Stronger Magnets, No Improvements in Accuracy: Comparing Efficacy of 3-T Magnetic Resonance Imaging (MRI) vs 1.5-T MRI in Detecting Associated Lesions in Patients with Lateral Ankle Instability

Abstract

Category: Ankle Arthritis Introduction/Purpose: Patients with lateral ankle instability often have other associated pathologies, including osteochondral lesions of the talus (OLT), peroneus brevis tears, and intra-articular loose bodies. If left untreated, these pathologies can lead to worsening instability, significant ankle pain, and progressive osteoarthritis. Arthroscopy has historically been the gold standard for diagnosing and treating these abnormalities, while magnetic resonance imaging (MRI) can be useful in preoperative evaluation and planning. Our group’s previous research evaluated a subset of the current sample, focusing on MRI diagnostic accuracy of OLTs, demonstrating that 3-T outperformed 1.5-T. Using a larger sample size, the purpose of this study is to assess the efficacy of 3-T MRI and 1.5-T MRI in diagnosing additional pathologies in patients undergoing Broström Gould procedure for lateral ankle instability. Methods: Following institutional review board approval, a database was obtained for all patients at a single institution who underwent a Broström Gould procedure with a concurrent diagnostic arthroscopy of the tibiotalar joint between 1/1/2014- 6/30/2022. Additionally, patients required a pre-operative ankle MRI for inclusion in the study. Patients who did not undergo a preoperative MRI, diagnostic arthroscopy, and Broström Gould procedure were excluded from the study. Additionally, patients with pre-operative MRIs in which the field strength could not be determined were also excluded from analysis. Patient charts were reviewed to determine the field strength of the preoperative MRIs, the efficacy of 3-T and 1.5-T MRIs in correctly identifying the presence or absence of OLTs, peroneus brevis tears, loose bodies, os trigonum, medial malleolus fractures, lateral malleolus fractures, and posterior impingement lesions. Intraoperative diagnostic arthroscopy findings were utilized as a reference standard. Results: One hundred twelve patients met our inclusion criteria of undergoing preoperative MRI with identifiable field strength, Broström Gould procedure, and diagnostic arthroscopy of the tibiotalar joint. The average age was 35.73 ± 21.01 years; 65 (58.0%) patients were female. Fifty-six (50.0%) patients had a preoperative 3-T MRI and 56 patients had a preoperative 1.5-T MRI. There were no differences observed regarding demographic data between groups. Fifty-one OLTs, 12 peroneus brevis tears, 14 loose bodies, two os trigonum, two medial malleolus fractures, two lateral malleolus fractures, and one posterior impingement lesion were identified in our sample (Figure 1A). Three tesla MRI test characteristics did not significantly differ from the test characteristics of 1.5-T MRI (Figures 1B, 1C). Conclusion: The sensitivity, specificity, and overall diagnostic accuracy of 3-T MRI compared against 1.5-T MRI did not significantly differ regarding each imaging modalities’ efficacy in identifying OLTs, peroneus brevis tears, loose bodies, os trigonum, medial and lateral malleolus fractures, and posterior impingement lesions. These findings demonstrate no significant improvement in the diagnostic accuracy of 3-T MRI over 1.5-T MRI in identifying pathologies associated with lateral ankle instability. While many lesions were correctly identified by both modalities, patients will continue to benefit from undergoing intraoperative arthroscopy to determine the most accurate diagnosis regarding their ankle instability.