Abstracts

Rationale: About a third of patients with epilepsy continue to have seizures despite “optimal” medical treatment and for some of these a resection of the epileptogenic focus may even lead to a “cure”.  Among multiple widely available diagnostic tools used to accurately localize the epileptogenic focus, SPECT is available only in the comprehensive epilepsy centers. Timely isotope injection for an iSPECT is critical for optimal yield but poses particular logistical challenges.True iSPECT shows an area of hyperperfusion in the epileptogenic region. It can correctly localize the epileptogenic focus in 70%–90% of cases with unilateral temporal lobe epilepsy and in 66% of cases with extratemporal lobe epilepsy. Injection of SPECT radioisotope in the Epilepsy Monitoring Unit (EMU) has been traditionally done manually. This method has limitations: it is operator-dependent, it requires the availability of trained staff, it may expose the staff to the radiation, and may increase the IL. The use of the ASIs can potentially solve all of these challenges. Methods: We retrospectively reviewed all cases admitted to the University of Pittsburgh Medical Center Presbyterian University Hospital EMU from Jan 1, 2010 to Dec 31, 2016 who underwent an iSPECT. Two ASIs (Spectris Solaris EP MR Injection System; Medrad, Inc., Indianola, PA) were initiated on Jul 1, 2013, and we compared the iSPECTs done with manual injections (Jan 1, 2010 - June 30, 2013) with those done with ASIs (July 1, 2013 - Dec 31, 2016) in terms of IL and number of radioisotope spills. The IL was defined as the time between the ultimately accepted EEG seizure onset and the actual injection. Results: A total of 118 ictal SPECTs were reviewed (64 males, 54%). 35 SPECTs were done in the “pre ASIs period” with the average IL of 66.3 sec and 7 (20%) being postictal injections. 83 SPECTs were done during the “ASIs period” and the average IL was 25.8 sec with 4 (4.8%) being postictal injections. This 2.6-fold shortening in IL was statistically significant (t-test). The number of isotope spills during the “pre ASIs period” was 3, and 0 during the “ASIs period”. This represents a considerable improvement. Conclusions: Utilization of ASIs leads to a significant shortening of the iSPECT IL which may result in an increased diagnostic yield (i.e. a better localization of the epileptogenic focus), which is a focus of an ongoing study. Current implementation of the ASIs provides a safer injection option for the EMU staff as compared with the traditional manual injection.  Funding: None