New Probe to Detect Inflammatory Bowel Disease During Routine Colonoscopy

A sensor that can detect inflammatory bowel disease (IBD), distinguishing between the two subtypes that exist, will spearhead better care for patients soon. The device is found to have greater sensitivity than currently used diagnostic methods. The development of this device would help identify individual symptoms and facilitate a more personalized care. Inflammatory bowel disease is a chronic inflammation of the bowel and it affects more than 1 million people in the US and 2.5 million in Europe. The diagnostic procedures that are currently available are based largely on trial and error and are not exact.

A pilot study reported in the Journal Biomedical Optics Express, includes details about a specially designed endoscope that uses Raman spectroscopy, the technique used to observe vibrational, rotational, and other low-frequency modes in a system. The chemical-fingerprinting technique helps identify molecular markers of IBD in the colon. This endoscope is minimally invasive and can be included in a colonoscopy exam.

Dr. Anita Mahadevan-Jansen who is the senior author of the study and from The Vanderbilt University, initiated the project after her tryst with IBD. "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. 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."

Identifying IBD

There are two subtypes of IBD

• Ulcerative colitis : A chronic, inflammatory bowel disease that causes inflammation in the
• innermost lining of the large intestine (colon) and rectum.
• Crohn’s disease : Inflammation that occurs in any part of the gastrointestinal tract.

The subtypes have similar symptoms and can lead to pain, fatigue, diarrhea, weight loss but the two subtypes differ in their response to treatment.

The current method of diagnosis involves the use of clinical, radiological as well as pathological methods to identify the type of IBD but all these measures are used to detect the symptoms rather than the subtype. The major drawback that nearly 15% of the patients do not know their subtype while another 15% may be reclassified based on how they react to treatment provided.

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Studies that were conducted earlier show that each of the subtype has a unique molecular signature. The device that has been developed detects the signatures and the inflammation state of the patients, providing a definite picture about the IBD and the subtype.

Dr. Mahadevan-Jansen added, "Most people go through baseline colonoscopy as part of routine care, and you could imagine using this to get a baseline Raman signal for each person. If someone presents with IBD symptoms later on, you can use our system again to determine if it's more likely to be UC or Crohn's. Then once they are being treated, you have an objective measure to track their response because you can use the device to actually quantify mild, moderate or severe inflammation."

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Developing the Probe

The researchers used samples of tissue as well as animal models to determine the initial biomarkers and the spectral signatures that were associated with IBD. After which a small portable Raman spectroscopy system was developed with a 785 nm diode laser along with a fibre optic probe which could deliver 80 mW to the colon surface.

Dr. Mahadevan-Jansen explained further, "The customization was both the packaging - to make sure it can fit easily in the endoscopy channel and bend through the turns of the colon - and to probe the right depth in the tissues we are looking at to make sure we can get a robust measurement."

This is not the first time that Raman spectroscopy has been used in medical applications, earlier it was shown to detect cancer in the gastrointestinal tract. There was a lot of subtlety involved in the use of this spectroscopy in the detection of inflammation as there are only minor changes that are visible. The research team involved in the study included special filters that removed the Raman signature that were caused due to the use of the probe.

• Pilot Test
• The device was used to detect inflammatory bowel disease in 15 patients with Crohn’s disease, 8 patients with Ulcerative colitis and 8 healthy volunteers.
• The results of the study showed that the device had high sensitivity, which is the ability to detect IBD but could not differentiate between the two subtypes.
• Among patients with active inflammation, the device detected Crohn’s disease with
• 90% sensitivity
• 75% specificity
• Among patients with all types of inflammation, the device detected Crohn’s disease with
• 86% sensitivity
• 39% sensitivity

Interpreting Results

A set of algorithms are currently being refines by the research team to facilitate easy understanding for the doctors. Apart from that, greater specificity is being gathered by understanding the gender, diet and demographic influence.

The device is very useful in detecting IBD a lot more precisely than the currently available diagnostic methods, aiding in better care.

References:

1. Isaac J. Pence, Dawn B. Beaulieu, Sara N. Horst, Xiaohong Bi, Alan J. Herline, David A. Schwartz, Anita Mahadevan-Jansen. Clinical characterization of in vivo inflammatory bowel disease with Raman spectroscopy. Biomedical Optics Express, (2017); 8 (2): 524 DOI: 10.1364/BOE.8.000524
What is Crohn’s Disease? - (http://www.ccfa.org/what-are-crohns-and-colitis/what-is-crohns-disease/)

Source-Medindia