Abstract
Patients with refractory epilepsy are not only free of seizures after resecting epileptic foci, but also experience significantly improved quality of life. Fluorine-18-fluorodeoxyglucose positron-emission tomography (18F-FDG PET) is a promising avenue for detecting epileptic foci in patients with magnetic resonance imaging (MRI)-negative refractory epilepsy. However, the detection of epileptic foci by visual assessment based on 18F-FDG PET is often complicated by a variety of factors in clinical practice. Easy imaging methods based on 18F-FDG PET images, such as statistical parameter mapping (SPM) and three-dimensional stereotactic surface projection (3D-SSP), can objectively detect epileptic foci. In this study, the regions of surgical resection of patients with over 1 year follow-up and no seizures were defined as standard epileptic foci. We retrospectively analyzed the sensitivity of visual assessment, SPM and 3D-SSP based on 18F-FDG PET to detect epileptic foci in MRI-negative refractory epilepsy patients and obtained the sensitivities of visual assessment, SPM and 3D-SSP are 57, 70 and 60% respectively. Visual assessment combined with SPM or 3D-SSP can improve the sensitivity of detecting epileptic foci. The sensitivity was highest when the three methods were combined, but decreased consistency, in localizing epileptic foci. We conclude that SPM and 3D-SSP can be used as objective methods to detect epileptic foci before surgery in patients with MRI-negative refractory epilepsy. Visual assessment is the preferred method for PET image analysis in MRI-negative refractory epilepsy. When the visual assessment is inconsistent with the patient’s electroclinical information, SPM or 3D-SSP was further selected to assess the epileptic foci. If the combination of the two methods still fails to accurately locate the epileptic foci, comprehensive evaluation can be performed by combining the three methods.
Highlights
According to results released by the World Health Organization (WHO), approximately 50 million people suffer from epilepsy worldwide (World Health Organization, 2019)
We used the regions of surgical resection of patients with over 1 year follow-up and no seizures as standard epileptic foci, allowing us to assess the true efficacies of different methods
Previous studies have shown that the sensitivity of visual assessment based on 18F-FDG PET in detecting epileptic foci in patients with refractory epilepsy ranges from 36 to 78.2% (Spencer, 1994; Kim et al, 2002; Desai et al, 2013; Wang et al, 2016; Jayalakshmi et al, 2019; Rossi Sebastiano et al, 2020), while the sensitivity of visual assessment based on 18F-FDG PET to detect epileptic foci in patients with magnetic resonance imaging (MRI)-negative refractory epilepsy ranges from 36 to 75% (Kim et al, 2002; Rossi Sebastiano et al, 2020)
Summary
According to results released by the World Health Organization (WHO), approximately 50 million people suffer from epilepsy worldwide (World Health Organization, 2019). Studies have shown that patients with refractory epilepsy are free of seizures after surgery, and experience significantly improved quality of life (Dwivedi et al, 2017; Engel et al, 2012). MRI results are negative in about 20–30% patients with refractory epilepsy, meaning that they cannot be directly treated with surgery and other methods are needed to assist in locating the epileptic foci (Muhlhofer et al, 2017; von Oertzen et al, 2002). Studies have shown that 18F-FDG PET can guide a second MRI reading to find hidden lesions, and provide surgeons with potential epileptic foci areas related to seizures (Chassoux et al, 2010; Rathore et al, 2014). Detection of abnormal metabolic areas from 18F-FDG PET is mainly performed by visual assessment; the detection of epileptic foci by visual assessment is often complicated by a variety of factors in clinical practice
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