Radiolabelled WBCs against [18F]FDG PET/CT for imaging infections: the eternal battle

DFIs and VGEIs represent two difficult scenarios from a diagnostic point of view and the prompt identification of the infection benefit from a multidisciplinary and multimodal approach in which NM plays a crucial role.
As far as DFIs is concerned, a plethora of radiological and NM modalities are available and can be used and combined for the diagnosis, but at the moment no definite diagnostic flowchart exists (Chapter 2). In Chapter 3, MRI, 99mTc-HMPAO WBC scintigraphy and [18F]FDG PET/CT showed a comparable sensitivity in detecting pedal OM. In Chapter 4, we compared MRI, 99mTc-HMPAO WBC scintigraphy and [18F]FDG PET/CT in detecting OM, STIs and Charcot in a large population of diabetic patients.
VGEI is another condition in which standardized diagnostic algorithms and a unanimous consensus on the most appropriate imaging modality are still needed. CTA, WBC scintigraphy and [18F]FDG PET/CT play a complementary role being CTA always the first-choice imaging modality (Chapter 5).
From our retrospective comparative study on CTA, radiolabelled WBCs and [18F]FDG PET/CT (Chapters 6), the addition of a NM examination resulted in a better patient’s management in our population. Recently published EANM guidelines (Chapter 7) fully assessed the role of different imaging modalities in the diagnostic setting of VGEI according to time elapsed from surgery. WBC scintigraphy can be performed at any time from surgery, given its high accuracy in discriminating post-surgical inflammation from an infection. [18F]FDG PET/CT should be performed at least 4 months after surgery, given the possibility of false positive findings due to sterile inflammation.