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Updated: Jun 30, 2026
Network Analysis of the Default Mode Network Using Functional Connectivity MRI in Temporal Lobe Epilepsy
Published on: August 5, 2014
18F-FCWAY and 18F-FDG PET in MRI-negative temporal lobe epilepsy
Clarissa J Liew1, Young-Min Lim, Robert Bonwetsch
1Clinical Epilepsy Section, National Institutes of Health, Bethesda, Maryland 20892, USA.
Background:
Positron emission tomography (PET) with (18)F-fluorodeoxyglucose (FDG) shows widespread hypometabolism even in temporal lobe epilepsy (TLE) patients with mesial temporal foci. (18)F-trans-4-fluoro-N-2-[4-(2-methoxyphenyl) piperazin-1-yl]ethyl-N-(2-pyridyl)cyclohexane carboxamide ((18)F-FCWAY) PET may show more specific 5-HT(1A)-receptor binding reduction in seizure initiation than in propagation regions. (18)FCWAY PET might be valuable for detecting epileptic foci, and distinguishing mesial from lateral temporal foci in MRI-negative patients with TLE.
Methods:
We performed (18)F-FCWAY-PET and (18)F-FDG-PET in 12 MRI-negative TLE patients who had had either surgery or subdural electrode recording, and 15 healthy volunteers. After partial volume correction for brain atrophy, free fraction-corrected volume of distribution (V/f1) measurement and asymmetry indices (AIs) were computed. We compared (18)F-FCWAY-PET and (18)F-FDG-PET results with scalp video electroencephalography (EEG), invasive EEG, and surgical outcome.
Results:
Mean (18)F-FCWAY V/f1, compared with normal controls, was decreased significantly in fusiform gyrus, hippocampus, and parahippocampus ipsilateral to epileptic foci, and AIs were significantly greater in hippocampus, parahippocampus, fusiform gyrus, amygdala, and inferior temporal regions. Eleven patients had clearly lateralized epileptogenic zones. Nine had congruent, and two nonlateralized, (18)F-FCWAY PET. One patient with bitemporal seizure onset had nonlateralized (18)F-FCWAY-PET. (18)F-FDG-PET showed congruent hypometabolism in 7 of 11 EEG-lateralized patients, bilateral hypometabolic regions in one, contralateral hypometabolism in one, as well as lateralized hypometabolism in the patient with bitemporal subdural seizure onset. Patients with mesial temporal foci tended to have lower superior and midtemporal (18)F-FCWAY V/f1 binding AI than those with lateral or diffuse foci.
Conclusion:
(18)F-FCWAY-PET can detect reduced binding in patients with normal MRI, and may be more accurate than (18)F-FDG-PET.
Insights
New positron emission tomography (PET) imaging using (18)F-FCWAY may detect reduced 5-HT(1A)-receptor binding in temporal lobe epilepsy (TLE) patients with normal MRI scans, potentially offering greater accuracy than (18)F-FDG-PET for identifying seizure foci.
Area of Science:
- Neurology
- Nuclear Medicine
- Radiochemistry
Background:
- Positron emission tomography (PET) with (18)F-fluorodeoxyglucose (FDG) reveals widespread hypometabolism in temporal lobe epilepsy (TLE) patients, even with mesial temporal foci.
- (18)F-trans-4-fluoro-N-2-[4-(2-methoxyphenyl) piperazin-1-yl]ethyl-N-(2-pyridyl)cyclohexane carboxamide ((18)F-FCWAY) PET may offer more specific detection of 5-HT(1A)-receptor binding reduction at seizure initiation.
- (18)F-FCWAY PET shows potential for identifying epileptic foci and differentiating mesial from lateral temporal foci in MRI-negative TLE patients.
Purpose of the Study:
- To evaluate the utility of (18)F-FCWAY PET in detecting reduced 5-HT(1A)-receptor binding in MRI-negative TLE patients.
- To compare the diagnostic accuracy of (18)F-FCWAY PET with (18)F-FDG-PET and electroencephalography (EEG) in lateralizing epileptic foci.
- To assess the correlation between (18)F-FCWAY binding patterns and seizure onset localization (mesial vs. lateral temporal).
Main Methods:
- (18)F-FCWAY PET and (18)F-FDG-PET were performed on 12 MRI-negative TLE patients and 15 healthy controls.
- Free fraction-corrected volume of distribution (V/f1) and asymmetry indices (AIs) were computed after partial volume correction for brain atrophy.
- PET results were compared with scalp/invasive EEG findings and surgical outcomes.
Main Results:
- (18)F-FCWAY V/f1 was significantly decreased in the fusiform gyrus, hippocampus, and parahippocampus ipsilateral to epileptic foci compared to controls.
- Significantly greater AIs for (18)F-FCWAY were observed in the hippocampus, parahippocampus, fusiform gyrus, amygdala, and inferior temporal regions.
- (18)F-FCWAY PET lateralized epileptogenic zones in 11 patients, showing congruent findings in 9; (18)F-FDG-PET was less concordant with EEG lateralization.
Conclusions:
- (18)F-FCWAY PET can detect reduced 5-HT(1A)-receptor binding in TLE patients with normal MRI.
- (18)F-FCWAY PET may be more accurate than (18)F-FDG-PET in identifying and lateralizing epileptic foci in TLE.
- This novel PET tracer shows promise for improving the diagnosis of MRI-negative TLE.
