Brain heterotopia

The analysis of 18 F-FDG PET/MRI, electroencephalography, and semiology in patients with gray matter heterotopia: A pilot study

OBJECTIVES

To describe ¹⁸ F-fluorodeoxyglucose positron emission tomography/magnetic resonance imaging (¹⁸ F-FDG PET/MRI) along with semiology and electroencephalography (EEG) in patients with gray matter heterotopia (GMH); to evaluate the concordance between ¹⁸ F-FDG PET/MRI and clinical epileptogenic zone (EZ).

MATERIALS & METHODS

GMH (subcortical heterotopia [SCH] and periventricular nodular heterotopia [PNH]) patients with epilepsy who underwent ¹⁸ F-FDG PET/MRI were retrospectively enrolled. Two radiologists evaluated brain MRI, while two nuclear medicine specialists assessed the ¹⁸ F-FDG PET. The SUVmax values of visually hypometabolic cortical areas were compared to the contralateral cortex using a SUVmax threshold value of 10%; the SUVmax values of GMH lesions were compared with that of the right precentral gyrus. The cortex or GMH with hypometabolism on ¹⁸ F-FDG PET/MRI was considered representative of the EZ. The clinical EZ was identified using EEG and semiology.

RESULTS

Thirty patients (19 PNH; 11 SCH) with a mean age of 28.46 ± 9.52 years were enrolled. The heterotopic nodules were ametabolic in 3 patients (10%), hypometabolic in 16 (33.33%), isometabolic in 13 (26.66%), and hypermetabolic in 4 (10%). ¹⁸ F-FDG PET/MRI demonstrated hypometabolism in the cortex and GMH in 22/30 (73.33%) and 16/30 (53.33%). We could identify a clinical EZ in 18 patients, and 15 out of 18 (83.33%) had concordant ¹⁸ F-FDG PET/MRI findings.

CONCLUSION

Heterotopic nodules in GMH patients show different metabolic patterns on ¹⁸ F-FDG PET/MRI, with nearly three-quarters of the patients having cortical hypometabolism. ¹⁸ F-FDG PET/ MRI findings are mostly concordant with the clinical EZ.

Three Different FDG Patterns in Periventricular Nodular Heterotopia Correlated to Video Stereoelectroencephalography

ABSTRACT

A 40-year-old woman with a drug-resistant focal epilepsy underwent cerebral FDG PET in phase 1 presurgical epilepsy study. MRI essentially showed multiple periventricular nodular heterotopias. The stereoelectroencephalography coupled to MRI and FDG PET helped to define the anatomofunctional correlation of the epileptogenic zone network. This procedure brought to light 3 distinct patterns of FDG consumption, corresponding to different anatomoelectroclinical features. This pattern was already found in a previous FDG PET reflecting a "stable" permanent intralesional intercritical stereoelectroencephalography activity, an electrical "signature" of the lesion. Finally, functional imaging improved thermocoagulation in this patient and emphasized the use of FDG in drug-resistant epilepsy.

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.