Jaykumar Raghavan Nair MD, Presenter: Nothing to Disclose

Christine Saint- Martin, Abstract Co-Author: Nothing to Disclose

Carlos I. Torres MD, Abstract Co-Author: Nothing to Disclose

Jean-Pierre Farmer MD, Abstract Co-Author: Nothing to Disclose

Jeffrey Atkinson, Abstract Co-Author: Nothing to Disclose

Jose Luis Montes MD, Abstract Co-Author: Nothing to Disclose

1) To emphasize the role of intra-operative MR imaging (MRI) in the post-surgical outcome of modified functional hemispherectomy performed for seizure control in pediatric epileptic patients. 2) Evaluate the role of DTI in intra-operative MRI, for determining complete disconnection of the white matter tracts for optimal post-surgical results.  

Ten pediatric patients with recurrent seizures underwent modified functional hemispherectomy for various etiologies of seizures [Congenital Middle Cerebral Artery Infarct with gliosis , Hemimegalencephaly , Rasmussen encephalopathy, Extensive Polymicrogyria, Cortical Dysplasia and Hemorrhagic Encephalitis] All patients had undergone previous MRI examination and presurgical evaluation.Intra-operative MRI sequences included 3D T1, T2-weighted images and 32 directional DTI. All cases were scanned on the same intra-operative 3T MR scanner. Diffusion tensor images were acquired with SENSE head coil. Each DTI dataset was acquired with multislice, single shot echo-planar imaging spin echo sequence. Transverse slices were acquired (parallel to the line connecting the anterior and posterior commissures) covering the whole brain with no slice gap and 2.5 mm isotropic resolution. Diffusion weighting was applied along 32 directions with b value of 1000 s/mm2. To improve the signal to noise ratio, additional DTI datasets were acquired and averaged after co-registration. The complete sequence took seven minutes. The images obtained were postprocessed on the Philips Workstation to obtain color maps and also for fiber tracking. The studies were evaluated simultaneously by two fellowship-trained pediatric neuroradiologist blindfolded to the findings of each other.  

Two out of the 10 patients had suspected incomplete disconnection on the conventional images which was confirmed further by DTI images. They proceeded for second surgery which showed complete disconnection on subsequent DTI.

Initial data suggests that addition of DTI sequence to intraoperative MRI, may significantly improve outcome in patients undergoing modified functional hemispherectomy which depends upon complete disconnection of the white matter tracts.

Complete dissection of the commissural fibers in modified functional hemispherectomy helps to control seizures in pediatric epileptic patients. Incomplete dissection could result in relapse of seizures.

Nair, J, Saint- Martin, C, Torres, C, Farmer, J, Atkinson, J, Montes, J, Intra-Operative MR Imaging with Diffusion Tensor Imaging at 3T for Evaluation of the Extent of Disconnection of White Matter Tracts in Modified Functional Hemispherectomy.  Radiological Society of North America 2014 Scientific Assembly and Annual Meeting, - ,Chicago IL. http://archive.rsna.org/2014/14017665.html