The first question an organization must ask itself is whether it can afford this technology.

There are currently 2 instruments that are available commercially that apply the principles of ultra-extended FOV PET/CT imaging; the µExplorer (United Imaging, China), which has an axial FOV of just under 2 m, and the Biograph Vision Quadra (Siemens Healthineers, USA), which has an axial FOV of just over 1 m. Enthusiasm for these devices is immense in the nuclear medicine community with many world-leading institutions rushing to install these scanners, creating supply chain challenges for the companies that manufacture them. The combination of these factors, along with the high complexity of the scanners and sheer volume of materials used to make them, means that these devices come at a premium price. They are more than twice as expensive as the next-best standard FOV digital PET/CT, and closer to 3–4 times the price of most of the installed base of analog PET/CTs in clinical use globally. Would it not be more cost-effective to just buy 2 or 3 conventional PET/CT devices?

Arguments against investing in more expensive technology were similarly raised at the time that PET/CT scanners first became available. When the Peter MacCallum Cancer Centre installed the 4th PET/CT in the world in 2001, there were radiologists in the department who questioned the rationality of having an expensive CT added to an already expensive PET scanner that had limited throughput compared to a stand-alone CT. Therein was the very answer. The comparison ought not to have been against the throughput of CT but rather against the amortization of the more expensive component of the scanner, the PET device. The replacement of transmission scanning by rapid CT for the purposes of attenuation correction effectively doubled patient throughput, not to mention the clinical advantages of anatomical co-registration for correlative purposes. Provided that there were enough cases to augment throughput, the capital costs of the equipment per scan were the same or less than for a stand-alone PET. In addition to direct capital costs, more expensive and complex technology also costs more to service and maintain. Here, again, amortization of costs becomes a critical factor.

The financial case for ultra-extended FOV PET/CT must lie, at least partially, in greater throughput. This is made possible by the very substantial gain in sensitivity provided by greater coverage of the body by detector material. For example, the Siemens Biograph Vision Quadra has been shown to be 8–tenfold more sensitive, depending on the radionuclide, than the Biograph Vision 600, a standard FOV PET/CT with otherwise identical digital detector technology with time-of-flight capability [10]. Without changing the administered activity, equivalent signal-to-noise ratios, which are critical to lesion contrast and therefore detectability, can be achieved in imaging from head to pelvis in 2 min or less. Accounting for time to get patients on and off the scanner bed, 6 patients per hour is feasible with upwards of 40 patients per day possible. For standard photomultiplier tube PET/CT scanners, acquisition times can significantly exceed 30 min and, allowing for patient transfers, a daily throughput of more than 12–15 patients can be challenging. Standard FOV digital PET/CT devices can shorten acquisition times through enhanced sensitivity but 3 per hour would be a typical throughput.

This isn’t, however, the only economy that can be achieved. Leveraging this greater sensitivity can also allow a reduction in the administered activity required to acquire high-quality scans if acquisition times are less dramatically reduced. For expensive radiopharmaceuticals, particularly if produced at relatively low yields, this could represent significant cost savings. Consider, for example, radiopharmaceuticals produced from gallium-68 generators that progressively produce less activity due to the decay of the parent radionuclide, germanium-68. While sufficient activity may be available from a single synthesis to scan 4–5 patients when the generator is new, by the end of its life, only 1–2 cases may be possible. Reducing the activity by half and the scanning time by half, comparable image quality could be obtained, while amortizing the production and generator costs to a greater extent. The shorter the physical half-life of a tracer, the greater the potential benefits of more rapid scanning and a lower administered activity for patient in terms of radiation exposure. These scanners potentially bring carbon-11 radiopharmaceuticals for which the 20-min half-life is clinically impractical back into relevance if administered activity remains unchanged. Conversely, long-lived radionuclides, like zirconium-89, for which the administered activity is often reduced to limit radiation dose to patients, long scanning times can be significantly reduced. There is also the possibility of doing very late imaging, which has potential advantages for monoclonal antibodies with slow blood-pool clearance [11]. The potential benefits of such scanners to improving the efficiency and feasibility of clinical use of radiotracers that are currently constrained by low production yields or a short half-life is discussed in detail in an earlier review in this series. In a new department, a conscious decision to limit administered activity to patients can also significantly reduce the cost of lead shielding for uptake rooms (see below).

Importantly, relatively fixed costs of running a department include those of maintaining clinical staffing. In many jurisdictions, radiation exposure for staff is strictly controlled and limits the number of patients that a nuclear medicine technologist or nurse can manage per day. Reducing the administered activity to patients can allow greater productivity of these important and often limited personnel. With the rapid potential throughput of these scanners, the rate-limiting resource may become the reporting clinician who may struggle to keep pace with the scans coming off the device.

In developing business models, the capital costs must be balanced against careful considerations of the potential case mix, as well as fixed and variable operating costs. Of course, in some settings, demand may be limited by reimbursement restrictions or staffing levels and such scanners are unlikely to be financially viable without either capital equipment grants from government agencies or philanthropic organizations that recognize the clinical and research opportunities that these devices provide.

Industry-funded research is a further source of operational revenue and ability to do the same workload in a shorter interval potentially opens greater capacity to accommodate research studies in a busy department.