The evolution of anatomic pathology from a discipline based upon direct observation of visual light images to whole spectrum multi-modality computer-intensive analysis is entering a phase of accelerated growth. However, the technologic base is expanding more rapidly than our ability to exploit it for diagnostic and experimental pathology. While the theoretical and practical underpinnings of the new technology are complex, the underlying principles are quite simple. Energy interactions with a biological specimen basically primarily involve four kinds of effects: absorption, reflection, scatter, and secondary emission. This holds true, for example, for both a radio wave perturbing aligned molecular dipoles or UV light shining at a slide. Radiologists have been quicker than pathologists at exploiting this generalization. The reasons for this may be found in the pixel level complexity of a microscopic slide as compared to a typical radiological image. The aim in pathology is reconstructing images from the data with resolution good enough for morphologic analysis at the cellular and tissue level, whereas the aim in radiology is to get enough visualization to identify the lesion or location of a biochemical event. Paradoxically, modern radiology deals with both ends of the spectrum (molecules and organs), while pathologists remain focused (pun intended) on cells and tissue architecture, and study molecular events in that context.

The purpose of this book is to present some of the promising new image-based and related technologies for the study of visualization, characterization, and analysis of abnormal cells and tissues that have evolved over the past few years and to discuss their current and potential applications in experimental pathology and, where feasible, clinical pathologic diagnosis. Just as the flourishing of molecular biology has led to a paradigm shift that has rejuvenated our field, the convergence of biomedicine, bioengineering, and sophisticated new tools of mathematical analysis will move us towards a more quantitative and analytic discipline.

Although Photonics is a term often used in relation to light-based circuits, it is actually more inclusive, including the generation, emission, transmission, modulation, and signal processing of light. Biophotonics can therefore be used to describe the development and application of optical techniques to the study of biological molecules, cells, and tissues. This can be applied to imaging-based modalities for the analysis of non-photonic data, such as various other biophysical parameters, an example of which (impedance) is included in this volume. This is the rationale for the title of this volume: “Biophotonics in Pathology”. As will be discussed in the final chapter, we are beginning to see a convergence of radiology and pathology, and pathologists must be quick to embrace the rapidly evolving new technology if they are to remain relevant, which is the rationale for the subtitle: “Pathology at the Crossroads”. In this regard, radiologists, as well as basic scientists and engineers working in these overlapping areas, should also find the material presented here of interest, as it shows the confluence of methodologies similar to those applied in radiology with morphologic analysis at the cellular and tissue level.

Unfortunately, the technologic basis for these approaches is expanding more rapidly than our ability to exploit it for both diagnostic and experimental pathology. While the theoretical and practical underpinnings of the new technology are complex, the underlying physical principles are straightforward. Collaboration of engineers and physical scientists with biomedical researchers is slowly increasing, but it is difficult for many of the biologically oriented to feel comfortable with the concepts and approaches of the physical sciences and their mathematical underpinnings. The converse is often true as well, and many of the excellent publications in the engineering literature, for example, make use of very unsophisticated biological models.

The authors, all experts in the field, have described this technology in a manner accessible to an audience consisting of pathologists, cell biologists, and biochemists as well as biomedical engineers, using their own research as well as literature review to provide descriptions and examples of the use of this new armamentarium. Although it has been written from the prospective of pathology, it should be of interest to this wider audience as well. Moreover, as I have suggested above, it appears likely that these approaches, as well as new techniques for in situ molecular imaging that are outside the scope of this book, as well as evolving non-invasive radiological procedures for screening and diagnosis will lead to a convergence of pathology and radiology, which would make for an even more profound paradigm shift.

Some of the material in this volume has appeared previously in review format in several issues of volumes 34 and 35 of Analytical Cellular Pathology. Analytical Cellular Pathology is a journal dedicated to the publication of original articles relating to the application of physical techniques, new imaging modalities, and computational analysis in addition to molecular approaches to the study of disease. It also publishes reviews, mini-reviews, and commentaries, which are also subject to review by its Editorial Board.

Stanley Cohen, M.D.

Director, The Center for Biophysical Pathology

UMDNJ–New Jersey Medical Center

Newark, N.Y.

E-mail: cohenst@ umdnj.edu