Berthold Australia Pty Ltd, through the research of its CRCBID-funded post-doctoral student, Dr Bryn Sobott,  is working to develop a clinical prototype system for non-invasive arterial monitoring of PET tracers.  This new system is built upon the earlier work of Dr Graeme O’Keefe and Dr Roger Rassool, who pioneered the initial concept.

The prototype NIAM system being developed through CRCBID - image courtesy Bryn Sobott

Some PET protocols require patients to have arterial blood samples drawn over the span of hours, and this procedure can be difficult. In contrast to the complex procedures involved with arterial sampling, the operation of NIAM is relatively simple.

The patient’s wrist is placed in the central bore of the scanner, which is surrounded by an array of position- sensitive detectors. These detectors are used to image and quantify the positron activity within the patient’s wrist.  The relative ease with which quantified imaging can be approached aims to facilitate tracer evaluation and improve patient comfort.

To obtain a quantitative measurement of radio-isotope concentration in arterial blood there needs to be an intrinsic spatial resolution of 2-3 mm, to distinguish the arteries in the wrist.  In developing the clinical scanner, the CRCBID team has concentrated on optimising the geometry and improving the data acquisition system with the anticipated outcome of realising a clinical device.

“A system such as this would allow the level of the PET isotope in the blood to be measured over time,” says Bryn, “and enable a quantitative analysis of the PET images obtained at particular times.  This analysis would allow us, for example, to measure the extent of receptor binding.”

Initial validation has commenced, with the results from NIAM indicating that its measurements provide a reasonable correlation to those obtained through measurement from blood samples.  “We expect that the correlation will improve further as the system is refined,” says Bryn.