During the past decade, Fourier transform infrared (FT-IR) microspectroscopy has been used successfully in many studies to differentiate normal and diseased tissue samples obtained from a variety of organs, including colon, cervix, prostate, and breast. IR images were constructed by collecting spectra point-by-point using a mapping stage on a FT-IR microscope equipped with a single-element detector. Five years ago, in collaboration with NIH scientists Dr. Neil Lewis and Dr. Ira Levin, Procter and Gamble researchers developed a technique for performing vibrational spectroscopic imaging microscopy using a liquid-nitrogen-cooled focal-plane array (FPA) detector and a step-scanning FT-IR spectrometer coupled to a refractive microscope. With this configuration, equipped with a new 64-pixel x 64-pixel Mercury-Cadmium-Telluride (MCT) FPA detector, we are able to image an 800-μm x 800-μm area of a specimen without moving the sample.

For all of these IR imaging studies, the tissue samples were prepared in a manner that was special and different from that commonly used in a pathology laboratory, i.e.,the histopathology sample was not identical to the spectroscopic sample.