Consensus-based identification of factors related to false-positives in ultrasound scanning of synovitis and tenosynovitis

IntroductionWe aimed to identify causes of false-positives in ultrasound scanning of synovial/tenosynovial/bursal inflammation and provide corresponding imaging examples.MethodsWe first performed systematic literature review to identify previously reported causes of false-positives. We next determined causes of false-positives and corresponding example images for educational material through Delphi exercises and discussion by 15 experts who were an instructor and/or a lecturer in the 2013 advanced course for musculoskeletal ultrasound organized by Japan College of Rheumatology Committee for the Standardization of Musculoskeletal Ultrasonography (JCR-CoSMUS).ResultsSystematic literature review identified 11 articles relevant to sonographic false-positives of synovial/tenosynovial inflammation. Based on these studies, 21 candidate causes of false-positives were identified in the consensus meeting. Of these items, 11 achieved a pre-defined consensus (≥ 80 %) in Delphi exercise and were classified as follows: I. Gray-scale assessment (A. Non-specific synovial findings, B. Normal anatomical structures which can mimic synovial lesions due to either their low echogenicity or anisotropy); II. Doppler assessment (A. Intra-articular normal vessels, B. Reverberation). Twenty-four corresponding examples with 49 still and 23 video images also achieved consensus.ConclusionsOur study provides a set of representative images that can help sonographers to understand false-positives in ultrasound scanning of synovitis and tenosynovitis.