Gout — SCE Rheumatology MCQ

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ModerateMusculoskeletal ImagingGoutSCE Rheumatology

A patient with suspected gout undergoes ultrasound of the first metatarsophalangeal joint. This demonstrates an irregular hyperechoic band over the superficial margin of the hyaline cartilage, parallel to the underlying subchondral bone and persisting when the insonation angle is changed. What is this ultrasound finding called?

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Correct answer: C — Double contour sign

The correct answer is C, the double contour sign. It represents monosodium urate deposition on the superficial surface of hyaline cartilage, producing an irregular hyperechoic band parallel to the echogenic subchondral bone interface. Persistence despite changing the insonation angle helps distinguish it from an artefact. Aggregates may produce a snowstorm appearance within synovial fluid, while a tophus is a larger heterogeneous deposit in synovial or periarticular tissue. Power Doppler synovitis demonstrates hypervascular inflammatory activity rather than crystal coating of cartilage. CPPD classically produces deposits within cartilage, although a pseudo-double-contour appearance can occasionally occur; dynamic assessment may help distinguish this mimic. The double contour sign is therefore characteristic of gout but is not absolutely disease-specific.

Reference: Neogi T et al. 2015 Gout classification criteria: an American College of Rheumatology/European League Against Rheumatism collaborative initiative, imaging domain. Ann Rheum Dis. 2015;74:1789–1798. https://ard.bmj.com/content/74/10/1789