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The association between breast tissue optical content and mammographic density in pre- and post-menopausal women.

Blackmore KM, Knight JA, Walter J, Lilge L - PLoS ONE (2015)

Bottom Line: Among pre-menopausal women, lipid content was significantly inversely associated with square root transformed PD (β = -0.05, p = 0.0002) and DA (β = -0.05, p = 0.019); water content was significantly positively associated with PD (β = 0.06, p = 0.008).Tissue oxygen saturation was marginally inversely associated with PD (β = -0.03, p = 0.057) but significantly inversely associated with DA (β = -0.10, p = 0.002).Among post-menopausal women lipid and water content were significantly associated (negatively and positively, respectively) with PD (β lipid = -0.08, β water = 0.14, both p<0.0001) and DA (β lipid = -0.10, p<0.0001; β water = 0.11, p = 0.001).

View Article: PubMed Central - PubMed

Affiliation: Lunenfeld Tanenbaum Research Institute, Mount Sinai Hospital, Toronto, Ontario, Canada; Princess Margaret Cancer Centre and Department of Medical Biophysics, University of Toronto, Ontario, Canada.

ABSTRACT
Mammographic density (MD), associated with higher water and lower fat content in the breast, is strongly related to breast cancer risk. Optical attenuation spectroscopy (OS) is a non-imaging method of evaluating breast tissue composition by red and near-infrared light transmitted through the breast that, unlike mammography, does not involve radiation. OS provides information on wavelength dependent light scattering of tissue and on absorption by water, lipid, oxy-, deoxy-hemoglobin. We propose that OS could be an alternative marker of breast cancer risk and that OS breast tissue measures will be associated with MD. In the present analysis, we developed an algorithm to estimate breast tissue composition and light scattering parameters using a spectrally constrained global fitting procedure employing a diffuse light transport model. OS measurements were obtained from 202 pre- and post-menopausal women with normal mammograms. Percent density (PD) and dense area (DA) were measured using Cumulus. The association between OS tissue composition and PD and DA was analyzed using linear regression adjusted for body mass index. Among pre-menopausal women, lipid content was significantly inversely associated with square root transformed PD (β = -0.05, p = 0.0002) and DA (β = -0.05, p = 0.019); water content was significantly positively associated with PD (β = 0.06, p = 0.008). Tissue oxygen saturation was marginally inversely associated with PD (β = -0.03, p = 0.057) but significantly inversely associated with DA (β = -0.10, p = 0.002). Among post-menopausal women lipid and water content were significantly associated (negatively and positively, respectively) with PD (β lipid = -0.08, β water = 0.14, both p<0.0001) and DA (β lipid = -0.10, p<0.0001; β water = 0.11, p = 0.001). The association between OS breast content and PD and DA is consistent with more proliferation in dense tissue of younger women, greater lipid content in low density tissue and higher water content in high density tissue. OS may be useful for assessing physiologic tissue differences related to breast cancer risk, particularly when mammography is not feasible or easily accessible.

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The attenuation spectra (optical density (OD) per cm over all wavelengths) of four main breast tissue components—water, lipid, oxyhemoglobin, and deoxyhemoglobin.
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pone.0115851.g001: The attenuation spectra (optical density (OD) per cm over all wavelengths) of four main breast tissue components—water, lipid, oxyhemoglobin, and deoxyhemoglobin.

Mentions: For each woman, transmission spectra were first converted into attenuation spectra (OD cm-1) using an optical system throughput calibration standard and corrected for dark noise [16–19]. A spectrally constrained global fitting procedure based on the previously published diffuse approximation of light transport in tissue [32], was used to estimate the concentrations of deoxy-hemoglobin (µM), oxy-hemoglobin (µM), lipid (%), water (%), as well as two light scattering parameters, scattering amplitude (µa, cm-1) and wavelength-dependent scattering power (b), for all measured positions. Standard absorption spectra for the four dominant chromophores of interest were obtained from the literature [33–35] (Fig. 1). The reduced light scattering coefficient (µs’cm-1) was modeled using an exponential function of wavelength (λ) given by µs’(λ) = a(λ)-b, where a and b are free fitting parameters, as defined above [36]. Hence, in total there were six free parameters, four chromophore concentrations and two scattering parameters, used in the fitting algorithm.


