Virtual reality presurgical planning for cerebral gliomas adjacent to motor pathways in an integrated 3-D stereoscopic visualization of structural MRI and DTI tractography

Resection of gliomas invading primary motor cortex and subcortical motor pathway is difficult in both surgical decision-making and functional outcome prediction. In this study, magnetic resonance (MR) diffusion tensor imaging (DTI) data were used to perform tractography to visualize pyramidal tract (PT) along its whole length in a stereoscopic virtual reality (VR) environment. The potential value of its clinical application was evaluated. Both three-dimensional (3-D) magnetic resonance imaging (MRI) and DTI datasets were obtained from 45 eligible patients with suspected cerebral gliomas and then transferred to the VR system (Dextroscope; Volume Interactions Pte. Ltd., Singapore). The cortex and tumor were segmented and reconstructed via MRI, respectively, while the tractographic PTs were reconstructed via DTI. All those were presented in a stereoscopic 3-D display synchronously, for the purpose of patient-specific presurgical planning and surgical simulation in each case. The relationship between increasing amplitude of the number of effective fibers of PT (EPT) at affected sides and the patients' Karnofsky Performance Scale (KPS) at 6 months was addressed out. In VR presurgical planning for gliomas, surgery was aided by stereoscopic 3-D visualizing the relative position of the PTs and a tumor. There was no significant difference between pre- and postsurgical EPT in this population. A positive relationship was proved between EPT increasing amplitude and 6-month KPS. 3-D stereoscopic visualization of tractography in this VR environment enhances the operators to well understand the anatomic information of intra-axial tumor contours and adjacent PT, results in surgical trajectory optimization initially, and maximal safe tumor resection finally. In accordance to the EPT increasing amplitude, surgeon can predict the long-term motor functional outcome.