FDG PET/CT of Infection: Should It Replace Labeled Leukocyte Scintigraphy of Inpatients?

The purpose of this study was to compare the sensitivity, specificity, and helpfulness to referring clinicians of labeled leukocyte scintigraphy versus FDG PET/CT in inpatients with suspected infection. In this retrospective study, labeled leukocyte scintigraphy and FDG PET/CT examinations performed from 2009 to 2017 for suspected infection in inpatients were identified. Sensitivity, specificity, and helpfulness of PET/CT versus labeled leukocyte scintigraphy were calculated by means of a mixed generalized linear model. Number of yearly tests and radiopharmaceutical costs were also assessed. Fifty-seven patients (30 men, 27 women; median age, 65 years; range, 21-91 years) underwent whole-body labeled leukocyte scintigraphy. Forty-two patients (30 male patients, 12 female patients; median age, 62.5 years; range, 12-91 years) underwent PET/CT for suspected infection. Labeled leukocyte scintigraphy was 66.7% sensitive, whereas the sensitivity of PET/CT was 89.7% ( = 0.0485). The higher sensitivity of PET/CT did not come at a cost to specificity, which was 73.3% as opposed to 76.9% for labeled leukocyte scintigraphy ( = 0.8050). The odds of a positive study being helpful increased 4.6-fold for PET/CT versus labeled leukocyte scintigraphy ( = 0.0412). From 2009 to 2011, 33 labeled leukocyte scintigraphic examinations were performed versus two PET/CT examinations; and from 2012 to 2014, 16 labeled leukocyte scintigraphic versus 22 PET/CT examinations; from 2015 to 2017, eight labeled leukocyte scintigraphic versus 18 PET/CT examinations. The cost of labeled leukocytes increased between 2009 and 2017, but that of FDG decreased. By 2017, a labeled leukocyte radiopharmaceutical dose was approximately 10 times the cost of an FDG dose. PET/CT was more sensitive than and as specific as labeled leukocyte scintigraphy for identifying a source of infection in inpatients, and it was more helpful to referring clinicians. Use of PET/CT increased over time and was associated with substantial savings in radiopharmaceutical cost.