Value of a Short Four-joint Ultrasound Test for Gout Diagnosis: a Pilot Study

Objectives: The goal of this study was to investigate the usefulness of a short ultrasound (US) assessment in gout.

Methods: Patients with gout, confirmed by urate crystal identification, and having at least one symptomatic flare in the last three months were included. Standardised US examinations of sixteen joints and eight tendons in the lower limbs were carried out. Six lesions were studied: hyperechoic spots in the synovial fluid, hyperechoic cloudy areas (HCA), bright stippled aggregates (BSA), the double contour sign (DCS), erosions and the Doppler signal. For reliability, inter-reader analyses were performed by five rheumatologists. With the results, a short US assessment was created.

Results: Twenty-nine consecutive patients were included (93% men). The Doppler signal, HCAs and BSAs appeared in 100%, 97% and 93% of the patients, respectively. The DCS was found in 69% of patients. The locations that were most affected were the first metatarsophalangeal joint (MTP) and the knee joints, both of which are in 93% of patients. Reliability analyses showed consistent results for erosions, the Doppler signal, HCAs and the DCS in the 1st MTP (k=0.818, k=0.958, k=0.739 and k= 0.697, respectively) and for the DCS in the knees (k=0.779). A six-minute US examination of four joints (knees and the 1st MTPs) detected HCAs or DCS in 97% of cases.

Conclusions: A US examination of four joints for two elemental lesions (the DCS and HCAs) is feasible, reliable and has face and content validity as a diagnostic test in patients with crystal-proven gout.