagittal localizer in the plane parallel to the ACL and the roof of the intercondylar notch (Blumensaat's line). A consultant orthopedic surgeon did a diagnostic arthros-copy for all included patients using standard parapatellar portals visualizing the ACL with direct visualizing of both bundles and accordingly classifying each bundle as torn or intact. Results: The Oblique coronal MRI showed a better agree-ment with the diagnostic arthroscopy than routine MRI [weight-ed Kappa; k=0.865 & 0.753 respectively]. For diagnosis of Anteromedial Bundle (AMB) tear the sensitivity was 90.9%, specificity 80%, with overall accuracy of 87.5%. For diagnosis of Posterolateral Bundle (PLB) tear. The sensitivity was 95.5%, specificity 90%, with overall accuracy of 93.8%. Conclusion: The adding of oblique coronal imaging to routine MRI protocol revealed better delineation of the ACL bundles, increasing the accuracy of diagnosis each or both bundle lesions, providing significant benefit in further man-agement and outcome in patient with suspected ACL injury.