Assessing Region of Interest Schemes for the Corticospinal Tract in Patients With Brain Tumors

Abstract

Diffusion tensor imaging (DTI) and diffusion tensor tractography (DTT) techniques are widely used for identifying the corticospinal tract (CST) white matter pathways as part of presurgical planning. However, mass effects in patients with brain tumors tend to cause anatomical distortions and compensatory functional reorganization of the cortex, which may lead to inaccurate mapping of white matter tracts. To overcome these problems, we compared different region-of-interest (ROI) selection schemes to track CST fibers in patients with brain tumors. Our study investigated the CSTs of 16 patients with intracranial tumors. The patients were classified into 3 subgroups according to the spatial relationships of the lesion and the primary motor cortex (PMC)/internal capsule. Specifically, we investigated the key factors that cause distorted tractography in patients with tumors. We compared 3 CST tractography methods that used different ROI selection schemes. The results indicate that CST fiber tracking methods based only on anatomical ROIs could possibly lead to distortions near the PMC region and may be unable to effectively localize the PMC. In contrast, the dual ROI method, which uses ROIs that have been selected from both blood oxygen level-dependent functional MRI (BOLD-fMRI) activation and anatomical landmarks, enabled the tracking of fibers to the motor cortex. The results demonstrate that the dual ROI method can localize the entire CST fiber pathway and can accurately describe the spatial relationships of CST fibers relative to the tumor. These results illustrate the reliability of using fMRI-guided DTT in patients with tumors. The combination of fMRI and anatomical information enhances the identification of tracts of interest in brains with anatomical deformations, which provides neurosurgeons with a more accurate approach for visualizing and localizing white matter fiber tracts in patients with brain tumors. This approach enhances surgical performance and perserves brain function.

Performance of unscented Kalman filter tractography in edema: Analysis of the two-tensor model

“…We note that it has been demonstrated in healthy subjects that the “brute-force” whole-brain seeding approach, in combination with multiple selection ROIs, improves DTI-based tractography when compared with local single-ROI seeding ( Huang et al, 2004 ). Seeding approaches have also been studied in patients with brain tumors, where whole-brain seeding or large area seeding was found to be more stable ( Radmanesh et al, 2015 , Niu et al, 2016 , Golby et al, 2011 ).…”

White matter tractography for neurosurgical planning: A topography-based review of the current state of the art

“…Of note is the fact that an optimal seeding region will depend not only on the neuroanatomy, but also on the tractography method. For example in the corticospinal tract of patients with brain tumors, deterministic methods are generally best seeded in a large region of white matter and not in the cortex where diffusion anisotropy is low ( Radmanesh et al, 2015 ), while probabilistic methods are often seeded many times within specific regions in the brainstem and cortex ( Farquharson et al, 2013 , Niu et al, 2016 ). Many studies have provided guidelines for ROI placement or anatomical atlas usage to define fiber tracts ( Catani and Thiebaut de Schotten, 2008 , Lawes et al, 2008 , Wakana et al, 2004 , Wassermann et al, 2016 ), though methods that rely on normal neuroanatomy may not produce sufficient results in patients with tract displacement due to mass lesions ( Schonberg et al, 2006 ).…”

“…Many studies have provided guidelines for ROI placement or anatomical atlas usage to define fiber tracts ( Catani and Thiebaut de Schotten, 2008 , Lawes et al, 2008 , Wakana et al, 2004 , Wassermann et al, 2016 ), though methods that rely on normal neuroanatomy may not produce sufficient results in patients with tract displacement due to mass lesions ( Schonberg et al, 2006 ). Specifically in patients with brain tumors, several groups have investigated optimal structural and functional ROIs for tract seeding and selection of the corticospinal tract ( Holodny et al, 2001a , Niu et al, 2016 , Radmanesh et al, 2015 , Schonberg et al, 2006 , Weiss et al, 2015 ). However, even when the ROIs are held constant, there is known variability in tract selection across expert raters and across tractography methods ( Burgel et al, 2009 , Colon-Perez et al, 2016 ).…”

Free water modeling of peritumoral edema using multi-fiber tractography: Application to tracking the arcuate fasciculus for neurosurgical planning

“…The use of preoperative imaging for neurosurgical planning is increasing, with the aim of preserving neurological function and precisely removing lesions [ 1 – 3 ]. The addition of diffusion magnetic resonance imaging (dMRI), the only technique for identifying white matter microstructure in vivo , has been shown to increase extent of tumor resection and improve survival [ 4 , 5 ].…”