Summary:Purpose: Functional magnetic resonance imaging (MRI) using two language-comprehension tasks was evaluated to determine its ability to lateralize language processing and identify regions that must be spared in surgery.Methods: Two parallel cognitive language tasks, one using auditory input and the other visual input, were tested in a group of control subjects and in temporal lobe epilepsy patients who were candidates for surgical intervention. The patient studies provide an opportunity to compare functional MRI language localization with that obtained using Wada testing and electrocorticography. All of the patients in this study underwent all three procedures and a battery of neuropsychological testing. Such studies provide an opportunity not only to validate the fMRI findings but also, by comparing the patient results with those obtained in control subjects, to provide insight into the impact of a pathology such as epilepsy on cortical organization or functional patterns of activation.Results: The results reveal both modality-dependent and modality-independent language-processing patterns for visual versus auditory task presentation. The visual language task activated distinct sites in Broca's area, BA (Brodmann area) 44 that were not activated in the auditory language task. The auditory language task strongly activated contralateral right BA22-21 area (homologous to Wernicke's area on the left). Language lateralization scores were significantly stronger for visual than for auditory task presentation. The conjunction of activation from the two different input modalities (modalityindependent areas) likely highlights regions that perform more abstract computations (e.g., syntactic or pragmatic processing) in language processing. Modality-specific areas (e.g., right Wernicke, left fusiform gyrus, Broca BA44, supramarginal gyrus), appear to cope with the computations relevant to making contact with these more abstract dimensions. Patients showed recruitment of contralateral homologous language areas (p < 0.005) that was significantly above that found in a normal control group. Extra-and intraoperative cortical stimulations were concordant with the fMRI data in eight of 10 cases. The fMRI lateralization scores were also consistent with the Wada testing in 8/10 patients.Conclusions: The fMRI results demonstrate that the epileptic brain may be a progressive model for cortical plasticity.

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Deep brain stimulation (DBS) surgery can significantly improve the quality of life for patients suffering from movement disorders, but the success of the procedure depends on the implantation accuracy of the DBS electrode array. Pre-operative surgical planning and navigation are based on the assumption that the brain tissue is rigid between the time of the acquisition of the pre-operative image set and the time of surgery. A shift of deep brain structures by only a few millimeters can potentially increase the number of required microelectrode and/or macroelectrode tracks and decrease implantation accuracy. We studied 25 subjects that underwent DBS surgery and analyzed brain shift between pre-operative and post-operative 3D MRI scans. Brain shift of up to 4 mm was observed in deep brain structures. On average, the recorded shift was in the direction of gravity, with deeper structures experiencing smaller shift than more superficial structures. The main conclusion of the study is that the brain shift is comparable to the size of the targets in deep brain stimulation surgery and should not be ignored. Techniques that minimize the amount of brain shift may therefore lead to increased accuracy of DBS lead implantation.

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Patients with rTOF have intra- and inter-ventricular dyssynchrony, which can be quantified from standard cine CMR. This new approach can potentially help determine the contribution of dyssynchrony to ventricular dysfunction in future studies.