Ictal SPECT using technetium-99m-HMPAO: methods for rapid preparation and optimal deployment of tracer during spontaneous seizures.

Ictal SPECT provides unique information for the clinician treating patients with refractory epilepsy and reveals insights into the pathophysiology of seizures. We describe our methods for the routine attainment of ictal images using 99mTc-HMPAO. We have devised and implemented techniques for rapid reconstitution of 99mTc-HMPAO adjacent to the video-EEG monitoring suite such that the tracer can be rapidly injected into patients when spontaneous seizures occur. Our quality assurance data show that this can be done safely outside a nuclear medicine department. The clinical results in patients with temporal lobe epilepsy show that ictal injections (97% correct lateralization of focus, 0% incorrect) are more sensitive and accurate compared to interictal studies (48% correct, 10% incorrect), demonstrating that the implementation of these techniques is worthwhile.