Diffusion Tensor Imaging Localizes the Epileptogenic Zone in Children with Drug Resistant Epilepsy
Abstract number :
1.111
Submission category :
2. Translational Research / 2C. Biomarkers
Year :
2022
Submission ID :
2204224
Source :
www.aesnet.org
Presentation date :
12/3/2022 12:00:00 PM
Published date :
Nov 22, 2022, 05:24 AM
Authors :
Christos Papadelis, PhD – Cook Children’s Health Care System; Margherita Matarrese, MSc – PhD student, Engineering Department, Università Campus Bio-Medico di Roma; Eleonora Tamilia, PhD – Instructor in Pediatrics, Department of Medicine, Boston Children's Hospital, Harvard Medical School; Scott Perry, MD – Head of Neurosciences, Jane and John Justin Neurosciences Center, Cook Children’s Health Care System; Phillip Pearl, MD – Director of Epilepsy and Clinical Neurophysiology, Department of Neurology, Boston Children's Hospital; Ludovica Corona, MSc – PhD student, Department of Bioengineering, University of Texas at Arlington
Rationale: Diffusion tensor imaging (DTI) is a noninvasive neuroimaging tool used to investigate structural changes in the brain by measuring the anisotropic water diffusion in neural fibers. To explore microstructural alterations in epileptic brain, we investigated the diffusion parameters computed in different fibers’ directions inside the resected areas (i.e., confirmed to be epileptogenic) in patients with drug resistant epilepsy (DRE) and in mirrored areas at the contralateral hemisphere. Such inter-hemispheric diffusion analysis may help in the presurgical evaluation of those patients by providing spatial information of the epileptogenic zone (EZ).
Methods: We retrospectively analyzed neuroimaging data of 19 seizure-free children with DRE (6 females, mean age: 12.7 years, median age: 12 years) who underwent neurosurgery (Engel I, follow-up range: 12-48 months). Mean age at epilepsy onset was 5 years (median: 5 years) and mean epilepsy duration was 7.7 years (median: 9 years). Ground truth of successful estimation of the EZ was defined using resection volumes obtained by co-registering the pre- and post-operative magnetic resonance imaging (MRIs). For each patient, we then mirrored the resection volume in the contralateral non-pathological hemisphere (used as control) (Figure 1A). Through a tractography software tool for diffusion MRI analysis (DSI studio), we extracted the following diffusion metrics: fractional anisotropy (FA), axial diffusivity (AD), mean diffusivity (MD), and radial diffusivity (RD). Each metric was then extracted from both the resection and the contralateral area (Figure 1B). To assess inter-hemispheric brain abnormalities, we computed two unique mean and median values of each diffusion metric for each patient and compared these values between resection and the contralateral area (Wilcoxon signed-rank test).
Results: We observed significantly higher median AD (p=0.044), MD (p=0.018), and RD (p=0.033) inside resection compared to the contralateral zone, as well as for mean MD (p=0.013), and RD (p=0.013) (Figure 2). Contrarily, FA did not show significant differences between these two regions. Although FA did not reach statistical significance, it showed increased median and mean values mostly inside the contralateral area (i.e., non-pathological hemisphere) and decreased values inside the EZ.
Conclusions: Our study shows that water molecule diffusion in neural fibers that reside in epileptogenic areas differs from homologous regions of the contralateral hemisphere. Our findings show the potential additional value of diffusion imaging in localizing the epileptogenic zone in patients with DRE. Combined with other neuroimaging noninvasive techniques, such as functional connectivity, DTI is a powerful tool that may help the presurgical evaluation of children with DRE by detecting pathological structural changes of brain networks associated with the epileptogenic focus.
Funding: RO1NS104116-01A1 and R21NS101373-01A1 by NINDS
Translational Research