Objective Detection of Epileptic Foci by¹⁸F-FDG PET in Children Undergoing Epilepsy Surgery

Abstract

PET has been used for the presurgical localization of epileptic foci for more than 20 y; still, its clinical role in children with intractable epilepsy remains unclear, largely because of variable analytic approaches and different outcome measures. The purpose of the present study was to evaluate and optimize the performance (lateralization and lobar localization value of epileptic foci) of objective voxel-based analysis of 18F-FDG PET scans in a pediatric epilepsy population. Methods Twenty children with intractable focal epilepsy (mean age ± SD, 11 ± 4 y; age range, 6–18 y) who underwent interictal 18F-FDG PET, followed by 2-stage epilepsy surgery with chronic subdural electrocorticographic monitoring, and were seizure-free after surgery were included in this study. PET images were analyzed using both a visual-analysis and a statistical parametric mapping (SPM) method. Lateralization value and performance of lobar localization (in lateral and medial surfaces of all lobes, total of 8 regions in each epileptic hemisphere), calculated for 3 different statistical thresholds, were determined against intracranial electrocorticography-determined seizure-onset region and surgical resection site. Results SPM using a statistical threshold of P less than 0.001 provided 100% correct lateralization, which was better than visual assessment (90%). Although visual and SPM analyses (with both P < 0.001 and P < 0.0001 thresholds) performed similarly well (with a sensitivity and specificity of 74%or above) in the localization of seizure-onset regions, SPM detected 7 of 9 seizure-onset regions, mostly in medial cortices, that were missed by visual assessment. Also, SPM performed equally well in both hemispheres, compared with visual analysis, which performed better in the left hemisphere. No statistical difference in performance was observed between visual and SPM analyses of children with abnormal versus normal MRI findings or of children with gliosis versus developmental pathology. Clinical variables, such as age, duration of epilepsy, age of seizure onset, and time between PET and last seizure, showed no correlation with sensitivity or specificity of either visual analysis or SPM analysis. Conclusion SPM analysis, using a young adult control group, can be used as a complementary objective analytic method in identifying epileptogenic lobar regions by 18F-FDG PET in children older than 6 y.

The Utility of Positron Emission Tomography in Epilepsy

“…Kumar et al 23 compared the results between V and SPM. The reported sensitivity from that study was 62% for V and 71% for SPM using a threshold of p < 0.001 (35% with a stricter threshold of p < 0.05).…”

“…23,[38][39][40] In one study, 23 the results for two methods of PET interpretation-visual analysis (V) and statistical parametric mapping (SPM)-were reported. SPM using a threshold of p < 0.001 provided a sensitivity of 86% when measured against intracranial EEG.…”

Glucose Metabolic Profile by Visual Assessment Combined with Statistical Parametric Mapping Analysis in Pediatric Patients with Epilepsy

“…Static 18 F-FDG PET image volumes were analyzed using the SPM8 software package developed at the Wellcome Department of Cognitive Neurology, Institute of Neurology (21). 18 F-FDG PET image volumes were spatially normalized into standard stereotactic space using an in-house pediatric PET template.…”

Seizures in Children with Brain Tumours — Epidemiology, Significance, Management, and Outcomes

“…In one study reported by Ibrahim et al, for example, the time from seizure onset to tumour diagnosis among ten children presenting with seizures ranged from two weeks to two years, averaging six months [37]. A wide range of opinions and practices exist regarding how aggressive to pursue diagnostic imaging in children presenting with seizures [36,41,51,79,80,100,[127][128][129][130][131][132][133]. For example, in one series of eighteen patients between the ages of 1 month and 13 years who presented with seizures and were discovered to have DNETs between January 1992 and December 2004, the preoperative evaluation included magnetic resonance (MR) imaging and interictal scalp electro-encephalography (EEG) in all patients, but functional MR imaging also was performed in eight patients, video monitoring with scalp EEG during seizures in 12 patients, interictal single-photon emission computerized tomography (SPECT) scanning in one patient, and ictal SPECT scanning in two patients [132].…”