Bottom-of-sulcus dysplasia: the role of 18F-FDG PET in identifying a focal surgically remedial epileptic lesion

Abstract

Purpose Bottom-of-sulcus dysplasia (BOSD) is a type of focal cortical dysplasia and an important cause of intractable epilepsy. While the MRI features of BOSD have been well documented, the contribution of PET to the identification of these small lesions has not been widely explored. The aim of this study was to investigate the role of F-18 fluorodeoxyglucose (18F-FDG) PET in the identification of BOSD. Methods Twenty patients with BOSD underwent both 18F-FDG PET and structural MRI scans as part of preoperative planning for surgery. Visual PET analysis was performed, and patients were classified as positive if they exhibited a focal or regional hypometabolic abnormality, or negative in the absence of a hypometabolic abnormality. MRI data were reviewed to determine if any structural abnormality characteristic of BOSD were observed before and after co-registration with PET findings. Results PET detected hypometabolic abnormalities consistent with the seizure focus location in 95% (19/20) of cases. Focal abnormalities were detected on 18F-FDG PET in 12/20 (60%) patients, while regional hypometabolism was evident in 7/20 (35%). BOSD lesions were missed in 20% (4/20) of cases upon initial review of MRI scans. Co-registration of 18F-FDG PET with MRI enabled detection of the BOSD in all four cases where the lesion was initially missed. Conclusion Our findings show that 18F-FDG PET provides additional clinical value in the localisation and detection of BOSD lesions, when used in conjunction with MRI.

Hypometabolic patterns are related to post‐surgical seizure outcomes in focal cortical dysplasia: A semi‐quantitative study

“…MRI abnormality signs could highly indicate its location, including cortical thickening at the sulcal bottom, blurring of the gray‐white matter boundary, abnormal signal intensity, and transmantle sign. However, when MRI is negative or doubtful, PET could be a crucial examination to make confirmation and enhance the detection rate 36–38 . On the one hand, PET hypometabolism itself could indicate epileptogenicity 39 .…”

“…However, when MRI is negative or doubtful, PET could be a crucial examination to make confirmation and enhance the detection rate. 36 , 37 , 38 On the one hand, PET hypometabolism itself could indicate epileptogenicity. 39 On the other hand, it can assist in the judgment of MRI signs.…”