Determination of perfusion abnormalities in subjects with status epilepticus

Abstract

Status epilepticus is a condition in which the brain is in a state of seizure activity without returning to its basal state for more than 5 minutes. Medication is the usual treatment, but when it is ineffective, surgical removal of the epileptogenic focus, the area responsible for seizures initiation, is considered. In patients with no apparent brain lesion, perfusion magnetic resonance imaging can be used to identify abnormal blood flow and locate the epileptogenic focus. Several studies have employed perfusion imaging to detect abnormal values in individuals with epilepsy. However, most of these methods need reference values on which to compare and establish what abnormality is. This thesis proposes a methodology to overcome the limitations of the state-of-the-art to assess brain perfusion abnormalities in subjects with status epilepticus. It is based on an individual voxel-based z-score to find outliers, and electroencephalographic recordings to confirm the location detected. A comparison with an asymmetry-based analysis has also been carried out. Additionally, a comparison between dynamic susceptibility contrast (DSC), the gold-standard perfusion imaging technique that uses contrast agent, and arterial spin labeling (ASL), a non-invasive magnetic resonance imaging sequence, has been performed. With the outlier methodology, perfusion abnormalities related to electroencephalographic locations were successfully detected in a similar percentage of patients (90.48% with DSC, 87.5% with ASL) than with the asymmetry-based approach (87.5% with DSC, 100.00% with ASL). In conclusion, the proposed methodology delivers high accuracy and reliability to localize the epileptogenic focus, enhancing presurgical planning for a precise resection of the focus.