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Biomedicine

Magnetic Spin to Revolutionize Medical Scanning

Novel technique boosts sensitivity one thousandfold.

A novel method of transferring magnetic spin can amplify the sensitivity of magnetic resonance imaging (MRI) a thousandfold, according to new research from the University of York in the United Kingdom. Scientists say the leap could be as revolutionary for medicine as the development of MRI was 30 years ago.

More magnetism: Shown here is an MRI image of a one-centimeter-wide tube containing smaller tubes covered with a molecule called pyridine. The pyridine has been polarized, using a new technique developed by scientists at the University of York in the United Kingdom, making the small tubes much more visible.

The technique has the potential to “bring benefits to diagnosis and treatment of virtually every area of medicine,” says Ian Greer, head of Hull York Medical School, who was not involved in the research. The technology allows MRI images to be captured much more rapidly and cheaply than is possible with existing methods.

MRI generates detailed images of organs and tissues throughout the body by using radio waves to generate changes in the magnetic field of hydrogen atoms in the sample under study. Special dyes, known as contrast agents, are often used in medical scans to improve the visibility of internal body structures. These dyes, such as the heavy metal gadolinium, are magnetic and thus easily detectable with MRI.

The new method, published today in the journal Science, enables the magnetization of a broad range of molecules–including drugs such as nicotine, and organic molecules such as antibodies designed to bind to tumors–so that they can be used as contrast agents.

Scientists first cool the molecule to create a form of molecular hydrogen, called parahydrogen, which has a highly ordered magnetic spin state. An iridium catalyst transfers the magnetic spin from the parahydrogen to other key elements, including oxygen, nitrogen, and carbon.

These polarized drugs or marker molecules are highly visible in MRI scans. “For example, you might use the technique to polarize the molecule that you know will stick to a brain tumor to see what’s happening with an MRI scan. Currently MRI is not sensitive enough to do this,” says York team member Gary Green, director of the York Neuroimaging Centre. Green notes that his team has already used the technique to polarize a range of key substances, including pyridine and nicotinic acid, which are present in many drugs.

“They managed to polarize such a wide range of molecules, which suggests a wide range of uses in medical and drug research,” says Richard Bowtell, a magnetic resonance physicist at the University of Nottingham in the U.K., who was not involved in the research.

This method isn’t the first to prime molecules for use in MRI by boosting magnetic spin. Dynamic Nuclear Polarization (DNP), under development in the U.S., uses spin taken from electrons. DNP requires temperatures of 20 Kelvin and several hours for substances to be polarized for use in MRI, a disadvantage compared to the new technique. However, it’s not yet clear whether Green’s team can match the level of polarization achieved with DNP. “They’ll need to do 10 times as much again to match the polarization you get with DNP,” says Kevin Brindle, a scientist at the University of Cambridge who is working on the DNP technique with backing from General Electric. “They say in the paper they can do this. Let’s wait and see.”

Green aims to begin animal tests of the technology this year, and clinical testing within five years. Extensive clinical testing needs to be done before this approach is approved for medical use.

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