A group of UK investigators from Cancer Research UK, University of Cambridge, and GE Healthcare are reporting in the latest Nature on a new method to accentuate contrast of MRI images. The core of their thinking was to use hyperpolarized 13C-labeled bicarbonate to visualize areas of low pH that often occur in and around cancer, ischemia and inflammation.
Cancer Research UK explains:
Almost all cancers have a lower pH than the surrounding tissue. Normally, the human body has a system of balancing chemicals with a low pH, acids, and chemicals with a high pH, alkalis, to maintain a constant, healthy pH level. In cancer, this balancing system is disturbed, and the tissue becomes more acidic.
Currently, there is no way to safely measure differences in pH in patients, but spotting these areas of acidity could be used to find cancers when they are very small.
Working with mice, the team found a new way to measure pH levels using this very sensitive MRI technique with a tagged form of bicarbonate. Bicarbonate, or baking soda, occurs naturally in the body, where it is involved in the acid-alkali balancing system.
Lead researcher Professor Kevin Brindle, from Cancer Research UK’s Cambridge Research Institute at the University of Cambridge, said: "This technique could be used as a highly-sensitive early warning system for the signs of cancer. Establishing such tools is a major challenge in cancer research.
"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. 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."
Using MRI, they looked to see how much of the tagged bicarbonate was converted into carbon dioxide within the tumour. In more acidic tumours, more bicarbonate is converted into carbon dioxide.
First author of the study, Dr Ferdia Gallagher who is a Cancer Research UK and Royal College of Radiologists clinical training fellow, based at the University of 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."
Dr Gallagher, who is also a radiologist at Addenbrooke’s Hospital in Cambridge, added: "Our technique allows the spatial distribution of pH to be imaged using MRI which is something that has not previously been possible in patients. This new method is important because the chemical we use isn’t toxic and is already administered safely to humans."
Press release: Body’s baking soda used to catch cancer early…
Abstract: Magnetic resonance imaging of pH in vivo using hyperpolarized 13C-labelled bicarbonate…
Image credit: Wellcome images: Fracture at C6…