Abstracts

RATIONALE: Inter ictal PET discloses a temporal lobe hypometabolism in the most of the MTLE, while Ictal SPECT can show a wide temporal lobe hyperfixation. There[scquote]s a high concordance between these results and the surgical outcome in published data. In the most of the cases, inter-ictal hypometabolism and ictal perfusion area spread to all the temporal lobe. In this case, the hypometabolism should be superposed to the hyper-perfusion area. To evaluate the intermodality correlation between SPECT, TEP, interictal and ictal EEG cartography. To evaluate the concordance of areas between TEP and ictal SPECT.
METHODS: 31 patients with refractory MTLE (age 29 y) were included. All the patients underwent standard EEG, perictal video-EEG, MRI and inter-ictal FDG TEP. 19 had an ictal 99m Tc ECD SPECT. 4 regions of interest were drawn in the different modality : 3 temporal areas and basal ganglia. All the data were compared by visual analysis.
RESULTS: In 2 /31 patients, TEP were normal. Among the 19 patient who had ictal SPECT, 4 TEP localized an hypometabolism controlateral to the SPECT hyperperfusion, and in 3/4 cases, it was contralateral to both SPECT and EEG data. 12 patients were concordant for all the data. For 9 of these 12 patients the area of EEG paroxysms, hypometabolism and ictal hyperperfusion were superimposed. 6 of them had surgery with a good surgical outcome. 3 patients who had not ictal SPECT were operated. 2 had a seizure recurrence.
CONCLUSIONS: There is not a perfect concordance between ictal SPECT and TEP data. When ictal SPECT is not obtained, the post surgical seizure recurrence risk seems higher in this little group (2/3). We underlie the importance of a complete intermodality concordance, and the necessity to obtain ictal SPECT. There is a concordance between the surface of the per-ictal EEG paroxysms, the ictal hyperperfusion and the inter-ictal hypometabolism.