Portable ultra-low-field magnetic resonance imaging enables postictal seizure imaging

The detection of transient peri-ictal magnetic resonance imaging (MRI) abnormalities has been variable after epileptic seizures. The most common reason for this variability is that abnormalities may disappear if the interval between seizure and scan acquisition is prolonged using conventional high-field systems. Here, we deployed a portable ultra-low-field MRI system in the presurgical evaluation at the bedside of individuals with epilepsy. We hypothesized that this novel technology enables rapid postictal scans and reliably shows focal peri-ictal MRI abnormalities in the seizure onset zone. A .064-T Swoop Portable MR Imaging System was used. Postictally, an axial diffusion-weighted sequence was acquired. The interictal MRI consisted of the diffusion-weighted and three-dimensional T1-weighted sequences. Postictal-interictal difference maps of diffusion-weighted volumes were calculated. Three individuals were included. Two individuals with focal aware seizures scanned 29 s and 19 min after the seizure, respectively, showed focal restrictions in diffusivity in the seizure onset zone, and a third individual scanned 5 h 45 min after a focal to bilateral tonic-clonic seizure showed global restrictions of diffusivity. Portable ultra-low-field MRI opens a new line of inquiry with the aim to establish postictal seizure imaging as part of the presurgical evaluation of people with epilepsy.