Test-Retest Reliability of Single Transverse versus Panoramic Ultrasound Imaging for Muscle Size and Echo Intensity of the Biceps Brachii

This study compared test-retest reliability and sensitivity to change for muscle size and echo intensity (EI) measurements from single transverse (EIST) versus panoramic (EIP) ultrasound (US) images of the biceps brachii. Forearm flexor muscle thickness and EIST and biceps brachii muscle cross-sectional area and EIP were quantified from single transverse and panoramic US images in 14 men (age = 21.8 ± 2.5 y [mean ± standard deviation]) on two separate days. The intra-class correlation coefficients, coefficients of variation, and minimum differences for muscle thickness, EIST, muscle cross-sectional area and EIP ranged from 0.78 to 0.99, from 2.26% to 3.29%, and from 6.26% to 9.12%, respectively. These findings suggested that single transverse imaging and panoramic US imaging are comparable, reliable techniques for quantifying muscle size and EI of the biceps brachii. Single transverse images may be simpler to obtain; thus, future studies may choose to quantify muscle size and EI from a single transverse US image in the biceps brachii.