The use of the agent FET in conjunction with Macquarie University Hospital’s advanced PET scanner is affording brain tumour patients a more accurate assessment – and more appropriate treatment of recurrent lesions.


“Accurate assessment is crucial for patients who have already had significant doses of radiation or chemotherapy as part of their cancer therapies,” said Dr John Fuller, Macquarie University Hospital Neurosurgeon.

“While the hospital has the best internationally standard gamma knife that delivers very targeted radiation beams, we still need to carefully consider a patient’s total dosage of radiation that has been received during the entirety of their treatment. It is important, in these patients, to determine more precisely what is occurring, so as to administer additional radiotherapy only if it is going to be advantageous.”

To reduce these crucial levels of uncertainty, Professor John Magnussen – Professor of Radiology and Head of Macquarie Medical Imaging – introduced the use of the agent Fluoroethyl-tyrosine (FET), an amino acid metabolism tracer that measures cell proliferation.

“FET is a better marker of the most common primary brain tumours than FDG because it does not accumulate significantly in the normal brain,” said Professor Magnussen. “When FET is used in PET brain imaging, we instead see a focal area light up, showing just the tumour, instead of being obscured by normal brain tissue.”

Macquarie University Hospital has a state-of-the-art, time-of- flight PET/CT scanner. Together with the high field strength MRI and new PET agents like FET, it provides much greater diagnostic certainty and, ultimately, better patient care.

Macquarie University Hospital doctors have had success diagnosing a recurrent glioblastoma, a particularly aggressive primary brain tumour, using FET. In this instance, it was important to diagnose tumour recurrence as the patient was running the risk of developing additional problems, such as speech difficulties, if the lesion was indeed active. Results from a head scan using FDG PET were equivocal. But when doctors used FET, they saw a clear indication of tumour recurrence.

On that basis, they could determine that the best possible treatment was a further course of radiotherapy, using Macquarie University Hospital’s new gamma knife technology.

“FET PET imaging is enormously advantageous to the patient,” said Professor Magnussen. “Previously, the best diagnostic method available would have been a biopsy to determine tumour recurrence. Instead, like the gamma knife, we can use a non-invasive approach to our tumour management.”