The role of musculoskeletal ultrasound in differentiating gouty arthritis from rheumatoid arthritis.

objectiveThis study aimed to evaluate the diagnostic value of musculoskeletal ultrasound (MSUS) for distinguishing between gouty arthritis (GA) and rheumatoid arthritis (RA) by comparing their sonographic features.

methodsThis retrospective study enrolled 100 patients with a confirmed diagnosis (50 with rheumatoid arthritis, RA; 50 with gouty arthritis, GA from Chengdu Rheumatism Hospital between February and August 2025). The MSUS features compared between the two groups included indicators of crystal deposition (e.g., double-track sign, tophi, punctate hyperechoic foci) and indicators of inflammation (e.g., synovitis, tenosynovitis, tendinitis). The diagnostic sensitivity, specificity, and area under the receiver operating characteristic curve (AUC) were calculated for each sonographic feature.

resultsUrate crystal deposition demonstrated excellent diagnostic performance for GA (sensitivity 98.0%, specificity 100.0%, AUC = 0.990). Tophi and punctate hyperechoic foci also showed high specificity (98.0% each). In the RA group, tendinitis was the most frequent finding (sensitivity 96.0%, specificity 68.0%, AUC = 0.820). A diagnostic model combining GA-specific features achieved superior accuracy (sensitivity 100%, specificity 98%, AUC = 0.990). Correlation analysis revealed a significant association between the presence of tophi and disease duration in GA patients (r = 0.349, P = 0.013), but no such correlations were found in the RA group.

conclusionMSUS provides high diagnostic value for GA by reliably detecting characteristic crystal-related features, particularly urate crystal deposition. For RA, MSUS is highly sensitive in detecting inflammatory and structural lesions such as tendinitis, tenosynovitis, and bone erosions; however, these features alone show limited specificity for differentiating RA from GA. Key Points • Musculoskeletal ultrasound (MSUS) demonstrates exceptional diagnostic value for gouty arthritis (GA), with the detection of urate crystal deposition showing near-perfect accuracy (sensitivity 98.0%, specificity 100.0%, AUC=0.990). • A diagnostic model combining characteristic GA features (urate deposition, tophi, and punctate hyperechoic foci) achieved superior performance (sensitivity 100%, specificity 98%, AUC=0.990), outperforming any single sonographic feature. • The presence of sonographic tophi was significantly correlated with longer disease duration in GA patients, underscoring its role as a marker of chronic disease burden. • While MSUS is highly sensitive for detecting inflammatory lesions in rheumatoid arthritis (RA), such as tendinitis and tenosynovitis, these features lack specificity for differentiating RA from GA.