Engineers create safer medical imaging technique

A medical imaging technique based on a new method for transferring magnetic spin could potentially reveal biological processes in the body without exposing patients to harmful radiation.

This is the goal of a GSK-supported research programme at York University, where engineers have developed a way for transferring the magnetic spin from parahydrogen, a molecule most notably used for fuelling the space shuttle. 

The team has taken parahydrogen and, through a reversible interaction with a specially designed molecular scaffold, transferred its magnetism to a range of molecules.

If this were applied to magnetic resonance imaging (MRI), it could potentially increase sensitivity a thousandfold by giving scanners the ability to detect more molecules in the body than what was previously possible.

According to Simon Duckett, a chemistry professor at York University, his research team has already demonstrated parahydrogen’s potential for magnetising molecules such as nicotine.

If properly harnessed, he said, parahydrogen could help image biological processes in the body, such as metabolisation.  

Duckett believes that this would enable doctors to spot tumours or signs of neurodegenerative diseases, such as Parkinson’s, earlier.

Much of this technology is currently possible with nuclear medicine imaging techniques such as Positron emission tomography (PET). With this method, a patient would be injected with a radioactive ‘tracer’ material that mimics a biologically active molecule in the body, such as glucose. A PET system would be able to visualise whether the glucose was being metabolised by a tumour, for example, by detecting pairs of gamma rays emitted indirectly by the tracer.

With MRI, images of organs and tissues in the body are generated using radio waves to create changes in the magnetic field of hydrogen atoms in a sample being examined. Often, these scans require magnetic contrast agents such as gadolinium. While not as harmful as the tracer agents used in PET, the magnetic contrast agents are heavy metal materials that can cause some health effects.

According to Duckett, the new technique would, potentially, require that patients are only injected with contrast material endogenous to the body, such as amino acids.

‘One of the benefits of the fact that the materials are endogenous to the body is you could repeat that measurement many times,’ he said. ‘Whereas with PET, you wouldn’t want to be repeating the measurement many times because it is toxic.’

Duckett said that the technology also removes the need for large magnets and high magnetic fields. This, he added, coupled with new detector technology means that it is theoretically possible these imaging systems could one day be shrunk down to a size that fits inside any GP office.

It may even be possible, said Duckett, to incorporate the detectors into a wearable shirt that patients could slip on for a scan. 

‘It relies on an awful lot coming together,’ he said. ‘I would like to think we’re probably ready for clinical applications, depending on how quick things happen, in the next five to 10 years.’