ICTAL AND INTERICTAL TECHNETIUM-99M-BICISATE BRAIN SPECT IN CHILDREN WITH REFRACTORY EPILEPSY

Identification of epileptogenic foci in patients with refractory epile psy remains a significant diagnostic challenge. Magnetic resonance ima ging studies frequently fail to reveal an anatomic origin for the seiz ures, and scalp electroencephalography is often limited to identificat ion of the involved hemisphere. Functional imaging modalities such as PET and SPECT are more promising tools for this application because th ey reflect the functional pathology associated with the seizure. These changes are more pronounced ictally, but until recently, no radiophar maceutical was available that could be used routinely for ictal SPECT. The present study was therefore undertaken to determine whether Tc-99 m-bicisate could be used in ictal SPECT in pediatric patients with ref ractory epilepsy, to compare the patterns of ictal and interictal bloo d flow in these patients and to compare the localization information p rovided by ictal SPECT with that available from other techniques. Meth ods: Technetium-99m-bicisate/SPECT was compared prospectively with sca lp EEG for its ability to identify a possible seizure focus in pediatr ic patients with refractory epilepsy. Ictal and interictal SPECT studi es were performed in 10 patients (3-19 yr old, mean age 10.9 +/- 4.3 y r; 7 female, 3 male) in whom MRI scans revealed no lesions that might be responsible for the seizures. Results: Ictal SPECT was performed in all patients, and all ictal studies revealed focal perfusion abnormal ities. By comparison, four of the interictal SPECT studies showed regi onal hypoperfusion that corresponded to the regions of hyperperfusion in the ictal studies, and three showed regional hyperperfusion corresp onding to the hyperperfused regions in the ictal studies. Three interi ctal studies revealed no abnormal perfusion. Scalp EEG provided locali zation information in five patients. Conclusion: These initial results suggest that ictal SPECT with Tc-99m-bicisate is a more promising too l for the identification of epileptogenic foci than interictal SPECT o r scalp EEG in patients without focal abnormalities on MRI.