Ultrasound Imaging Analysis of the Lumbar Multifidus Muscle Echo Intensity: Intra-Rater and Inter-Rater Reliability of a Novice and an Experienced Rater

Maryse Fortin,Jerome Levesque,Neil Nandlall,Brent Rosenstein

doi:10.3390/medicina57050512

Abstract

Background and Objectives: Ultrasound echo intensity (EI) of the lumbar multifidus muscle (LMM) could offer valuable insights regarding muscle quality in people with low back pain (LBP). However, whether the rater’s experience noticeably influences the reliability and precision of LMM EI measurements has not been established. The aims of this study were to investigate the intra-rater and inter-rater reliability of LMM EI measurements, and to compare the reliability and SEM between a novice and an experienced rater. Materials and Methods: Twenty athletes (10 females, 10 males) with a history of LBP were included in this study. Transverse ultrasound images of LMM were taken at L5 in prone. LMM EI measurements were obtained bilaterally by tracing the maximum ROI representing the LMM cross-sectional area (CSA), avoiding the inclusion of bone or surrounding fascia. All measurements were performed by two novice raters and an experienced researcher. Each measurement was acquired by each rater three times for each side on three different images, and the average was used in the analyses. Raters were blinded to each other’s measurements and the participant’s clinical information. Intra-class correlation coefficients (ICCs) were obtained to assess the intra-rater and inter-rater reliability. Results: The intra-rater ICC values for the LMM measurements for the experienced rater were excellent (ICC all > 0.997). The inter-rater reliability ICC values showed moderate to excellent reliability (0.614 to 0.994) and agreement between the novice raters and the experienced rater, except for Novice 1 for the right LMM, which revealed lower ICCs and a wider 95% CI. Intra-rater and inter-rater reliability results were similar when separately looking at the right and left side of the muscle and participant gender. Conclusions: Our findings support the clinical use of ultrasound imaging for the assessment of LMM EI in individuals with LBP.

Highlights

Biomechanical studies have highlighted the important role of the lumbar multifidus muscle (LMM) to provide arthrokinetic control of the vertebral segment, spinal stiffness [1,2], and proprioception of the lumbar spine [3]
The inter-rater reliability Intra-class correlation coefficients (ICCs) values showed moderate to excellent reliability and agreement between the novice raters and the experienced rater, except for Novice 1 for the right LMM, which revealed lower ICCs and a wider 95% CI
The current study revealed that LMM echo intensity (EI) reliability indices were similar between the male and female participants, this needs to be replicated in the older population

Summary

Introduction

Biomechanical studies have highlighted the important role of the lumbar multifidus muscle (LMM) to provide arthrokinetic control of the vertebral segment, spinal stiffness [1,2], and proprioception of the lumbar spine [3]. Magnetic resonance imaging (MRI) and ultrasound imaging studies of athletes and non-athletes with LBP have reported morphological changes and functional deficits of the LMM, such as LMM atrophy [5,6,7,8,9], LMM cross-sectional area (CSA) asymmetry [5,7,10,11,12], increased fatty infiltration [13,14,15,16], and increased or decreased muscle activity [17,18,19]. Ultrasound imaging is a more accessible and less expensive imaging technique that provides valuable information about muscle function [20,21,22]. All measurements were performed by two novice raters and an experienced researcher

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