Computed tomography arthrography versus magnetic resonance imaging for diagnosis of osteochondral lesions of the talus

Introduction Osteochondral lesions of the talus (OLT) usually have non-specific clinical symptoms, and radiographs have a low sensitivity for detecting OLT. The purpose of this study is to compare the diagnostic value of CT arthrography (CTa) with that of MRI using arthroscopy as the reference standard for grading OLT. Materials and methods We retrospectively reviewed patients who had OLT between 2015 and 2020. Patients with symptomatic OLT as a surgical indication, who were treated arthroscopically, and underwent both CTa and MRI before surgery were included. OLT was evaluated by both CTa and MRI using arthroscopy as the standard. We graded CTa, MRI, arthroscopic findings using Mintz classification. Results Thirty-five patients were included. Accuracy rates of MRI and CTa for grading OLT, compared to those of arthroscopy, were 57.1% and 88.6%, respectively. Among 15 mismatched cases in MRI, 12 lesions (80%) were matched in CTa and arthroscopy. CTa had significantly higher diagnostic performance than MRI for the detection of grade III lesions ( p = 0.041). Using the receiver operating characteristics curves, the area under the curve values for lesion grading were 0.893 for CTa and 0.762 for MRI. Conclusion CTa was statistically significantly better in detecting chondral flapping or subchondral exposure lesions for OLT than MRI on using arthroscopy as the reference standard. Because the stability of the OLT is essential in determining the treatment method, if an OLT is observed on MRI and is suspected to cause ankle pain, we recommend additional CTa examination to determine the more correct treatment strategies for OLT. Level of evidence Diagnostic Level III.