We demonstrate the proof of concept for use of a fiber optic FTIR instrument to perform in vivo detection of
colonic neoplasia as an adjunct to medical endoscopy. FTIR is sensitive to the molecular composition of tissue, and can
be used as a guide for biopsy by identifying pre-malignant tissue (dysplasia). First, we demonstrate the use of a silver
halide optical fiber to collect mid-infrared absorption spectra in the 950 to 1800 cm-1 regime with high signal-to-noise
from biopsy specimens of colonic mucosa tissue ex vivo. We observed subtle differences in wavenumber and magnitude
of the absorbance peaks over this regime. We then show that optimal sub-ranges can be defined within this spectral
regime and that spectral pre-processing can be performed to classify the tissue as normal, hyperplasia, or dysplasia with
high levels of performance. We used a partial least squares discriminant analysis and a leave-one-subject-out crossvalidation
strategy to classify the spectra. The results were compared with histology, and the optimal thresholds resulted
in an overall sensitivity, specificity, accuracy, and positive predictive value of 96%, 92%, 93%, and 82%, respectively
for this technique. We demonstrate that mid-infrared absorption spectra can be collected remotely with an optical fiber
and used to identify colonic dysplasia with high accuracy. We are now developing an endoscope compatible optical
fiber to use this technique clinically for the early detection of cancer.
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