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

OBJECTIVE: To 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). METHODS: This 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. RESULTS: By 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. CONCLUSION: Measurements 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.

Shear wave elastography for assessing lateral abdominal muscles in thoracolumbar scoliosis: A preliminary study.

BACKGROUND: There are no studies on the scoliotic population in which lateral abdominal muscle (LAM) was measured. OBJECTIVE: The aim of the study was to deliver the first results on LAM elasticity assessed by shear wave elastography (SWE) in right-side and left-side thoracolumbar scoliosis patients. METHOD: Twelve patients (mean age 12.25) with thoracolumbar scoliosis were included in the study. Muscle thickness and SWE of the obliquus external (OE), obliquus internal, and transversus abdominis (TrA) were measured with an ultrasound scanner. Measurements were taken at rest and during isometric contraction. RESULTS: An analysis showed that in right-side scoliosis, the OE muscle on the convex side was stiffer by 7.25 kPa compared to the concave side. The OE muscle on the convex side in right-side scoliosis was also stiffer by 11.6 kPa compared to the convex side in left-side scoliosis. In left-side scoliosis, the TrA muscle on the concave side was stiffer by 7.84 kPa compared to the convex side. CONCLUSION: Changes in LAM elasticity of thoracolumbar scoliosis were observed. A different pattern of LAM stiffness in different curve directions may be expected. OE and TrA shear moduli are the most sensitive to change in adolescent spinal deformation.

Supersonic Shear Imaging for Quantification of Lateral Abdominal Muscle Shear Modulus in Pediatric Population with Scoliosis: A Reliability and Agreement Study.

The aim of this study was to assess the intra- and inter-rater reliability/agreement of the lateral abdominal muscle (LAM) stiffness and thickness measurements at rest and during contraction and to determine the relationship between the superficial fat thickness and the LAM stiffness measurements. LAM stiffness and thickness were measured using supersonic shear wave elastography (SSI) in pediatric participants. The reliability of LAM stiffness and thickness measurements ranged from moderate to excellent. There was an inverse correlation between fat thickness and between-rater difference in the resting external oblique stiffness (r > -0.37) and the contracted external and internal oblique stiffness (r > -0.40). SSI is a reliable method for assessing LAM stiffness and thickness in pediatric populations. To remove potential systematic errors: (i) the first round of measurements should be performed to familiarize patients with procedures; (ii) the examiner should pay more attention while performing LAM measurements on the opposite side of the body.

Reliability of the lateral abdominal muscle thickness measurements in idiopathic scoliosis patients.

BACKGROUND: To date, the reliability of ultrasound imaging (US) measures of the abdominal muscle thickness in idiopathic scoliosis (IS) patients during early stages of adolescence has not been confirmed. OBJECTIVE: To assess the intra-rater reliability of US measures of the thickness of the external oblique (EO), internal oblique (IO), and transversus abdominis (TrA) on convex and concave body sides in adolescents with IS. DESIGN: One-way repeated-measures analysis of variance (ANOVA) and reliability study. METHODS: Fifteen patients diagnosed IS were included between the ages of 9 and 14 years. Three repeated US measurements were recorded in the supine resting position over 2 sessions, 24 h apart. RESULTS: By assessing the mean value from the first two measurements (ICC3,2), the reliability was between .76 and .95 for all examined muscles on the convex and concave sides. The reliability for the mean values from three measurements (ICC3,3) was between .81 and .96. The smallest detectable difference values for single measurements were twice as high on the convex side than on the concave side for all examined abdominal muscles. CONCLUSION: US measurements of the thickness of the EO, IO, and TrA muscles in supine rest position in adolescent IS patients are reliable. In order to increase measurement reliability, and due to variability in reliability between concave and convex body side, we recommend using the mean of three consecutive measurements of the EO, IO, and TrA muscles for adolescents with IS.