Positron emission tomography/computed tomography scanning for the diagnosis of occult sepsis in the critically injured

Background: Although the site of nosocomial sepsis in the critically ill ventilated patient is usually identifiable, it may remain occult, despite numerous investigations. The rapid results and precise anatomical location of the septic source using positron emission tomography (PET) scanning, in combination with computed tomography (CT), has promoted this modality as the diagnostic tool of choice for pyrexias of unknown origin. Methods: The objective of this study was to report our experience using PET/CT scanning for the localisation of a septic focus in critically injured patients in whom no source could be identified using conventional investigations. Results: Two patients with gunshot wounds and two who had sustained multiple fractures following motor vehicle collisions developed pyrexias of unknown origin during their stay in the trauma intensive care unit. Routine screening for a septic focus was unrewarding, and 18F-fluorodeoxyglucose PET/CT scanning was used to identify the possible source. PET/CT scanning identified the septic focus in all patients. Abscesses were drained successfully in those with penetrating trauma and in one with blunt polytrauma. Pulmonary tuberculosis, not apparent on initial radiology, was identified using PET/CT in one patient with blunt thoracic trauma. Conclusion: PET/CT scanning appears to both confirm and localise the source of sepsis in a variety of pathologies in critically ill patients who develop pyrexias for which no source can be identified by conventional screening techniques.