Abstract
AIM: This study aimed to (1) determine the intraobserver and interobserver reliability of ultrasonographic measurement of muscle thickness (MT) and cross-sectional area (CSA) of the rectus femoris and biceps brachii, correlating these values with manual measurements on dissected cadavers and (2) develop the first semiquantitative musculoskeletal ultrasound (MSUS) scoring system of muscle morphology in sarcopenia and assess its intraobserver and interobserver reliability. In addition, the MSUS morphology score was compared with the corresponding histological images to verify concurrent validity. METHODS: Ten cryopreserved limbs of 10 cadavers aged 68-91 years were evaluated. The MSUS scoring system was based on the severity of muscle degeneration on a 3-point qualitative scale: grade 1 (normal), grade 2 (moderate changes) and grade 3 (severe changes). Reliability was assessed with intraclass correlation coefficient (ICC) for the MT and CSA and with Cohen's kappa coefficients (κ) for the MSUS scoring system. Concurrent validity was analysed with ICC. RESULTS: The results showed excellent intraobserver and interobserver reliability for both the MSUS evaluation of MT and CSA (ICC ≥0.93). The MSUS scoring system showed excellent intraobserver reliability (κ=1.0) and very good interobserver reliability (κ=0.85). There was also a high intra- and inter-observer reliability for the histological scorings (ĸ ≥0.85 and mean ĸ=0.70, respectively), as well as high reliability between the histology and MSUS scoring systems (ICC=0.92). All results were statistically significant (p≤0.001). CONCLUSION: MSUS measures of MT and CSA and the novel MSUS scoring system for degenerative muscle changes in sarcopenia was found to be reliable and strongly associated with histological findings.