Subclinical seizures as a pitfall in 18F-FDG PET imaging of temporal lobe epilepsy

Area of Science:

• Neurology
• Nuclear Medicine
• Epilepsy Research

Background:

• A 61-year-old male with a history of substance abuse and viral hepatitis presented with seizures.
• Initial magnetic resonance imaging (MRI) suggested temporal lobe epilepsy.
• The patient had a history of hypertension.

Observation:

• An initial 18F-fluorodeoxyglucose Positron Emission Tomography (FDG-PET) brain scan revealed a hypermetabolic focus in the left temporal lobe.
• The patient was asymptomatic during this initial PET scan.
• Subsequent review of electroencephalography (EEG) recordings identified a subclinical seizure occurring concurrently with the PET imaging.

Findings:

• The hypermetabolic focus on the brain PET scan correlated with a subclinical seizure event.
• A repeat whole-body 18F-FDG PET scan performed four days later, with normal EEG tracings, showed no abnormal brain metabolic activity.
• This indicates that the observed hypermetabolism was transient and related to the seizure activity.

Implications:

• Simultaneous EEG monitoring during FDG-PET imaging is crucial for accurately interpreting focal brain hypermetabolism in epilepsy.
• FDG-PET can detect metabolic changes associated with seizure activity, even when subclinical.
• This case underscores the importance of correlating imaging findings with electrophysiological data for accurate diagnosis and management of epilepsy.