Correlation between Body Composition and Inter-Examiner Errors for Assessing Lumbar Multifidus Muscle Size, Shape and Quality Metrics with Ultrasound Imaging

Abstract

Ultrasound imaging (US) is widely used in several healthcare disciplines (including physiotherapy) for assessing multiple muscle metrics such as muscle morphology and quality. Since measuring instruments are required to demonstrate their reliability, accuracy, sensitivity, and specificity prior to their use in clinical and research settings, identifying factors affecting their diagnostic accuracy is essential. Since previous studies analyzed the impact of sociodemographic but not body composition characteristics in US errors, this study aimed to assess whether body composition metrics are correlated with ultrasound measurement errors. B-mode images of the lumbar multifidus muscle at the fifth lumbar vertebral level (L5) were acquired and analyzed in 49 healthy volunteers by two examiners (one experienced and one novel). Cross-sectional area, muscle perimeter and mean echo intensity were calculated bilaterally. A multivariate correlation matrix was calculated for assessing the inter-examiner differences with body composition metrics. Results demonstrated excellent reliability (intraclass correlation coefficient, ICC > 0.9) for assessing the muscle cross-sectional area and perimeter, and good reliability for assessing the muscle shape and mean echo intensity (ICC > 0.7). Inter-examiner errors for estimating muscle size were correlated with participants’ age (p value, p < 0.01), weight (p < 0.05), total and trunk lean mass (both, p < 0.01) and water volume (p < 0.05). Greater shape descriptors and mean brightness disagreements were correlated with older ages (p < 0.05) and total lean mass (p < 0.05). No correlations between age and body composition metrics were found (p > 0.05). This study found US to be a reliable tool for assessing muscle size, shape and mean brightness. Although aging showed no correlations with body composition changes in this sample, it was the main factor correlated with US measurement errors.

Body Composition and Demographic Features Do Not Affect the Diagnostic Accuracy of Shear Wave Elastography

“…Up to the authors’ knowledge, this is the first study investigating the association between demographic and body composition features with SWE errors. However, this is not the first study analyzing the test–retest reliability of SWE for quantifying the AS stiffness [ 32 ] or aiming to analyze the association between US errors with anthropometric, demographic, and body composition characteristics [ 33 , 34 ].…”

“…Varol et al found age to be one of the most important contributors to B-mode US measurement errors for assessing cross-sectional area, circularity, aspect ratio, roundness, and mean echo intensity (defined as the average brightness intensity of pixels, measured on a 256 grayscale, over a given area) characteristics of the lumbar multifidus [ 33 ] and the mean echo-intensity of the cervical multifidus [ 34 ]. Additionally, water volume was reported to be another important contributor to B-mode measurement errors, as it was correlated with lumbar multifidus cross-sectional area errors [ 33 ] and cervical multifidus cross sectional areas, perimeters, and roundness measurement errors [ 34 ]. In parallel to our SWE results, BMI did not influence any B-mode metric measurement error in these studies [ 33 , 34 ].…”

“…Additionally, water volume was reported to be another important contributor to B-mode measurement errors, as it was correlated with lumbar multifidus cross-sectional area errors [ 33 ] and cervical multifidus cross sectional areas, perimeters, and roundness measurement errors [ 34 ]. In parallel to our SWE results, BMI did not influence any B-mode metric measurement error in these studies [ 33 , 34 ]. Surprisingly, we found that these parameters were not associated with the stiffness estimation error in our study.…”

Levator Scapulae Stiffness Measurement Reliability in Individuals with and without Chronic Neck Pain by Experienced and Novel Examiners

“…Ultrasound imaging (US) is a fast, cost-effective, and portable tool used for diagnostics (i.e., assessing the muscle size, shape, quality, and function in other neck muscles [ 17 , 18 , 19 ]) and therapeutic (i.e., needle guidance for invasive procedures and as a biofeedback tool for facilitating the learning and execution of motor control exercises [ 20 , 21 ]) purposes. In addition, advances in US methods for assessing tissues’ elasticity (i.e., shear-wave elastography, SWE) allow clinicians and researchers to acquire quantitative and objective stiffness data with absolute values (in contrast with strain technology, which is limited to relative information) [ 22 ].…”

Convergent Validity between Electromyographic Muscle Activity, Ultrasound Muscle Thickness and Dynamometric Force Measurement for Assessing Muscle

“…For instance, US is portable, safe (as no ionizing radiation is used for acquiring the images), fast, accessible and provides real-time information, allowing the examination of immediate changes [ 8 ]. Due to these advantages and the range of imaging methods based on US (e.g., B-mode, M-mode, Doppler US, strain elastography, shear-wave elastography and panoramic US, among others [ 9 ]), it is a tool that is widely used in health sciences for the educational (i.e., teaching anatomy and pathologies [ 10 ]), research (i.e., to obtain objective measurements of muscle function, size, shape and composition [ 11 ]) and clinical settings (e.g., as a supportive tool for guiding needle interventions, visual feedback for motor control exercises or monitoring changes after interventions [ 12 ]). However, important limitations should be acknowledged.…”