F-18-fluorodeoxyglucose positron emission tomography combined with CT in critically ill patients with suspected infection

Abstract

Purpose: To assess the value of F-18-fluorodeoxyglucose positron emission tomography (FDG-PET) combined with CT in critically ill patients suspected of having an infection.

Methods: FDG-PET CT scans requested for evaluation of a suspected infection or inflammatory process in critically ill, mechanically ventilated patients were analyzed (blinded for the final clinical diagnosis) and compared with clinical follow-up.

Results: Thirty-five FDG-PET/CT scans performed in 33 ICU patients (28 adults and 5 children), median age 58 years (range 1 month-72 years), were analyzed. Twenty-one FDG-PET/CT scans were true positive. Three FDG-PET/CT scans were considered false positive, in one case leading to additional diagnostic procedures (specificity 79%). Additionally, 11 true negatives were found (sensitivity 100%), leading to an overall accuracy of 91%.

Conclusions: FDG-PET/CT scanning is of additional value in the evaluation of suspected infection in critically ill patients in whom conventional diagnostics did not lead to a diagnosis. Apart from the high accuracy, in this study it appeared that, in addition to conventional diagnostic techniques that were routinely performed, a normal FDG-PET/CT ruled out important infections requiring prolonged antibiotic therapy or drainage. Since sensitivity is lower in highly metabolic active tissues (e.g., endocarditis, meningitis), the FDG-PET/CT scan is not suited to detect infections in these tissues.

Fig. 1

This 17-year-old male with sickle cell trait was admitted to the ICU because of sepsis. He was treated with piperacilline/tazobactam, and blood cultures grew Streptococcus milleri. After 9 days, a FDG-PET/CT scan was performed because of persistent fever, which showed increased FDG uptake in the right mandible, suspect for a dental abscess. A dental surgeon subsequently confirmed a dental abscess, which was drained successfully, after which the patient improved rapidly

Fig. 2

This 51-year-old patient had recently received an allogenic stem cell transplantation because of myelodysplastic syndrome. He was admitted to the ICU with respiratory failure. A FDG-PET/CT scan was performed after 3 weeks of ICU admission because of fever that persisted despite antibiotics and antifungal treatment, showing abnormal accumulation of the tracer in the right thyroid lobe, suggestive of an abscess. A subsequent hemithyroidectomy confirmed the presence of an abscess. Cultures of this material showed C. albicans