Refractive index of carcinogen-induced rat mammary tumours

Abstract

Near-infrared optical techniques for clinical breast cancer screening in humans are rapidly advancing. Based on the computational inversion of the photon diffusion process through the breast, these techniques rely on optical tissue models for accurate image reconstruction. Recent interest has surfaced regarding the effect of refractive index variations on these reconstructions. Although many data exist regarding the scattering and absorption properties of normal and diseased tissue, no measurements of refractive index appear in the literature. In this paper, we present near-infrared refractive index data acquired from N-methyl-N-nitrosourea-induced rat mammary tumours, which are similar in pathology and disease progression to human ductal carcinoma. Eight animals, including one control, were employed in this study, yielding data from 32 tumours as well as adjacent adipose and connective tissues.

Differentiation of ex vivo human breast tissue using polarization-sensitive optical coherence tomography

“…These previous studies have shown that breast cancer appears more highly scattering than healthy tissue and disrupts the normal structure of adipose and stroma found in the breast. However, solid invasive tumors may be difficult to distinguish from islands of fibrous stromal tissue [19,28]. This may be due to a lack of clear structures and similar refractive indices [28].…”

Group refractive index reconstruction with broadband interferometric confocal microscopy

“…To find the field scattered to the pinhole by the sample, we consider the field u(r) in the object space V. The field satisfies the inhomogeneous reduced wave equation: (1) where k is the free-space wavenumber of the field, n 0 (r) is the refractive index representing the optical system of Fig. 1 without an object, and n(r) is the inhomogeneneous refractive index of the object, which is treated as a perturbation on the order of a small parameter ε.…”

“…However, few instruments are able to probe the group refractive index of media at the micrometer scale. Recent work [1] has indicated that the group refractive index has potential diagnostic capability to distinguish breast cancer from normal tissues. To be able to further investigate the origin of the group refractive index contrast at the scale of organelles, we propose a new instrument.…”

“…In addition to materials applications such as polymer composition measurement [6], crystal growth evaluation [7], and optical fiber assessment [8], a number of biomedical properties are observable based on refractive index changes. Recent studies have shown, for example, that refractive index variations hold significance for breast cancer evaluation [1]. Since the breast is comprised primarily of fat tissue, which has an elevated refractive index due to its high lipid concentration, the functional epithelial structures, having a much lower refractive index, are easily identified by direct measurement.…”

Design, construction, and performance of a real-time holographic refractometry prototype for liquid analysis

“…In biological sciences, refractometry was employed to determine salinity levels due to total plasma protein (TPP) in fish blood samples 1 and in avian species, 2 to study the molecular basis of virus entry by analyzing the interactions between cellular receptors of herpes virus and the viral glycoproteins in a molecular level, 3 to evaluate the purity and the quality of antimalarial drugs, 4 to rapidly measure glucose concentration in blood, 5,6 and to diagnose and evaluate the evolution of tumors in breast tissues. 7 By performing refractive index measurements, the study of bubble flow, 8 as well as the characterization of optical, 9 polymeric, 10,11 and chemical 12,13 materials can be carried out. For such a large variety of applications many refractometry devices were proposed and developed concerning the particularities of each application.…”