Consistency Of Novel Ultrasound Equations For Estimating Percent Intramuscular Fat

Keywords

knee extensors; MRI; muscle quality; obesity; quadriceps

Abstract

Introduction: Echo intensity reflects both intramuscular adiposity and fibrous tissue content. Recently, equations that allow investigators to estimate the percentage of intramuscular fat for individual muscles via measurements of echo intensity and subcutaneous fat were created. However, as the trial-to-trial consistency of these values has not been reported in the literature, it is unclear if they can be used to track changes during physical activity and/or nutritional interventions. The purpose of this study was to examine the test-retest reliability of rectus femoris percent intramuscular fat. Methods: Nineteen healthy adults (mean ± SD age = 22 ± 3 year; ten females, nine males) with a body mass index ≤ 30 kg/m2 participated. On three occasions, B-mode ultrasonography was used to acquire panoramic images of the dominant rectus femoris in the transverse plane. ImageJ software was used to quantify echo intensity, subcutaneous fat thickness and cross-sectional area. Rectus femoris percent intramuscular fat was estimated with sex-specific equations. Results: Uncorrected and corrected echo intensity, subcutaneous fat and cross-sectional area exhibited excellent consistency (P > 0·05, intraclass correlation coefficients [ICCs] ≥.900, standard errors of measurement [SEMs] ≤ 7·26%). Percent intramuscular fat for all participants also demonstrated satisfactory reliability (ICC = 0·980, SEM = 3·07%), with similar findings for males (ICC = 0·970, SEM = 3·63%) and females (ICC = 0·968, SEM = 1·41%). Discussion: The high ICCs and low SEMs suggest that ultrasonography-derived rectus femoris percent fat may be a reliable tool for tracking changes in lower extremity intramuscular adiposity.

Publication Date

11-1-2018

Publication Title

Clinical Physiology and Functional Imaging

Volume

38

Issue

6

Number of Pages

1062-1066

Document Type

Article

Personal Identifier

scopus

DOI Link

https://doi.org/10.1111/cpf.12532

Socpus ID

85054158138 (Scopus)

Source API URL

https://api.elsevier.com/content/abstract/scopus_id/85054158138

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