Abstract
Purpose: To investigate the diagnostic performance of 18F-fluoro-2-deoxy-D-glucose (FDG) positron emission tomography (PET)/computed tomography (CT) for the detection of an infection focus in patients with a bloodstream infection (BSI) and to identify factors influencing the diagnostic yield of FDG-PET/CT. Methods: This retrospective single-center study included 185 consecutive patients with a BSI who underwent an FDG-PET/CT scan for the detection of an infection focus between 2010 and 2017. The final diagnosis at hospital discharge was used as reference standard. Diagnostic performance of FDG-PET/CT for the detection of an infection focus was assessed, and logistic regression analyses were performed to identify factors associated with FDG-PET/CT yield. Results: An infection focus was identified on FDG-PET/CT in 120 of 185 patients (64.8%). FDG-PET/CT achieved a sensitivity of 80.2%, specificity of 79.6%, positive predictive value of 90.8%, and a negative predictive value of 61.4% for detecting an infection focus in patients with a BSI. Blood cultures positive for enterococci (OR=0.14, p=0.019) and days of antibiotic treatment before FDG-PET/CT (OR=0.94 per day increase, p=0.014) were statistically significant independent predictors of a lower odds of detecting an infection focus on FDG-PET/CT. In patients who received antibiotics for less than 7 days before FDG-PET/CT, an infection focus was found in 71% (56/79). In patients who received antibiotics for 8 to 14 days before FDG-PET/CT, an infection focus was found in 52% (22/42). After 15 to 21 days of antibiotic treatment, an infection focus was found in 61% (8/13), and for 22 days or more, this declined to 38% (5/13). Conclusion: FDG-PET/CT is a useful method for detecting an infection focus in patients with BSI. However, longer duration of antibiotic treatment before FDG-PET/CT and bacteremia with enterococci reduces the diagnostic yield of FDG-PET/CT. These factors should be taken into account when considering an FDG-PET/CT scan for this indication. Funding: No funding was received for this study. Conflicts of Interest: All authors declare they have no conflicts of interest. Ethics Approval Statement: The local institutional review board approved this retrospective single-center study and waived the requirement for written informed consent (IRB number: 201700145).
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