Spectroscopy enhances the information content of optical mammography

Abstract

Abstract. Near-infrared (NIR) diffuse optical spectroscopy and imaging may enhance existing technologies for breast cancer screening, diagnosis, and treatment. NIR techniques are based on quantitative measurements of functional contrast between healthy and diseased tissue. In this study we measured the spectral dependence of tissue absorption ( a ) and reduced scattering ( s Ј) in the breasts of 30 healthy women and one woman with a fibroadenoma using a sevenwavelength frequency-domain photon migration probe. Subjects included pre-and postmenopausal women between the ages of 18 and 64. Multi-spectral measurements were used along with a fourcomponent fit to determine the concentrations of de-oxy and oxyhemoglobin, water and lipids in breast. The scattering spectral shape was also quantified. Our measurements demonstrate that the measured concentrations of NIR analytes correlate well with known breast physiology. Although the tissue scattering at a single wavelength was found to have little value as a functional parameter, the dependence of the scattering on wavelength provided key insights into breast composition and physiology. Lipids and scattering spectra in the breast were found to increase and decrease, respectively, with increasing body mass index. Simple calculations are also provided to demonstrate potential penalties from ignoring the contributions of water and lipids in breast measurements. Finally, water is shown to be a possible indicator for detecting a fibroadenoma, whereas the hemoglobin saturation was found to be a poor indicator. Multi-spectral measurements, compared to measurements restricted to one or two wavelengths, provide additional information that may be useful in managing breast disease.

Predicting response to breast cancer neoadjuvant chemotherapy using diffuse optical spectroscopy

“…Calculations using the Beer-Lambert law and known absorber extinction coefficients were used to convert the absorption spectra (Fig. 2 Left) into the tissue concentrations of ctHHb (M), ctO 2 Hb (M), ctH 2 O (%), and bulk lipids (%), which are the primary NIR absorbers in breast tissue (57). ctH 2 O is the concentration of measured tissue water divided by pure water concentration (55.6 M).…”

Interpreting hemoglobin and water concentration, oxygen saturation, and scattering measured in vivo by near-infrared breast tomography

“…Some uncertainty exists regarding the absorption from lipids in this spectral region. Recent studies have suggested that the effect, if present, is minimal (20); hence, the absorption due to lipids is not included in our analysis.…”

Detection and characterization of breast tumours by time-domain scanning optical mammography

“…From diffusely transmitted or reflected NIR light, absorption and scattering properties of normal and diseased breast tissue can be inferred using appropriate models for light transport in a tissue [12,13]. In particular, when broad band red to near infrared radiation is employed or light at several selected wavelengths within this spectral range is used for diffuse optical spectroscopy, absorption and reduced scattering coefficients derived in this way can be related to composition, vascularization, blood oxygen saturation, and structural properties of normal breast tissue, benign lesions and tumours as well [14]. This paper reviews mostly the results obtained by scientific and medical research groups in Berlin on time-domain optical mammography, in particular the outcome of a clinical study comprising 154 patients with 102 carcinomas that were validated by histology.…”