Identifying Demographic, Clinical, Muscular and Histological Factors Associated with Ultrasound Cervical Multifidus Measurement Errors in a Chronic Neck Pain Population

Cervical Multifidus Stiffness Assessment in Individuals with and without Unilateral Chronic Neck Pain: An Inter-Examiner Reliability Study

This study aimed to evaluate the inter-examiner reliability of shear wave elastography (SWE) for measuring cervical multifidus (CM) muscle stiffness in asymptomatic controls and patients with chronic neck pain. A longitudinal observational study was conducted to assess the diagnostic accuracy of a procedure. SWE images, following a detailed procedure previously tested, were acquired by two examiners (one novice and one experienced) to calculate the shear wave speed (SWS) and Young's modulus. The painful side was examined for the experimental cases while the side examined in the control group was selected randomly. Data analyses calculated the intra-class correlation coefficients (ICCs), absolute errors between examiners, standard errors of measurement, and minimal detectable changes. A total of 125 participants were analyzed (n = 54 controls and n = 71 cases). The Young's modulus and SWS measurements obtained by both examiners were comparable within the asymptomatic group (both, p > 0.05) and the chronic neck pain group (both, p > 0.05). Nonetheless, a notable distinction was observed in the absolute error between examiners for shear wave speed measurements among patients with neck pain, where a significant difference was registered (p = 0.045), pointing to a sensitivity in measurement consistency affected by the presence of chronic neck pain. ICCs demonstrated moderate-to-good reliability across both groups, with ICC values for asymptomatic individuals reported as >0.8. Among the chronic neck pain patients, ICC values were slightly lower (>0.780). The study revealed moderate-to-good consistency, highlighting the practicality and generalizability of SWE.

Shear wave elastography for assessing the anterior scalene elasticity in patients with neck pain

PURPOSE

Shear-wave elastography (SWE) provides quantitative and absolute metrics for analyzing the elasticity of soft tissues. Despite the anterior scalene muscle (AS) is a key structure in patients with neck pain and nerve compressive syndromes, the majority of SWE studies only included asymptomatic subjects. This study aimed to analyze the Young's modulus and shear wave speed test-retest reliability in a sample of patients with neck pain symptoms to characterize the AS stiffness.

METHODS

A diagnostic accuracy study acquiring a set of ultrasound images at C7 level in 42 patients with mechanical neck pain by one experienced examiner. After blinding the participants' identity, trial and side, the Young's modulus and shear wave velocity were measured by an independent experienced rater in randomized order. Intra-class correlation coefficients (ICC), standard error of measurement (SEM), minimal detectable changes (MDC) and coefficient of variation (CV%) were calculated.

RESULTS

The sample reported moderate pain intensity (5.9/10 points) and disability (17.38/100 points). AS stiffness metrics assessed showed no significant differences between males and females, left and right side nor painful and non-painful side. (all, p > 0.05). Intra-examiner reliability was excellent for calculating the Young's modulus for shear wave speed (ICC > 0.90).

CONCLUSION

The results support the use of this procedure for assessing the AS stiffness in populations with mechanical neck pain as excellent reliability estimates were obtained. However, future research should analyze case-control differences and the association between SWE metrics with clinical severity indicators.

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

Shear-wave elastography (SWE) is an imaging method that can be used to estimate shear wave speed and the Young's modulus based on the measured shear wave speed under certain conditions. Up to date, no research has analyzed whether body composition factors contribute to ultrasound attenuation, refraction, reflection, and, consequently, SWE measurement errors. Therefore, this study aimed to analyze the association between demographic and body composition features with SWE errors for assessing the anterior scalene stiffness (which is a key structure in patients with neck pain and nerve compressive syndromes). Demographic (sex, age, height, weight, and body mass index), body composition (water volume, fat mass, and lean mass), and anterior scalene muscle stiffness (Young's modulus and shear wave speed) data were collected from a sample of asymptomatic subjects. After calculating the absolute SWE differences between trials and the reliability estimates, a correlation matrix was generated to quantify the association among all the variables. A total of 34 asymptomatic subjects (24 males) were included in the analyses. Test-retest reliability was excellent for assessing the Young's modulus and shear wave velocity (ICC = 0.912 and 0.923, respectively). No significant associations were found between age, height, weight, body mass index, body fat, lean mass, or water volume with SWE errors (p > 0.05). However, the Young's modulus error was associated with the stiffness properties (p < 0.01), whereas shear wave speed was associated with none of them (all, p > 0.05). A detailed procedure can reliably assess the AS muscle stiffness. None of the sociodemographic or body composition features assessed were correlated with SWE errors. However, baseline stiffness seems to be associated with Young's modulus error.

