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.
