Advances of Molecular Imaging in Epilepsy

Abstract

Positron emission tomography (PET) is a neuroimaging method that offers insights into the molecular functioning of a human brain. It has been widely used to study metabolic and neurotransmitter abnormalities in people with epilepsy. This article reviews the development of several PET radioligands and their application in studying the molecular mechanisms of epilepsy. Over the last decade, tracers binding to serotonin and γ-aminobutyric acid (GABA) receptors have been used to delineate the location of the epileptic focus. PET studies have examined the role of opioids, cannabinoids, acetylcholine, and dopamine in modulating neuronal hyperexcitability and seizure termination. In vivo analyses of drug transporters, e.g., P-glycoprotein, have increased our understanding of pharmacoresistance that could inform new therapeutic strategies. Finally, PET experiments targeting neuroinflammation and glutamate receptors might guide the development of novel biomarkers of epileptogenesis.

Keywords: Epilepsy; Neuroimaging; Positron-emission tomography; Seizures.

Fig. 1

[¹⁸F]GE-179 PET/MR scan in a 57-year old temporal lobe epilepsy patient with signal abnormality in left inferior temporal cortex. a PET/MR fusion image (left) and MR FLAIR sequence (right) displaying parts of the lesion (empty arrow) and the hippocampus (full arrow). b Bilateral comparison of time-activity curves (TACs) in the inferior temporal cortex (above) and the hippocampus (below). Both visual analysis and TACs show reduced tracer uptake in the lesioned temporal cortex and slightly increased uptake in the ipsilateral hippocampus. Hypothetically, the extralesional increase of NMDA-receptor activation in the ipsilateral hippocampus could point to ongoing epileptogenesis and prospective studies will be needed to prove this assumption