High Accuracy Fiber Tracking (HAFT) Correlates with SEEG-Defined Epileptogenic Zones
Abstract number :
1.239
Submission category :
5. Neuro Imaging / 5A. Structural Imaging
Year :
2021
Submission ID :
1826679
Source :
www.aesnet.org
Presentation date :
12/9/2021 12:00:00 PM
Published date :
Nov 22, 2021, 06:56 AM
Authors :
Jessica Barrios-Martinez, MD - University of Pittsburgh; Fang-Cheng Yeh – University of Pittsburgh; Joseph Mettenburg – University of Pittsburgh Medical Center; Patrick Chauvel – University of Pittsburgh Medical Center; David Fernandes-Cabral – University of Pittsburgh Medical Center; Catherine Liegeois-Chauvel – University of Pittsburgh; Witold Lipski – University of Pittsburgh; F.-Xavier Alario – University of Pittsburgh; Jorge Gonzalez-Martinez – University of Pittsburgh Medical Center
Rationale: White matter structural connectivity changes in epilepsy are not well understood. Although, several studies have observed impaired structural connectivity in these patients, there has not been a consensus for anatomical impairment due to the absence of imaging biomarkers of epileptogenicity in white matter. Intracranial recordings obtained by stereo electroencephalography (SEEG) provide information limited to functional connectivity, thus advance techniques for the study of structural connectivity are needed. Here, we intend to study the correlation between SEEG-defined Epileptogenic Zones (EZ) and adjacent white matter structural connectivity using high accuracy fiber tracking (HAFT) in patients with medically refractory focal epilepsy.
Methods: In a prospective observational study, we evaluated all patients with focal and medically intractable epilepsy who underwent simultaneous SEEG evaluation for EZ localization and HAFT for structural connectivity assessment. Diffusion MRI was acquired preoperatively. Imaging data reconstruction and HAFT were performed using DSI Studio software. Atlas-based regions were placed at SEEG-defined EZ locations including bilateral superior, middle, and inferior temporal gyri, amygdala, hippocampus, and orbitofrontal gyrus. Only fibers terminating at and in the vicinity of the EZ were selected. The normalized quantitative anisotropy (nQA) values were measured in different anatomical positions in relation to the epileptic cortical areas, from proximal to distal in relation to the EZ, and in both hemispheres for comparison. Age, gender, dominance side, MRI results, duration of epilepsy syndrome, epilepsy age of onset, and location of EZ were statistically compared with nQA values from fibers that were anatomically related to the EZ locations.
Results: In total, eleven patients (age range: 23-68 years; mean [SD] = 39 [14.6] years; sex [M/F] = 7/4; duration of syndrome range= 2-44 years; mean [SD] = 17.2 [12.7]) with diagnosis of focal and intractable epilepsy were studied. Based on SEEG, nine patients had EZ located in temporal and mesial structures (81.8%), one patient at lingual gyrus (9.1%), and 1 patient at orbitofrontal cortex (9.1%). Based on nQA measurements, increased structural connectivity was observed in a total of eight patients (72.7%) when compared with the contralateral side. The nQA values varied in relation to the distance from the cortical epileptogenic areas, with higher connectivity in close proximity with the EZ, and lower connectivity in further locations. In three patients (27.3%), nQA values were decreased in areas in close proximity with the EZ, when compared with contralateral side.
Conclusions: We demonstrate evidence of increased structural connectivity in white matter areas that are in close proximity with SEEG-defined EZs. The evidence suggests that focal changes in white matter structural connectivity are specifically associated with epileptogenicity. Increased nQA values in HAFT may represent an imaging biomarker for pathological epileptic cortical regions.
Funding: Please list any funding that was received in support of this abstract.: No funding.
Neuro Imaging