Is musculoskeletal ultrasonography an operator-dependent method or a fast and reliably teachable diagnostic tool? Interreader agreements of three ultrasonographers with different training levels.

Objectives. To assess interreader agreements and a learning curve between three (senior, junior, and beginner) different experienced musculoskeletal ultrasonographers. Senior served as the imaging "gold standard". Methods. Clinically dominant joints (finger, shoulder, knee, tibiotalar, and talonavicular) of 15 rheumatoid arthritis (RA) patients were examined by three different experienced ultrasonographers (senior 10 years, junior 10 months, and beginner one month). Each patient's ultrasonographic findings were reported unaware of the other investigators' results. κ coefficients, percentage agreements, sensitivities, and specificities were calculated. Results. 120 joints of 15 RA patients were evaluated. Comparing junior's and beginner's results each to the senior's findings, the overall κ for all examined joints was 0.83 (93%) for junior and 0.43 (76%) for beginner. Regarding the different joints, junior's findings correlate very well with the senior's findings (finger joints: κ = 0.82; shoulder: κ = 0.9; knee: κ = 0.74; tibiotalar joint: κ = 0.84; talonavicular joint: κ = 0.84) while beginner's findings just showed fair to moderate agreements (finger joints: κ = 0.4; shoulder: κ = 0.42; knee: κ = 0.4; tibiotalar joint: κ = 0.59; talonavicular joint: κ = 0.35). In total, beginner's results clearly improved from κ = 0.34 (agreement of 67%) at baseline to κ = 0.78 (agreement of 89%) at the end of the evaluation period. Conclusions. Ultrasonographic evaluation of a ten-month-experienced investigator in comparison to a senior ultrasonographer was of substantial agreement. Agreements between a beginner and a highly experienced ultrasonographer were only fair at the beginning, but during the study including ultrasonographical sessions of 15 RA patients, the beginner clearly improved in musculoskeletal ultrasonography.