Background Dual-energy computed tomography (DECT) is advanced imaging modality that shows the deposition of monosodium urate (MSU) crystal in tissue as a color signal. The MSU crystal deposit around the symptomatic joint is considered as positive finding, but the clinical significance of urate deposition around the tendon is still unclear.
Objectives The aim of this study was to compare the clinical characteristics and DECT findings in people with MSU crystal deposition in the joints and people with urate deposition in the tendons.
Methods DECT was performed in 71 patients who complained of recurrent painful swelling of the joints, and 35 of them showed MSU crystal deposition in the joints on DECT. Clinical manifestation and serum uric acid level data were collected.
Results Most of the included patients were middle-aged (mean age 50 years, SD 15) and 67 patients (94%) were male. All patients who had MSU crystal deposition in joints on DECT had a history of typical gout attacks, and 29 patients (81%) had a history of gout attacks among patients with urate deposition only in tendons (p=0.011). The mean uric acid level of patients included in the study was as high as 7.5±2.2 mg/dL. In the highest uric acid level, the absolute value was higher in patients with urate deposition in joints, but there was no statistical significance. The correlation between the gout attack site and the urate deposit sites was 91% in patients with joint involvement, but only 6% in patients without joint involvement (p<0.001). There were 4 patients (11%) who showed gouty erosion without MSU crystal deposition in joints on DECT.
Conclusions The MSU crystal deposition in the tendon was not correlated well with clinical features, suggesting that it is more likely to be associated with artifact or asymptomatic hyperuricemia. However, in some patients, MSU crystal deposition may be observed only in the tendon, even with gouty erosion. Therefore, careful interpretation of the DECT results is necessary.
Disclosure of Interest None declared