476
S. Biswas et al.
has seen a fundamental change in using spectroscopy for cancer pathology [8].
most practitioners now recognize that imaging is absolutely essential for complex
tissues, imaging technology has vastly improved and methods to analyze data [9]
are better understood and better applied. Exciting advances in all spheres of the development of this technology are taking place in a renaissance of sorts [1]. A particular area of focus has been biomedical applications [10] and, especially, in disease
diagnosis. here, we review the needs in pathology, recent developments in various
aspects of the technology and present a brief description of some applications.
16.2 Current Techniques in Clinical Histopathology
16.2.1 General Methods and Techniques—A Brief Overview
histopathology refers to the microscopic examination of the different cell types in a
tissue with the aim of diagnosing signs of disease. one of the most important areas
in which this technique may have impact is in cancer diagnosis, grading and guidance of therapy. the procedure employed today for determining whether a tissue
has malignant disease or not after suspicious screening is as follows: a biopsy is
employed first to obtain a sample from the suspicious area from the affected tissue,
it is then fixed, for example—with formalin, to prevent degradation of the tissue and
maintain structural integrity during subsequent processing. Next, it is chemically
processed and embedded in paraffin wax, such that well-preserved two-dimensional
sections, 3–7 μm thick, can be sliced from it with the help of a microtome. These
sections are then most commonly floated onto glass slides; the slides are washed and
stained, following a standard protocol. Native tissue does not have much contrast
in brightfield microscopy. hence, a stain is used to allow a pathologist to visualize
structure. the most common stain used is a combination of hematoxylin and eosin
(h&E). hematoxylin stains the nuclei blue, whereas eosin stains cytoplasm and the
extracellular matrix pink. other types of stains commonly used include safranin, oil
Red o, congo red, silver salts and other artificial dyes. the purpose of staining is to
provide contrast between the various cell types in the tissue and counterstains can
also be used further to make visualization clearer by producing additional contrast.
Pathologists are trained to distinguish the different cell types by observing stained
tissues using a microscope, as shown in Fig. 16.1.
16.2.2 Manual Diagnostic Techniques
morphology of individual cells as well as their patterns to form functional units
such as glands, shapes of both cells and glands, numbers and (distorted) organizations of cells all provide useful evidence to differentiate between normal and malignant tissues. A pathologist typically examines the tissue at different magnifications
and determines by manual decision-making whether the tissue can be classified into
a specific grade. As may be imagined, there are several shortcomings to this manual
S. Biswas et al.
has seen a fundamental change in using spectroscopy for cancer pathology [8].
most practitioners now recognize that imaging is absolutely essential for complex
tissues, imaging technology has vastly improved and methods to analyze data [9]
are better understood and better applied. Exciting advances in all spheres of the development of this technology are taking place in a renaissance of sorts [1]. A particular area of focus has been biomedical applications [10] and, especially, in disease
diagnosis. here, we review the needs in pathology, recent developments in various
aspects of the technology and present a brief description of some applications.
16.2 Current Techniques in Clinical Histopathology
16.2.1 General Methods and Techniques—A Brief Overview
histopathology refers to the microscopic examination of the different cell types in a
tissue with the aim of diagnosing signs of disease. one of the most important areas
in which this technique may have impact is in cancer diagnosis, grading and guidance of therapy. the procedure employed today for determining whether a tissue
has malignant disease or not after suspicious screening is as follows: a biopsy is
employed first to obtain a sample from the suspicious area from the affected tissue,
it is then fixed, for example—with formalin, to prevent degradation of the tissue and
maintain structural integrity during subsequent processing. Next, it is chemically
processed and embedded in paraffin wax, such that well-preserved two-dimensional
sections, 3–7 μm thick, can be sliced from it with the help of a microtome. These
sections are then most commonly floated onto glass slides; the slides are washed and
stained, following a standard protocol. Native tissue does not have much contrast
in brightfield microscopy. hence, a stain is used to allow a pathologist to visualize
structure. the most common stain used is a combination of hematoxylin and eosin
(h&E). hematoxylin stains the nuclei blue, whereas eosin stains cytoplasm and the
extracellular matrix pink. other types of stains commonly used include safranin, oil
Red o, congo red, silver salts and other artificial dyes. the purpose of staining is to
provide contrast between the various cell types in the tissue and counterstains can
also be used further to make visualization clearer by producing additional contrast.
Pathologists are trained to distinguish the different cell types by observing stained
tissues using a microscope, as shown in Fig. 16.1.
16.2.2 Manual Diagnostic Techniques
morphology of individual cells as well as their patterns to form functional units
such as glands, shapes of both cells and glands, numbers and (distorted) organizations of cells all provide useful evidence to differentiate between normal and malignant tissues. A pathologist typically examines the tissue at different magnifications
and determines by manual decision-making whether the tissue can be classified into
a specific grade. As may be imagined, there are several shortcomings to this manual