Morton's neuroma: the role of MR scanning in diagnostic assistance

Abstract

Introduction: The clinical presentation of Morton's neuroma can be variable and investigations are often used for confirmation. Imaging modalities include ultrasound, CT and MR scanning. We report the sensitivity of MR for assessing Morton's neuroma. Method: Twenty-one clinically suspected and histologically confirmed cases of Morton's neuroma were analysed retrospectively. All patients have had magnetic resonance scanning as part of pre-operative assessment. The sequences used were T1 (TR 682 ms, TE 20 ms), STIR (TR 4700 ms, TE 60 ms, TI 100 ms) and T1W fat suppressed (TR 572 ms, TE 17 ms) pre- and post-contrast coronal images. Two consultant radiologists analysed and reported all scans. Results: Magnetic resonance imaging correctly identified a Morton's neuroma in 14 (66.7%) patients but was reported normal in 7 patients. T1-weighted sequences had a sensitivity of 28.5% (6 cases) in detecting Morton's neuroma whereas STIR sequences improved this to 61.9% (13 cases). T1 with fat suppression pre- and post-contrast did not improve the sensitivity. Conclusion: Our findings provide a contrast to earlier studies that have reported 83% sensitivity and 100% specificity of MR scan for detecting Morton's neuroma. A negative MR scanning does not conclusively exclude the presence of Morton's neuroma. A good clinical history and examination remains vitally important.