Magnetic Resonance Imaging Bone Edema Is Not a Major Feature of Gout Unless There Is Concomitant Osteomyelitis: 10-year Findings from a High-prevalence Population

Abstract

Magnetic resonance imaging (MRI) is commonly used in autoimmune inflammatory arthritis to define disease activity and damage, but its role in gout remains unclear. The aim of our study was to identify and describe the MRI features of gout. Over a 10-year period we identified patients with gout who underwent MRI scanning of the hands or feet. Scans were reviewed for erosions, synovitis, tenosynovitis, tendinosis, bone edema, and tophi by a musculoskeletal radiologist and 2 rheumatologists in a blinded manner. MRI features in patients with uncomplicated gout were compared with features where concomitant osteomyelitis was diagnosed. A total of 47 patients with gout (51 scans) were included: 33 (70%) had uncomplicated gout and 14 (30%) had gout complicated by osteomyelitis. MRI features included tophi in 36 scans (71%), erosions in 35 (69%), bone edema in 27 (53%), synovitis in 15 (29%), tenosynovitis in 8 (16%), and tendinosis in 2 (4%). Uncomplicated gout and gout plus osteomyelitis did not differ for most MRI features. However, "severe bone marrow edema" was much more common in gout plus osteomyelitis, occurring in 14/15 scans (93%) compared with 3/36 scans (8%) in uncomplicated gout (OR 154.0, 95% CI 14.7-1612, p < 0.0001). Sensitivity and specificity of "severe bone edema" for concomitant osteomyelitis were 0.93 (95% CI 0.68-0.99) and 0.92 (95% CI 0.78-0.98), respectively. MRI reveals that gout affects the joints, bones, and tendons. Bone edema in patients with chronic tophaceous gout is frequently mild and this contrasts with the "severe bone edema" observed in patients with concomitant osteomyelitis.