COMPARISON OF [F-18] FDG-PET, [TC-99M]-HMPAO-SPECT, AND [I-123] IOMAZENIL-SPECT IN LOCALIZING THE EPILEPTOGENIC CORTEX

Objectives-Firstly, to compare the findings of interictal F-18-fluorod eoxyglucose (FDG) positron emission tomography (PET) and of single pho ton emission computed tomography (SPECT) using Tc-99M-hexamethyl propy lene-amine-oxime (HMPAO) and I-123-iomazenil in localising the epilept ogenic cortex in patients who were candidates for epilepsy surgery, bu t in whom clinical findings, video EEG monitoring (V-EEG), MRI, and ne uropsychological evaluations did not give any definite localisation of the seizure onset. Secondly, to assess the ability of these functiona l methods to help in the decision about the epilepsy surgery. Methods- Eighteen epileptic patients were studied with FDG-PET and iomazenil-SP ECT. HMPAO-SPECT was performed in 11 of these 18 patients. Two referen ces for localisation was used-ictal subdural EEG recordings (S-EEG) an d the operated region. Results-Fifteen of 18 patients had localising f indings in S-EEG. FDG-PET findings were in accordance with the referen ces in 13 patients and iomazenil-SPECT in nine patients. HMPAO-SPECT v isualised the focus less accurately than the two other methods. In thr ee patients S-EEG showed independent bitemporal seizure onset. In thes e patients FDG-PET showed no lateralisation. However, iomazenil-SPECT showed temporal lobe lateralisation in two of them. Conclusion-FDG-PET seemed to localise the epileptogenic cortex more accurately than inte rictal iomazenil-SPECT in patients with complicated focal epilepsy.