Application of Diffusion Tensor Imaging (DTI) Tractography as a Targeting Modality for Deep Brain Stimulation (DBS) of the Subthalamic Nucleus (STN)

Abstract

Introduction: We carried out diffusion tensor imaging (DTI) to detect the corticospinal tract (CST) during deep brain stimulation (DBS) of the subthalamic nucleus (STN), and we examined whether CST-based targeting could provide reliable internal fiducial markers for STN-DBS. Materials and Methods: Twenty-eight patients underwent bilateral simultaneous implantation of DBS electrodes for STN-DBS. We calculated the absolute values of the differences in the coordinates between the implanted DBS electrodes and the CST demonstrated by tractography in each patient at the level 3 mm inferior to the superior border of the red nucleus (RN). We also compared the distance between the implanted DBS electrodes and the estimated target points planned by RN-based and CST-based targeting. Results: The average distance from the center of the CST to the center of the implanted DBS electrode was 7.0 2.3 mm in the x-direction, 2.1 1.3 mm in the y-direction, and-4.3 1.4 mm from the level of the AC-PC line as the z-coordinate. The average distance between the DBS electrode and planned targets estimated by RN-based targeting was 2.5 1.1 mm, and that estimated by CST-based targeting was 3.9 1.6 mm. The variances of these planned targets were not significantly different (p = 0.06, Mann-Whitney U-test). Conclusions: The stereotactic coordinates between the target points of STN and CST were confirmed by CST-based targeting in this study. The results were not significantly different between RN-based targeting and DTI-based targeting for STN-DBS. The DTI-based targeting method using an internal fiducial marker has a possibility to become a powerful tool in stereotactic surgery.