Value of ultra‐high‐field MRI in patients with drug‐resistant focal epilepsy and negative 3T MRI (EpiUltraStudy): Diagnostic gain of 7T structural analysis

Objective Resective epilepsy surgery is an evidence‐based treatment option for patients with focal drug‐resistant epilepsy (DRE). Seizure outcome after surgery is largely dependent on detection and delineation of an epileptogenic lesion on magnetic resonance imaging (MRI). However, detection fails in 30% of patients at 3 Tesla (T) MRI, thereby limiting surgical options. Diagnostic and therapeutic gain of ultra‐high‐field MRI in patients with 3T MRI‐negative DRE is evaluated in the EpiUltraStudy. Here we report the diagnostic gain of structural 7T MRI. Methods Inclusion criteria were age ≥12 years and DRE with a suspected epileptogenic focus and negative conventional 3T MRI during pre‐surgical workup. Images were evaluated independently by two neuroradiologists and a neurologist or neurosurgeon in two runs: blinded (Run 1) and with the results of additional clinical investigations (Run 2). Results Sixty patients underwent 7T MRI. No persistent adverse events were reported. Visual assessment of 7T MRI identified lesions in 9 cases (15%), undetected on prior 3T MRI. Possible positive scan rates increased from 17% (10/60) in the blinded run to 47% (28/60) in the informed run. However, after consensus review, many of these were reclassified as negative. Eight of nine positive 7T MRI scans were initially identified by only one or two assessors. After reassessment, a total of 56% (5/9) of 7T lesions were retrospectively identified on 3T. Significance Our data suggest a benefit of 7T MRI for the detection of subtle epileptogenic lesions in patients with DRE and negative 3T MRI. Although the detection rate may appear modest compared to other reports, we present a nuanced discussion of our methodology and patient population, contributing meaningful context to the current literature. The availability of multimodal information and consensus reviews enhanced diagnostic accuracy but with higher rates of false positives, underscoring the importance of multidisciplinary cooperation in the clinical care for patients with DRE. Trial Registration Number www.trialregister.nl : NTR7536.