Adiposity Assessment with a Novel Portable Ultrasound Device

OBJECTIVES: Ultrasound (US) systems are increasingly being used to quantify total body and regional adiposity (Epub 2015. PMID: 26,740,255) along with providing estimates of muscle fat infiltration (echogenicity; Epub 2020. PMID: 33,111,338). The aim of the current study was to evaluate the feasibility of a small, relatively low-cost ultrasound device (ButterflyIQ; Butterfly Network, Guilford, CT) that interfaces with an iPad to assess total body fat quantified with dual-energy X-ray absorptiometry (DXA). METHODS: Participants were a convenience sample of 59 healthy adults who were diverse in age, ethnicity, and adiposity. Total and regional fat masses were measured using DXA (Hologic, Marlborough, MA). Fat thicknesses were taken using the Butterfly at two points on the right thigh. Echogenicity of the rectus femoris was also determined using ImageJ (NIH, Bethesda, MD). Regression analysis was used to evaluate the associations between US-derived fat thickness and DXA-measured total body and leg fat mass. Correlations were also examined between US echogenicity and phase angle at 50 kHz (InBody S10; Seoul, South Korea), an established method for estimating muscle quality. RESULTS: Of the 59 participants, 2 females and 1 male were excluded due to low US image quality. Mid-thigh US adipose tissue layer thickness showed the strongest correlations (R(2)s) with total and right leg fat mass: females, 0.80 and 0.87; males, 0.56 and 0.53 (all p < 0.001). Corresponding correlations at the third-thigh site were smaller in magnitude (0.68 and 0.79; 0.41 and 0.37). A significant (p < 0.05) inverse relationship (R(2), 0.10) was present between US echogenicity and phase angle at 50 kHz. CONCLUSIONS: The evaluated small and portable US device has the important potential to phenotype adiposity and muscle quality in clinical and field settings that lack availability of larger, more costly, and complex measurement systems. FUNDING SOURCES: This work was partially supported by National Institutes of Health NORC Center Grants P30DK072476, Pennington/Louisiana; and P30DK040561, Harvard; and R01DK109008, Shape UP! Adults.