Time domain diffuse optical spectroscopy:In vivoquantification of collagen in breast tissue

Abstract

Time-resolved diffuse optical spectroscopy provides non-invasively the optical characterization of highly diffusive media, such as biological tissues. Light pulses are injected into the tissue and the effects of light propagation on re-emitted pulses are interpreted with the diffusion theory to assess simultaneously tissue absorption and reduced scattering coefficients. Performing spectral measurements, information on tissue composition and structure is derived applying the Beer law to the measured absorption and an empiric approximation to Mie theory to the reduced scattering.The absorption properties of collagen powder were preliminarily measured in the range of 600-1100 nm using a laboratory set-up for broadband time-resolved diffuse optical spectroscopy.Optical projection images were subsequently acquired in compressed breast geometry on 218 subjects, either healthy or bearing breast lesions, using a portable instrument for optical mammography that operates at 7 wavelengths selected in the range 635-1060 nm. For all subjects, tissue composition was estimated in terms of oxy-and deoxy-hemoglobin, water, lipids, and collagen. Information on tissue microscopic structure was also derived.Good correlation was obtained between mammographic breast density (a strong risk factor for breast cancer) and an optical index based on collagen content and scattering power (that accounts mostly for tissue collagen). Logistic regression applied to all optically derived parameters showed that subjects at high risk for developing breast cancer for their high breast density can effectively be identified based on collagen content and scattering parameters.Tissue composition assessed in breast lesions with a perturbative approach indicated that collagen and hemoglobin content are significantly higher in malignant lesions than in benign ones.

Breast density quantification using structured-light-based diffuse optical tomography simulations

“…For younger women, this may not be the best option. Using optics to measure breast density is becoming an attractive alternative, with research groups able to distinguish between the BI-RADS groups [49], determine low or high risk [22], and quantify the %BDs [20] in patients. Widespread reporting of quantitative %BD values may help elucidate the association between breast cancer risk and breast density through epidemiological studies.…”

The Use of Supercontinuum Laser Sources in Biomedical Diffuse Optics: Unlocking the Power of Multispectral Imaging

“…They were able to characterize bones [47][48][49], thyroid tissues [50], adipose tissues [51], collagen [46,52], and elastin [53]. This groundwork was crucial in order to investigate the tissue composition of breast for example, which can help for diagnosis of cancerous tissue [54,55]. Finally, we can report that the latest reported system has also been used to monitor the thermal effect of Radio Frequency (RF) on tissues [56,57].…”

Optical spectroscopy-based imaging techniques for the diagnosis of breast cancer: A novel approach

“…The choice of the operating wavelength is based on characterizing specific tissue biomarker, for e.g., selective absorption of oxygenated hemoglobin and deoxygenated hemoglobin occurs between 635 nm and 785, lipid absorption peak around 920 nm, water absorption peak around 975 nm, and collagen absorption peak around 1060 nm. [39,126] Additionally, considering rapid diagnosis, the development cost of the system should be minimal, while being portable. The TD systems [97,116,127] reportedly have higher cost due to expensive detector and source/detector driving system; however, FD [71,81,106,107,112] systems are reported as an alternative, still requiring costly instruments such as source modulation driving circuit and biasing network; while low-cost alternative are considered as CW [100][101][102][103]115] system albeit with lower information (i.e., no tissue scattering property).…”