Measurement of intramuscular fat by muscle echo intensity

TLDR

The study aims to compare ultrasound echo intensity with high‑resolution T1‑weighted MRI and develop calibration equations to estimate intramuscular fat percentage, and to extend this approach to other muscle groups. Thirty‑one participants underwent paired ultrasound and MRI scans of the rectus femoris, biceps femoris, tibialis anterior, and medial gastrocnemius to assess echo intensity. Strong correlations (r ≈ 0.76–0.91) were found between MRI‑derived intramuscular fat and ultrasound echo intensity, leading to three calibration equations that demonstrate ultrasound as a practical, reproducible method for estimating muscle fat. Published in *Muscle Nerve*, 2015, vol.

Abstract

ABSTRACT Introduction : The aim of this study was to compare ultrasound echo intensity (EI) with high‐resolution T 1 ‐weighted MRI and to establish calibration equations to estimate percent intramuscular fat from EI. Methods : Thirty‐one participants underwent both ultrasound and MRI testing of 4 muscles: rectus femoris (RF); biceps femoris (BF); tibialis anterior (TA); and medial gastrocnemius (MG). Results : Strong correlations were found between MRI percent fat and muscle EI after correcting for subcutaneous fat thickness ( r = 0.91 in RF, r = 0.80 in BF, r = 0.80 in TA, r = 0.76 in MG). Three types of calibration equations were established. Conclusions : Muscle ultrasound is a practical and reproducible method that can be used as an imaging technique for examination of percent intramuscular fat. Future ultrasound studies are needed to establish equations for other muscle groups to enhance its use in both research and clinical settings. Muscle Nerve 52 : 963–971, 2015