MRI is a cornerstone in presurgical evaluation of epilepsy. Despite guidelines, clinical practice varies. In light of the E-PILEPSY pilot reference network, we conducted a systematic review and meta-analysis on the diagnostic value of MRI in the presurgical evaluation of epilepsy patients. We included original research articles on diagnostic value of higher MRI field strength and guideline-recommended and additional MRI sequences in detecting an epileptogenic lesion in adult or paediatric epilepsy surgery candidates. Lesion detection rate was used as a metric in meta-analysis. Eighteen studies were included for MRI field strength and 25 for MRI sequences, none were free from bias. In patients with normal MRI at lower-field strength, 3T improved lesion detection rate by 18% and 7T by 23%. Field strengths higher than 1.5T did not have higher lesion detection rates in patients with hippocampal sclerosis (HS). The lesion detection rate of epilepsy-specific MRI protocols was 83% for temporal lobe epilepsy (TLE) patients. Dedicated MRI protocols and evaluation by an experienced epilepsy neuroradiologist increased lesion detection. For HS, 3DT1, T2, and FLAIR each had a lesion detection rate at around 90%. Apparent diffusion coefficient indices had a lateralizing value of 33% for TLE. DTI fractional anisotropy and mean diffusivity had a localizing value of 8% and 34%. A dedicated MRI protocol and expert evaluation benefits lesion detection rate in epilepsy surgery candidates. If patients remain MRI negative, imaging at higher-field strength may reveal lesions. In HS, apparent diffusion coefficient indices may aid lateralization and localization more than increasing field strength. DTI can add further diagnostic information. For other additional sequences, the quality and number of studies is insufficient to draw solid conclusions. Our findings may be used as evidence base for developing new high-quality MRI studies and clinical guidelines.

Centre for Medical Image Computing University College London London United Kingdom MRI Unit Epilepsy Society Chalfont St Peter United Kingdom

Department of Biomedical Engineering School of Biomedical Engineering and Imaging Sciences Kings College London London UK and UCL Great Ormond Street Institute of Child Health London United Kingdom

Department of Medical Radiation Sciences University of Gothenburg Gothenburg Sweden MedTech West at Sahlgrenska University Hospital Campus Gothenburg Sweden

Department of Neurology Charles University 2nd Faculty of Medicine Motol University Hospital Prague Czech Republic

Department of Neurology Christian Doppler University Hospital Paracelsus Medical University affiliated EpiCARE Member and Centre for Cognitive Neuroscience Salzburg Austria

Department of Neurology Christian Doppler University Hospital Paracelsus Medical University affiliated EpiCARE Member and Centre for Cognitive Neuroscience Salzburg Austria Department of Neurology Medical University of Innsbruck Innsbruck Austria

Department of Neurology Christian Doppler University Hospital Paracelsus Medical University affiliated EpiCARE Member and Centre for Cognitive Neuroscience Salzburg Austria Neuroscience Institute Christan Doppler University Hospital Paracelsus Medical University and Centre for Cognitive Neuroscience Salzburg Austria Department of Public Health Health Services Research and Health Technology Assessment UMIT University for Health Sciences Medical Informatics and Technology Hall in Tirol Austria

Department of Neurology University of Ulm and Universitäts and Rehabilitationskliniken Ulm Ulm Germany

Department of Neurosurgery University Hospital Saint Ivan Rilski Sofia Bulgaria

Department of Psychiatry and Neurology Budapest Hungary

Great Ormond Street Hospital for Children NHS Trust Department of Neurosurgery and UCL Great Ormond Street Institute of Child Health London United Kingdom

MR Research Center Semmelweis University Budapest Hungary

UMC Utrecht Brain Center University Medical Center Utrecht Department of Neurology and Neurosurgery Utrecht University the Netherlands

References provided by Crossref.org

Harmonization of MRI sequences across ERN EpiCARE centers