18F-FCWAY and 18F-FDG PET in MRI-negative temporal lobe epilepsy.
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.


CONCLUSIONS
(18)F-FCWAY-PET can detect reduced binding in patients with normal MRI, and may be more accurate than (18)F-FDG-PET.
Liew
Clarissa J
CJ
Clinical Epilepsy Section, National Institutes of Health, Bethesda, Maryland 20892, USA.
Lim
Young-Min
YM
Bonwetsch
Robert
R
Shamim
Sadat
S
Sato
Susumu
S
Reeves-Tyer
Patricia
P
Herscovitch
Peter
P
Dustin
Irene
I
Bagic
Anto
A
Giovacchini
Giampiero
G
Theodore
William H
WH
D000293:Adolescent; D000328:Adult; D000679:Amygdala / Q000000981:diagnostic imaging; D038481:Anterior Temporal Lobectomy; D001786:Blood Glucose / Q000378:metabolism*; D001921:Brain / Q000000981:diagnostic imaging; D003510:Cyclohexanes; D004292:Dominance, Cerebral / Q000502:physiology; D004569:Electroencephalography; D004833:Epilepsy, Temporal Lobe / Q000000981:diagnostic imaging* / Q000601:surgery; D005260:Female; D019788:Fluorodeoxyglucose F18; D005625:Frontal Lobe / Q000000981:diagnostic imaging; D006624:Hippocampus / Q000000981:diagnostic imaging; D006801:Humans; D007091:Image Processing, Computer-Assisted; D008279:Magnetic Resonance Imaging; D008297:Male; D020534:Parahippocampal Gyrus / Q000000981:diagnostic imaging; D010879:Piperazines; D049268:Positron-Emission Tomography / Q000379:methods*; D044282:Receptor, Serotonin, 5-HT1A / Q000378:metabolism; D013702:Temporal Lobe / Q000000981:diagnostic imaging* / Q000601:surgery; D014741:Video Recording; D055815:Young Adult
D001786:Blood Glucose; D003510:Cyclohexanes; C493883:N-(2-(4-(2-methoxyphenyl)piperazino))-N-(2-pyridinyl) trans-4-fluorocyclohexanecarboxamide; D010879:Piperazines; D019788:Fluorodeoxyglucose F18; D044282:Receptor, Serotonin, 5-HT1A
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