SUMMARYObjective: To assess the diagnostic yield of 7T magnetic resonance imaging (MRI) in detecting and characterizing structural lesions in patients with intractable focal epilepsy and unrevealing conventional (1.5 or 3T) MRI. Methods: We conducted an observational clinical imaging study on 21 patients (17 adults and 4 children) with intractable focal epilepsy, exhibiting clinical and electroencephalographic features consistent with a single seizure-onset zone (SOZ) and unrevealing conventional MRI. Patients were enrolled at two tertiary epilepsy surgery centers and imaged at 7T, including whole brain (three-dimensional [3D] T 1 -weighted [T1W] fast-spoiled gradient echo (FSPGR), 3D susceptibility-weighted angiography [SWAN], 3D fluid-attenuated inversion recovery [FLAIR]) and targeted imaging (2D T 2 *-weighted dual-echo gradient-recalled echo [GRE] and 2D gray-white matter tissue border enhancement [TBE] fast spin echo inversion recovery [FSE-IR]). MRI studies at 1.5 or 3T deemed unrevealing at the referral center were reviewed by three experts in epilepsy imaging. Reviewers were provided information regarding the suspected localization of the SOZ. The same team subsequently reviewed 7T images. Agreement in imaging interpretation was reached through consensus-based discussions based on visual identification of structural abnormalities and their likely correlation with clinical and electrographic data. Results: 7T MRI revealed structural lesions in 6 (29%) of 21 patients. The diagnostic gain in detection was obtained using GRE and FLAIR images. Four of the six patients with abnormal 7T underwent epilepsy surgery. Histopathology revealed focal cortical dysplasia (FCD) in all. In the remaining 15 patients (71%), 7T MRI remained unrevealing; 4 of the patients underwent epilepsy surgery and histopathologic evaluation revealed gliosis. Significance: 7T MRI improves detection of epileptogenic FCD that is not visible at conventional field strengths. A dedicated protocol including whole brain FLAIR and GRE images at 7T targeted at the suspected SOZ increases the diagnostic yield.

BACKGROUND AND PURPOSE Polymicrogyria is a malformation of cortical development that is often identified in children with epilepsy or delayed development. We investigated in vivo the potential of 7T imaging in characterizing polymicrogyria to determine whether additional features could be identified. MATERIALS AND METHODS Ten adult patients with polymicrogyria previously diagnosed by using 3T MR imaging underwent additional imaging at 7T. We assessed polymicrogyria according to topographic pattern, extent, symmetry, and morphology. Additional imaging sequences at 7T included 3D T2* susceptibility-weighted angiography and 2D tissue border enhancement FSE inversion recovery. Minimum intensity projections were used to assess the potential of the susceptibility-weighted angiography sequence for depiction of cerebral veins. RESULTS At 7T, we observed perisylvian polymicrogyria that was bilateral in 6 patients, unilateral in 3, and diffuse in 1. Four of the 6 bilateral abnormalities had been considered unilateral at 3T. While 3T imaging revealed 2 morphologic categories (coarse, delicate), 7T susceptibility-weighted angiography images disclosed a uniform ribbonlike pattern. Susceptibility-weighted angiography revealed numerous dilated superficial veins in all polymicrogyric areas. Tissue border enhancement imaging depicted a hypointense line corresponding to the gray-white interface, providing a high definition of the borders and, thereby, improving detection of the polymicrogyric cortex. CONCLUSIONS 7T imaging reveals more anatomic details of polymicrogyria compared with 3T conventional sequences, with potential implications for diagnosis, genetic studies, and surgical treatment of associated epilepsy. Abnormalities of cortical veins may suggest a role for vascular dysgenesis in pathogenesis.

Objective: Drug-resistant temporal lobe epilepsy (TLE) often requires thorough investigation to define the epileptogenic zone for surgical treatment. We used simultaneous interictal scalp EEG-fMRI to evaluate its value for predicting longterm post-surgical outcome.Methods: 30 patients undergoing pre-surgical evaluation and proceeding to temporal lobe (TL) resection were studied.Interictal epileptiform discharges (IEDs) were identified on intra-MRI EEG and used to build a model of hemodynamic changes. In addition, topographic electroencephalographic correlation maps were calculated between the average IED during video-EEG and intra-MRI EEG and used as a condition. This allowed the analysis of all data irrespective of the presence of IED on intra-MRI EEG. Mean follow-up after surgery was 46 months. ILAE outcomes 1 and 2 were considered good and 3 to 6 poor surgical outcome. Hemodynamic maps were classified according to the presence (Concordant) or absence (Discordant) of BOLD change in the TL overlapping with the surgical resection. Results:The proportion of patients with good surgical outcome was significantly higher (13/16; 81%) in Concordant than in Discordant group (3/14; 21%) (Chi-squared test, Yates correction, p=0.003) and multivariate analysis showed that Concordant BOLD maps were independently related to good surgical outcome (p=0.007). Sensitivity and specificity of EEG-fMRI results to identify patients with good surgical outcome were 81% and 79%, respectively and positive and negative predictive values were 81% and 79%, respectively.

The study is a prospective observational cohort study specifically designed to assess the impact of EEG-fMRI on the clinical decision making process, suggesting a significant influence of EEG-fMRI on epilepsy surgery planning.

Topiramate (TPM) is a new antiepileptic drug approved for the prevention of migraine headache. However its use is limited by treatment-emergent adverse events; in particular, therapy can exert profound impact on language function. In this investigation, we used functional magnetic resonance imaging (fMRI) to study the anatomofunctional correlates of language disturbances in TPM patients experiencing subjective cognitive impairment. Ten right-handed individuals receiving therapy (five with and five without language disfluency) and five matched healthy control subjects took part in this study. During fMRI subjects alternately rested and performed a word-generating task. The task comprised the silent generation of words beginning with a different input letter visually presented. The activation paradigm consisted of six activation blocks alternating with six baseline rest blocks. The main fMRI measure was the pattern activation of the prefrontal regions (Brodmann's areas 44, 45, and 46) in both left and right hemispheres. Patients receiving TPM (50-100 mg/day) significantly reduced mean monthly migraine frequency. However several differences in fMRI activation were evident in the subject group comparison. Notably, changes in brain activity were observed during the phonemic task in patients with language disturbances. It is likely that TPM therapy is associated with a "remapping" of the language cerebral network.

For ZTE and FLAIR, limits on maximum local and global SAR were met in all subjects, both adults and children. To enhance safety in adults and children with 7.0 Tesla MR systems, we suggest the possibility of using SAR prediction. J. MAGN. RESON. IMAGING 2016;44:1048-1055.

Purpose of reviewThis review examines recent reports on the use of advanced techniques to map the regions and networks involved during focal epileptic seizure generation in humans.Recent findingsA number of imaging techniques are capable of providing new localizing information on the ictal processes and epileptogenic zone. Evaluating the clinical utility of these findings has been mainly performed through post-hoc comparison with the findings of invasive EEG and ictal single-photon emission computed tomography, using postsurgical seizure reduction as the main outcome measure. Added value has been demonstrated in MRI-negative cases. Improved understanding of the human ictiogenic processes and the focus vs. network hypothesis is likely to result from the application of multimodal techniques that combine electrophysiological, semiological, and whole-brain coverage of brain activity changes.SummaryOn the basis of recent research in the field of neuroimaging, several novel imaging modalities have been improved and developed to provide information about the localization of epileptic foci.

No abstract