Objective: This study aimed to study the feasibility of measuring the arterial input function (AIF) in dynamic positron emission tomography (PET) studies using both PET and computed tomographic (CT) images.
Material and methods: Eighteen newly diagnosed patients with head and neck cancer were recruited, and dynamic PET-CT scan was performed with contrast-enhanced CT. Phantom study with PET-CT scan was also performed for partial volume effect (PVE) correction. The PET-CT AIF was measured from both PET-CT images and corrected for PVE, together with the PET AIF, which was calculated from PET images. Both AIFs were used for calculating the net flux of [18F]fluoro-2-deoxy-D-glucose, Ki, and the correlation between these 2 sets of Ki was studied by Spearman correlation.
Results: The PET-CT AIF was much larger than the PET AIF, whereas the Ki's by PET-CT AIF were much lower than the Ki's by PET AIF. However, the 2 sets of Ki were highly correlated (r = 0.969, P < 0.001).
Conclusions: It is feasible to measure AIF in PET-CT images without blood sampling. The PET-CT AIF is very different from the PET AIF calculated by PET images only without PVE correction. The PET-CT AIF may be a better choice because the Ki by PET AIF can be overestimated.