Quantitative Surgical Targeting of FDG-PET Hypometabolism Relates to Long-term Seizure Outcomes
Abstract number :
2.314
Submission category :
5. Neuro Imaging / 5B. Functional Imaging
Year :
2024
Submission ID :
706
Source :
www.aesnet.org
Presentation date :
12/8/2024 12:00:00 AM
Published date :
Authors :
Presenting Author: Lucas Sainburg, BS – Vanderbilt University
Joseph Hoang, MD – Vanderbilt University Medical Center
Derek Doss, BE – Vanderbilt University
Ghassan Makhoul, BA – Vanderbilt University
Todd Peterson, PhD – Vanderbilt University Medical Center
Gary Smith, MD – Vanderbilt University Medical Center
Dario Englot, MD, PhD – Vanderbilt University Medical Center
Victoria Morgan, PhD – Vanderbilt University Medical Center
Rationale: Interictal FDG-PET is a standard part of the presurgical workup for epilepsy and a significant predictor of postsurgical seizure outcomes1. However, the clinical assessments of FDG-PET scans are typically only qualitative or semi-quantitative and many patients who undergo FDG-PET as part of their standard workup continue to have seizures after surgery. Here we quantitatively assess the surgical targeting of FDG-PET hypometabolism and its relation to long-term seizure outcomes.
Methods: This study included 46 patients with drug-resistant temporal lobe epilepsy (32 right-sided) who underwent either selective amygdalohippocampectomy (n = 37) or anterior temporal lobectomy with at least 3 years of follow-up. All patients underwent standard presurgical workup including interictal FDG-PET (resolution = 1.2-3.3 mm). PET scans were given a clinical grade by a radiologist (JH) as either normal, diffuse, subtle focal or focal with respect to the resection.
T1-weighted MRI scans were collected before and after surgery to assess the extent of surgical resection. T1-weighted scans were segmented into 117 cortical and subcortical regions2. Resection cavities were segmented on the postsurgical scans with ResectVol3 and regions with at least 25% reduction in volume were considered resected.
PET image intensity was converted to relative standardized uptake values (SUVR) at each voxel by Z-scoring across the grey matter. PET laterality was calculated by taking the mean SUVR at each region minus the mean SUVR of its contralateral homologue (Fig 1A-B, top). The discriminability of PET laterality between resected and spared regions (DRS)4 was calculated for each patient as a quantitative measure of how well surgery targeted their PET hypometabolism (Fig 1A-B, bottom). A lower DRS corresponds to better surgical targeting of the hypometabolism.
Area under the receiver operating curve (AUC) analysis was used to assess how PET DRS and the PET clinical read could each distinguish Engel I from Engel II-IV patients at both 1- and 3-years postsurgery.
Results: The PET clinical read did not distinguish patients who were Engel I from Engel II-IV at 1-year after surgery (p > 0.05; Fig 2C), but PET DRS moderately distinguished the groups (AUC = 0.68, p = 0.08; Fig 2A). The PET clinical read distinguished patients who were Engel I from Engel II-IV at 3-years after surgery (AUC = 0.68, p = 0.03; Fig 2D), but PET DRS was found to distinguish these groups more accurately (AUC = 0.83, p = 0.0001; Fig 2B).
Conclusions: These results suggest that quantitative analysis of FDG-PET is strongly related to long-term seizure outcomes and could potentially be used prospectively for surgical planning. Further studies are needed to validate these findings in external cohorts with foci outside of the temporal lobe.
Funding: Funded by NIH F31NS135908, T32EB021937, R01NS108445, R01NS110130, and R00NS097618.
References
1. Courtney et al., Neurology 2024; 102(9):e209304.
2. Huo et al., NeuroImage 2016; 138:197-210.
3. Casseb et al., Epilepsia Open 2021; 6(4):720-726.
4. Wang et al., Epilepsia 2020; 61(7):1417-1426.
Neuro Imaging