Identification of monosodium urate crystal deposits in patients with asymptomatic hyperuricemia using dual-energy CT

Abstract

ObjectivesDual-energy CT (DECT) scan is a sensitive and specific tool used to visualise and quantify monosodium urate (MSU) crystal deposits in the joints. Few studies have examined MSU crystal deposits in patients with asymptomatic hyperuricemia (ie, hyperuricemia in the absence of gout) using DECT.MethodsWe conducted a prospective, non-interventional cross-sectional study to detect MSU crystal deposits on DECT scans among patients with asymptomatic hyperuricemia. We also examined patient factors associated with subclinical MSU crystal deposits. Out of 130 subjects aged ≥40 years with metabolic syndrome screened for serum uric acid (sUA) levels ≥6.5 mg/dL, 46 underwent a foot/ankle DECT scan.ResultsThe mean age of the study participants was 62 (±8) years, 41% were men and the mean sUA level was 7.8 (±1.0) mg/dL. Seven (15%) of 46 patients had MSU crystal deposits on DECT with a mean total volume of 0.13 (±0.14) cm3. In the univariable logistic regression analysis, older age had a significant association with presence of MSU crystal deposits (OR 1.20, 95% CI 1.03 to 1.39), but sUA did not (OR 1.36, 95% CI 0.63 to 2.95). In the univariable analysis, sUA levels showed a trend towards a modest linear association (β=0.11, P=0.09) with total volume of MSU crystal deposits.ConclusionsFifteen per cent of patients with asymptomatic hyperuricemia had subclinical MSU crystal deposits on foot/ankle DECT scans. Older age, but not sUA, was significantly associated with presence of subclinical MSU crystal deposits among patients with asymptomatic hyperuricemia. Clinical significance of these subclinical MSU crystal deposits needs to be determined.

Asymptomatic hyperuricemia and coronary flow reserve in patients with metabolic syndrome

“…Among patients with no diabetes (n = 25), the median (IQR) HOMA-IR was 4.6 (3.8-5.7) and there was no significant association between SUA and HOMA-IR (β = 2.08, p = 0.1). None had DECT-detectable subclinical urate deposits in the neck, while 15% of these patients had subclinical urate deposits in the foot DECT scan (results published elsewhere) [25].…”

“…It may be partially explained by the fact that most patients were hyperuricemic but their SUA were not too high with the upper quartile SUA level of 8.4 mg/dL. Furthermore, the sensitivity of DECT for the vasculature in asymptomatic hyperuricemia patient may be too low as 15% of the study cohort had DECT-positive urate deposits in their feet [25].…”

“…We excluded pregnant or nursing women, patients with diagnosis of gout, symptomatic coronary artery disease or pulmonary disease, moderate-to-severe valvular heart disease requiring surgery, end-stage renal disease, renal replacement therapy, active malignancy requiring treatment, or those who used xanthine oxidase inhibitors, colchicine or probenecid. Details of this study cohort is described elsewhere [25].…”

“…We then used a commercial software post-processing program ('Gout' , Syngo CT Workplace, Siemens Medical Systems) to produce digital colorcoded images, where MSU deposits were marked as green. As a part of the main study, the study patients also underwent a DECT scan of the foot described elsewhere [25].…”

Association of Specific Comorbidities with Monosodium Urate Crystal Deposition in Urate-Lowering Therapy-Naive Gout Patients: A Cross-Sectional Dual-Energy Computed Tomography Study

“…Patient age and gout duration were expected to play important roles in the formation of the MSU crystal burden. The few studies that have investigated MSU deposition with DECT in subjects not receiving ULT focused only on asymptomatic hyperuricemia [15,16]. These studies reported that increasing age, and therefore likely hyperuricemia duration, was associated with silent MSU crystal deposition.…”