Reliability of musculoskeletal ultrasound imaging to measure calcific deposits in patients with calcified rotator cuff tendinopathy

Abstract

Introduction. This reliability study was designed to assess intra-rater and inter-rater reliability of musculoskeletal ultrasound as a diagnostic modality to measure calcific deposits in subjects with rotator cuff tendinopathy. Methods. Overall, 15 participants (10 males, 5 females) with calcified shoulder, aged 32-55 years, were examined in the same sitting posture. Two experienced radiologists imaged calcific deposits, measured twice daily by both raters with an interval of 2 hours for within-day reliability and re-measured after 1 week for between-day reliability. Data were analysed by using intra- -class and inter-class correlation coefficient. Results. The mean size of calcific deposits in supraspinatus tendons was 14.61 ± 1.78, 14.87 ± 1.77, and 14.88 ± 1.88 mm for the first rater and 14.89 ± 1.78, 14.98 ± 1.792, and 15.13 ± 1.84 mm for the second rater. The results reflected excellent reliability, with the intra-class correlation coefficient for within-day comparison calculated as 0.989 (0.975-0.996) for the first rater and 0.984 (0.963-0.994) for the second rater (p = 0.000). The inter-class correlation coefficient for between-rater comparison equalled 0.991 for the first measurements by the first and second raters, 0.984 for the second measurements, and 0.986 for the third measurements. Conclusions. A high degree of within-day and between-day reliability was observed between the successive measurements. This shows that musculoskeletal ultrasound is a highly reliable diagnostic tool for measuring the size of calcific deposits in patients with tendinopathy.