Quantitative analysis of the most hypometabolic foci on PET brain scan using MIMneuro software and correlation with electroencephalography

Objectives About one-third of patients with epilepsy are refractory to medications and may require resective brain surgery. Many are non-lesional on brain MRI and the challenge for surgical planning is the identification of the seizure onset zone. We postulate that the most hypometablic foci on PET may correlate with the seizure onset zone and provide a target for epilepsy surgery. The primary aim of this proof of concept study is to evaluate most hypo-metabolic foci on brain PET using MIMneuro (software for quantitative analysis of neurological disorders by PET) and comparing them with the potential epileptogenic region determined by scalp electroencephalography (EEG).

Methods We retrospectively reviewed a sample of 24 PET scans of the brain for adult patients requiring evaluation for epilepsy surgery at Emory University Hospital in the past 2 years. Using MIMneuro we identified the most hypo-metabolic foci, if present, on the PET. We then compared the location of the focus with the reported location of the inter-ictal epileptiform discharges on the EEG performed during the PET scan.

Results The 24 patients’ ages ranged from 17 to 60 years (mean age 30 years, 14 female). MIMneuro identified 23 patients (96%) with hypometabolic foci. The one patient without a hypometabolic focus had a normal EEG. Of those 23 with hypometabolic foci detected, 14 had an abnormal EEG with epileptiform discharges (the other 9 had a normal EEG). All 14 (100%) had hypometabolic foci by MIMneuro that correlated with the regional location of the epileptiform discharges.

Conclusions Based on this pilot data, we conclude there is a potential correlation between the most hypometabolic foci on brain PET using MIMneuro and the epileptogenic zone represented by surface EEG. Further analysis with larger sample sizes and comparison with intracranial surgical EEG monitoring is warranted.