Digistain: a digital staining instrument for histopathology.

We describe a new mid-infrared (mid-IR) imaging method specifically designed to augment the H + E tissue staining protocol. Images are taken with bespoke IR filters at wavelengths that enable chemical maps to be generated, corresponding to the cytoplasmic (amide) and nuclear (phosphodiester) components of unstained oesophageal tissue sections. A suitably calibrated combination of these generates false colour computer images that reproduce not only the tissue morphology, but also accurate and quantitative distributions of the nuclear-to-cytoplasmic ratio throughout the tissue section. This parameter is a well documented marker of malignancy, and because the images can be taken and interpreted by clinically trained personnel in a few seconds, we believe this new "digistain" approach makes spectroscopic mid-IR imaging techniques available for the first time as a practical, specific and sensitive augmentation to standard clinical cancer diagnosis methods.