(411) Temporalis Muscle Intramuscular Adipose Tissue Correlates With Cardiorespiratory Fitness

Introduction: Myosteatosis assessed with CT is known to be associated with reduced Cardiorespiratory fitness (CRF). Musculoskeletal Ultrasound (MSK-US) is a non-invasive bedside point-of-care (POC) method to assess muscle morphology and mass. MuscleSound can assess myosteatosis (%intramuscular adipose tissue) and area by analyzing ultrasound dicom images. The primary aim of this study was to compare ultrasound-derived % intramuscular adipose tissue corrected for the area (%IMAT/cm2) of the temporalis muscle (TMM) against CRF (VO2max)

Methods: All individuals underwent a 6-minute incremental Steptest (6MIST) to assess CRF using a portable metabolic cart (mean VO2 max 29.72 ±12.36 ml/kg/min). A trained sonographer obtained four B-mode long- and short-axis images from the TMM. IMAT-index (%IMAT/cm2) was extracted using MuscleSound technology.

Results: The sample population consisted of 33 females and 17 males, with a mean age of 45 ±18 (range 18-79) years and a mean BMI of 26.98 ±6.55 Kg.m-2. IMAT-index of the long-axis TMM showed a strong negative correlation with CRF (r=-0.6175, p < 0.0001). No correlation was observed of the short-axis TMM IMAT-index (r=-0.2814, p=0.0582)

Conclusions: Our study reveals that long-axis POC assessment of the temporalis muscle predicts CRF, indicating its utility for patient triage and risk evaluation. The robust negative correlation between the IMAT-index from long-axis temporalis muscle ultrasound and CRF emphasizes its potential as a non-invasive, bedside alternative for metabolic cart CRF assessment.