Subcortical pathways serving cortical language sites: initial experience with diffusion tensor imaging fiber tracking combined with intraoperative language mapping

Abstract

The combination of mapping functional cortical neurons by intraoperative cortical stimulation and axonal architecture by diffusion tensor MRI fiber tracking can be used to delineate the pathways between functional regions. In this study the authors investigated the feasibility of combining these techniques to yield connectivity associated with motor speech and naming. Diffusion tensor MRI fiber tracking provides maps of axonal bundles and was combined with intraoperative mapping of eloquent cortex for a patient undergoing brain tumor surgery. Tracks from eight stimulated sites in the inferior frontal cortex including mouth motor, speech arrest, and anomia were generated from the diffusion tensor MRI data. The regions connected by the fiber tracking were compared to foci from previous functional imaging reports on language tasks. Connections were found between speech arrest, mouth motor, and anomia sites and the SMA proper and cerebral peduncle. The speech arrest and a mouth motor site were also seen to connect to the putamen via the external capsule. This is the first demonstration of delineation of subcortical pathways using diffusion tensor MRI fiber tracking with intraoperative cortical stimulation. The combined techniques may provide improved preservation of eloquent regions during neurological surgery, and may provide access to direct connectivity information between functional regions of the brain.

Identifying preoperative language tracts and predicting postoperative functional recovery using HARDI q-ball fiber tractography in patients with gliomas

“…4 In particular, qball algorithms have been shown to improve the resolution of white matter fiber tractography in regions with crossing fiber populations. 3,5,14,21 The application of updated tracking methods to presurgery planning for language tracking in brain tumor patients enables the exploration of white matter pathways that could not be accurately reconstructed using older DTI methods.…”

“…The presurgery program delineating functional white matter pathways that we implemented 15 years ago 3,14 has benefited from significant technological developments. This program started with delineation of the corticospinal tract using DTI fiber tracking 4,5,21 and then evolved to include probabilistic q-ball fiber tracking methods 4 and visual pathways.…”

Multimodal Approach to the Surgical Removal of Gliomas in Eloquent Brain Regions

“…Finally, the most fascinating application of DTI is the fiber-tracking technique (DTI-FT) that is able to identify and reconstruct the main white matter connections. This information is very useful for presurgical planning, delineating the spatial relationships of eloquent structures and tumors in order to preserve the functional pathways intraoperatively (Holodny et al 2002;Tummala et al 2003;Henry et al 2004). Since the images generated by DTI-fiber tracking are the result of complex mathematical modeling aimed at resolving the hypercomplex structure of white matter, several authors have worked to answer some practical problems.…”

“…DTI-FT is currently intended to virtually reconstruct white matter tracts, but it is not able to investigate the function related to a tract. CSES is the gold standard to map subcortical pathways, and DTI-FT findings can be integrated with intraoperative CSES with or without the implementation of intraoperative navigation devices (Henry et al 2004;Kinoshita et al 2005;Bello et al 2008;Ozawa et al 2009, Leclercq et al 2010Spena et al 2010). The fundamental observation that preoperative DTI-FT cannot itself account for the determination of the presence or absence of functional subcortical tracts in or in the vicinity of the tumor is clearly demonstrated by cases of cystic tumors in which, because of the absence of infiltration and edema, the white matter tract reconstructions are very reliable ( fig.…”

Optimizing signal‐to‐noise ratio of high‐resolution parallel single‐shot diffusion‐weighted echo‐planar imaging at ultrahigh field strengths

“…Diffusion-weighted imaging is clinically promising since the acquisition is noninvasive, relatively fast and requires neither contrast agents nor ionizing radiation. In addition, dedicated tracking algorithms have been developed that allow for the reconstruction of virtual fiber pathways in the human brain which enable presurgical planning and image-guided surgery (2,3).…”