Inter-modality comparisons of seizure focus lateralization in complex partial seizures

Area of Science:

• Neuroimaging
• Epilepsy Diagnosis
• Neurology

Background:

• Anterior temporal lobectomy is effective for drug-refractory complex partial seizures (CPS) originating from the temporal lobe.
• Accurate spatial localization of seizure foci is crucial for surgical planning.
• Electroencephalography (EEG) is standard, but functional and morphologic imaging methods aid in defining seizure origin.

Purpose of the Study:

• To compare the diagnostic merits of fluorine-18 fluorodeoxyglucose positron emission tomography (FDG-PET), magnetic resonance imaging (MRI), and single-voxel proton magnetic resonance spectroscopy (MRS) for lateralizing temporal lobe seizure foci.
• To evaluate the agreement of these imaging modalities with surface EEG and surgical outcomes in patients with temporal lobe epilepsy (TLE).

Main Methods:

• Retrospective review of clinical charts and imaging data from 43 CPS patients.
• Patients underwent FDG-PET, MRS, and MRI within six weeks.
• Comparison of imaging results with surface EEG lateralization and outcomes of anterior temporal lobectomy in 15 patients.

Main Results:

• FDG-PET showed significantly higher agreement (0.93) with the side of successful temporal lobectomy compared to MRI (0.60; P=0.03).
• MRS concordance with successful lobectomy side was intermediate (0.75).
• Combined MRS/MRI demonstrated significantly more lateralized temporal lobe abnormalities in non-TLE cases than FDG-PET/MRI (0.90 vs. 0.17; P<0.01).

Conclusions:

• FDG-PET appears to be the most reliable imaging method for lateralizing temporal lobe seizure foci.
• In TLE cases, MRS combined with MRI may be a cost-effective, faster, and radiation-free alternative to FDG-PET, especially when both modalities agree on seizure focus lateralization.
• MRS/MRI offers significant value in identifying lateralized abnormalities in non-TLE cases, potentially aiding differential diagnosis.