title: alpha-[11C]-Methyl-L-tryptophan PET identifies the epileptogenic tuber and correlates with interictal spike frequency.
abstract: Epilepsy surgery has been successfully performed in patients with tuberous sclerosis complex (TSC) and seizures arising from a restricted epileptogenic area. The outcome of cortical excision depends on accurate pre-surgical identification of the epileptogenic tuber. [11C] alpha-methyl-L-tryptophan (alpha-MTrp) was originally developed to measure serotonin synthesis in vivo with positron emission tomography (PET). However in pathologic conditions its uptake may also depend on the synthesis of quinolinic or kynurenic acid via the kynurenine pathway. Increased levels of serotonin and quinolinic acid have been observed in epileptogenic lesions, raising the possibility that alpha-MTrp PET may localize the epileptogenic area. The aim of this study was to correlate alpha-MTrp PET uptake with the localization of the epileptogenic area and with interictal spike frequency in patients with TSC. alpha-MTrp uptake was measured in 8 patients (2 males, mean age 29.6+/-14.9 years, range 3-50 years) with intractable partial epilepsy due to TSC. All patients underwent scalp EEG monitoring during the PET scan. In four (50%), increased uptake of alpha-MTrp occurred in the epileptogenic area alone. Two (25%) patients showed multifocal abnormalities and the remaining two (25%) did not show focal changes. PET localization was mostly seen in patients with frequent interictal abnormalities on the EEG. Furthermore, there was a significant correlation between alpha-MTrp uptake and the frequency of interictal spikes (r=0.6; P<0.05). alpha-MTrp PET is a promising diagnostic tool in the localization of the epileptogenic area in patients with TSC.
authors.affiliation: Department of Neurology, Montreal Neurological Institute and Hospital, McGill University, Que., Montreal, Canada.
authors.forename: Marco
authors.initials: M
authors.lastname: Fedi
authors.forename: David C
authors.initials: DC
authors.lastname: Reutens
authors.forename: Frederick
authors.initials: F
authors.lastname: Andermann
authors.forename: Hidehiko
authors.initials: H
authors.lastname: Okazawa
authors.forename: Warren
authors.initials: W
authors.lastname: Boling
authors.forename: Carole
authors.initials: C
authors.lastname: White
authors.forename: François
authors.initials: F
authors.lastname: Dubeau
authors.forename: Akio
authors.initials: A
authors.lastname: Nakai
authors.forename: Donald W
authors.initials: DW
authors.lastname: Gross
authors.forename: Eva
authors.initials: E
authors.lastname: Andermann
authors.forename: Mirko
authors.initials: M
authors.lastname: Diksic
mesh_terms: D000293:Adolescent; D000328:Adult; D002250:Carbon Radioisotopes; D002675:Child, Preschool; D004569:Electroencephalography; D005260:Female; D006801:Humans; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D019275:Radiopharmaceuticals / Q000493:pharmacokinetics; D012640:Seizures / Q000000981:diagnostic imaging*; D014055:Tomography, Emission-Computed; D014364:Tryptophan / Q000031:analogs & derivatives* / Q000493:pharmacokinetics; D014402:Tuberous Sclerosis / Q000000981:diagnostic imaging*
chemical_list: D002250:Carbon Radioisotopes; D019275:Radiopharmaceuticals; C020774:alpha-methyltryptophan; D014364:Tryptophan