Abstract
Introduction: [18F]fluorodeoxyglucose (18F-FDG) positron emission tomography (PET) is part of the regular preoperative work-up in medically refractory epilepsy. As a complement to visual evaluation of PET, statistical parametric maps can help in the detection of the epileptogenic zone (EZ). However, software packages currently available are time-consuming and little intuitive for physicians. We develop a user-friendly software (referred as PET-analysis) for EZ localization in PET studies that allows dynamic real-time statistical parametric analysis. To evaluate its performance, the outcome of PET-analysis was compared with the results obtained by visual assessment and Statistical Parametric Mapping (SPM).Methods: Thirty patients with medically refractory epilepsy who underwent presurgical 18F-FDG PET with good post-operative outcomes were included. The 18F-FDG PET studies were evaluated by visual assessment, with SPM8 and PET-analysis. In SPM, parametric T-maps were thresholded at corrected p < 0.05 and cluster size k = 50 and at uncorrected p < 0.001 and k = 100 (the most used parameters in the literature). Since PET-analysis rapidly processes different threshold combinations, T-maps were thresholded with multiple p-value and different clusters sizes. The presurgical EZ identified by visual assessment, SPM and PET-analysis was compared to the confirmed EZ according to post-surgical follow-up.Results: PET-analysis obtained 66.7% (20/30) of correctly localizing studies, comparable to the 70.0% (21/30) achieved by visual assessment and significantly higher (p < 0.05) than that obtained with the SPM threshold p < 0.001/k = 100, of 36.7% (11/30). Only one study was positive, albeit non-localizing, with the SPM threshold corrected p < 0.05/k = 50. Concordance was substantial for PET-analysis (κ = 0.643) and visual interpretation (κ = 0.622), being fair for SPM (κ = 0.242).Conclusion: Compared to SPM with the fixed standard parameters, PET-analysis may be superior in EZ localization with its easy and rapid processing of different threshold combinations. The results of this initial proof-of-concept study validate the clinical use of PET-analysis as a robust objective complementary tool to visual assessment for EZ localization.
Highlights
Surgical resection is the potentially curative treatment option in one third of epileptic patients who remain uncontrolled despite polytherapy with antiepileptic drugs
We introduced some methodological improvements which we thought were necessary for positron emission tomography (PET) studies in the field of epilepsy based on our daily clinical experience
Hypometabolic areas were detected by visual assessment in 28/30 (93.3%) of PET studies, and the presurgical epileptogenic zone (EZ) was correctly localized in 21/30 (70.0%) of patients
Summary
Surgical resection is the potentially curative treatment option in one third of epileptic patients who remain uncontrolled despite polytherapy with antiepileptic drugs. Visual interpretation of brain PET imaging can be improved by means of objective complementary software tools which compare each study to a normal control group using statistical parametric analysis. This is essential in epilepsy in which subtle hypometabolic changes may be overlooked by the naked eye. Software packages currently available for interpretation of brain imaging studies such as Statistical Parametric Mapping (SPM) [8] are of generic purpose and do not allow making real-time dynamic changes in the level of detectability. The outcome of PET-analysis was compared with the results obtained by visual assessment and SPM processing using the standard parameters from literature
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
