Prognostic value of CA4/DG volumetry with 3 T magnetic resonance imaging on postoperative outcome of epilepsy patients with dentate gyrus pathology

• We traced hippocampal subfields on MRI in patients with temporal lobe epilepsy.
• The boundary of CA4/DG in hippocampal body could be clearly identified on 3 T MRI.
• The volumes for CA4/DG segment were smaller in patients with DG pathology.
• Patients with DG pathology showed better postoperative outcomes.
• CA4/DG volumetry with presurgical MRI has prognostic value in postsurgical outcome.

SummaryPurposeHippocampal sclerosis (HS), the most common feature of mesial temporal lobe epilepsy (MTLE), is widely accepted as surgical indication for refractory epilepsy. Pathological hallmarks in hippocampal dentate gyrus (DG), including granule cell loss (GCL) and granule cell dispersion (GCD), are known to be closely related to the status epilepticus and spontaneous seizure. Our aim was to assess the association between volumetric changes in the hippocampal CA4/DG determined with 3-Tesla (3 T) magnetic resonance imaging (MRI) and the postoperative seizure outcomes in MTLE patients with or without dentate gyrus pathology (DGP).MethodsHigh-resolution T2- and T1-weighted three-dimensional (3D) MRI scans were performed on 39 MTLE patients before surgery with a 3 T Philips scanner. ITK-SNAP software was used for segmentation and volumetry of the CA4/DG segment, and NASP software was used for 3D reconstructions of the CA4/DG region. Immunostaining for Neuronal Nuclei (NeuN) was performed on resected hippocampal specimens after surgery to verify the accuracy of CA4/DG segmentation and histopathological changes in DG.ResultsThe CA4/DG subfield could be precisely segmented with high-resolution 3 T MRI and confirmed by comparison of NeuN-immunoreactive slices with MRI results. MTLE patients with DGP showed smaller CA4/DG volume and favorable postoperative seizure outcomes.ConclusionThe volumetry of CA4/DG was associated with the pathological changes in DG in MTLE patients. The volumetry of CA4/DG with preoperative 3 T MRI could predict the postoperative seizure outcomes in those patients.