3-T MRI Outperforms 1.5-T MRI in Diagnosis of Osteochondral Lesions of the Talus in Patients Undergoing Broström Repair

Abstract

Category: Ankle; Arthroscopy Introduction/Purpose: Osteochondral lesions of the talus (OLT) are commonly seen in patients with lateral ankle instability. If left undiagnosed, OLTs can cause significant ankle pain, progressive osteoarthritis, and contribute to increased morbidity after an ankle sprain. Arthroscopy has long been the gold standard for OLT diagnosis. While MRI is a useful imaging modality for pre- operative evaluation and planning, prior research on the diagnostic utility of pre-operative MRI for OLTs observes low detection rates. With 3-T scanners replacing 1.5-T scanners, long considered the clinical standard, there is potential that 3-T MRIs may improve MRI's diagnostic efficacy. The purpose of this study is to assess the efficacy of 3-T MRI and 1.5-T MRI in diagnosing OLTs in patients undergoing Broström Gould procedure for lateral ankle instability. Methods: Following institutional review board approval, a database was obtained for all patients from 2/11/2015 to 1/21/2019 who underwent a Broström Gould procedure for lateral ankle instability in addition to diagnostic arthroscopy of the tibiotalar joint. Additionally, patients required a pre-operative MRI for inclusion in the study. Patients who underwent the Broström Gould procedure, but did not have a diagnostic arthroscopy or did not have a pre-operative MRI were excluded from the study. Patient charts were then reviewed to determine the field strength of the preoperative MRIs, and the efficacy of 3-T MRIs and 1.5-T MRIs in correctly identifying the presence or absence of OLTs using diagnostic arthroscopy as a reference standard. Patients with pre- operative MRIs where the field strength was either unlabeled or could not be determined, as they were conducted at outside institutions, were excluded from analysis. Results: Forty (49.4%) out of 81 patients were identified of having preoperative MRI with identifiable field strength, Broström Gould procedure for lateral ankle instability, and diagnostic arthroscopy of the tibiotalar joint. The average age was 37.3 +- 14.2 years. Twenty-four (60.0%) patients were female and 16 (40.0%) were male. Nineteen (47.5%) patients had OLTs identified via diagnostic arthroscopy. Twenty-one patients had a preoperative 3-T MRI, and 19 patients had a preoperative 1.5-T MRI (Table 1). The sensitivity and specificity of 3-T MRI was 75% and 100%; the sensitivity and specificity of 1.5-T M was 72.7% and 87.5%, respectively. For 3-T MRI, six patients were correctly identified as having OLTs, and 13 patients were correctly identified as not having OLTs. For 1.5-T MRI, eight patients were correctly identified as having OLTs, and seven patients were correctly identified as not having OLTs. Conclusion: Three-Tesla MRI appears to be superior to 1.5-T MRI in diagnosing OLTs in patients undergoing Broström Gould procedure for lateral ankle instability. Three-Tesla MRI demonstrates a sensitivity and specificity of 75.0% and 100%, respectively, whereas 1.5-T MRI is associated with a sensitivity and specificity of 72.7% and 87.5%. Three-Tesla MRI's low false positive rate provides support for the efficacy of this imaging modality to rule in OLTs and prompt arthroscopic surgery with subsequent OLT treatment. This suggests that 3-T MRIs may prove useful in clinical decision making regarding OLTs in patients undergoing Broström Gould procedure for lateral ankle instability.