Ictal and interictal Tc-99M HM-PAO brain perfusion spect in medically intractable epilepsy: Addition of substraction technique

Twenty-one patients [15 males and 6 females] aged 23.7 +/- 6.9 years were presented with partial [focal] seizures intractable to medical therapy and candidates for surgery. All of them were subjected to brain perfusion SPECT using Tc-99 HM-PAO [10.6 MBq/kg body weight/study], in addition to MRI and EEG. SPECT were performed in the ictal [under inpatient video-EEG long term monitoring], interictal and both phases in 5, 9 and 7 patients, respectively. The results showed that all the above cases exhibited successful postoperative outcome of the partial seizures according to Engels' scale. In correlation with MRI, neurophysiologic, and/or surgical localization, and/or surgical outcome, accurate localization of the epileptogenic focus was proved in all the seven cases [100%] with dual-phase and subtraction study. This successful localization was revealed in four cases each in the groups of the ictal [90%] and interictal [44%] studies, respectively. In conclusion, the dual-phase Tc-99m HM-PAO brain perfusion SPECT [ictal and interictal] with subsequent subtraction technique may be more accurate than either study alone for localization of epileptogenic focus in medically intractable epilepsy, particularly in cases with negative MRI