Global Survey Reveals Why PET/CT Scans Remain Rare in Intensive Care Units

Positron emission tomography combined with computed tomography, the imaging technique known the world over as PET/CT, has transformed the way physicians hunt down hidden disease. By pairing the exquisite sensitivity of a radioactive glucose tracer with the anatomical precision of computed tomography, it can expose occult infection, malignancy and inflammation long before conventional scans show anything amiss. For patients in the intensive care unit, whose infections are frequently cryptic and whose inflammation is often diffuse, this diagnostic power would appear tailor-made. Yet a new international survey published in the European Journal of Nuclear Medicine and Molecular Imaging reveals that in the setting of critical illness, PET/CT remains a remarkably rare event, and the reasons why are as practical as they are scientific.

The study, led by Camilla Genovese of the Department of Infectious Diseases at Ospedale Luigi Sacco in Milan, together with Jean-François Timsit and Michael Thy of Bichat-Claude Bernard University Hospital and INSERM research units in Paris, set out to map how intensivists and nuclear medicine physicians around the world actually use 2-deoxy-2-[18F] fluoro-D-glucose PET/CT, or [18F]-FDG-PET/CT, in critically ill patients. The researchers distributed an electronic questionnaire worldwide through two of the most influential societies in the field: the European Society of Intensive Care Medicine, known as ESICM, and the European Association of Nuclear Medicine, known as EANM. The instrument collected demographic information, hospital characteristics, the availability and physical location of nuclear medicine services, the clinical indications for which PET/CT is requested in intensive care, the frequency of use, details of workflow organisation, and the obstacles that clinicians perceive when considering the test.

Forty-one respondents from 16 countries completed the survey. Although the sample is modest, its composition is telling. Most participants, 63 percent, worked in university hospitals, and the respondents divided almost neatly into two professional worlds: 71 percent specialised in intensive care medicine while 29 percent specialised in nuclear imaging. That split mirrors the very fault line the study set out to explore. PET/CT in the critically ill sits at the intersection of two specialties, and the survey suggests that neither has yet built the shared routines that would make the examination routine. A nuclear medicine department was available in 78 percent of the centres that responded, which sounds reassuring until one examines the geography: only 60 percent of those departments were co-located with the intensive care unit. In a patient whose blood pressure is maintained by infusions of vasopressors and whose oxygenation depends on a mechanical ventilator, distance is not a trivial detail. Every metre of corridor is a corridor of risk.

The raw numbers on utilisation are striking. Among centres that do use the technique, 43 percent performed only one to five scans per year, and a quarter of respondents performed just one or two scans per month. In an environment where diagnostic uncertainty is a daily companion, those figures suggest that a technology capable of resolving that uncertainty is being left largely on the shelf. The survey also asked what the scans were actually being used for. Infection topped the list, serving as the primary diagnostic indication in 74 percent of cases, followed by suspected malignancy at 57 percent and fever of unknown origin at 49 percent. The pattern makes physiological sense. Critically ill patients frequently harbour deep-seated infections, ventilator-associated pneumonia, catheter-related bloodstream infection, intra-abdominal sepsis, that conventional imaging fails to localise. Because activated immune cells and many tumour cells consume glucose avidly, the fluorinated glucose analogue accumulates precisely where the disease hides, and the paired CT supplies the anatomical coordinates clinicians need to intervene.

How, then, does the examination actually proceed in practice? The survey provides a snapshot of workflow that is as revealing as it is fragmented. Radiotracer administration took place mainly within the nuclear medicine department, in 77 percent of sites, meaning that the unstable patient had to be physically transported for the injection even before the imaging itself. Protocols for the dietary preparation that PET/CT demands, typically fasting to suppress endogenous insulin and ensure that glucose competition does not blunt tracer uptake, existed in only half of the participating centres. The absence of such standardisation matters at a technical level. Blood glucose levels that are too high reduce FDG uptake in target tissues and can degrade diagnostic sensitivity, which in a septic patient on parenteral nutrition is a genuine challenge. That only 50 percent of sites had formal preparation protocols suggests that much of the current practice is improvised rather than codified, and that image quality, and therefore diagnostic yield, may vary considerably from one centre to another.

