The detection of mucosal dysplasia at endoscopy relies on random sampling for this endoscopically "invisible" malignant precursor. We have investigated the potential application of diffuse reflectance spectroscopy performed during colonoscopy to assess its ability to obtain histological information such as the presence of dysplasia. The objective of this study was to develop a technique that can provide pathological information to the endoscopist in real time. Reflectance spectra (range: 360-685 nm wavelength) were collected during colonoscopy from 11 adenomatous polyps and adjacent normal-appearing mucosa in 11 patients. A 1.4 mm diameter fiber optic probe passed via the accessory channel of a standard videocolonoscope was used for data collection. The collected spectra were characterized using a physical model of light propagation in tissue incorporating tissue properties such as light absorption and scattering, and a multilayered tissue structure. The model was formulated in terms of four parameters, 1) hemoglobin concentration, 2) mucosal thickness, 3) hemoglobin oxygenation, and 4) overall intensity of the reflectance spectra. Application of the model showed that it can accurately predict the clinical data. A unique set of the four parameters were obtained characterizing each tissue site. A detailed analysis of the four parameters showed that the adenomatous polyps contained a higher concentration of hemoglobin and were comprised of thicker mucosa when compared to the adjacent endoscopically normal-appearing mucosal sites tested. These observations were consistent with the histopathological findings. In addition, spectral intensity was found to be consistently lower and hemoglobin concentration was minimally higher in adenomatous polyps. Incorporation of this technique into a system using multi-excitation fluorescence spectroscopy (currently in progress) will provide a system with an enhanced ability to detect mucosal dysplasia at endoscopy.
ASJC Scopus subject areas
- Radiology Nuclear Medicine and imaging