Reliability of colour Doppler ultrasonography of the major salivary glands in Sjögren's disease

OBJECTIVES: To analyse intraobserver and interobserver reliability of colour Doppler (CD) ultrasonography of the major salivary glands (SGUS) in patients clinically suspected of Sjögren's disease (SjD).

METHODS: One hundred consecutive outpatients visiting the University Medical Center Groningen for a diagnostic trajectory because of a suspicion of SjD were evaluated using CD ultrasonography of the submandibular and parotid salivary glands. All images were independently assessed by four observers (two experienced observers, one lesser experienced resident, one inexperienced trainee) in two sessions using the Outcome Measures in Rheumatology (OMERACT) CD scoring system (scale 0-3). A total score was calculated as the sum of the scores of the 4 glands (scale 0-12). Intra- and interobserver reliability, and reliability of live versus static scores were determined. Factors influencing variability in scores were analysed.

RESULTS: Intraobserver weighted Cohen's kappa's of individual glands ranged from 0.23 (inexperienced observer) to 0.81 (experienced observer). Intraclass Correlation Coefficients (ICCs) for intraobserver reliability of the total CD score ranged from 0.53 (inexperienced observer) to 0.90 (experienced observer). The ICC for intraobserver reliability of live scoring compared to static images was 0.72. ICCs for interobserver reliability of the total CD score were 0.81 for session 1 and 0.71 for session 2. Patient variance was 74.1%, whereas residual variance contributed 15.5% to the total variance.

CONCLUSIONS: CD SGUS is a reliable imaging technique to visualise intraparenchymal vasculature in patients suspected of SjD, and therefore could be an asset in daily clinical practice. It requires, however, experience and prior training.