Researchers in the UK have developed a new method to detect cancer early by using highly sensitive MRI scans to follow the chemical breakdown of the body’s naturally occurring bicarbonate of soda (also known as baking soda).
The study is the work of scientists at the leading charity Cancer Research UK and other colleagues and is published in the current issue of Nature.
Magnetic Resonance Imaging (MRI) has traditionally been used to scan the body by detecting the distribution of water and fat in tissue. But boosting the sensitivity by more than 20,000 times transforms the MRI machine into one that can “see” molecules that cancer cells use to make energy and grow.
Developed by UK-based GE Healthcare, the new scanning technique, which is based on an emerging technology called “dynamic nuclear polarization”, can detect tumours and see if cancer treatments are working at a much earlier stage.
The technique relies on an almost universal property of even very small cancerous growths – they tend to be more acidic than surrounding tissue, that is their pH level is lower than healthy tissue. The body tries to re-balance the pH to normal by using its own natural source of bicarbonate of soda.
Using laboratory mice, the researchers used the new ultra sensitive MRI scanner with a tagged form of bicarbonate to locate places where the body is trying to re-balance the pH level, which is likely to be where cancer occurs.
The technique works because the new type of MRI scanner measures the signal intensity of the tagged form of bicarbonate and compares it to the signal intensity of one of its byproducts, the tagged carbon dioxide, which is produced when the body tries to re-balance the pH to a less acidic level.
Professor Kevin Brindle, from Cancer Research UK’s Cambridge Research Institute at the University of Cambridge led the research. He said that this new MRI technique could become an early warning system for cancer.
“By exploiting the body’s natural pH balancing system, we have found a potentially safe way of measuring pH to see what’s going on inside patients,” said Brindle.
“MRI can pick up on the abnormal pH levels found in cancer and it is possible that this could be used to pinpoint where the disease is present and when it is responding to treatment,” he explained.
With the highly sensitive MRI tool, the researchers could see how much of the tagged bicarbonate was turned into carbon dioxide inside the tumour; the more acidic the tumour, the more carbon dioxide it produces.
First author of the study, Dr Ferdia Gallagher, who is a clinical training fellow at Cancer Research UK and Royal College of Radiologists, and also a radiologist at Addenbrooke’s Hospital in Cambridge, said:
“Although it’s early days, if this technique proves to be safe and effective in cancer patients it has the potential to be a crucial tool in detecting cancer earlier – which is often the key to successful treatment.”
“Our technique allows the spatial distribution of pH to be imaged using MRI which is something that has not previously been possible in patients,” added Gallagher, explaining that:
“This new method is important because the chemical we use isn’t toxic and is already administered safely to humans.”
The researchers concluded that:
“Given that bicarbonate is an endogenous molecule that can be infused in relatively high concentrations into patients, we propose that this technique could be used clinically to image pathological processes that are associated with alterations in tissue pH, such as cancer, ischaemia and inflammation.”
Director of cancer information at Cancer Research UK, Dr Lesley Walker, said it was really important to find new ways of diagnosing cancer early, and also to establish whether drugs are working or not.
“So if clinical trials show that this technique is as safe and effective in cancer patients as we expect, this could be a very useful tool in the early detection of cancer and may save many lives,” said Walker.
“Magnetic resonance imaging of pH in vivo using hyperpolarized 13C-labelled bicarbonate.”
Ferdia A. Gallagher, Mikko I. Kettunen, Sam E. Day, De-En Hu, Jan Henrik Ardenkjær-Larsen, René in ‘t Zandt, Pernille R. Jensen, Magnus Karlsson, Klaes Golman, Mathilde H. Lerche & Kevin M. Brindle.
Nature, Published online 28 May 2008.
DOI:10.1038/nature07017
Source: Cancer Research UK.
Written by: Catharine Paddock, PhD