Value of 3.0T MR imaging in refractory partial epilepsy and negative 1.5T MRI

BACKGROUND High-field 3.0 T MR scanners provide an improved signal-to-noise ratio which can be translated in higher image resolution, possibly allowing critical detection of subtle epileptogenic lesions missed on standard-field 1.0-1.5 T MRIs. In this study, the authors explore the potential value of re-imaging at 3.0 T patients with refractory partial epilepsy and negative 1.5 T MRI. METHODS We retrospectively identified all patients with refractory partial epilepsy candidate for surgery who had undergone a 3.0 T MR study after a negative 1.5 T MR study. High-field 3.0 T MRIs were reviewed qualitatively by neuroradiologists experienced in interpreting epilepsy studies with access to clinical information. Relevance and impact on clinical management were assessed by an epileptologist. RESULTS Between November 2006 and August 2009, 36 patients with refractory partial epilepsy candidate for surgery underwent 3.0 T MR study after a 1.5 T MR study failed to disclose a relevant epileptogenic lesion. A potential lesion was found only in two patients (5.6%, 95% CI: 1.5-18.1%). Both were found to have hippocampal atrophy congruent with other presurgical localization techniques which resulted in omission of an invasive EEG study and direct passage to surgery. CONCLUSIONS The frequency of detection of a new lesion by re-imaging at 3.0 T patients with refractory partial epilepsy candidate for surgery was found to be low, but seems to offer the potential of a significant clinical impact for selected patients. This finding needs to be validated in a prospective controlled study.