066 The Utility of 18-FDG PET imaging in the preoperative workup for epilepsy surgery

Abstract

For patients with refractory focal epilepsy, surgical resection of the epileptogenic zone can lead to a drastic reduction in seizure frequency. Careful localisation of the epileptogenic zone is imperative in the presurgical workup. Up to 20% patients with refractory focal epilepsy have a normal MRI and are less likely to be referred for epilepsy surgery. As a result, 18-FDG-PET has been employed to localise the epileptogenic focus, which appears as a region of hypometabolism. This study examines the real-world utility of 18-FDG-PET imaging among patients undergoing for presurgical assessments over a 5-year period.Between January 2015 and March 2020, 65/90 patients referred for presurgical assessment underwent 18-FDG PET. In total, 26/65 (40%) patients had corresponding focal abnormalities on 18-FDG PET and MRI studies, of whom 22 had focal epileptiform activity on video-EEG (80.1%). Therefore, where 18-FDG PET and MRI agree, there is a high predictive value for successful seizure localisation with video-EEG moni- toring. Furthermore, 33/65 (40.7%) patients had MRI-negative epilepsy, of whom 17/33 (51.1%) had focal hypometabolism on 18-FDG PET. Thus, over half of our patient cohort with “non-lesional” or MRI-negative epilepsy were able to proceed to intracranial video-EEG monitoring or resective surgery with the help of supportive data from 18-FDG PET imaging.