Ex‐SPECTing success: Predictors of successful SPECT radiotracer injection during presurgical video‐EEG admissions

Abstract

Abstract Objectives To determine predictors of successful ictal single photon emission computed tomography (SPECT) injections during Epilepsy Monitoring Unit (EMU) admissions for patients undergoing presurgical evaluation for drug‐resistant focal epilepsy. Methods In this retrospective study, consecutive EMU admissions were analyzed at a single center between 2019 and 2021. All seizures that occurred during the admission were reviewed. “Injectable seizures” occurred during hours when the radiotracer was available. EMU‐level data were analyzed to identify factors predictive of an EMU admission with a successful SPECT injection (successful admission). Seizure‐level data were analyzed to identify factors predictive of an injectable seizure receiving a SPECT injection during the ictal phase (successful injection). A multivariate generalized linear model was used to identify predictive variables. Results 125 EMU admissions involving 103 patients (median 37 years, IQR 27.0–45.5) were analyzed. 38.8% of seizures that were eligible for SPECT (n = 134) were successfully injected; this represented 17.4% of all seizures (n = 298) that occurred during admission. Unsuccessful admissions were most commonly due to a lack of seizures during EMU‐SPECT (19.3%) or no injectable seizures (62.3%). Successful EMU‐SPECT was associated with baseline seizure frequency >1 per week (95% CI 2.1–3.0, P 1 per week, a PET hypometabolic focus, and a patient's ability to indicate seizure onset were identified as predictors of success. These findings may assist EMUs in optimizing their SPECT protocols, patient selection, and resource allocation.

Keywords

• epilepsy monitoring unit
• epilepsy surgery
• focal epilepsy
• refractory epilepsy
• single photon emission computed tomography