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Positron emission tomography (PET) was first proposed in the 1960s, but it is only recently that its importance as a clinical tool has been recognised in the UK.
In PET, the patient is injected with a pharmaceutical labelled with a radioactive substance (radiopharmaceutical). By detecting the radiation as it emerges from the patient, an image forms showing the distribution of the pharmaceutical in the body.
This image gives doctors information about the function of tissues, whereas x-ray or ultrasound imaging mainly gives information about how organs look. PET is a very useful tool for detecting early cancer or its recurrence after treatment, and for detecting brain abnormalities in conditions such as epilepsy and dementia.
Researchers at Hammersmith Hospital in London were major pioneers of PET in the UK, and the team there developed software called ‘SPM’ that is now used worldwide to analyse PET images and detect subtle changes in tissues.
They also developed the applications of 3D PET in the UK, and the general methodology for producing carbon-labelled radiopharmaceuticals.
A second PET centre was set up in the UK at the University of Aberdeen in the 1980s, where researchers demonstrated how valuable PET could be in routine medical practice, for example in detecting cancers.
In 1992, a commercial PET centre was established at Guy's and St Thomas' Hospitals, focusing on providing a clinical PET imaging service.
PET scanners are now combined with CT Imagers. This is a powerful imaging tool as it gives images showing both anatomy and tissue function.
Combining PET and MRI is a future possibility being looked at by research groups, at the University of Oxford for example. Such a system would provide highly-detailed views of internal organs and the workings of the brain, while giving the patient a lower dose of radiation.
Researchers, such as groups at the University of Liverpool and the Institute of Cancer Research, are refining PET systems by designing new gamma-ray detectors which would provide clearer images, or cheaper and more portable machines.
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