Intraobserver repeatability and interobserver reproducibility in musculoskeletal ultrasound imaging measurements

Abstract

Objective: To assess the repeatability and reproducibility of ultrasonographic measurements at the anterior surface of the femoral neck and iliofemoral ligament and on 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 and each other's results. On the phantom both observers had taken 10 vertical measurements at 6 cm deep where two objects were placed at 2 cm from each other. Calculation of measurement 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 deviation was 0.4 mm. The intraobserver error was 4.75%. The second investigator's within-subject standard deviation was 0.6 mm and his intraobserver error was 7.00%. The interobserver error was 10.91%. After 20 phantom examinations the first investigators's intraobserver error was 1.11% and the second investigator's intraobserver error was 1.47%.

Conclusion: An inexperienced musculoskeletal sonographer can achieve an acceptable performance if given appropriate training.