18F-Fluoro-deoxy-glucose (18F-FDG) positron emission tomography (PET) has a high sensitivity for temporal lobe epilepsy (TLE), the most common form of focal epilepsy, with a detection range of 86-90% . Therefore, 18F-FDG PET is a useful tool to identify the epileptogenic zone (ETZ) in the inter-ictal phase of drug-resistant temporal epilepsy during pre-surgical evaluation . Based on stereotactic electroencephalography (SEEG) findings, a correspondence between electrical data and metabolic changes on PET was found at the group level by identifying four different patterns of TLE . As expected, hypometabolism was not limited to the EZ defined by SEEG, but underlay broader epileptic networks . Because of the different electroclinical presentations of TLE, 18F-FDG PET appears to be a very useful tool in these temporal epilepsies. Indeed, it has been recently demonstrated that a gradient of PET hypometabolism from the uninvolved area to the spreading area, then to the epileptogenic area and to the lesion area is observed with consequently a good performance of 18F-FDG PET in defining the EZ .

Therefore, it is interesting to study PET metabolism as a network and not as a combination of regional metabolic measures in epilepsy.

Inclusion Criteria:

• Patients with drug-resistant temporal epilepsy with an accurate diagnosis on SEEG
• Patients with epilepsy who have had a PET/CT scan with 18F-FDG as part of a pre-operative assessment
• Person having received complete information on the organization of the research and not having objected to the use of these data;
• Patients affiliated to a social security system

Exclusion Criteria:

• Person who has not received full information on the organization of the research and who has opposed the use of this data
• A person of full age who is the subject of a legal protection measure (guardianship, curatorship, safeguard of justice).
• A person of full age who is unable to give consent and who is not subject to a legal protection measure

Patients who came to the nuclear medicine department between 2009 and 2021 for an 18F-FDG PET/CT scan as part of a pre-operative assessment for epilepsy surgery