Comparative study of MRI and power Doppler ultrasonography of the heel in patients with spondyloarthritis with and without heel pain and in controls.

INTRODUCTION Imaging of heel enthesopathy in spondyloarthritis (SpA) could potentially be useful for diagnosis and monitoring. The aim of this study was to assess the diagnostic capacities of MRI and power Doppler ultrasonography (PDUS) of the heel to distinguish patients with SpA from controls and to distinguish between patients with SpA with and without enthesopathy. METHODS A cross-sectional single-centre study was performed in 51 patients (102 heels) with definite SpA according to Amor's criteria. Patients with degenerative non-inflammatory low back pain (n=24, 48 heels) were included as controls. Bilateral heel MRI and PDUS were performed by two senior musculoskeletal radiologists blinded to the clinical and biological data on the same day as the clinical evaluation. The data were analysed by patient and by heel. RESULTS Neither MRI nor PDUS could discriminate between patients with SpA and controls; bone oedema on MRI was the only abnormality specific to SpA (94%), but with a poor sensitivity (22%). However, among patients with SpA, painful heels had more inflammatory abnormalities (81% by MRI, 58% by PDUS) than heels with no pain (56% at MRI, 17% at PDUS). CONCLUSION Heel MRI and PDUS frequently show inflammatory lesions in SpA, particularly in painful heels. However, they were also often abnormal in controls. These results suggest that heel MRI and PDUS cannot be used for the diagnosis of SpA. However, PDUS and MRI may be useful for the depiction and assessment of enthesis inflammatory lesions in patients with SpA with heel pain.