The interaction of light within tissue has been used to recognize disease since the mid-1800s. The recent developments of small light sources, detectors, and fiber optic probes provide opportunities to quantitatively measure these interactions, which yield information for diagnosis at the biochemical, structural, or (patho)physiological level within intact tissues. However, because of the strong scattering properties of tissues, the reemitted optical signal is often influenced by changes in biochemistry (as detected by these spectroscopic approaches) and by physiological and pathophysiological changes in tissue scattering. One challenge of biomedical optics is to uncouple the signals influenced by biochemistry, which themselves provide specificity for identifying diseased states, from those influenced by tissue scattering, which are typically unspecific to a pathology. In this review, we describe optical interactions pursued for biomedical applications (fluorescence, fluorescence lifetime, phosphorescence, and Raman from cells, cultures, and tissues) and then provide a descriptive framework for light interaction based upon tissue absorption and scattering properties. Finally, we review important endogenous and exogenous biological chromophores and describe current work to employ these signals for detection and diagnosis of disease.

Quantitative optical spectroscopy for tissue diagnosis

Keywords: Photomedicine group Reference LPAS-ARTICLE-1998-003View record in Web of Science Record created on 2007-07-20, modified on 2016-08-08

https://onlinelibrary.wiley.com/doi/pdf/10.1111/j.1751-1097.1998.tb02521.x

In Vivo Fluorescence Spectroscopy and Imaging for Oncological Applications

Cells contain molecules, which become fluorescent when excited by UV/Vis radiation of suitable wavelength. This fluorescence emission, arising from endogenous fluorophores, is an intrinsic property of cells and is called auto-fluorescence to be distinguished from fluorescent signals obtained by adding exogenous markers. The majority of cell auto-fluorescence originates from mitochondria and lysosomes. Together with aromatic amino acids and lipo-pigments, the most important endogenous fluorophores are pyridinic (NADPH) and flavin coenzymes. In tissues, the extracellular matrix often contributes to the auto-fluorescence emission more than the cellular component, because collagen and elastin have, among the endogenous fluorophores, a relatively high quantum yield. Changes occurring in the cell and tissue state during physiological and/or pathological processes result in modifications of the amount and distribution of endogenous fluorophores and chemical-physical properties of their microenvironment. Therefore, analytical techniques based on auto-fluorescence monitoring can be utilized in order to obtain information about morphological and physiological state of cells and tissues. Moreover, auto-fluorescence analysis can be performed in real time because it does not require any treatment of fixing or staining of the specimens. In the past few years spectroscopic and imaging techniques have been developed for many different applications both in basic research and diagnostics.

Cell and tissue autofluorescence research and diagnostic applications

Fluorescence Spectroscopy of Neoplastic and Non-Neoplastic Tissues

Diagnostic techniques based on optical spectroscopy have the potential to link the biochemical and morphological properties of tissues to individual patient care. In particular, these techniques are fast, noninvasive and quantitative. Furthermore, they can be used to elucidate key tissue features, such as the cellular metabolic rate, vascularity, intravascular oxygenation and alterations in tissue morphology. These tissue features can be interpreted to shed light on a variety of clinical problems, such as precancerous and cancerous growth and atherosclerosis. The goal of this report is to review the development and application of optical spectroscopy in the ultraviolet (UV) and visible (VIS) spectral regions, as a diagnostic tool in clinical applications. A particular emphasis is placed on steady-state, UV/VIS fluorescence spectroscopy for the detection of precancers and cancers, in vivo.

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Fluorescence Spectroscopy In Vivo

The fluorescence spectra have been measured from native chromophores in malignant and normal human breast and lung tissues. The spectra profiles were found to be different in both species. In addition, one normal breast tissue exhibited Raman spectra.

D. S. J. Choy

Papers

Fluorescence spectra from cancerous and normal human breast and lung tissues

Steady state and time-resolved laser fluorescence from normal and tumor lung and breast tissues