Comparison of a handheld ultrasound device with cart-based ultrasound for the assessment of gout lesions in people with established gout

OBJECTIVES: Use of handheld portable ultrasound is increasing and would improve access for people with rheumatic disease when conventional, cart-based ultrasound is unavailable. This study compared handheld and cart-based ultrasound for the assessment of gout lesions in people with gout.

METHODS: The lower limbs of 21 participants with gout were independently scanned at six sites (1st and 2nd metatarsophalangeal joints, knee, patellar ligament, Achilles tendon, and peroneal tendons) using cart-based (LOGIQ P9) and handheld (Vscan Air™) ultrasound by two rheumatologists. One rheumatologist was randomized to scan the right or left leg first with the cart-based or handheld ultrasound. The other rheumatologist scanned the legs in the opposite order with the imaging devices reversed. Images were saved and blinded images scored for double contour, tophus, erosion and aggregates using OMERACT definitions by two rheumatologists experienced in gout ultrasound.

RESULTS: On handheld ultrasound, 90% of participants had at least one site with double contour, tophus and erosions, and 100% had at least one site with aggregates. There were similar findings using cart-based ultrasound. However, site-level inter-device analysis showed only fair-good agreement: kappa (percentage agreement) for double contour 0.22 (67%), tophus 0.46 (77%), erosion 0.63 (83%) and aggregates 0.37 (75%). There were more aggregates detected by cart-based ultrasound in joints and more tophi detected by handheld ultrasound in ligaments and tendons.

CONCLUSIONS: Handheld ultrasound can detect gout lesions in people with established gout. However, concordance between cart-based and handheld ultrasound in detection of some gout lesions is low, particularly double contour and aggregates.