Scientists at The Nottingham Digestive Diseases Biomedical Research Unit (NDDBRU) at Nottingham University Hospitals NHS Trust are leading the world in exploiting MRI technology to assist in the treatment and diagnosis of Irritable Bowel Syndrome (IBS), a condition that causes serious inconvenience and discomfort to sufferers.
The three papers examine the effectiveness of using MRI to study the colon instead of x-rays. By using MRI, researchers have been able to image the bowel continuously with no risk to the patient from radiation, enabling them to learn more about the inner workings of the gut.
In the first study ‘Fasting and post-prandial volumes of the undisturbed colon’ published online in “Neurogastroenterology and Motility” scientists were able to image the colon and divide it in to three functional regions — the ascending colon, which is a storage and fermentation area, where unabsorbed residue is broken down by bacteria; the transverse colon, which is a storage area for the residue remaining after bacterial processing, and the descending colon which is a propulsive organ which pushes waste down and out of the body.
With MRI, scientists can also measure the volumes of these regions, which they have never been able to do before.
Professor Spiller, Lead Director of NDDBRU said: “We studied people with accelerated transit and to our surprise, we found that the colon size was rather similar to those with normal transit — suggesting people regulate their bowel habit to keep the colonic size constant. We also know that when you eat a meal the ascending colon expands as the meal is pushed down into it to make space in the small bowel for the new meal.
We found that this increase was smaller in IBS patients than in healthy volunteers, suggesting that the IBS patient’s ascending colon can’t relax enough. With MRI we can actually measure this change in a way that we’ve never been able to do before.”
In the second paper — ‘Novel MRI tests of orocaecal transit time and whole gut transit time: studies in normal subjects’ published online in “Neurogastroenterology and Motility”, MRI was used to measure the actual time it takes for contents to transit the bowel, using specially designed MRI visible markers which subjects ingest. Scientists can then image the bowel 24 hours later to see how far they have moved; something which was previously measured using x-rays.
“The use of x-rays in this type of procedure is undesirable for children or young women of child rearing age — which is unfortunate as both of these groups can suffer with bowel function that may need investigating. So developing this alternative method of examination has particular appeal, particularly in children — who tend to suffer with a wide range of bowel problems,” says Professor Spiller.
In the third study — ‘Differential effects of FODMAPS on small and large intestinal contents in healthy subjects shown by MRI’ published online in American Journal of Gastroenterology, researchers used the colonic imaging technique again, but this time, to improve their understanding of the causes of IBS.
By looking at fructose, a sugar commonly found in fruit, and fructans (polymers of fructose), researchers were able see what effects these had on the gut of healthy volunteers. Fructans and fructose are part of a group of chemicals called FODMAPs (Fermentable Oligo, Di — Mono Saccharides and Polyhydric alcohols), whose characteristics are that they are relatively hard to absorb, but they are fermentable, so when they go in to the colon they are exposed to the bacteria and produce gas.
“We already know that fructose is difficult to absorb, but the novelty with this new method, is that we are now able to image the end effect of this mal-absorption which is the distension of the small intestine and colon. We are currently repeating these studies in patients with IBS to see whether their symptoms correlate with the distension of the colon.”
Professor Spiller continues: “It’s been found that diets that restrict the intake of these things improve symptoms and our MRI studies show us scientifically why that improvement might occur. We were able to show that while fructose alone was poorly absorbed and distended the small bowel, when it was combined with glucose the poor absorption was prevented. We also found that fructans have little effect in the small bowel but a large effect on the colon. In future, will be able to use our MRI techniques to test specific foods to understand how they will affect IBS”.