Evaluation of FDG-PET and ECD-SPECT in patients with subcortical band heterotopia

Objective: The purpose of this retrospective study was to clarify the cellular activities of ectopic neurons in subcortical bands and to evaluate the imaging features of (18)F-fluorodeoxyglucose (FDG) positron emission tomography (PET) and (99m)Tc ethyl cysteinate dimer (ECD) single-photon emission computed tomography (SPECT) in a series of patients with subcortical band heterotopia (SBH).

Materials and methods: The cases of 12 patients with SBH (3 men and 9 women; age range, 2-51 years) were evaluated on the basis of their MRI findings. Eight (18)F-FDG PET and 12 (99m)Tc-ECD SPECT images were obtained. The uptakes of these images were compared with electroencephalography (EEG) or MRI findings such as band thickness. In all patients, easy Z-score Imaging System (eZIS) software was used to statistically analyze the SPECT images.

Results: Of the eight (18)F-FDG PET images, five showed higher uptake in the thick subcortical bands than in the overlying cortex. Of the 12 (99m)Tc-ECD SPECT examinations with eZIS images, nine indicated increased regional cerebral blood flow (rCBF) areas corresponding to the band locations. Of the eight (18)F-FDG PET examination findings, six were congruent with the rCBF distributions on the eZIS images. Eight of the 12 patients showed correspondence to the increased rCBF on the eZIS images, the band locations on MRI, and abnormal discharge sites on EEG.

Conclusions: Ectopic neurons in subcortical bands may have higher glucose metabolism and/or increased rCBF compared to the overlying cortex. (18)F-FDG PET and (99m)Tc-ECD SPECT using eZIS can be helpful to clearly detect the cellular activities of ectopic neurons in patients with SBH.