Three-dimensional Visualization Of Deep Brain Stimulation Electrodes Localization

Deep brain stimulation(DBS) is the only effective approach for many neural and psychiatric diseases. The accurate implantation of the deep brain stimulation electrodes is the key to the success of the surgery, which has been made harder for the tiny anatomic structure of DBS target nuclei such as subthalamic nucleus. Multimodal medical images like magnetic resonance imaging(MRI) and computed tomography have already been used to assist electrodes localization clinically. While the target nuclei can be easily identified by the high resolution MRI, low resolution MRI or CT scanning are usually applied for intra-operative or post-operative electrodes localization due to the metal property of the electrodes. Therefore, it is essential to develop an accurate electrode localization method based on clinical images for the improvement of the treatment effects.This paper proposed a 3D visualization method based on intra-operative MRI and post-operative MRI/CT for the localization of electrodes in DBS surgery. Being accurate and fast, the proposed technique is expected to provide a vivid stereo image for the neurosurgeon, which could not be realized by the traditional imaging slices. The main contents were as follows.First, the intra-operative and post-operative images were normalized into the standard stereotactic space after co-registration with the high resolution pre-operative MRI, to improve the qualities of low resolution intra- and post-operative images. The intra-operative MRI was normalized by using a 3-step linear algorithm for the fast and precise intra-operative electrodes localization, while the post-operative MRI was normalized into the standard space by the non-linear DARTEL algorithm due to the more significant artifacts and brain tissue deformation caused by the leads. The post-operative CT was also normalized by the DARTEL algorithm after co-registration with the pre-operative MRI based on the edge detecting algorithm. The results showed that the matching error of the linear algorithm was 1.29 mm and 0.96 mm respectively, and the latter one was less than a pixel.Second, the lead trajectories were reconstructed automatically with a specially designed mask based on the normalized axial intra-operative MRI and post-operative MRI/CT. Then the electrode contacts were searched along the lead trajectories by the cross-correlation algorithm. The coronary images were used to revise the reconstructed lead trajectories and contacts. The results were consistent with the clinical operative images.Third, the DBS target nuclei such as subthalamic nuclei and globus pallidus and other nuclei nearby were segmented based on the atlas data, and then was visualized by the binary surface rendering reconstruction algorithm and pseudo-color processing technology in three dimensions, fusing the three-dimensional electrodes model at the same time. The results showed that the location of every electrode was consistent in three different visualization images based on different atlases, and consistent with the clinical treatment by the surgeons. Additionally the 3D visualization could help surgeons check the intra- and post-operative electrode location from different angles.