Background/Purpose: Detection of double contour sign (DCS) and hyperechoic aggregates (HAG) is a reliable method in detecting urate crystal deposition by ultrasound (US) which has been studied extensively. Worldwide attempts have been made to assess response by measuring Tophi size, but USG has not shown good correlation with other modalities in assessing Tophi size. Our study was aimed at progression / resolution of presence of DCS and HAGs after urate lowering therapy.

Methods: 14 patients of proven gout were followed up for progression / resolution of US findings after one year of urate lowering therapy. US evaluation was done at the beginning of urate lowering therapy and repeat US was done at one year. The ultrasound scans were obtained applying guidelines issued by The Working Group for Musculoskeletal Ultrasound in the EULAR Standing Committee on International Clinical Studies including Therapeutic Trials. DCS was looked for at three articular cartilage sites (first metatarsal, tibiotalar and femoral condyle) whereas HAGs were looked for at three joint sites (radiocarpal, first metatarsal and femoral condyle) and two tendon sites (patellar and triceps). Ultrasound was done using multifrequency linear array transducer (8–13 MHz) of Logiq E; GE Medical Systems Ultrasound, on B mode gray scale (GS).

Results: In 14 patients, 84 sites were examined for double contour sign (DCS) and 140 sites for hyperechoic aggregates (HAG). In the initial evaluation, DCS was present in 34 out of 84 sites which got reduced to 27 in the follow up (20.5% reduction). HAG were present in 23 out of 140 sites in the initial study which got reduced to 11 out of 140 in the follow up (52 % reduction). Overall there was a 33.3% reduction of US abnormalities over one year follow up after urate lowering therapy. The mean serum uric acid level was 9.44 mg/dl (range- 2.6-13.7mg/dl) before initiation of urate lowering therapy and was 6.7 mg/dl (range 3.9-10.3) at one year follow up. Among the fourteen patients, compliance to drugs and dietary modifications were good for eleven patients and three were non-compliant. The mean serum uric acid levels in the good compliance group was 9.09 mg/dl at the initiation of therapy and mean levels got reduced to 6.0mg/dl after one year of follow up. The resolution of US abnormalities was seen in the compliant group while there was no resolution of US abnormalities in the non-compliant group.

Conclusion: Urate lowering therapy results in marked resolution of DCS and HAGs in gout. Compliance to urate lowering therapy and diet in resolution of US abnormalities is important. Qualitative assessment of presence and absence of DCS and HAGs can be used a guide to successful therapy.

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ACR Meeting Abstracts - https://acrabstracts.org/abstract/urate-lowering-therapy-regresses-ultrasound-abnormalities-in-gout/