Localizing the seizure onset zone by comparing patient postictal hypoperfusion to healthy controls

Area of Science:

• Neurology
• Radiology
• Medical Imaging

Background:

• Arterial Spin Labeling (ASL) MRI is a valuable tool for localizing the seizure onset zone (SOZ) in epilepsy patients.
• Current clinical use of ASL MRI requires two scans (interictal and postictal), limiting its widespread implementation.
• The need for two scans is a barrier to the routine clinical use of ASL MRI for SOZ localization.

Purpose of the Study:

• To investigate the feasibility of using a single postictal ASL MRI scan compared to healthy controls for SOZ localization.
• To compare the diagnostic performance of patient postictal vs. control baseline ASL (pvcASL) with standard subtraction ASL (sASL).

Main Methods:

• Eighteen epilepsy patients (aged 20-55) underwent ASL MRI within 90 minutes post-seizure and during the interictal period.
• Postictal ASL scans were compared to average baseline ASL scans from 100 healthy controls (pvcASL).
• pvcASL maps were also compared against standard subtraction ASL (sASL) maps derived from patient interictal and postictal scans.

Main Results:

• Postictal hypoperfusion was detected in 94.4% of patients using pvcASL and 77.8% using sASL.
• Concordance with the SOZ was observed in 59% of pvcASL maps and 86% of sASL maps.
• pvcASL identified significant hypoperfusion in two cases where sASL showed none, indicating its utility in specific scenarios.

Conclusions:

• Patient postictal vs. control baseline ASL (pvcASL) is a clinically useful method for SOZ localization.
• While potentially having a lower overall concordance rate than sASL, pvcASL can detect hypoperfusion missed by sASL.
• pvcASL offers valuable localizing or lateralizing information in specific epilepsy cases, potentially reducing the need for multiple scans.