Intrarater Reliability of Shear Wave Elastography for the Quantification of Lateral Abdominal Muscle Elasticity in Idiopathic Scoliosis Patients

Abstract

ObjectiveTo date, studies evaluating the reliability of shear wave elastography (SWE) measures of the lateral abdominal muscles (LAMs) in adolescent patients with idiopathic scoliosis (AIS) have never been performed. The aim of the study was to assess the intrarater reliability of SWE and thickness of the LAMs at rest and during isometric contraction (10% of maximal voluntary contraction). MethodsThis was a single-group, repeated-measures intrarater reliability study. Twenty-four patients with AIS between ages 10 and 17 years took part in the study. Two and 3 repeated SWE measurements were recorded in the supine resting position and during isometric contraction, respectively. Two sessions were performed with a 7-day interval. ResultsBy using the mean of 2 measures in the supine, resting position, intraexaminer reliability point estimates (intraclass correlation coefficient [ICC]3.2) ranged from 0.75 to 0.84 for external oblique, internal oblique, and transversus abdominis muscles. During the isometric contraction, the ICC3.3 results ranged from 0.70 to 0.83. The ICC results for muscle thicknesses in both conditions ranged from 0.89 to 0.96. ConclusionMeasurements of LAM elasticity are reliable in patients with AIS. The superficial fat layer did not influence the measurement error between 2 sets of measurements in the examined adolescent population. The images extracted from SWE can successfully be used to assess LAM thicknesses with high reliability.