Clinical Value of the First Dedicated, Commercially Available Automatic Injector for Ictal Brain SPECT in Presurgical Evaluation of Pediatric Epilepsy: Comparison with Manual Injection

Abstract

The most challenging technical problem in ictal brain SPECT for localization of an epileptogenic focus is obtaining a timely injection of a radiopharmaceutical. In our institution, the first dedicated commercially available, remotely controlled automatic injector has been used in the pediatric epilepsy unit in conjunction with 24-h video and electroencephalogram monitoring. The goal of this study was to demonstrate the improved success rate of ictal injection by use of the automatic injector in the pediatric population. Methods: Eighty-four pediatric patients and eighty-four 99m Tc-ethylcysteinate dimer ( 99m Tc-ECD) ictal brain SPECT studies were retrospectively analyzed in a masked manner. The group with manual injection consisted of 45 studies performed from 2004 to 2010 before the introduction of the automatic injector. The group with automatic injection consisted of 39 studies performed from 2010 to 2011 after the introduction of the automatic injector. The 2 groups were comparable in the total duration of seizure, injected dose, and time from the injection to the image acquisition. The latency time from the seizure onset to the initiation time of injection, the ratio of latency time to total duration of seizure (L/T), the number of patients with repeated studies, the number of days of additional hospitalization for each study, and the localization rate for identifying a single focus in each study were compared between the groups. Results: The median latency time in the group with automatic injection (8 s) was significantly lower than that of the group with manual injection (18 s) (P , 0.05). Also there was a statistically significant decrease in the number of patients with repeated studies in the group with automatic injection (2/39 [5%]), compared with the group with manual injection (14/45 [31%]) (P , 0.05). The median number of days of additional hospitalization in the group with manual injection (range, 0-7) was statistically significantly different, compared with the group with automatic injection (range, 0-1) (P , 0.05). In the group with automatic injection, 31 of 39 scans demonstrated a single localizing focus, compared to 22 of 45 scans from the manual-injection group, a significant difference (P , 0.05). The radiation exposure rate to nursing staff during the periods with automatic injection was lower than during the periods with manual injection. Conclusion: The automatic injector combined with 24-h video and electroencephalogram monitoring demonstrated significant clinical value by decreasing latency time, the number of patients with repeated studies, and the number of days of additional hospitalization while increasing the number of studies with a single localizing focus.

The promise of subtraction ictal SPECT co-registered to MRI for improved seizure localization in pediatric epilepsies: Affecting factors and relationship to the surgical outcome

“…Despite these limitations, this relatively large study confirms previous findings on the impact of the injection delay on the localization value of ictal SPECT in children and highlights the importance of automating the radiotracer injection using robust EEG-based seizure detectors and predictors 39 . Finally, this study also highlights that imaging a dynamically evolving seizure is a complex process that may depend on multiple factors beyond the radiotracer injection, including seizure dynamics and the origin of seizure onset.…”

How to Inject Ictal SPECT? From Manual to Automated Injection

“…These results may be explained by the fact that the manual TI in our sample was very short (average of 14 s), thanks to the experience of our technicians in the injection of radiotracers under these conditions. Our findings are in contrast with the work of Kim et al 11 who reported that the rate of SPECT seizure focus localization increased with the use of an automated injector system (from 49% with manual injection to 79% with their automated injection system).…”

“…More recently, some studies have demonstrated that an automated injection system can overcome the main limitations of manual injections in ictal SPECT. Some epilepsy units have developed their own injection systems [7][8][9] or commercially available injectors of radiological contrast that has been re-adapted to inject radioactive doses [10][11][12] . However, no dedicated commercially manufactured injection system for ictal SPECT is currently available.…”

Nuclear medicine in pediatric refractory epilepsy

“…5, 6). If fully developed, this approach could increase the proportion of successful ictal SPECTs [35,[37][38][39][40][41][42][43][44][45].…”