Ultrasound for body composition assessment: a narrative review

Ultrasound has become an increasingly valuable tool for the assessment of body composition, offering several applications and indications in clinical practice. Ultrasound allows bedside evaluation of muscle mass, fat compartments, and extravascular water, providing a cost-effective, portable, and accessible alternative to traditional methods, such as Dual-energy X-ray Absorptiometry (DEXA), Bioelectrical Impedance Analysis (BIA), Computed Tomography (CT), and Magnetic Resonance Imaging (MRI). It is particularly useful in evaluating conditions, such as malnutrition, sarcopenia, and sarcopenic obesity, which require poor muscle mass to establish a diagnosis. The potential uses of ultrasound in body composition assessment include measurement of muscle thickness, cross-sectional area, pennation angle, and echo-intensity, which are indicative of muscle health. Additionally, ultrasound can be used to evaluate various fat compartments, including visceral, subcutaneous, and ectopic fat, which are important for understanding metabolic health and cardiovascular risk. However, the widespread adoption of ultrasound is challenged by the lack of standardized measurements and the absence of ultrasound measures in the validated diagnostic criteria. This article reviews the current applications of ultrasound in body composition assessment, highlighting the recent advancements and the correlation between ultrasound parameters and clinical outcomes. It discusses the advantages of ultrasound while also addressing its limitations, such as the need for standardized protocols and cut-off points. By providing a comprehensive update based on recent publications, this article aims to enhance the clinical utility of ultrasound in assessing and monitoring body composition and pave the way for future research in this field.