Intraobserver repeatability and interobserver reproducibility in musculoskeletal ultrasound imaging measurements

Objective. To assess the repeatability and reproducibility of ultrasonographic measure ments at the anterior surface of the femoral neck and iliofemoral ligament and an a human tissue-mimicking phantom. Methods. Two independent investigators studied 22 consecutive hips. One investigator had previous experience in musculoskeletal ultrasonography (US). The other investigator had undergone a short course in hip sonography (only 3 hours) . Both investigators were blinded to their own a nd each other's results. O n the phantom both observers had taken 10 vertical measurements at 6 cm dee p where two objects were placed at 2 cm from each other: Calculation of mea surement errors, percent errors and the Bland-Altman graphic technique were used for analysis of data. Results. After 132 examinations the first investigator's within-subject standard dev iation was 0.4 mm. The intra-observer error was 4.75%. The second investiga tor's within-subject standard deviation was 0.6 mm and his intraobserver er r-or was 700%. The interobserver error was 10.91%. After 20 phantom examina tions the first investigators's intraobserver error was 1.11% and the secon d investigator's intra-observer error was 1.47%. Conclusion. An inexperienced musculoskeletal sonographer can achieve an acceptable perf ormance if given appropriate training.