Development of innovative neurosurgical operation support method by mixed-reality computer graphics

Abstract Background In neurosurgery, it is important to inspect the spatial correspondence between the preoperative medical image (virtual space), and the intraoperative findings (real space) to improve the safety of the surgery. Navigation systems and related modalities have been reported as means for matching this correspondence. However, because of the influence of brain shift accompanying craniotomy, registration accuracy is reduced. In this study, to overcome these issues, we developed a spatially accurate registration method of medical fusion three-dimensional computer graphics and the intraoperative brain surface photograph, and its registration accuracy was measured. Methods The subjects comprised 16 patients with glioma. Non-rigid registration using the landmarks and thin-plate spline methods was performed for the fusion three-dimensional computer graphics and the intraoperative brain surface photograph, which was termed mixed-reality computer graphics. Regarding the registration accuracy measurement, the target registration error was measured by two neurosurgeons, with 10 points for each case at the midpoint of the landmarks. Results The number of target registration error measurement points was 160 in 16 cases. The target registration error was 0.72 ± 0.04 mm. Aligning the intraoperative brain surface photograph and the fusion three-dimensional computer graphics required approximately 10 min on average. The average number of landmarks used for alignment was 24.6. Conclusions Mixed-reality computer graphics enabled highly precise spatial alignment between the real space and virtual space. Mixed-reality computer graphics have the potential to improve the safety of the surgery by allowing complementary observation of brain surface photographs and fusion three-dimensional computer graphics.