Early warning system

The detection and treatment of cancer tumours could be dramatically improved by techniques being developed to make medical imaging technology up to one million times more sensitive. The techniques also have possible uses in the oil and gas industries.

A UK project, involving Cancer Research UK, Nottingham and York Universities and the Rutherford Appleton Laboratory, is developing technologies to significantly increase the magnetic alignment of materials, called hyperpolarisation.

This will improve the sensitivity of magnetic resonance imaging (MRI) and spectroscopy up to a million fold, enabling new applications in cancer research, said Prof Martin Leach, director of Cancer Research UK’s clinical magnetic resonance research group. ‘Hyperpolarisation is a very new approach, but it has incredible potential,’ he said.

The research team hopes the technique will improve the treatment of most solid tumours, through quicker diagnosis and the study of new cancer drugs. With all cancerous tumours the earlier they can be detected the quicker and more effectively they can be treated.

Hyperpolarised molecules can act as magnetic labels, and when attached to antibodies targeted at a tumour can be injected into patients and used to highlight the area for MRI scanning, improving diagnosis. The labels produce a strong signal that the MRI scanner picks up, enabling it to create highly detailed images.

Hyperpolarised carbon-13 molecules can also be attached to drugs, allowing researchers to follow their progress using MR imaging, said Leach. ‘We have a major interest in trying to identify whether new drugs are working, so we need to develop probes to tell us whether pathways are being inhibited, and if the drugs are being delivered.’

Nuclear MRI is a powerful diagnostic tool, but is severely limited in its range of applications because of its poor sensitivity, said Peter Morris, professor of physics at Nott-ingham University. Improving this sensitivity by such a degree using conventional means would take magnets with enough power to attract the Earth from Mars.

Hyperpolarised gases are already been investigated by researchers in Denmark and Germany for their use in taking images of the lung, which cannot be done using standard MR methods as the surface effects cause signal loss.

Hyperpolarising molecules is a means of tagging magnetically rather than radioactively, said Morris. The absence of radioactivity makes it safer for scanning special groups, such as children.

Oil industry benefits

The development of hyperpolarisation will also benefit researchers in the oil and gas industry, he said. ‘In the oil industry the problem is that once you have located the oil you then have to get it out, which can be difficult. One way to help with this would be to put a label in and study the flow.’

Pharmaceutical companies could use the technique to label molecules of therapeutic interest, and use this to study their make-up or interaction with a substrate, to assist in both the design and delivery of new drugs, he said.

Hyperpolarisation techniques

There are various methods of hyperpolarising nuclei, and the research teams will be investigating each to determine which is the most effective, as part of the £21m Basic Technology Programme funded by Research Councils UK.

Researchers at York University are investigating the use of parahydrogen, a form of molecular hydrogen in which its two proton spins are aligned antiparallel to each other. When used as the feedstock for a particular chemical reaction the molecules produced are hyperpolarised, and as a result have a much stronger nuclear magnetic resonance signal, which can be picked up by MRI equipment.

Prof Peter Morris’ team at Nottingham University is planning to generate hyperpolarisation by polarising the electrons of gaseous metal atoms using a laser, and then transfer this polarisation across via collision to the nuclei of noble gases such as xenon or helium.

Another option is to cool a noble gas to an extremely low temperature, then put it into a high magnetic field, enticing it into a low energy state. Once the gas has been hyperpolarised, the effect can be transferred to other types of molecule.

Cancer Research UK has found the most effective transfer method is to place the two molecules in close proximity by freezing them or converting them into a liquid state, said Prof Martin Leach.