Ictal SPECT success rate using a single SPECT session protocol

Ictal single-photon emission computed tomography (SPECT) provides additional information on the localisation of the epileptogenic zone. However, ictal SPECT is labour-intensive and expensive. We have developed a more affordable protocol with a single SPECT radiotracer session during a 48-hour video-EEG monitoring (VEM). This study aimed to determine the success rate of ictal SPECT with a single SPECT session (HMPAO or ECD).

This retrospective observational study included all VEM cases performed in the University Malaya Medical Centre, Kuala Lumpur, Malaysia from 1st January 2011 to 30th April 2024, with SPECT as part of the pre-surgical evaluation.

A total of 189 cases were included. The mean age was 33.3 years old (range 9-68), and 105 (55.6 %) were male. The mean baseline seizure frequency before VEM was 21.8 per month. The mean number of seizures recorded during a 48-hour VEM was 10.9. A total of 44 (23.3 %) patients had ictal SPECT with a single SPECT session. Ictal SPECT was significantly associated with a higher number of seizures during 48-hour VEM (31.5 ± 58.7 vs 4.4 ± 6.3, p < 0.001) and younger age (29.9 ± 11.8 vs 34.2 ± 11.9, p < 0.05). On multivariate analysis, only the number of seizures during 48-hour VEM was a significant predictor for ictal SPECT (95 % CI, 1.03-1.12; odds ratio, 1.073; p = 0.002). Those with at least three seizures during VEM had a ≥ 30 % chance of having ictal SPECT and ≥ 40 % in those with six or more seizures.

A single SPECT session on day 3 of VEM can be a cost-effective option, particularly in those patients with multiple seizures in the first 48 hours of monitoring following a fast medication taper.