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    Systems and methods facilitating high definition fiber tracking are disclosed. These systems and methods can utilize a directional Axonal Volume (dAV) value that can quantify the direction and volume of anisotropic water diffusion in axons to assess brain connection integrity. dAV provides a robust and anatomically interpretable measurement of connectivity strength of axon tracts. One method include receiving diffusion magnetic resonance imaging (dMRI) data, quantifying a vector axonal directional diffusion axon volume while removing extracellular isotropic water, segmenting fiber tracks from the data, voxelizing the fiber tracks into voxels, determining voxel dAV values for each voxel and directions, and determining fiber dAV values for each fiber track based on voxel dAV values. This non-invasive method can measure strength and integrity of brain tracts. Such measurements aid in detection of connection disorders like traumatic brain injury and mapping the location of brain tracts and their projection fields to improve neurosurgical outcomes.
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  • KNN classifier based approach for multi-class sentiment analysis of twitter data

    Hota, Soudamini   Pathak, Sudhir  

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  • In Vivo Mapping of Microstructural Somatotopies in the Human Corticospinal Pathways

    Verstynen, Timothy   Jarbo, Kevin   Pathak, Sudhir   Schneider, Walter  

    Verstynen T, Jarbo K, Pathak S, Schneider W. In vivo mapping of microstructural somatotopies in the human corticospinal pathways. J Neurophysiol 105: 336-346, 2011. First published November 10, 2010; doi:10.1152/jn.00698.2010. The human corticospinal pathway is organized in a body-centric (i.e., somatotopic) manner that begins in cortical cell bodies and is maintained in the axons as they project through the midbrain on their way to spinal motor neurons. The subcortical segment of this somatotopy has been described using histological methods on non-human primates but only coarsely validated from lesion studies in human patient populations. Using high definition fiber tracking (HDFT) techniques, we set out to provide the first in vivo quantitative description of the midbrain somatotopy of corticospinal fibers in humans. Multi-shell diffusion imaging and deterministic fiber tracking were used to map white matter bundles that originate in the neocortex, navigate complex fiber crossings, and project through the midbrain. These fiber bundles were segmented into premotor (dorsal premotor, ventral premotor, and supplementary motor area) and primary motor sections based on the cortical origin of each fiber streamline. With HDFT, we were able to reveal several unique corticospinal patterns, including the cortical origins of ventral premotor fibers and small (similar to 1-2 mm) shifts in the midbrain location of premotor versus primary motor cortex fibers. More importantly, within the relatively small diameter of the pyramidal tracts (similar to 5 mm), we were able to map and quantify the direction of the corticospinal somatotopy. These results show how an HDFT approach to white matter mapping provides the first in vivo, quantitative mapping of subcortical corticospinal topographies at resolutions previously only available with postmortem histological techniques.
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  • Integration of Magnetoencephalography-Generated Functional Brain Maps into Dose Planning during Arteriovenous Malformation Radiosurgery

    Niranjan, Ajay   Laing, Erika   Pathak, Sudhir   Flickinger, John   Lunsford, L. Dade  

    Background: Magnetoencephalography (MEG) can delineate critical regions of the cortex and facilitate conformal stereotactic radiosurgery (SRS) dose planning. Despite the substantial role of Gamma Knife SRS in arteriovenous malformation (AVM) management, MEG-generated maps of critical regions have never been utilized to improve dose planning. Purpose: To assess the value of integrating functional brain mapping using MEG with dose planning during treatment of brain AVMs with SRS. Methods: This case series encompassed 5 patients with motor region AVMs. Noninvasive eloquent cortex mapping was achieved using a whole-head 306-channel Neuromag((R)) Vectorview MEG System 5-10 days before SRS. On the day of SRS, the functional brain maps were integrated onto the intraoperative dose planning magnetic resonance imaging for Leksell GammaPlan((R)) version 10. The median AVM volume treated was 12.7 cm(3), and 18 Gy was the median margin dose. Results: Functional image integration of MEG improved the recognition of critical brain structures adjacent to the AVM. This facilitated anatomical planning designed to reduce the dose to adjacent critical structures while maintaining a therapeutic dose to the AVM target. The 5 patients had no adverse radiation effects during the follow-up. Conclusion: Coregistration of MEG data improves the accuracy and dose sparing needed for optimal planning during Gamma Knife SRS. (c) 2014 S. Karger AG, Basel
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