PET - at what cost?

A number of articles and letters on the subject of positron emission tomography (PET) have been published in recent weeks in The Sunday Times. The most recent article, written by Jean Pierre Fava (September 2) asks whether we need PET technology.

The answer is that we obviously do. However, he failed to ask the question: At what cost? Whereas I am sure that all authors have the interests of cancer patients at heart, I feel that a few clarifications need to be made.

I will not go into the technical details of PET as these have already been discussed by others. What needs to be said, however, is that these days, nobody talks about stand-alone PET anymore but PET/CT, where the metabolic information provided by the PET scan is superimposed on the anatomical structures depicted on the CT scan.

In fact, sales of stand-alone PET systems these days are less than one per cent of total PET sales. These hybrid machines can be used in several ways. Their main role is whole body imaging of cancer patients.

As the CT component of the current generation is multi-slice CT (from 16 slice upwards), these scanners can also be used as stand-alone CT scanners for sophisticated imaging procedures, such as non-invasive coronary angiography.

This technology is not cheap. If one were to look at our more affluent northern neighbours, one would see that there is a wide variation in service provision between the different countries. In 2003, there was only one scanner per 10 million in the UK, whereas there was one per 400,000 in Austria.

Nowadays, these figures have changed as various health authorities have recognised the importance of investing in such technology following intense lobbying by the European nuclear medicine community. In fact, the established catchment population for one scanner these days is considered to be 500,000 in Western Europe.

Thus, in theory, Malta's population should justify such an investment if not for one very basic difference between our European neighbours and us.

The radioactive substances used in PET (tracers) are very short-lived isotopes, the most widely used being 18FFDG with a half-life of approximately two hours. This means that if 100 units of the substance are shipped, only 50 units are left after two hours due to isotope decay.

These substances are produced in cyclotrons and then transported over the road or rail networks to hospitals lying within a radius of 300 km. Every shipment, therefore, has to reach the hospital in as short a time as possible for it to be used in patients.

On the European mainland, one central cyclotron provides isotopes to several satellite hospitals daily. Thus, hospitals do not have to go into the capital expenditure and running costs of producing such isotopes.

In Malta, we do not have the luxury of having a cyclotron sited within a short distance and we would thus have to look at all options available, as well as the cost of these options, before embarking on such a project. It would be a complete waste of taxpayers' money if one were to purchase a PET/CT scanner without ensuring that this goes hand in hand with a reliable and affordable provision of the radioactive tracers used.

We now have over 12 years of experience in shipping of radioisotopes from mainland Europe to St Luke's Hospital and the shortest lived isotope that we have been successful in using in our hospital has a half-life of 13 hours, using commercial flights.

Each time that we use this isotope in our paediatric cancer patients, we need to ensure that all parties involved know exactly what needs to be done. A simple delay or a missed connection means that the shipment would be wasted.

An isotope with a half-life of two hours is much more critical and would need to arrive in our hospital six hours after production at the latest. Thus our options for purchasing FDG are extremely limited.

- identify a site in mainland Europe (Italy) and ship daily using commercial flights;

- identify a site in Sicily and use a helicopter or a small plane for shipment;

- identify companies that produce and ship these isotopes using their own planes; or

- set up a cyclotron in Malta.

The first three options require no capital investment but are very expensive on a daily basis. Of the three, option one is the cheapest. We will still, however, be at the mercy of the elements, congested airports and other highly unpredictable factors.

The last option requires a huge capital outlay, but is low on running costs. There will, however, be a problem with the staffing of such a facility in the first few years.

Interesting developments on the horizon include generator-produced isotopes for PET imaging, similar to technetium generators used nowadays for imaging with a gamma camera. These generators might, one day, do away with the need of using cyclotron-produced isotopes. However, these developments have not yet made it to the market.

It would be irresponsible to embark on a PET/CT project in Malta without taking a holistic approach to the problem. Whereas no one in his right mind would put the clinical utility of PET/CT in question, the fact that we live on an island has significant cost implications on such a project and costing models used in mainland Europe cannot apply here.

These would significantly underestimate the cost of this technology in our country. Nevertheless, such costings should and are being done. Our role as clinicians is to provide the information to the budget holders and to lobby in the interests of our patients.

The ultimate decision as to whether to invest in PET/CT will however be in the hands of the policymakers. Comments, such as those made by Mr Fava in an attempt to denigrate Mater Dei Hospital, do not contribute in any way to a scientific debate.