18F-FDG PET/CT for the pre-surgical localization of epileptogenic focus among paediatric patients with drug resistant epilepsy in Malaysia: perspective of a nuclear medicine physician.

ABSTRACT

BACKGROUND: Scalp video electroencephalography monitoring (VEM) and brain MRI sometime fail to identify the epileptogenic focus (EF) in patients with drug resistant epilepsy (DRE). 18F-FDG PET/CT has been shown to improve the detection of EF in patients but is not widely used in Malaysia. Thus, the objective of this study was to identify whether 18F-FDG PET/CT conferred an added benefit in the pre-surgical evaluation of DRE. METHODS: Retrospective review of 119 consecutive paediatric patients referred for 18F-FDG-PET/CT at the Department of Nuclear Medicine of the National Cancer Institute, Putrajaya. All had DRE and underwent evaluation at the Paediatric Institute, Hospital Kuala Lumpur. Visually detected areas of 18F-FDG-PET/CT hypometabolism were correlated with clinical, MRI and VEM findings. RESULTS: Hypometabolism was detected in 102/119 (86%) 18FFDG- PET/CT scans. The pattern of hypometabolism in 73 patients with normal MRI was focal unilobar in 16/73 (22%), multilobar unilateral in 8/73 (11%), bilateral in 27/73 (37%) and global in 5/73 (7%) of patients; whilst 17/73 (23%) showed normal metabolism. In 46 patients with lesions on MRI, 18F-FDG-PET/CT showed concordant localisation and lateralization of the EF in 30/46 (65%) patients, and bilateral or widespread hypometabolism in the rest. Addition of 18FFDG PET/CT impacted decision making in 66/119 (55%) of patients; 24/73 with non-lesional and 30/46 patients with lesional epilepsies were recommended for surgery or further surgical work up, whilst surgery was not recommended in 11/46 patients with lesional epilepsy due to bilateral or widespread hypometabolism. 25 patients subsequently underwent epilepsy surgery, with 16/25 becoming seizure free following surgery. CONCLUSION: 18F-FDG-PET/CT has an added benefit for the localization and lateralization of EF, particularly in patients with normal or inconclusive MRI.