March 20, 2013
TORONTO (Canadian Press) -- Researchers have taken a page out of Google's book to develop an advanced scope that may enable doctors to look deeper into the colon and with more precision to better detect signs of cancer.
The scope would not only allow doctors performing a colonoscopy to get the standard forward-looking view, but would also capture images of the sides of the large bowel, similar to the way Google Street View provides a 360-degree picture of a road and its buildings.
"Unlike conventional colonoscopy, which only looks straight ahead, this new method can be likened to Google Street View, giving us a panoramic view of the colon and helping us identify the exact locations of suspicious growths or lesions," says Dr. Qiyin Fang, Canada Research Chair in Biophotonics at McMaster University.
The device is armed with a near-infrared light camera that takes thousands of pictures and uses blood vessels as landmarks to create a map of the colon.
Like blood vessels in the skin and retina, the pattern of arteries and veins inside the colon are virtually unique to each person, said Dr. David Armstrong, a gastroenterologist at McMaster, who is part of the development team.
"We'll be able to see where they branch, where they join together, where there are different patterns of branching and joinings together, so we can construct what looks like a map of the colon," Armstrong said Monday from Hamilton.
"And because it's likely to be unique as we go around (inside the colon), we'll be able to tell firstly how far the scope has gone in and then secondly is there a unique pattern, like a street pattern, that you can look at and say, 'OK, I know where about in the colon that is.'"
The views captured by the scope would be combined with pattern-recognition software to pinpoint certain locations on the map of a patient's colon, a long, stretchy tube inside the abdomen that looks somewhat like an inverted "U."
"And that means if we find a polyp or an abnormality there and we've got a picture of it, then we can go back and find that same thing again," he said. "We can say that's the junction of 4th and 52nd Street.
"If I do the procedure again in two years, I can retrieve the map that I had before and I can go around and say, 'OK, there's a funny little bit there, but that's actually a different place from where we took the polyp off last time. It's not a recurrence, it's a new lesion.'"
Being able to identify as many pre-cancerous polyps and already malignant lesions as possible is critical for preventing and/or diagnosing and treating colorectal cancer, the second most common cause of cancer death for men and women combined.
Last year, an estimated 23,300 Canadians were diagnosed with colorectal cancer and 9,200 died of the disease, says the Canadian Cancer Society, which announced a $194,000 grant Tuesday for testing the innovative imaging technology.
Armstrong said it can be challenging for doctors performing a colonoscopy to advance the scope to the top of the right-hand side of the bowel, known as the ascending colon.
It is an area that often houses more deadly tumours, possibly because they are harder to detect in the pre-cancerous polyp phase. Typically, polyps look like blobs of tissue that grow on stalk-like appendages.
"But what we're realizing is on the right-hand side of the colon, these polyps may be a little different, they may be flat rather than raised like little mushrooms and therefore they're more difficult to see," he said.
"One of the other things that may come out of it -- it's not clear, but it may -- is if we're using near-infrared images that show blood vessel patterns, if there are flat lesions they may actually distort the blood vessel pattern so it may make it easier to pick them up."
Fang said the team plans to start testing a miniaturized version of the scope on animals -- in this case, small pigs whose intestinal tract mimics that of humans -- in about 18 months.
If the results are promising, clinical trials in people would follow in about another two to three years, he said.
The hope is to replace the current technology.
"If we have this, we won't need the standard colonoscope because this provides a much better view and the ability to locate and remember where any abnormalities were," Armstrong said.
"I think it's exciting. I think it addresses a real need."
The Canadian Press, 2013