Focal hypermetabolism in suspected non-convulsive status epilepticus

Area of Science:

• Neuroimaging
• Nuclear Medicine
• Epileptology

Background:

• Non-convulsive status epilepticus (NCSE) diagnosis can be challenging, often requiring advanced neuroimaging.
• ¹⁸F-fluorodeoxyglucose positron emission tomography (FDG-PET) offers metabolic insights into brain activity.
• Establishing FDG-PET as a reliable biomarker for NCSE is crucial for clinical management.

Purpose of the Study:

• To evaluate FDG-PET as a biomarker for suspected NCSE.
• To characterize electroclinical-metabolic correlations in NCSE patients.
• To quantify focal hypermetabolism detected by FDG-PET.

Main Methods:

• Adult patients with rhythmic and periodic patterns undergoing FDG-PET for suspected NCSE were included.
• Electroencephalography (EEG) and FDG-PET images were analyzed for focal hypermetabolism and correlated with EEG findings.
• A novel SUV z-score method was developed and compared against traditional SUVR methods for hypermetabolism detection.

Main Results:

• FDG-PET revealed focal hypermetabolism in 92% of suspected NCSE cases, showing strong concordance with EEG lateralization.
• The developed SUV z-score technique demonstrated superior performance (AUC=0.92) compared to SUVR methods (AUC=0.55-0.64).
• In patients with lateralized periodic discharges (LPDs), hypermetabolic volumes varied significantly across different discharge frequencies.

Conclusions:

• FDG-PET is a valuable biomarker for detecting focal hypermetabolism in suspected NCSE, even with equivocal EEG patterns.
• The quantitative SUV z-score approach enhances the accuracy of FDG-PET in identifying metabolic abnormalities in NCSE.
• The extent of hypermetabolism in LPDs is variable, suggesting complex underlying pathophysiology.