Fourier transform infrared (FTIR) spectroscopy is sensitive to the molecular composition of tissue and has the potential to identify premalignant tissue (dysplasia) as an adjunct to endoscopy. We demonstrate collection of mid-infrared absorption spectra with a silver halide (AgCl0.4Br0.6) optical fiber and use spectral preprocessing to identify optimal subranges that classify colonic mucosa as normal, hyperplasia, or dysplasia. We collected spectra (n=83) in the 950 to 1800 cm−1 regime on biopsy specimens obtained from human subjects (n=37). Subtle differences in the magnitude of the absorbance peaks at specific wave numbers were observed. The best double binary algorithm for distinguishing normal-versus-dysplasia and hyperplasia-versus-dysplasia was determined from an exhaustive search of spectral intervals and preprocessing techniques. Partial least squares discriminant analysis was used to classify the spectra using a leave-one-subject-out cross-validation strategy. The results were compared with histology reviewed independently by two gastrointestinal pathologists. The optimal thresholds identified resulted in an overall sensitivity, specificity, accuracy, and positive predictive value of 96%, 92%, 93%, and 82%, respectively. These results indicated that mid-infrared absorption spectra collected remotely with an optical fiber can be used to identify colonic dysplasia with high accuracy, suggesting that continued development of this technique for the early detection of cancer is promising.
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<sup>-1</sup> 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.
Science & Technology International (STI) has developed, under contract with the Office of Naval Research, a system of multispectral airborne sensors and processing algorithms capable of detecting mine-like objects in the surf zone. STI has used this system to detect mine-like objects in a littoral environment as part of blind tests at Kaneohe Marine Corps Base Hawaii, and Panama City, Florida. The airborne and ground subsystems are described. The detection algorithm is graphically illustrated. We report on the performance of the system configured to operate without a human in the loop. A subsurface (underwater bottom proud mine in the surf zone and moored mine in shallow water) mine detection capability is demonstrated in the surf zone, and in shallow water with wave spillage and foam. Our analysis demonstrates that this STI-developed multispectral airborne mine detection system provides a technical foundation for a viable mine counter-measures system for use prior to an amphibious assault.