Optimising EEG-fMRI for Localisation of Focal Epilepsy in Children
Maria Centeno1,2, Tim M Tierney1, Suejen Perani1,3
1Developmental imaging and biophysics Section, Institute of child health, University College London, London, United Kingdom.
Insights
Watching a movie during electroencephalography-functional magnetic resonance imaging (EEG-fMRI) improves tolerability and reduces movement in children with epilepsy. This optimization allows for effective localization of the epileptic focus without sedation, making the test more accessible for pediatric patients.
Area of Science:
- Neuroscience
- Medical Imaging
- Pediatric Neurology
Background:
- Early surgical intervention for drug-resistant epilepsy in children offers benefits but requires minimally invasive diagnostic tests.
- Electroencephalography-functional magnetic resonance imaging (EEG-fMRI) shows promise for localizing epileptic foci but has historically had a low yield.
- Current pediatric EEG-fMRI often involves sedation, posing risks and potential confounds, unlike adult studies performed under resting conditions.
Purpose of the Study:
- To assess the impact of viewing a movie, movement, interictal epileptiform discharges (IEDs), scan duration, and design efficiency on EEG-fMRI tolerability and results in children.
- To optimize EEG-fMRI parameters for wider availability and improved outcomes in the pediatric population.
Main Methods:
- Forty-six children with focal epilepsy and 20 controls (aged 6-18) underwent EEG-fMRI.
- Two 10-minute "rest sessions" (eyes closed, lying still) and two "movie sessions" (watching a child-friendly movie) were conducted.
- Interictal epileptiform discharges (IEDs) were mapped, and resulting EEG-fMRI maps were classified as concordant or discordant with the presumed epileptogenic focus.
Main Results:
- Movie viewing reduced in-scanner movement by approximately 40% within the first 20 minutes.
- Scan duration (20 vs. 40 minutes) did not affect the ability to map the epileptogenic region.
- Movie viewing did not impact the occurrence of IEDs or the concordance of the EEG-fMRI results.
- Design efficiency was found to be predictive of concordance.
Conclusions:
- Child-friendly stimuli like movies enhance EEG-fMRI tolerability and reduce movement in pediatric patients without compromising IED detection or map quality.
- This approach enables EEG-fMRI in children as young as 6 without sedation, providing crucial localizing information.
- ~20 minutes is suggested as the optimal scan duration for pediatric EEG-fMRI in patients with frequent IEDs.
- The efficiency of the fMRI design, based on spontaneous IEDs, is critical for achieving concordant results.
Background:
Early surgical intervention in children with drug resistant epilepsy has benefits but requires using tolerable and minimally invasive tests. EEG-fMRI studies have demonstrated good sensitivity for the localization of epileptic focus but a poor yield although the reasons for this have not been systematically addressed. While adults EEG-fMRI studies are performed in the "resting state"; children are commonly sedated however, this has associated risks and potential confounds. In this study, we assessed the impact of the following factors on the tolerability and results of EEG-fMRI in children: viewing a movie inside the scanner; movement; occurrence of interictal epileptiform discharges (IED); scan duration and design efficiency. This work's motivation is to optimize EEG-fMRI parameters to make this test widely available to paediatric population.
Methods:
Forty-six children with focal epilepsy and 20 controls (6-18) underwent EEG-fMRI. For two 10 minutes sessions subjects were told to lie still with eyes closed, as it is classically performed in adult studies ("rest sessions"), for another two sessions, subjects watched a child friendly stimulation i.e. movie ("movie sessions"). IED were mapped with EEG-fMRI for each session and across sessions. The resulting maps were classified as concordant/discordant with the presumed epileptogenic focus for each subject.
Findings:
Movement increased with scan duration, but the movie reduced movement by ~40% when played within the first 20 minutes. There was no effect of movie on the occurrence of IED, nor in the concordance of the test. Ability of EEG-fMRI to map the epileptogenic region was similar for the 20 and 40 minute scan durations. Design efficiency was predictive of concordance.
Conclusions:
A child friendly natural stimulus improves the tolerability of EEG-fMRI and reduces in-scanner movement without having an effect on IED occurrence and quality of EEG-fMRI maps. This allowed us to scan children as young as 6 and obtain localising information without sedation. Our data suggest that ~20 minutes is the optimal length of scanning for EEG-fMRI studies in children with frequent IED. The efficiency of the fMRI design derived from spontaneous IED generation is an important factor for producing concordant results.
More Related Videos
09:57Author Spotlight: Advancing Pediatric Epilepsy Surgery in Children Through Novel Biomarkers and Enhanced Localization
Published on: September 20, 2024
10:23Equipment Setup and Artifact Removal for Simultaneous Electroencephalogram and Functional Magnetic Resonance Imaging for Clinical Review in Epilepsy
Published on: June 23, 2023