Epilepsy is one of the most common brain diseases, especially in children and elderly adults. It affects up to 2 million people in the United States. Epilepsy can be treated by drugs, but it is refractory to medical treatment in 10-15% of cases. In patients with intractable partial epilepsy (where seizures begin in a relatively small location of the brain), resection of these epileptogenic regions may alleviate seizures and can result in the improvement of cognitive functions and quality of life.
PET is a powerful non-invasive method that helps to localize epileptic brain regions. It is especially helpful when structural neuroimaging (CT, MRI, and/or electroencephalography EEG) do not provide a consistent information about epileptogenic areas.
In our center we use three different tracers to define epileptic foci:
18 Fluoro-Deoxy Glucose (FDG) PET is very useful in several childhood epilepsy syndromes (including infantile spasms, hemimegalencephaly, Sturge-Weber syndrome, etc.) as well as partial epilepsies in adulthood. It does not only detect focal abnormalities consistent with epileptic cortex, but also provides unparalleled information about the functional integrity of the remaining brain regions.
[11C]Flumazenil (FMZ) PET is a useful method of analyzing GABA/benzodiazepine receptors in brain. These represent the most important inhibitory receptors in human brain, and their impaired function can be a marker of epileptogenicity. FMZ PET is a very sensitive technique in temporal lobe epilepsy and also in extratemporal, non-lesional epilepsies (where MRI does not give any clue about abnormal brain regions). The latter represents the most challenging group of focal epilepsies and FMZ PET reliably delineates extratemporal epileptogenic regions. FMZ PET can also reveal epileptic cortex around structural lesions (tumors, infarcts, etc.), thus, it can help to tailor cortical resection to preserve eloquent brain areas (motor or speech cortex).
As a part of the presurgical evaluation, we combine high-resolution MRI with PET by coregistering them. Thus, PET abnormalities can be displayed on the three-dimensionally reconstructed brain surface, and directly correlated with electrophysiological (e.g. subdural grid monitoring) data. This sophisticated technique represents a state of the art method of multimodality imaging, which provides a comprehensive information about the site, extension and nature of functional abnormalities of the affected cortex; it can be a great help for the neurosurgeon.
[11C]Alpha-methyl Tryptophan (AMT) PET is a promising new method for defining epileptic cortex. It is able to differentiate between epileptogenic and non-epileptogenic tubers in patients with tuberous sclerosis complex, but it might be a powerful diagnostic method in epileptic patients with cortical dysplasia as well as in non-lesional epilepsies.
Autism Maturational pattern in autistic children.
Congenital Heart Disease
Tuberous Sclerosis Complex (TSC) is an autosomal dominant genetic disorder that primarily affects the brain, heart, kidney, liver, and skin. Tubers in the brain are one of the characteristic of this disease condition. These tubers can be found anywhere in the cerebral hemisphere, though they are mainly present in the cortex. Epilepsy often arises from these tubers, which can then be surgically resected. The AMT PET Scan is useful to differentiate epileptogenic tubers from non-epileptogenic tubers in patients with TSC.
Sturge-Weber Syndrome (SWS) is a congenital disorder with unknown etiology. It is characterized by leptomeningeal and facial angiomatosis, and ocular defects. Various neurological abnormalities such as epilepsy, mental retardation or hemiplegia are frequently observed in patients with SWS. We can evaluate the cerebral glucose metabolic pattern in children with SWS using FDG PET scans, which may predict epileptogenic foci and cognitive function.