How much intravenous contrast is needed in FDG-PET/CT?

Intravenous, iodinated contrast agents are used routinely for CT (ceCT) imaging but only applied reluctantly for FDG-PET/CT due to possible artefacts. Only for few oncological PET/CT indications, the role of IV contrast agent has been clarified. Essentially, if any knowledge regarding vascular structures or tumour invasion into adjacent structures are needed, a ceCT as part of the combined PET/CT exam should be implemented. However, for some indications like lymphoma, contrast seems not to be necessary. Therefore, imaging procedures for the use of IV contrast for PET/CT have to be adapted individually for each FDG-PET/CT indication to especially reduce unnecessary radiation burden to the patient.