Abstracts

Rationale: 123I-iomazenil (IMZ) single photon emission computerized tomography (SPECT) imaging has been shown to visualize the cerebral blood flow in the early images after injection of the radioactive nuclide as well as the distribution of benzodiazepine receptors (BZR) in the delayed images (IMZ-D). The clinical usefulness of the delayed images was evaluated by many studies using a large number of patients in Japan, but only a few studies have been conducted for early IMZ SPECT imaging (IMZ-E) and there are no previous studies on pediatric patients. We evaluated the effectiveness of IMZ-E comparing with conventional cerebral blood flow SPECT, 99mTc ethyl cysteinate dimer SPECT (ECD) and 123I-iodoamphetamine SPECT (IMP) for the children with localization-related epilepsy. Methods: Twenty-four children, 17 males and 7 females (1 - 15 years old), who had MRI-evident brain lesions corresponding to epileptic foci, were the subjects for SPECT imaging using 2 gamma camera systems. Images were obtained 20 minutes (early image) and 3 hours (delayed image) after intravascular administration of IMZ. IMZ imaging results were compared with those of ECD (N=15) and / or IMP (N=14). All images were performed with a written informed consent in all cases. Results: 1) The IMZ-E showed positive findings in 17 / 24. The laterality of abnormal findings was concordant with the epileptic foci in 15 cases. 2) IMP revealed positive findings in 10 of 14 cases examined. The localization was coincident with that shown by IMZ-E.The positive region was larger and more remarkable in comparison with IMZ-E. 3) ECD exhibited positive findings in 6 of 15 cases examined. The localization was concordant with that shown by IMZ-E. 4) IMZ-D revealed positive results in 21 cases. 5) Three cases without positive finding in ECD showed positive in IMZ-E and one case without positive sign in IMZ-E showed positive in IMP. Conclusions: This study suggested that early images of IMZ reflect abnormal distribution of cerebral blood flow corresponding to probable epileptic foci as well as IMP/ECD. A single intravenous administration of IMZ can visualize both the cerebral blood flow distribution in early images and benzodiazepine receptor distribution in delayed images, and is therefore advantageous to pediatric patients who need sedation during examinations. Further studies are required with a larger number of patients.