When the researchers asked respondents directly what stood in the way, a coherent picture of systemic friction emerged. The barriers most commonly reported included the lack of standardised protocols, the prolonged duration of the procedure, limited imaging slots, ambiguous clinical indications, insufficient staff expertise and the logistical difficulties of transporting unstable intensive care patients. Each barrier deserves unpacking. A PET/CT examination is not a five-minute chest radiograph; it involves tracer production or delivery, injection, a waiting period of roughly an hour for uptake, and then acquisition on a scanner that is often shared with oncology services whose demand for slots is enormous. Staff expertise is a second constraint: positioning, monitoring and safely transporting a ventilated, sedated patient require a coordinated team of intensivists, nurses, radiographers and nuclear medicine physicians, and many centres simply lack experience in this choreography. Ambiguous indications compound the problem. Because no formal guidelines exist to direct the use of [18F]-FDG-PET/CT in the intensive care unit, clinicians have no authoritative framework telling them when the scan will genuinely change management and when it will merely delay it.

That absence of guidance is perhaps the survey’s most consequential finding. The authors emphasise that routine use of the technique in intensive care remains sporadic and that there are, at present, no formal guidelines governing its application. Medicine has repeatedly shown that imaging technologies with real diagnostic power underperform when their indications are left to individual judgement. The result is a vicious circle: because guidelines are lacking, use is rare; because use is rare, centres never develop the protocols, training and logistics that would make scans safe and efficient; and because the infrastructure never matures, the evidence base needed to write guidelines remains thin. The survey’s data, collected from both sides of the specialty divide, provide the empirical foundation needed to break that circle.

The study’s authors are explicit about the trajectory they hope the findings will set. The data, they write, highlight an unmet need for consensus guidelines and streamlined workflows to optimise the diagnostic value of [18F]-FDG-PET/CT in critical-care patients, and the results will inform forthcoming joint recommendations to be issued by ESICM and EANM. Such recommendations, grounded in the real-world practice patterns the survey documented, could specify which patients are most likely to benefit, how dietary preparation and glucose control should be managed, how transport of ventilated patients should be organised and staffed, and how scanner time might be reserved for intensive care indications. The stated aim is ultimately clinical rather than technical: to enhance patient outcomes through evidence-based imaging protocols. In intensive care, where every day of undiagnosed infection carries a measurable mortality cost, a scan that localises the source of sepsis and redirects therapy is not a luxury but a potential lifeline.

The survey is not without limitations, and the authors are careful about what it can and cannot claim. It is a self-reported questionnaire study with 41 respondents, and it captures practice rather than outcome: no one can yet say from these data whether PET/CT in the intensive care unit improves survival, shortens ventilation or reduces antibiotic exposure. The study involved no direct interaction with human subjects and relied entirely on secondary data, an ethical design that facilitated its broad international reach. What it delivers instead is a baseline, a map of where the world currently stands. It reveals a technology of proven diagnostic sensitivity for the very conditions that complicate critical illness, used only a handful of times a year in most centres, hampered by distance, duration, cost, protocol gaps and uncertainty about when it helps. Closing that gap between capability and practice is now a defined task, and the joint guidelines that ESICM and EANM are preparing will be the first serious attempt to define it. If they succeed, the hidden infections and tumours that PET/CT can illuminate may finally be found, not in the rarest of cases, but wherever a critically ill patient needs them found.

Subject of Research: Use of FDG PET/CT imaging in critically ill intensive care patients

Article Title: Practices and barriers in PET/CT use for critically ill patients: an international survey

Article References: Genovese, C., Timsit, J.-F., & Thy, M. (2026). Practices and barriers in PET/CT use for critically ill patients: an international survey. European Journal of Nuclear Medicine and Molecular Imaging. https://doi.org/10.1007/s00259-026-08172-y

Image Credits: AI Generated

DOI: 10.1007/s00259-026-08172-y

Keywords: PET/CT, FDG PET, intensive care, critical care imaging, nuclear medicine, occult infection, fever of unknown origin, international survey, ESICM, EANM, diagnostic imaging, clinical guidelines