Comparison of Ultrasound Imaging and MR fat fraction in the Rectus Femoris and Biceps Brachii Muscles

Background Sarcopenia, characterised by muscle mass and strength loss, is common in the ageing population, leading to disability and higher healthcare costs. While MRI is accurate for muscle analysis, it is costly and less accessible. Ultrasound (US) offers a cost-effective alternative. This study evaluates ultrasound attenuation imaging (ATI) and echo intensity (EI) as alternatives to Dixon MRI fat fraction (MR-FF) for assessing muscle quality in the rectus femoris (RF) and biceps brachii (BB) muscles.

Methods A prospective multicentre study was conducted with 34 volunteers (20 female, aged 21-88) who had previously undergone whole-body MRI. Ultrasound images were obtained using a routine clinical scanner equipped with advanced linear attenuation imaging tools. Measurements were taken by tracing the borders of the right RF and BB muscles. Corresponding T1-weighted Dixon VIBE fat and water images were used for MRI fat fraction percentage calculations. Correlation analysis was performed to compare MR-based fatty infiltration with US imaging.

Results Correlations between US EI and MRI were 0.67 and 0.59 for the BB, and 0.73 and 0.64 for the RF, as assessed by the two operators. Ultrasound attenuation showed no correlation with EI, with values of 0.17 and -0.16 for the RF. Inter-operater agreement was excellent, with correlation indices of 0.91 for the RF and 0.95 for the BB. Echo intensity demonstrated a strong correlation with MRI fat fraction, suggesting its potential as a low-cost, noninvasive screening tool for sarcopenia

Conclusion Echo intensity offers a promising ultrasound-based imaging modality for screening patients at risk for sarcopenia, providing a cost-effective and widely accessible alternative to MRI. However, no correlation was found between ATI and MRI fat fraction percentage or between ATI and EI. This study underscores the need for continued research to refine ultrasound-based methods for evaluating muscle quality in clinical settings.

Publication History

Article published online:
16 October 2025