Comparison of multifidus muscle intramuscular fat by ultrasound echo intensity and fat-water based MR images in individuals with chronic low back pain

PURPOSE

The aim of this observational cross-sectional study was to examine correlations of intramuscular fat content in lumbar multifidus (LM) by comparing muscle echo intensity (EI) and percent fat signal fraction (%FSF) generated from ultrasound (US) and magnetic resonance (MR) images, respectively.

METHODS

MRI and US images from 25 participants (16 females, 9 males) selected from a cohort of patients with chronic low back pain (CLBP) were used. Images were acquired bilaterally, at the L4 and L5 levels (e.g., 4 sites). EI measurements were acquired by manually tracing the cross-sectional border of LM. Mean EI of three US images per site were analyzed (e.g., raw EI). A correction factor for subcutaneous fat thickness (SFT) was also calculated and applied (e.g., corrected EI). Corresponding fat and water MR images were used to acquire %FSF measurements. Intra-rater reliability was assessed by intraclass coefficients (ICC). Pearson correlations and simple linear regression were used to assess the relationship between %FSF, raw EI and corrected EI measurements.

RESULTS

The intra-rater ICCs for all measurements were moderate to excellent. Correlations between %FSF vs. raw EI and corrected EI were moderate to strong (0.40 < r < 0.52) and (0.40 < r < 0.51), respectively. Moderate correlations between SFT and EI were also identified.

CONCLUSION

US is a low-cost, non-invasive, accessible, and reliable method to examine muscle composition, and presents a promising solution for assessing and monitoring the effect of different treatment options for CLBP in clinical settings.

Panoramic ultrasound imaging does not produce muscle morphology deformation during imaging acquisition: A validity study

PURPOSE

Despite panoramic ultrasound imaging (US) is a promising advance for the morphological and histological assessment of large musculature which cannot be entirely assessed using B-mode, there is no evidence assessing if this technology produces muscle deformation during imaging acquisition. We aimed to analyze differences in size, shape and brightness descriptors between B-mode and panoramic US images and to assess the concordance between both methods. Methods We analyzed size (cross-sectional area and perimeter), shape (circularity, aspect ratio and roundness) and brightness (mean echo-intensity) features of cervical multifidus (CM) and short rotators (SR) in 46 healthy volunteers. Images were acquired in B-mode and extended field-of-view mode. For validity analysis, mean differences between methods were calculated. For agreement analysis, intraclass correlation coefficients (ICCs), standard error of measurements (SEM), minimal detectable changes (MDC) and coefficient of variation (CV%) were calculated.

RESULTS

All parameters showed no significant differences between both methods for either CM or SR (P > 0.05). Panoramic US showed excellent concordance with B-mode for assessing all CM parameters (all ICCs > 0.9), while for SR the agreement ranged from good-to-excellent (ICC from 0.861 to 0.978).

CONCLUSION

Panoramic US seems to be a valid tool for assessment of muscle size, shape and brightness as no deformation in comparison with B-mode images was seen. Further research is needed to corroborate these findings comparing panoramic US imaging with Gold Standard methods.

Inter-Examiner Disagreement for Assessing Cervical Multifidus Ultrasound Metrics Is Associated with Body Composition Features

Ultrasound imaging (US) is a biosensing technique that is widely used in several healthcare disciplines (including physiotherapy) for assessing multiple muscle metrics, such as muscle morphology and quality. Since all biosensors need to be tested in order to demonstrate their reliability, accuracy, sensitivity, and specificity, identifying factors that affect 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 associated with ultrasound measurement errors. B-mode images of the lumbar multifidus muscle at the L5 level were acquired and analyzed in 47 healthy volunteers by two examiners (one experienced and one novice). The cross-sectional area, muscle perimeter, and mean echo intensity were calculated bilaterally. A correlation analysis and a multivariate linear regression model were used for assessing the inter-examiner differences with respect to body composition metrics. The results demonstrated good-to-excellent reliability estimates for the cross-sectional area, muscle perimeter, aspect ratio, roundness, circularity, and mean brightness metrics (all ICC > 0.85). However, solidity showed unacceptable reliability (ICC < 0.7). Age, height, total lean mass, trunk lean mass, and water volume were associated with inter-examiner disagreement on mean echo intensity. Cross-sectional area, perimeter, and roundness measurement errors were associated with lean mass and water volume.

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

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.