Local Spread of Resting-State fMRI Activity in Mesial Temporal Structures Is Related to Surgical Outcomes in TLE
Abstract number :
2.171
Submission category :
5. Neuro Imaging / 5B. Functional Imaging
Year :
2021
Submission ID :
1825576
Source :
www.aesnet.org
Presentation date :
12/5/2021 12:00:00 PM
Published date :
Nov 22, 2021, 06:43 AM
Authors :
Lucas Sainburg, BS - Vanderbilt University; Baxter Rogers, PhD - Vanderbilt University Institute of Imaging Science - Vanderbilt University Medical Center; Catie Chang, PhD - Department of Electrical Engineering and Computer Science - Vanderbilt University; Dario Englot, MD, PhD - Department of Neurological Surgery - Vanderbilt University Medical Center; Victoria Morgan, PhD - Vanderbilt University Institute of Imaging Science - Vanderbilt University Medical Center
Rationale: Mesial temporal lobe epilepsy (mTLE) can be treated by resection of the epileptogenic zone (EZ), which is typically the hippocampus. Poor surgical outcomes, as well as focal to bilateral tonic-clonic seizures (FBTCS) are often attributed to spread of the EZ. Amplitude of low frequency fluctuations (ALFF) using resting-state fMRI (rsfMRI) measures brain activity and may identify the EZ. We hypothesized that the ALFF of the ipsilateral hippocampus (iHip) as well as nearby connected mesial temporal regions (ipsilateral entorhinal cortex (iEnt) and parahippocampal gyrus (iPHG)) would indicate spread of the EZ, and therefore be related to FBTCS and surgical outcomes in mTLE.
Methods: 43 unilateral mTLE patients (13 left mTLE, 30 selective amygdalohippocampectomies (SAH), 9 temporal lobectomies, 2 ablations, 2 no surgery) along with 70 controls took part in this study. Subjects underwent a presurgical T1-weighted scan (1x1x1 mm3) for segmentation and two 10-minute rsfMRI scans (TR = 2s, 3x3x4 mm3) on a 3T MRI. Amplitude of low frequency fluctuations (ALFF)1 was calculated by taking the voxel-wise Fourier Transform of the preprocessed rsfMRI data, summing amplitudes across the 0.005-0.1 Hz range, and normalizing across the grey matter for each of 109 ROIs.
ALFF of right and left mTLE patients was compared with controls using t-tests at each ROI with Bonferroni correction. Patients were split into groups based on presence of FBTCS and 1-year Engel outcome. ALFF of the iHip, followed by the iEnt and iPHG were compared between controls and groups of patients by ANOVA, followed by FDR corrected post-hoc t-tests.
Results: ALFF was increased in mesial temporal and subcortical regions and decreased in parietal and cingulate regions of mTLE patients compared to controls. ALFF was specifically increased in the iHip, iEnt and iPHG of right mTLE patients and the iHip of left mTLE patients (p < 0.05, corrected, Fig 1). ALFF was increased in the iEnt and iPHG of left mTLE patients prior to correction (p < 0.05).
Patients without FBTCS had higher iHip ALFF than patients with FBTCS (p< 0.05, Fig 2A). No ALFF differences of iHip, iEnt and iPHG were detected between patients based on outcomes (Fig 2C-D); however, patients who underwent SAH and ablation with Engel 1b-4 outcomes had increased iHip, iEnt and iPHG ALFF compared to patients with Engel 1a outcomes (p< 0.05, Fig 2E-F).
Neuro Imaging