Urs Utzinger

In-vivo fluorescence EEM collection of normal and cancerous epithelial tissue in the hamster cheek pouch model

Fluorescence spectroscopy has been shown to be a viable technique for the diagnosis of epithelial dysplasia and neoplasia both in-vitro and in-vivo.1 Since excision and fixation change important characteristics of tissue such as vascularity and metabolic rate, it is desirable to obtain excitation-emission matrices (EEMs) in-vivo for more accurate assessment of the fluorescence properties of the tissue being probed. We have designed and constructed an instrument which allows for the collection of fluorescence emission spectra at 18 different excitation wavelengths in about 3 minutes, a time short enough to allow in-vivo probing. The system consists of a white light source which is filtered by a monochromator and delivered to the sample via an optic fiber probe. The same probe collects the fluorescence which is passed through long-pass filters into an imaging spectrograph and detected with a TE-cooled CCD camera. The entire system is under computer control.

Acetic acid: A contrast agent in optical imaging and spectroscopy of tissue

Contrast agents are commonly applied to tissue in vitro and in vivo to aid in the extraction of diagnostically useful information from the sample. For example, staining techniques are commonly used to highlight cellular structures when using light microscopy to examine tissue samples. On a more gross level, sensitive differentiation between normal tissue and neoplasia in various tissue sites has been recently demonstrated through the use of 5-aminolevulinic acid induced protoporphyrin IX fluorescence [1].