The assessment of task-specific changes in glucose metabolism previously required repeated scans and radioligand applications, with drawbacks of increased radiation burden and variance due to differences in task performance, motivation and habituation.
Functional PET (fPET) imaging with the radiotracer [18F]FDG refers to a novel method to study dynamic changes in glucose metabolism within a single scanning session. The constant infusion protocol provides free radiotracer throughout the scan, which is then available to bind according to the actual metabolism as induced by the experimental task. The term fPET furthermore underlines the similarity to fMRI with respect to repeated task performance in a block design and the analysis with the general linear model to separate task effects from baseline metabolism.
The task specific time activity during visual stimulation shows an increase in [18F]FDG Uptake during the task. Subsequent quantification of the cerebral metabolic rate of glucose and statistical analysis yields a significant increase in the primary visual cortex. [Image adapted from Rischka et al., NeuroImage 181: 323, 2018, post-print]
Together with hybrid PET/MR imaging systems, this technique offers new possibilities to study multiple domains of human brain function during task performance.
Direct comparison between fPET and fMRI shows strong spatial overlap of task-specific neuronal activation and glucose metabolism between the two imaging modalities. [Image from Rischka et al., NeuroImage 181: 323, 2018, post-print]
