Significance: Blood lipid levels (i.e., triglycerides (TGs) and cholesterol) are a strong predictor of cardiovascular disease (CVD) risk. Current methods for measuring blood lipids require invasive blood draws and traditional lab testing, limiting their practicality for frequent monitoring. Optical measurements of lipoproteins, which carry TG and cholesterol in blood, may lead to simpler invasive or non-invasive methods for more frequent and rapid blood lipid measurements.
Aim: To investigate the effect of lipoproteins on optical properties of blood before and after a high-fat meal (i.e., the pre- and post-prandial state).
Approach: Simulations were performed using Mie theory to estimate lipoprotein scattering properties. A literature review was conducted to identify key simulation parameters including lipoprotein size distributions and number density. Experimental validation of ex-vivo blood samples was conducted using spatial frequency domain imaging.
Results: Our results indicated that lipoproteins in blood, particularly very low-density lipoproteins and chylomicrons, are highly scattering in the visible and near-infrared wavelength region. Estimates of the increase in the reduced scattering coefficient () of blood at 730 nm after a high-fat meal ranged from 4% for a healthy individual, to 15% for those with type 2 diabetes, to up to 64% for those suffering from hypertriglyceridemia. A reduction in blood scattering anisotropy () also occurred as a function of TG concentration increase.
Conclusion: These findings lay the foundation for future research in the development of optical methods for invasive and non-invasive optical measure of blood lipoproteins, which could improve early detection and management of CVD risk.
Keywords: blood lipids; blood optical properties; cardiovascular disease; diffuse optics; lipoproteins; optical scattering; spatial frequency domain imaging.
© 2023 The Authors.