# Real Color Model of a Cadaver for Deep Brain Stimulation of the Subthalamic Nucleus
## 4 Discussion  
The real color volume model of this study is the convergence between an actual cadaver dissection and MRI processing. The strong points of the real color volume model for DBS surgery are as follows.  
The real color volume model enables observations of minute anatomical structures. It can be difficult for medical students to identify deep brain structures in gray scale images of an MRI or CT. By virtue of the real color of the volume model, medical students can be familiar with the sectional brain's anatomy before they study DBS surgery. In the case of neurosurgeons performing DBS surgery, misplacement of the DBS electrode on the medial lemniscus or substantia nigra can result in various adverse effects. Even within the subthalamic nucleus, its motor, limbic, and associative subdivisions have different functions [23; 24]. Therefore, neurosurgeons interpret preoperative MRIs of patients to plan the DBS approach and perform an actual cadaver dissection to grasp the detailed anatomy of the deep brain [10]. These minute structures of the deep brain can be observed on the real color volume model, owing to the voxel size of 0.5 mm \(\times\) 0.5 mm \(\times\) 0.5 mm. The real color volume can be helpful in associating the actual cadaver to medical images of patients (Figure 1).  
The volume model of the segmentation data is helpful in learning the sectional anatomy. For example, it is difficult for medical students to identify the sulci and gyri of the cerebral cortex on the horizontal, coronal, and sagittal planes. Even for experts, identifying the sulci and gyri on the oblique planes is not easy. Owing to the head folding during development, structures derived from the telencephalon have a complicated spatial relationship. The cerebral cortex and deep brain structures can be identified by sectioning the volume model of the segmentation data (Figure 2).  
The volume model can be correlated to the data of other trajectories for DBS surgery. In this study, the averages of the coordinates from 31 patients were adopted to determine the trajectory of the electrode. Since the coordinates were based on the clinical data, the entry points and target points were determined by minimizing the potential adverse effects of electrode insertion. If the coordinates of the entry and target points of other DBS trajectories are adopted, the related anatomical structures can be displayed on the real color volume model of this study (Figures 3-5). By analyzing the structures along the trajectory of the electrode, potential adverse effects of the other DBS trajectories can be discovered. Through this trial, the model may propose new ideas for improved trajectories in DBS surgery for neurosurgeons.  
The limitation of this study was that the volume model was produced based on a single cadaver, although it had no pathological finding in the brain [14]. Deep brain structures can individually vary according to the size of the head and brain. Therefore, the users should keep in mind that the images of a single cadaver cannot represent the anatomical variations of individual patients. The standardized brain anatomy can be complemented by the existing coordination system and registration algorithm, which also can be obtained gratis [18; 25].  
DBS of the subthalamic nucleus requires neurosurgeons to target small-sized structures precisely because minute misplacement of the electrode can have adverse effects. The real color volume model of this study enables users to identify detailed anatomical structures not only in classical planes but also in oblique planes. The volume model can be helpful for students or novice neurosurgeons to study the anatomy of the deep brain and plan DBS surgery thanks to the real color. Furthermore, the model may propose ideas to find improved approaches in DBS surgery for neurosurgeons by observing arbitrary oblique planes.