Quantitation methods for determining the intrinsic composition of breast tissue in vivo using near-infrared transillumination

摘要

Abstract: We have measured transillumination spectra collected at various sites on the breasts of normal subjects. The absolute concentration of hemoglobin, lipids and water are derived using ratiometric methods. The lipids and deoxyhemoglobin signals overlap at 760 nm; the accurate separation of these thus requires explicit account to be taken of the diffusion of photons through the breast. The concentrations of Hb, lipids and water vary substantially from site to site, which will influence wavelength selection in imaging systems. Finite element calculations and solid phantom measurements demonstrate that this variability is not due to boundary effects. The spatial variation of $mu$- a$/ at wavelengths 720 nm, 820 nm, 930 nm and 970 nm is illustrated schematically. It is noted that $mu$-a$/ at 930 nm shows the least heterogeneity amongst the 8 normal subjects studied.!24