Comparison of different tractography algorithms and validation by intraoperative stimulation in a child with a brain tumor.

Abstract

Advanced modalities such as functional magnetic resonance imaging (MRI) and diffusion MR tractography offer in vivo information about brain networks and are therefore increasingly used for neurosurgical planning in children also. This study aims to study the application of routine and advanced tractography algorithms and its comparison with intraoperative subcortical electrical stimulation. Presurgical functional MRI and MR diffusion tractography were performed on a 6-year-old patient presenting with seizures, but no motor symptoms, due to a neuroectodermal tumor in the left central region. Three different tractography algorithms were compared: deterministic diffusion tensor imaging (DTI)-tracking, probabilistic DTI-tracking, and probabilistic constrained spherical deconvolution tracking (pCSD). All three tractography algorithms could localize the core of the corticospinal tract with good agreement. The pCSD-tracking algorithm was more sensitive in revealing the anatomically most realistic fiber distribution and a proportion of fibers traversing a solid part of the tumor. Intraoperative stimulation confirmed these fibers close to the tumor. As a result, only a subtotal resection was performed, preventing postoperative sensorimotor deficits. Although, all tractography algorithms successfully identified the core of the corticospinal pathway, deterministic DTI-tractography, as widely used in clinical neuronavigation software, only insufficiently visualized critical fibers here. We believe these results argue for a stronger consideration of advanced tractography approaches in neurosurgical planning.