Exploring Optical Contrast in Ex-Vivo Breast Tissue Using Diffuse Reflectance Spectroscopy and Tissue Morphology

In this research, ex-vivo breast tissue is evaluated to determine which sources of optical contrast have the potential to detect malignancy at the margins in women of differing breast composition. Then, H&E images of ex-vivo breast tissue sites are quantified to further deconstruct the relationship between optical scattering and the underlying tissue morphology.;H&E images were taken of the malignant and benign sites and quantified to describe the % adipose, % collagen and % glands. Adipose sites, images at 10x, were predominantly fatty and quantified according to adipocyte morphology. H&E-stained adipose tissue sections were analyzed with an automated image processing algorithm to extract average cell area and cell density. Non-adipose sites were imaged with a 2.5x objective. Grids of 200µm boxes corresponding to the 3mm x 2mm area were overlaid on each non-adipose image. The non-adipose images were classified as the following: adipose and collagen (fibroadipose); collagen and glands (fibroglandular); adipose, collagen and glands (mixed); and malignant sites. Correlations between <μs&feet;> and % collagen in were determined in benign sites. Age, BMI, and MBD were then correlated to <μs&feet;> in the adipose and non-adipose sites. Variability in <μs&feet;> was determined to be related to collagen and not adipose content. In order to further investigate this relationship, the importance of age, BMI and MBD was analyzed after adjusting for the % collagen. Lastly, the relationship between % collagen and % glands was analyzed to determine the relative contributions of % collagen and % glands <μ s&feet;>. Statistics were calculated using Wilcoxon rank-sum tests, Pearson correlation coefficients and linear fits in R.;Further deconstructing the relationship between optical scattering and tissue morphology resulted in a positive relationship between <μ s&feet;> and % collagen. Increased variability was observed in sites with a higher percentage of collagen. In adipose tissues MBD was negatively correlated with age, BMI and average cell area. but positively related to the log of the average cell density. In addition, BMI was positively correlated to average cell area and negatively related to log of the cell density. In non-adipose sites, age was negatively correlated to <μs&feet;> in benign and malignant sites and this correlation varied significantly by the collagen level. BMI was negatively correlated to <μs&feet;> in benign and malignant sites but this relationship did not vary by collagen level. MBD was positively correlated to <μs&feet;> in benign and malignant sites. Optical scattering was shown to be tied to patient demographics. Lastly, the analysis of collagen vs. glands was narrowed to investigate sites with glands between 0-40% (the dynamic range of the data), the linear model reflected an equivalent relationship to scattering from % glands and the % collagen in benign sites. In addition, the malignant sites showed a stronger positive relationship to <μs&feet;> compared to the benign sites.;The data indicate that the ability of an optical parameter to differentiate benign from malignant breast tissues is dictated by patient demographics. Scattering differentiated between malignant and adipose sites and would be most effective in post-menopausal women. [β-carotene] or [THb] may be more applicable in pre-menopausal women to differentiate malignant from fibrous sites. Patient demographics are therefore an important component to incorporate into optical characterization of breast specimens. Through the subsequent stepwise analysis of tissue morphology, <μs&feet;> was positively correlated to collagen and negatively correlated to age and BMI. Increased variability of <μs&feet;> with collagen level was not dependent on the adipose contribution. A stronger correlation between age and <μ s&feet;> was seen in high collagen sites compared to low collagen sites. Contributions from collagen and glands to <μs&feet;> were independent and equivalent in benign sites; glands showed a stronger correlation to <μs&feet;> in malignant sites than collagen. This information will help develop improved scattering models and additional technologies from separating fibroglandular sites from malignant sites and ultimately improve margin assessment. (Abstract shortened by UMI.).