We developed an Er: YAG laser surgery system for glioma removal. The purpose of our laser system is to ablate brain tumor as precisely and efficiently as possible, without collateral tissue damage. In order to evaluated the efficiency of ablation and the thermal damage to the tissue around the ablation holes, we irradiated an Er: YAG laser to pig brain tissues in vitro with respect to laser repetition rate (10, 20, 25Hz) at a fluence (113.7J/cm²), a scan speed (1mm/s). This report showed that it could be applied as our laser system for the brain tumor removal, which the most efficient ablation condition was under a specific site at10Hz using an Er: YAG laser surgery system.

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Image-guided surgery has been a standard technique in the field of neurosurgery. However, brain shift throughout the surgical procedure has been a major issue affecting the spatial accuracy of conventional neuronavigation system. This phenomenon is not negligible in the currently available navigation system because the imaging data used in such system is based on the preoperative data. This study aims at developing the anatomically detailed three-dimensional finite element brain model and demonstrating the prediction capability of gravity-induced brain shift using the developed finite element brain model without additional acquisition of intraoperative imaging data. Although precise anatomical structure such as gyri and sulci on the surface, falx, tentorium cerebelli and ventricle may influence the brain tissue deformation as a mechanical boundary condition of the deformation field, most of the previously published brain finite element models did not include these anatomies. In this study, the patient-specific finite element brain model with brain substructures, falx cerebri with tentorium, as anatomical constraint was developed by manual segmentation of magnetic resonance imaging, and the brain model coregistered with rigid skull model segmented by computed tomography images. The model of brain parenchyma consisted of 253, 278tetrahedral elements whose material property was hyper-viscoelastic model presented in the literature. The computation of the gravity-induced brain shift by assuming that the patient was positioned lateral (left fronto-temporal craniotomy) was conducted using ABAQUS/Explicit. Deformation of the brain surface due to gravity after dura opening was demonstrated in 3D view with color-coded surface rendering and good agreement with the clinically experienced brain shift reported in the literature. The deformed gyri and sulc i on the surface also displayed with keeping high spatial resolution. The deep structure exhibited smaller amount of shift than the surface structure. The illustrative results successfully demonstrated the gravity-induced brain shift after left front-temporal craniotomy in three-dimension using the developed model.

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An effective interface of a three-dimensional (3-D) interactive visualization tool helps neurosurgeons to diagnose abnormalities in patients and to determine the optimal surgical approach. In this paper, we have introduced our newly developed software Synchronous Editable Interface (SEI), which can interactively display and edit3-D and two-dimensional (2-D) images, and evaluated our proposed method by comparing with films of2-D images in determining the surgical approach in patients with brain tumors. A significant difference was observed between SEI and reading of2-D image films by neurosurgeons, thus demonstrating the usefulness of SEI in determining the surgical approach to brain tumor. In conclusion, the feasibility of SEI in determining the surgical approach to brain tumor was confirmed.

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We have developed a real-time MR image-guided surgical support system. To assist the operation-guide imaging anddisplay technique, we developed an image controller by integrating an improved two-dimensional real-time image-guide
(Interactive Scan Control: ISC), a three-dimensional high-resolution image-guide (3D-navigation) and an image fusiontechnique (Augmented reality-navigation) that has improved the function of displaying segmented images of individualorgans. Moreover, an additional preoperative planning function has been prototyped, which perioperatively displayspositional information of access path calculated on three-dimensional MRI images using the three-dimensionalhigh-resolution image-guide.
Application of this system to an in-vivo experiment confirmed the operator to easily puncture the target with these fourfunctions.

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