The association between breast tissue optical content and mammographic density in pre- and post-menopausal women.

Blackmore KM, Knight JA, Walter J, Lilge L - PLoS ONE (2015)

The attenuation spectra (optical density (OD) per cm over all wavelengths) of four main breast tissue components—water, lipid, oxyhemoglobin, and deoxyhemoglobin.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4295879&req=5

pone.0115851.g001: The attenuation spectra (optical density (OD) per cm over all wavelengths) of four main breast tissue components—water, lipid, oxyhemoglobin, and deoxyhemoglobin.
Mentions: For each woman, transmission spectra were first converted into attenuation spectra (OD cm-1) using an optical system throughput calibration standard and corrected for dark noise [16–19]. A spectrally constrained global fitting procedure based on the previously published diffuse approximation of light transport in tissue [32], was used to estimate the concentrations of deoxy-hemoglobin (µM), oxy-hemoglobin (µM), lipid (%), water (%), as well as two light scattering parameters, scattering amplitude (µa, cm-1) and wavelength-dependent scattering power (b), for all measured positions. Standard absorption spectra for the four dominant chromophores of interest were obtained from the literature [33–35] (Fig. 1). The reduced light scattering coefficient (µs’cm-1) was modeled using an exponential function of wavelength (λ) given by µs’(λ) = a(λ)-b, where a and b are free fitting parameters, as defined above [36]. Hence, in total there were six free parameters, four chromophore concentrations and two scattering parameters, used in the fitting algorithm.

Bottom Line: Among pre-menopausal women, lipid content was significantly inversely associated with square root transformed PD (β = -0.05, p = 0.0002) and DA (β = -0.05, p = 0.019); water content was significantly positively associated with PD (β = 0.06, p = 0.008).Tissue oxygen saturation was marginally inversely associated with PD (β = -0.03, p = 0.057) but significantly inversely associated with DA (β = -0.10, p = 0.002).Among post-menopausal women lipid and water content were significantly associated (negatively and positively, respectively) with PD (β lipid = -0.08, β water = 0.14, both p<0.0001) and DA (β lipid = -0.10, p<0.0001; β water = 0.11, p = 0.001).

View Article: PubMed Central - PubMed

Affiliation: Lunenfeld Tanenbaum Research Institute, Mount Sinai Hospital, Toronto, Ontario, Canada; Princess Margaret Cancer Centre and Department of Medical Biophysics, University of Toronto, Ontario, Canada.

ABSTRACT
Mammographic density (MD), associated with higher water and lower fat content in the breast, is strongly related to breast cancer risk. Optical attenuation spectroscopy (OS) is a non-imaging method of evaluating breast tissue composition by red and near-infrared light transmitted through the breast that, unlike mammography, does not involve radiation. OS provides information on wavelength dependent light scattering of tissue and on absorption by water, lipid, oxy-, deoxy-hemoglobin. We propose that OS could be an alternative marker of breast cancer risk and that OS breast tissue measures will be associated with MD. In the present analysis, we developed an algorithm to estimate breast tissue composition and light scattering parameters using a spectrally constrained global fitting procedure employing a diffuse light transport model. OS measurements were obtained from 202 pre- and post-menopausal women with normal mammograms. Percent density (PD) and dense area (DA) were measured using Cumulus. The association between OS tissue composition and PD and DA was analyzed using linear regression adjusted for body mass index. Among pre-menopausal women, lipid content was significantly inversely associated with square root transformed PD (β = -0.05, p = 0.0002) and DA (β = -0.05, p = 0.019); water content was significantly positively associated with PD (β = 0.06, p = 0.008). Tissue oxygen saturation was marginally inversely associated with PD (β = -0.03, p = 0.057) but significantly inversely associated with DA (β = -0.10, p = 0.002). Among post-menopausal women lipid and water content were significantly associated (negatively and positively, respectively) with PD (β lipid = -0.08, β water = 0.14, both p<0.0001) and DA (β lipid = -0.10, p<0.0001; β water = 0.11, p = 0.001). The association between OS breast content and PD and DA is consistent with more proliferation in dense tissue of younger women, greater lipid content in low density tissue and higher water content in high density tissue. OS may be useful for assessing physiologic tissue differences related to breast cancer risk, particularly when mammography is not feasible or easily accessible.

Show MeSH
Related in: MedlinePlus