Spectroscopy Sensor Detects Inflammatory Bowel Disease

A customized endoscope uses Raman spectroscopy to detect molecular markers of inflammatory bowel disease (IBD) in the colon.

Developed by researchers at Vanderbilt University, the Medical College of Georgia, and other institutions, the Raman spectroscopy probe is based on a 785 nm diode laser and a fiber-optic probe that delivers an 80 mW beam of light to the surface of the colon. When the laser beam of light interacts with the tissue, part of it is reflected and part of it is scattered. The scattered radiation contains data on constituents of the tissue, the chemical bonds that connect them, symmetry of the molecule structure, and the physico-chemical environment where they reside.

In a pilot study, the researchers used the device in 15 patients with an existing diagnosis of Crohn's disease, eight patients with ulcerative colitis, and eight healthy volunteers. The probe detected Crohn's disease with a sensitivity of 90% and a specificity of 75%, compared to 86% and 39%, respectively, when the results are averaged across all disease states, inflammation levels, and locations within the colon. According to the researchers, this suggests high sensitivity for IBD but poor specificity in the ability to differentiate between subtypes. The study was published in the February 2017 issue of Biomedical Optics Express.

“With current methods, ultimately the diagnosis is dependent on how the patient responds to therapy over time, and you often don't know the diagnosis until it's been a few years,” said senior author Anita Mahadevan-Jansen, PhD, of Vanderbilt University. “That's why we decided to use a light-based method to probe the biochemistry of what's going on in the colon. Our goal is to use Raman spectroscopy to look at the actual inflammatory signals.”

IBD, which includes ulcerative colitis and Crohn’s disease, affects over one million Americans and two million Europeans, and the incidence is increasing worldwide. Both usually involve severe diarrhea, pain, fatigue, and weight loss. Ulcerative colitis causes long-lasting inflammation and ulceration in the large intestine and rectum. Crohn's disease causes an inflammation that can involve different areas of the digestive tract, the large intestine, small intestine, or both.