The Role of Interictal ¹⁸F-FDG Brain PET/MRI in Patients with Focal Pharmacoresistant Epilepsy

Pharmacoresistant epilepsy remains a significant challenge in modern neurology, affecting around 30 % of patients who do not respond to medication. Conventional neuroimaging methods often fail to provide sufficient diagnostic information in patients with MRI-negative findings and discordant EEG and MRI data. Optimizing preoperative mapping through noninvasive, high-precision neuroimaging techniques is critical to improving surgical outcomes and patient prognosis. Hybrid PET/MRI imaging with ¹⁸F-FDG offers new possibilities for enhanced preoperative localization in such patients.

Objective. To evaluate the diagnostic value and clinical applicability of hybrid PET/ MRI with ¹⁸F-FDG in the preoperative mapping of epileptogenic zones in patients with pharmacoresistant epilepsy, including MRI-negative cases. To perform a quantitative analysis of ¹⁸F-FDG hypometabolism in relation to the type of epilepsy, as well as the frequency and duration of epileptic seizures.

Materials and Methods. A screening of 10 healthy volunteers and an evaluation of 130 patients with drug-resistant epilepsy were performed according to the hybrid PET/MRI protocol with ¹⁸F-FDG. Both qualitative and quantitative analyses of hypometabolic brain regions were conducted, with findings correlated to clinical data, video-EEG monitoring results, and MRI findings. This approach enabled integrated assessment of functional and structural abnormalities, provided improved localization of epileptogenic zones, and facilitated the interpretation of metabolic, electrophysiological, and neuroanatomical correlates in the study cohort.

Results. The use of interictal brain PET/MRI with ¹⁸F-FDG significantly improved the detection rate of epileptogenic zones compared with standalone epilepsy-protocol MRI. This effect was particularly pronounced in MR-negative cases and in patients with subtle structural abnormalities, which were subsequently recognized upon targeted MRI re-evaluation guided by metabolic findings from PET imaging. In healthy individuals, no significant interhemispheric asymmetry of glucose metabolism was observed; physiologically, temporal regions demonstrate lower SUV values compared with frontal, parietal, and occipital cortices. Across all age groups of patients with pharmacoresistant epilepsy, moderate interhemispheric asymmetry of ¹⁸F-FDG metabolism was identified (asymmetry index range ~ 0.25–0.5). Disease duration and seizure frequency showed no clear linear relationship with focal SUV values. However, in MRI-positive cases with daily seizures, a relative increase in SUV within the epileptogenic focus was noted, likely reflecting postictal metabolic activity without materially affecting overall hemispheric asymmetry. The most pronounced ¹⁸F-FDG hypometabolism was observed in structural focal epilepsy, while higher metabolic activity characterized focal epilepsy of unknown etiology and mixed focal-generalized forms. These findings emphasize that hybrid ¹⁸F-FDG PET/MRI provides an advanced diagnostic advantage through its ability to integrate metabolic and structural data, allowing for improved localization of epileptogenic foci — even in subtle or MRI-negative cases — and thereby enhancing presurgical evaluation and treatment planning.

Conclusion. The use of hybrid ¹⁸F-FDG PET/MRI expands the diagnostic capabilities of neuroimaging in patients with focal pharmacoresistant epilepsy. Incorporation of PET/MRI into the presurgical planning workflow has the potential to improve the effectiveness of surgical treatment and enhance patient quality of life.

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