Diagnosis of gout by ultrasound

Objectives. To establish the usefulness of ultrasonography (US) for diagnosing gout and to determine whether there are sonographic features that are characteristic for gout but not for other arthropathies. Methods. We retrospectively compared joint images of gout patients with matching images from patients with other rheumatic conditions. Images of 37 joints of 23 patients with monosodium urate (MSU) crystal-proven gout were reviewed. MSU crystals were identified in at least one joint in each patient. Our control group had 23 randomly selected patients with 33 examined joints with rheumatic conditions other than gout. Results. Specific diagnostic features included a hyperechoic, irregular band over the superficial margin of the articular cartilage described as a double contour sign in 92% of gouty joints and in none of the controls (P<0.001); hypoechoic to hyperechoic, inhomogeneous material surrounded by a small anechoic rim, representing tophaceous material, was seen in all gouty metatarsophalangeal (MTP) joints, in all metacarpophalangeal (MCP) joints and in none of the controls (P < 0.001); erosions adjacent to tophaceous material were seen in 65% of MTP joints and in 25% of MCP joints. One erosion was seen in a MTP joint in a control patient with psoriatic arthritis. Conclusions. US can detect deposition of MSU crystals on cartilaginous surfaces (P < 0.001) as well as tophaceous material and typical erosions. US may serve as a non-invasive means to diagnose gout.