Spectral discrimination of breast pathologies in situusing spatial frequency domain imaging

Abstract

IntroductionNationally, 25% to 50% of patients undergoing lumpectomy for local management of breast cancer require a secondary excision because of the persistence of residual tumor. Intraoperative assessment of specimen margins by frozen-section analysis is not widely adopted in breast-conserving surgery. Here, a new approach to wide-field optical imaging of breast pathology in situ was tested to determine whether the system could accurately discriminate cancer from benign tissues before routine pathological processing.MethodsSpatial frequency domain imaging (SFDI) was used to quantify near-infrared (NIR) optical parameters at the surface of 47 lumpectomy tissue specimens. Spatial frequency and wavelength-dependent reflectance spectra were parameterized with matched simulations of light transport. Spectral images were co-registered to histopathology in adjacent, stained sections of the tissue, cut in the geometry imaged in situ. A supervised classifier and feature-selection algorithm were implemented to automate discrimination of breast pathologies and to rank the contribution of each parameter to a diagnosis.ResultsSpectral parameters distinguished all pathology subtypes with 82% accuracy and benign (fibrocystic disease, fibroadenoma) from malignant (DCIS, invasive cancer, and partially treated invasive cancer after neoadjuvant chemotherapy) pathologies with 88% accuracy, high specificity (93%), and reasonable sensitivity (79%). Although spectral absorption and scattering features were essential components of the discriminant classifier, scattering exhibited lower variance and contributed most to tissue-type separation. The scattering slope was sensitive to stromal and epithelial distributions measured with quantitative immunohistochemistry.ConclusionsSFDI is a new quantitative imaging technique that renders a specific tissue-type diagnosis. Its combination of planar sampling and frequency-dependent depth sensing is clinically pragmatic and appropriate for breast surgical-margin assessment. This study is the first to apply SFDI to pathology discrimination in surgical breast tissues. It represents an important step toward imaging surgical specimens immediately ex vivo to reduce the high rate of secondary excisions associated with breast lumpectomy procedures.

Estimate of tissue composition in malignant and benign breast lesions by time-domain optical mammography

“…Only in some studies, an extension of the spectral range was performed for the quantification also of water and lipids, since they are dominant constituents of the breast tissue. Up to now, preliminary studies on malignant breast lesions were performed, showing a reduction of lipid content and an increase of water and blood compared to normal breast tissue [29][30][31][32][33][34].…”

Plum pudding random medium model of biological tissue toward remote microscopy from spectroscopic light scattering

“…(3,4). For most tissues, the size parameter of their core within visible and near-infrared spectral range is less than 1.245 |m c − 1| −1.725 and resides in the neighborhood of 2 |m c − 1| −1 .…”

“…Given the background squared scattering amplitude (6) and (8) specified, respectively, in the fractal and Whittle-Matern models, the scattering properties originating from the background refractive fluctuation is simply determined by Eqs. (2)(3)(4). Figure 1 shows the trends of various scattering properties: the scattering coefficient μ s , the reduced scattering coefficient μ s , the anisotropy factor g ≡ 1 − μ s /μ s , and the scattering power b (μ s ∝ λ −b ) predicted by the two models.…”

“…Scattered light carries important information about the morphology and optical properties of the individual scatterers and can be used to identify structural alterations or heterogeneities in tissue due to disease or physiological variations [2][3][4]. The scattering and absorption properties of tissue determine light transport (such as penetration, reflection, and transmission) and energy deposition in tissue, key to both diagnostic and therapeutic applications of light.…”

Real-time, profile-corrected single snapshot imaging of optical properties

“…in a multipixel approach). SFDI has shown significant promise in performing wide-field surgical guidance and specimen examination, both in animals and in humans, ex vivo and in vivo [7][8][9][10][11][12][13].…”