Authors :
Presenting Author: Alfredo Lucas, BS, MS – University of Pennsylvania
Eli Cornblath, MD, PhD – University of Pennsylvania; Nishant Sinha, PhD – University of Pennsylvania; lorenzo Caciagli, MD, PhD – University of Pennsylvania; Peter Hadar, MD – Massachusetts General Hospital; Ashley Tranquille, BS – University of Pennsylvania; Joel Stein, MD, PhD – University of Pennsylvania; Sandhitsu Das, PhD – University of Pennsylvania; Kathryn Davis, MD – University of Pennsylvania
Rationale:
Resting-state functional magnetic resonance imaging (rs-fMRI) at ultra high-field strengths (≥7T) is known to provide superior signal-to-noise and statistical power than comparable acquisitions at lower field strengths. In this study, we aim to provide a direct comparison of the seizure onset-zone (SOZ) lateralizing ability of 7T rs-fMRI and 3T rs-fMRI.
Methods:
We investigated a cohort of 70 temporal lobe epilepsy (TLE) patients. A paired cohort of 19 patients had 3T and 7T rs-fMRI acquisitions for direct comparison between the two field strengths. Forty-three patients had only 3T, and eight patients had only 7T rs-fMRI acquisitions. We quantified the functional connectivity between the hippocampus and other nodes within the default mode network (DMN) using seed-to-voxel connectivity, and measured how hippocampo-DMN connectivity could inform SOZ lateralization at 7T and 3T field strengths.
Results:
Differences between hippocampo-DMN connectivity ipsilateral and contralateral to the SOZ were significantly higher at 7T (pFDR=0.008) than at 3T (pFDR=0.80) when measured in the same subjects. We found that our ability to lateralize the SOZ, by distinguishing subjects with left TLE from subjects with right TLE, was superior at 7T (AUC = 0.97) than 3T (AUC = 0.68). Our findings were reproduced in extended cohorts of subjects scanned at either 3T or 7T. Our rs-fMRI findings at 7T, but not 3T, are consistent and highly correlated (Spearman Rho=0.65) with clinical FDG-PET lateralizing hypometabolism. Finally, only by increasing the sample size of the 3T cohort we were able to see effect sizes for SOZ lateralization comparable to those seen at 7T, suggesting that small sample sizes at 7T replicate findings in large samples at 3T.
Conclusions:
We show superior SOZ lateralization in TLE patients when using 7T relative to 3T rs-fMRI, supporting the adoption of high-field strength functional imaging in the epilepsy presurgical evaluation.
Funding:
AL and KAD received support from NINDS (R01NS116504). NS received support from American Epilepsy Society (953257) and NINDS (R01NS116504).