Authors :
Presenting Author: Kelly Pu, – Duke University School of Medicine
Ming-Kai Chen, MD, PhD – Yale University School of Medicine; Charlotte Chen, BA – University of Connecticut; Alex King, BA – University of California, Berkeley; Evan Collins, MS – Massachusetts Institute of Technology; Dennis Spencer, MD – Yale University School of Medicine; Hitten Zaveri, PhD – Yale University School of Medicine
Rationale:
PET-defined hypometabolism is a biomarker of the seizure onset area (SOA). In previous work, PET imaging of epilepsy patients has focused on lobar and sub-lobar determinations of hypometabolism. We sought to quantitatively evaluate PET imaging from epilepsy patients at five spatial resolutions ranging from the hemisphere to the SOA using the Yale Brain Atlas (YBA). A more accurate determination of the hypometabolism observed in epilepsy patients would be valuable for clinical decision making on locating the SOA for intracranial electrode placement and pathophysiological correlation.
Methods:
Epilepsy patients at Yale New Haven Hospital between 2014 to 2021 who underwent an intracranial EEG study where PET was obtained during pre-surgical evaluation were retrospectively identified.
For each patient, the SOA defined during intracranial EEG study was mapped onto the YBA, which divides the brain into 690 parcels each about 1 cm in size according to well-defined neuroanatomical features. Using a custom pipeline developed by MIM Software and the Yale PET Center, z-scores were generated for each YBA parcel, which compares the PET value at that parcel to the corresponding value from a database of healthy controls. Using the YBA parcellation, PET z-scores were evaluated between the area ipsilateral and the area contralateral to the seizure onset at the spatial levels of brain hemisphere, lobe, region, gyrus, and SOA.Results:
A total of 50 focal epilepsy patients who met the inclusion criteria were identified. The seizure onset lobes represented are right temporal (n = 14), left temporal (n = 13), right frontal (n = 8), left frontal (n = 4), right parietal (n = 5), left parietal (n = 4), right insula (n = 1), and left insula (n = 1).
Across all 50 patients, the mean ipsilateral PET z-score was significantly lower than the mean contralateral PET z-score at all spatial resolutions examined (Figure 1). This was observed at the level of hemisphere (-0.02 vs. 0.25, p< 0.001), lobe (-0.34 vs. 0.10, p< 0.001), region (-0.41 vs. 0.11, p< 0.001), gyrus (-0.48 vs. 0.02, p< 0.001), and SOA (-0.52 vs. -0.001, p< 0.001). Ipsilateral hypometabolism from the level of hemisphere to SOA was also seen in the right and left temporal and right and left frontal seizure onset lobe groups.