Synovitis detection in rheumatology: a systematic review and meta-analysis of contrast-enhanced ultrasound and magnetic resonance imaging.

BACKGROUND

Synovial tissue proliferation in the bare area of the joint is an early indicator of synovitis. Vascularization of the pannus helps differentiate between inactive and inflammatory processes, directly impacting therapeutic management. Synovitis can be diagnosed through clinical assessment, ultrasound, and magnetic resonance imaging (MRI); however, uncertainty remains regarding the optimal imaging modality.

OBJECTIVE

This study aimed to determine the accuracy of ultrasonography with microbubble contrast and contrast-enhanced MRI in diagnosing synovitis, irrespective of its etiology. In addition, the study aimed to determine the joints that were most accurately assessed for synovitis using microbubble ultrasound.

METHODS

Electronic searches were conducted in the Cochrane Library, MEDLINE, EMBASE, LILACS, SCOPUS, CINAHL, and Web of Science up to February 8, 2025, with additional screening of reference lists. Studies assessing diagnostic accuracy or detection rates of contrast-enhanced ultrasound (CEUS) and contrast-enhanced MRI for synovitis were included without restrictions on language or publication status. Two studies were selected after quality assessment using QUADAS-2, and eight studies were assessed using the RTI item bank methodology.

RESULTS

Diagnostic accuracies of contrast-enhanced ultrasonography (87%) and contrast-enhanced MRI (87.7%) were comparable. For knee evaluation, CEUS showed a higher detection rate (93.8%) than MRI (82.9%). Across different joints and underlying diseases, the detection rates were 81.9% and 88.3% for contrast-enhanced MRI. In patients with rheumatoid arthritis, MRI demonstrated a higher detection rate (96.2%) compared with ultrasound (67.2%). These findings indicate a similar overall diagnostic performance, although the limited number of included studies restricted generalizability.

CONCLUSION

CEUS demonstrated diagnostic accuracy comparable to contrast-enhanced MRI, except in patients with rheumatoid arthritis. Given its low cost, portability, and favorable safety profile, CEUS may serve as a useful screening or follow-up tool for synovitis, pending validation in larger multicenter studies.