Rationale and Objectives. Near-infrared (NIR) diffuse optical spectroscopy
and imaging may enhance existing technologies for breast cancer screening,
diagnosis, and treatment, NIR techniques are based on sensitive, quantitati
ve measurements of functional contrast between healthy and diseased tissue.
In this study, the authors quantified the origins of this contrast in heal
Materials and Methods. A seven-wavelength frequency-domain photon migration
probe was used to perform noninvasive NIR measurements in the breasts of 2
8 healthy women, both pre- and postmenopausal, aged 18-64 years. A diffusiv
e model of light transport quantified oxygenated and deoxygenated hemoglobi
n, water, and lipid by their absorption signatures. Changes in the measured
light-scattering spectra were quantified by means of a "scatter power" par
Results. Substantial quantitative differences were observed in both absorpt
ion and scattering spectra of breast as a function of subject age. These ph
ysiologic changes were consistent with long-term hormone-dependent transfor
mations that occur in breast. Instrument response was not adversely affecte
d by subject age or menopausal status.
Conclusion. These measurements provide new insight into endogenous optical
absorption and scattering contrast mechanisms and have important implicatio
ns for the development of optical mammography. NIR spectroscopy yields quan
titative functional information that cannot be obtained with other noninvas
ive radiologic techniques.