Optical study on the dependence of breast tissue composition and structure on subject anamnesis

Time domain multi-wavelength (635 to 1060 nm) optical mammography was performed on 200 subjects to estimate their average breast tissue composition in terms of oxy- and deoxy-hemoglobin, water, lipid and collagen, and structural information, as provided by scattering parameters (amplitude and power). Significant (and often marked) dependence of tissue composition and structure on age, menopausal status, body mass index, and use of oral contraceptives was demonstrated

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

partially_open10noThe optical characterization of malignant and benign breast lesions is presented. Time-resolved transmittance measurements were performed in the 630-1060 nm range by means of a 7-wavelength optical mammograph, providing both imaging and spectroscopy information. A total of 62 lesions were analyzed, including 33 malignant and 29 benign lesions. The characterization of breast lesions was performed applying a perturbation model based on the high-order calculation of the pathlength of photons inside the lesion, which led to the assessment of oxy- and deoxy- hemoglobin, lipids, water and collagen concentrations. Significant variations between tumor and healthy tissue were observed in terms of both absorption properties and constituents co ncentration. In particular, benign lesions and tumors show a statistically significant discrimination in terms of absorption at several wavelengths and also in terms of oxy-hemoglobin and collagen content.G. Quarto; L. Spinelli; A. Pifferi; A. Torricelli; R. Cubeddu; F. Abbate; N. Balestreri; S. Menna; E. Cassano; P. TaroniQuarto, Giovanna; Spinelli, Lorenzo; Pifferi, ANTONIO GIOVANNI; Torricelli, Alessandro; Cubeddu, Rinaldo; F., Abbate; N., Balestreri; S., Menna; E., Cassano; Taroni, Paol

Breast tissue composition and its dependence on demographic risk factors for breast cancer: non-invasive assessment by time domain diffuse optical spectroscopy.

BACKGROUND:Breast tissue composition is recognized as a strong and independent risk factor for breast cancer. It is a heritable feature, but is also significantly affected by several other elements (e.g., age, menopause). Nowadays it is quantified by mammographic density, thus requiring the use of ionizing radiation. Optical techniques are absolutely non-invasive and have already proved effective in the investigation of biological tissues, as they are sensitive to tissue composition and structure. METHODS:Time domain diffuse optical spectroscopy was performed at 7 wavelengths (635-1060 nm) on 200 subjects to derive their breast tissue composition (in terms of water, lipid and collagen content), blood parameters (total hemoglobin content and oxygen saturation level), and information on the microscopic structure (scattering amplitude and power). The dependence of all optically-derived parameters on age, menopausal status, body mass index, and use of oral contraceptives, and the correlation with mammographic density were investigated. RESULTS:Younger age, premenopausal status, lower body mass index values, and use of oral contraceptives all correspond to significantly higher water, collagen and total hemoglobin content, and lower lipid content (always p < 0.05 and often p < 10-4), while oxygen saturation level and scattering parameters show significant dependence only on some conditions. Even when age-adjusted groups of subjects are compared, several optically derived parameters (and in particular always collagen and total hemoglobin content) remain significantly different. CONCLUSIONS:Time domain diffuse optical spectroscopy can probe non-invasively breast tissue composition and physiologic blood parameters, and provide information on tissue structure. The measurement is suitable for in vivo studies and monitoring of changes in breast tissue (e.g., with age, lifestyle, chemotherapy, etc.) and to gain insight into related processes, like the origin of cancer risk associated with breast density

7-WAVELENGTH TIME-RESOLVED OPTICAL MAMMOGRAPH: UPGRADE FOR BEST PERFORMANCE

Congresso Fotonica 201

Effects of tissue heterogeneity on the optical estimate of breast density

Breast density is a recognized strong and independent risk factor for developing breast cancer. At present, breast density is assessed based on the radiological appearance of breast tissue, thus relying on the use of ionizing radiation. We have previously obtained encouraging preliminary results with our portable instrument for time domain optical mammography performed at 7 wavelengths (635–1060 nm). In that case, information was averaged over four images (cranio-caudal and oblique views of both breasts) available for each subject. In the present work, we tested the effectiveness of just one or few point measurements, to investigate if tissue heterogeneity significantly affects the correlation between optically derived parameters and mammographic density. Data show that parameters estimated through a single optical measurement correlate strongly with mammographic density estimated by using BIRADS categories. A central position is optimal for the measurement, but its exact location is not critical

Tissue composition and scattering parameters of subjects ≤ 50 y and > 50 y.

<p>^aAverage values and standard deviation (in round brackets).</p><p>^bIn square brackets, <i>p</i>-value (Mann-Whitney test) for the difference between the mean values reported in the above and below cells. Reported only when significant (<i>p</i> < 0.05).</p><p>Tissue composition and scattering parameters of subjects ≤ 50 y and > 50 y.</p

Dependence of optically derived tissue parameters on BMI.

<p><b>A)</b> water (blue) and lipid (orange), <b>B)</b> collagen, <b>C)</b> total hemoglobin content <i>tHb</i>, <b>D)</b> oxygen saturation <i>SO</i>_<i>2</i>, <b>E)</b> scattering amplitude <i>a</i>, and <b>F)</b> scattering power <i>b</i>.</p

Average absorption and reduced scattering spectra of 189 subjects classified in different BI-RADS categories.

<p><b>A)</b> Absorption spectra and <b>B)</b> reduced scattering spectra averaged over <i>N</i> = 27 subjects in Bi-RADS category 1 (red diamonds), <i>N</i> = 55 subjects in category 2 (orange squares), <i>N</i> = 70 subjects in category 3 (green triangles), and <i>N</i> = 37 in category 4 (blue circles). The error bars show the standard deviation of the absorption (A) or reduced scattering (B) values calculated on all subjects that belong to the same BI-RADS category.</p