Ex vivo ultra-high field magnetic resonance imaging of human epileptogenic specimens from primarily the temporal lobe: A systematic review

PurposeMagnetic resonance imaging (MRI) is the preferred diagnostic tool for the detection of structural cerebral lesions in patients with epilepsy. Ultra-high field (UHF) MRI with field strengths >= 7 Tesla has been reported to improve the visualization and delineation of epileptogenic lesions. The use of ex vivo UHF MRI may expand our knowledge on the detection and detailed micromorphology of subtle epileptogenic lesions by bridging the gap between in vivo MRI and histopathology.MethodsA systematic review of available literature was conducted following PRISMA guidelines. A descriptive analysis of included articles was performed, focusing on (I) the ability of ex vivo UHF MRI to detect subtle abnormalities related to epilepsy, (II) different post-processing methods, and (III) concordance between UHF MRI and histopathology.ResultsEleven studies with focus on the depiction of focal cortical dysplasia (n = 4) or hippocampal sclerosis (n = 7) as causative lesion of drug-resistant epilepsy were included. Ex vivo UHF MRI proved its ability to visualize the anatomy of cortical and hippocampal structures in greater detail when compared to ex vivo conventional field strengths. Different MRI post-processing methods enabled differentiation between lesional subtypes and provided novel insights into (peri)lesional characteristics. Concordance between ex vivo UHF MRI findings and histopathology was high.ConclusionAcquisition of ex vivo UHF MRI and its image processing has the potential to depict epileptogenic abnormalities in greater detail with a spatial resolution approximating histological images. The translation of ex vivo UHF MRI features to in vivo clinical settings remains challenging and urges further exploration.