The Role of Diffuse Optical Spectroscopy in the Clinical Management of Breast Cancer

Abstract

Diffuse optical spectroscopy (DOS) of breast tissue provides quantitative, functional information based on optical absorption and scattering properties that cannot be obtained with other radiographic methods. DOS-measured absorption spectra are used to determine the tissue concentrations of deoxyhemoglobin (Hb-R), oxyhemoglobin (Hb-O2), lipid, and water (H2O), as well as to provide an index of tissue hemoglobin oxygen saturation (StO2). Tissue-scattering spectra provide insight into epithelial, collagen, and lipid contributions to breast density. Clinical studies of women with malignant tumors show that DOS is sensitive to processes such as increased tissue vascularization, hypoxia, and edema. In studies of healthy women, DOS detects variations in breast physiology associated with menopausal status, menstrual cycle changes, and hormone replacement. Current research involves using DOS to monitor tumor response to therapy and the co-registration of DOS with magnetic resonance imaging. By correlating DOS-derived parameters with lesion pathology and specific molecular markers, we anticipate that composite “tissue optical indices” can be developed that non-invasively characterize both tumor and normal breast-tissue function.

Real-time In Vivo Tissue Characterization with Diffuse Reflectance Spectroscopy during Transthoracic Lung Biopsy: A Clinical Feasibility Study

“…The OCI was defined as the relative difference in the waterto-scattering ratio between tumor and lung tissue within the same individual. Similar composite optical parameters have been applied by other research groups (9,24,25). The OCI was calculated using the simple formula: …”

Dynamic Functional and Mechanical Response of Breast Tissue to Compression

“…I AC is the measured AC amplitude of the diffusely reflected light, Φ the corresponding phase shift, S Φ and S AC are the slopes characterizing the assumed linear relationship between the source detector separation r, and Φ and ln(r 2 I AC ), respectively. Oxy-hemoglobin ([HbO 2 ]) and deoxy-hemoglobin ([HbR]) concentrations were then derived from a spectral fit to the measured optical properties assuming a water fraction value of 30% [35][36][37].…”

Tomographic imaging of oxygen by phosphorescence lifetime

“…2) are typically approximated by point sources, positioned at the locations m s of the boundary, firing at the moments t 0 , and possessing infinitely short time constants: (5) Sources q p (r s , t) inside the medium [Eq. (2)] are represented by the functions of the probe absorption coefficient μ a p (r s , λ ex ), the probe quantum yield ϕ 0 in the absence of oxygen, 37 the distribution of the excitation photon density U ex (r s , t), and the lifetime τ(r s ): (6) The absorption coefficient μ a p (r s , λ ex ) is the product of the probe concentration c(r s ) and the probe molar extinction coefficient ε(λ ex ).…”