Reliability and validity of different ankle MRI scanning planes for the anterior talofibular ligament injury diagnosis: a cadaveric study

BACKGROUND: The objective of the current study is to compare reliability, accuracy, sensitivity, and specificity in magnetic resonance imaging (MRI) evaluation of anterior talofibular ligament (ATFL) among the routine axial scanning plane, oblique axial-coronal scanning plane, and oblique axial-sagittal scanning plane. METHODS: Twenty cadaveric feet were studied. ATFL was exposed before scanning. Routine axial, oblique axial-coronal, and oblique axial-sagittal MRI scanning of 20 ATFL-intact cadaveric feet were acquired utilizing a 1.5-T MRI unit. The scans were repeated on the 20 cadaveric feet after the ATFL was artificially injured. In total, 120 sets of MR images were obtained and were randomly numbered. Three independent observers who were blinded to the experiment evaluated the images. Interobserver agreement, sensitivity, specificity, and accuracy were calculated and compared between different scanning planes utilizing the McNemar test. RESULTS: The interobserver agreement was fair to good (kappa, 0.55 to 0.65) in the routine axial plane, fair to good (kappa, 0.557 to 0.75) in the oblique axial-sagittal plane, and excellent (kappa, 0.85 to 0.95) in the oblique axial-coronal plane. The accuracy was significantly higher when utilizing oblique axial-coronal MRI scanning than routine axial MRI scanning (reader 1: p = .018; reader 2: p = .005). CONCLUSIONS: The diagnostic accuracy of oblique axial-coronal plane MRI was higher than the routine axial plane concerning ATFL injury, and the interobserver agreement was excellent. The oblique axial-coronal plane could be added to the MRI scanning protocol during clinical practices to improve the diagnostic accuracy of ATFL injury.