Manual Hippocampal Subfield Segmentation Using High-Field MRI: Impact of Different Subfields in Hippocampal Volume Loss of Temporal Lobe Epilepsy Patients

Author(s):Show less -

Peixoto-Santos, Jose Eduardo ^{[1, 2, 3]} ; Drumond de Carvalho, Luciana Estefani ^[4] ; Kandratavicius, Ludmyla ^[1] ; Beserra Diniz, Paula Rejane ^[5] ; Scandiuzzi, Renata Caldo ^[1] ; Coras, Roland ^{[2, 3]} ; Bluemcke, Ingmar ^{[2, 3]} ; Assirati, Joao Alberto ^[6] ; Carlotti, Carlos Gilberto ^[6] ; Marconato Simoes Matias, Caio Cesar ^[6] ; Garrido Salmon, Carlos Ernesto ^[7] ; dos Santos, Antonio Carlos ^[8] ; Velasco, Tonicarlo R. ^[1] ; Moraes, Marcio Flavio D. ^[9] ; Leite, Joao Pereira ^[1]

Affiliation

^[1] Univ Sao Paulo, Ribeirao Preto Med Sch, Dept Neurosci & Behav Sci, Ribeirao Preto - Brazil

^[2] Univ Hosp Erlangen, Neuropathol Inst, Erlangen - Germany

^[3] Friedrich Alexander Univ Erlangen Nuremberg, Erlangen - Germany

^[4] Fed Univ Sao Joao del Rey, Dept Physiol & Biophys, Divinopolis - Brazil

^[5] Univ Fed Pernambuco, Dept Clin Med, Recife, PE - Brazil

^[6] Univ Sao Paulo, Ribeirao Preto Med Sch, Dept Surg & Anat, Ribeirao Preto - Brazil

^[7] Univ Sao Paulo, Dept Phys & Math, Fac Philosophy Sci & Languages Ribeirao Preto, Ribeirao Preto - Brazil

^[8] Univ Sao Paulo, Ribeirao Preto Med Sch, Dept Internal Med, Ribeirao Preto - Brazil

^[9] Univ Fed Minas Gerais, Ctr Technol & Res Magnetoresonance, Dept Physiol & Biophys, Belo Horizonte, MG - Brazil

• Document type: Journal article
• Source: FRONTIERS IN NEUROLOGY; v. 9, NOV 20 2018.
• Web of Science Citations: 4

Abstract

In patients with temporal lobe epilepsy (TLE), presurgical magnetic resonance imaging (MRI) often reveals hippocampal atrophy, while neuropathological assessment indicates the different types of hippocampal sclerosis (HS). Different HS types are not discriminated in MRI so far. We aimed to define the volume of each hippocampal subfield on MRI manually and to compare automatic and manual segmentations for the discrimination of HS types. The T2-weighted images from 14 formalin-fixed age-matched control hippocampi were obtained with 4.7T MRI to evaluate the volume of each subfield at the anatomical level of the hippocampal head, body, and tail. Formalin-fixed corona! sections at the level of the body of 14 control cases, as well as tissue samples from 24 TLE patients, were imaged with a similar high-resolution sequence at 3T. Presurgical three-dimensional (3D) T1-weighted images from TLE went through a FreeSurfer 6.0 hippocampal subfield automatic assessment. The manual delineation with the 4.7T MRI was identified using Luxol Fast Blue stained 10-mu m-thin microscopy slides, collected at every millimeter. An additional section at the level of the body from controls and TLE cases was submitted to NeuN immunohistochemistry for neuronal density estimation. All TLE cases were classified according to the International League Against Epilepsy's (ILAE's) HS classification. Manual volumetry in controls revealed that the dentate gyrus (DG)+CA4 region, CA1, and subiculum accounted for almost 90% of the hippocampal volume. The manual 3T volumetry showed that all TLE patients with type 1 HS (TLE-HS1) had lower volumes for DG+CA4, CA2, and CA1, whereas those TLE patients with HS type 2 (TLE-HS2) had lower volumes only in CA1 (p <= 0.038). Neuronal cell densities always decreased in CA4, CA3, CA2, and CA1 of TLE-HS1 but only in CA1 of TLE-HS2 (p <= 0.003). In addition, TLE-HS2 had a higher volume (p = 0.016) and higher neuronal density (p < 0.001) than the TLE-HS1 in DG + CA4. Automatic segmentation failed to match the manual or histological findings and was unable to differentiate TLE-HS1 from TLE-HS2. Total hippocampal volume correlated with DG+CA4 and CA1 volumes and neuronal density. For the first time, we also identified subfield-specific pathology patterns in the manual evaluation of volumetric MRI scans, showing the importance of manual segmentation to assess subfield-specific pathology patterns. (AU)

• FAPESP's process: 17/03739-8 - Histopathological correlates of magnetic resonance imaging in patients with drug-resistant epilepsies
• Grantee: José Eduardo Peixoto Santos
• Support Opportunities: Scholarships abroad - Research Internship - Post-doctor
• FAPESP's process: 15/20840-9 - Histopathological correlates of magnetic resonance imaging in patients with drug-resistant epilepsies
• Grantee: José Eduardo Peixoto Santos
• Support Opportunities: Scholarships in Brazil - Post-Doctoral
• FAPESP's process: 16/17882-4 - Drug-resistant epilepsies: diagnostic challenges, associated comorbidities and new experimental approaches
• Grantee: João Pereira Leite
• Support Opportunities: Research Projects - Thematic Grants