Development of spectral markers for the discrimination of ulcerative colitis and Crohn's disease using Raman spectroscopy

BACKGROUND: Ulcerative colitis and Crohn's disease are 2 distinct forms of IBD that can overlap radiologically, endoscopically, and pathologically. This difficulty complicates surgical options. The development of new technologies providing accurate diagnosis of IBD is needed. Raman spectroscopy is a noninvasive method that uses the intrinsic properties of tissue and that tissue's vibrational energy in reaction to light. PURPOSE: We hypothesize that Raman spectroscopy can detect the structural and compositional changes that occur in the tissue during the development of inflammatory bowel disease, and thus may offer increased diagnostic certainty in the differentiation between Crohn's disease and ulcerative colitis. METHODS: Fresh frozen colon tissue biopsies from patients with ulcerative colitis (n = 12) and with Crohn's disease (n = 9) were measured in vitro using a customdesigned Raman fiber-optic probe. For spectra collection, the probe was placed in gentle contact with the mucosa surface for 3 seconds, with excitation power at 150 mW. Five spectra were acquired from each biopsy to increase the signal-to-noise ratio and to ensure repeatability of data collection. Mean spectra were analyzed for peak difference and molecular origin. RESULTS: Significant difference was observed between the spectra from each disease in the spectral regions assigned to nucleic acid, phenylalanine, and lipids. Tissue samples from patients with ulcerative colitis demonstrated higher content of lipid and lower amount of phenylalanine and nucleic acid. These characteristic Raman features could serve as spectral markers that can potentially be applied to distinguish ulcerative colitis and Crohn's disease. CONCLUSIONS: This study presents the only application of Raman spectroscopy in the diagnosis of inflammatory bowel disease. The feasibility of this technique in differentially detecting molecular alterations in ulcerative colitis and Crohn's disease has been demonstrated, indicating the potential to improve diagnostic accuracy of inflammatory bowel disease.