Magnetic resonance imaging evaluation of tubercular arthritis of the ankle and foot

BACKGROUND: Ankle and foot tuberculosis is relatively uncommon. Magnetic resonance imaging (MRI) is highly sensitive in detecting the changes but there is limited experience with MRI evaluation and differentiation from other mono-articular arthritis, particularly pyogenic arthritis, is a challenge. PURPOSE: To report MRI findings in ankle and foot tuberculosis. MATERIAL AND METHODS: MRI was performed in 17 selected patients with ankle and foot tuberculosis. T1-weighted, proton density (PD) weighted, T2-weighted, and postcontrast sequences were performed in multiple imaging planes. Recorded findings included: number of bones involved; specific bones involved; extent of involvement; erosions; joint effusion, synovial thickening, tenosynovitis; joint effusion; adjacent soft-tissue changes; and involvement of sinus tarsi. Clinical data of all patients were also reviewed. Radiographic correlation at the time of MRI was available in selected patients. RESULTS: The most common abnormality was synovial thickening. Signal abnormality was noted most frequently in the talus (n = 14). Erosions and intra-osseous abscesses were noted in 10 (58%) and eight (47%) patients, respectively. Tenosynovitis was present in eight (47%) patients. Soft tissue changes were noted in all patients, including abscesses in 13 patients (76%). CONCLUSION: A multiplicity of findings (both osseous and extra-osseous) on MRI favors the diagnosis of tuberculosis. Three findings (intra-osseous abscess, soft tissue abscess, tenosynovitis), when present together, have a high sensitivity and specificity.