Abstracts

Rationale: Determination of seizure onset zone (SOZ) in refractory epilepsy is essential for epilepsy surgery-Focal cortical dysplasia (FCD) is the most common cause of refractory epilepsy in children and 2nd/ 3rd most common cause in adults-18F-fluorodeoxyglucose-positron emission tomography (PET) hypometabolism may correspond to SOZ-PET has lower spatial resolution than magnetic resonance imaging (MRI), limiting areas identified as possible SOZ to larger volumes of brain including both gray and white matter-Gray matter isolated from the T1 MRI sequence can be used as a mask to isolate gray matter volumes in functional neuroimagingWe hypothesize that segmentation of PET can improve localization of FCD.  Methods: •31 pediatric and adult patients aged 2 years to 60 years were selected based on epilepsy surgery workups that included a PET and a volumetric MRI along with MRI and/or pathology positive findings of cortical dysplasia.
•A total of 34 areas of cortical dysplasia were identified
•PETs were segmented to view only gray matter portions.
•The locations of the most hypometabolic PET regions in both segmented and nonsegmented images were compared to MRI positive and/or pathology positive findings.
•The level of correspondence in segmented and non-segmented PET scans was recorded as same: subgyrus (highest level of correspondence), gyrus, sublobe, lobe, hemisphere, or no correspondence.
•The primary outcome is  evaluate how well segmentation corresponds to the anatomic localization of the FCD Results: •Segmented PET scans showed a high degree of correspondence to the localization of the FCD and most often resulted in higher anatomical concordance to MRI-positive and/or pathology-positive cortical dysplasias than non-segmented PET scans
•In 28 of 34 cases segmented PET scans localized to the same subgyrus as MRI-positive and/or pathology-positive findings
•Segmented PET scans were significantly more likely than unsegmented PET scans to correspond to a correct localization at anatomical levels more precise than hemispheric Conclusions: •PET segmentation adds significant anatomical specificity in identifying FCDs
•This method may be more helpful than conventional PET in identifying or confirming the localization of epileptogenic FCDs
•PET segmentation could be useful in guiding intracranial electroencephalogram placement Funding: University of Georgia- Augusta Unviersity Medical Scholars Program provide support for Gabriel Pajartes Hurtado's participation in the research.