The following article is a part of conference coverage from the American College of Rheumatology Convergence 2020, being held virtually from November 5 to 9, 2020. The team at Rheumatology Advisor will be reporting on the latest news and research conducted by leading experts in rheumatology. Check back for more from the ACR Convergence 2020.

Dual-energy computed tomography (DECT) is more accurate than ultrasound for the diagnosis of gout, and there may be no added benefit in combining both modalities vs DECT alone, according to study results presented at the American College of Rheumatology (ACR) Convergence 2020, held virtually from November 5 to 9, 2020.

The objective of the current study was to determine the diagnostic accuracy of DECT vs ultrasound, or their combination, for the diagnosis of gout.

Study authors examined the sensitivity, specificity, positive and negative predictive value, and area under the receiver operating characteristic curve (AUC) of DECT and ultrasound, and their combination, for gout diagnosis. Diagnosis of gout was based on the evidence of monosodium urate crystals in synovial fluid (gold standard) and the 2015 American College of Rheumatology and European League Against Rheumatism classification criteria (ACR/EULAR; silver standard)

The study included the data of 147 patients (mean age, 64.7±14.3 years) from an outpatient rheumatology clinic. Mean symptom duration was 9.2 years. Synovial fluid analysis was performed in 48 patients, of whom 38 had monosodium urate crystals. A total of 113 patients (77%) met the modified ACR/EULAR classification criteria for gout.


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In the analysis of the diagnostic accuracy of DECT and ultrasound for gout, the study authors noted that compared to monosodium urate crystals in synovial fluid, ultrasound double contour sign had low sensitivity (76%) and negative predictive value (40%). However, feet and knee DECT had high sensitivity (87% and 91%, respectively) and specificity (100% and 87%, respectively).

The overall accuracy of ultrasound double contour sign was low (AUC, 0.68) compared to feet (AUC, 0.93), followed by knee (AUC, 0.89) DECT, both of which had the highest overall accuracy for gout diagnosis. Combined DECT and ultrasound offered no additional increase in overall diagnostic accuracy (AUC, 0.74).

“In a single-center rheumatology clinic study, feet or knee DECT had the best overall accuracy statistics for the diagnosis of gout. DECT/ultrasound combination or multiple joint imaging may offer no additional increase in overall diagnostic accuracy,” the study authors concluded.

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Reference

Singh J, Becce F, Budzik J-F, Pascart T. Dual-energy CT versus ultrasound, alone or in combination, for the diagnosis of gout: a diagnostic performance study. Presented at: ACR Convergence 2020; November 5-9, 2020. Abstract 0647.