Echogenicity Quantified By Ultrasonographic Panoramic Scans Compared To Still-images In Collegiate Men

Abstract

Measuring the echo intensity (EI) of skeletal muscle via ultrasonography has been used to estimate muscle quality and diagnose pathological and neurological conditions. When assessing skeletal muscle, ultrasonographic (US) still-images do not always permit the entire muscle to be viewed in a single image, so panoramic US scans have been developed. In addition, homogeneity of fibrous tissue throughout a single muscle is often assumed for easy assessment, however, muscles may not be homogeneous. Many studies continue to use still-images to quantify EI without regard to the size or possible heterogeneity of the muscle. PURPOSE: To determine if the EI quantified via US panoramic transverse scans (PTS) is related to the EI of US longitudinal still-images (LSI) taken of the vastus lateralis (VL) muscle in collegiate males. METHODS: Twenty-four collegiate men (20.2 ± 1.6 y; BMI: 25.8 ± 3.3 kg·m-2) participated in this study. Muscle EI of the VL was assessed in the self-reported dominant limb (DOM) via three PTS and three LSI. PTS were captured using extended-field-of-view ultrasonography, and LSI were captured using B-mode ultrasonography. Intra-class correlations (ICC), standard errors of measurement (SEM), and minimal differences (MD) were calculated between each of the three images for both PTS and LSI. EI was quantified for each image using histogram analysis through an image analysis software. RESULTS: ICCs, SEM, and MD reported for the EI of the PTS and for the EI of the LSI were ICC = 0.956, SEM = 1.640, and MD = 4.546, and ICC = 0.991, SEM = 1.059, and MD = 2.935, respectively. A significant positive correlation existed between the EI of the PTS and the EI of the LSI (r = 0.744, p < 0.001). Significant differences between the EI of the PTS (μ = 57.97; σ = 8.26) and the EI of the LSI (μ = 65.39; σ = 10.88) were observed (p < 0.001). CONCLUSION: While there is a strong positive correlation between the EI values quantified by both PTS and LSI, the use of LSI yielded a slightly higher reliability measurement with a smaller SEM and smaller MD compared to PTS. In addition to the higher reliability and sensitivity, the LSI measurement also requires less time, and therefore may be more advantageous when assessing EI of the VL in collegiate males.