Stereotactic implantation of deep brain stimulation electrodes: a review of technical systems, methods and emerging tools <s> Intraoperative data visualisation <s> The long term objective of our research is to develop a system that will automate as much as possible DBS implantation procedures. It is estimated that about 180,000 patients/year would benefit from DBS implantation. Yet, only 3000 procedures are performed annually. This is so because the combined expertise required to perform the procedure successfully is only available at a limited number of sites. Our goal is to transform this procedure into a procedure that can be performed by a general neurosurgeon at a community hospital. In this work we report on our current progress toward developing a system for the computer-assisted pre-operative selection of target points and for the intra-operative adjustment of these points. The system consists of a deformable atlas of optimal target points that can be used to select automatically the pre-operative target, of an electrophysiological atlas, and of an intra-operative interface. The atlas is deformed using a rigid then a non-rigid registration algorithm developed at our institution. Results we have obtained show that automatic prediction of target points is an achievable goal. Our results also indicate that electrophysiological information can be used to resolve structures not visible in anatomic images, thus improving both pre-operative and intra-operative guidance. Our intra-operative system has reached the stage of a working prototype that is clinically used at our institution. <s> BIB001 </s> Stereotactic implantation of deep brain stimulation electrodes: a review of technical systems, methods and emerging tools <s> Intraoperative data visualisation <s> We present the development of a visualization and navigation system and its application in pre-operative planning and intra-operative guidance of stereotactic deep-brain neurosurgical procedures for the treatment of Parkinson's disease, chronic pain, and essential tremor. This system incorporates a variety of standardized functional and anatomical information, and is capable of non-rigid registration, interactive manipulation, and processing of clinical image data. The integration of a digitized and segmented brain atlas, an electrophysiological database, and collections of final surgical targets from previous patients facilitates the delineation of surgical targets and surrounding structures, as well as functional borders. We conducted studies to compare the surgical target locations identified by an experienced stereotactic neurosurgeon using multiple electrophysiological exploratory trajectories with those located by a non-expert using this system on 70 thalamotomy, pallidotomy, thalamic deep-brain stimulation (DBS), and subthalamic nucleus (STN) DBS procedures. The average displacement between the surgical target locations in both groups was 1.95 +/- 0.86 mm, 1.83 +/- 1.07 mm, 1.88 +/- 0.89 mm and 1.61 +/- 0.67 mm for each category of surgeries, respectively, indicating the potential value of our system in stereotactic deep-brain neurosurgical procedures, and demonstrating its capability for accurate surgical target initiation. <s> BIB002 </s> Stereotactic implantation of deep brain stimulation electrodes: a review of technical systems, methods and emerging tools <s> Intraoperative data visualisation <s> Stereotactic neurosurgery and neurophysiological microelectrode recordings in both humans and monkeys are typically done with conventional 2D atlases and paper records of the stereotactic coordinates. This approach is prone to error because the brain size, shape, and location of subcortical structures can vary between subjects. Furthermore, paper record keeping is inefficient and limits opportunities for data visualization. To address these limitations, we developed a software tool (Cicerone) that enables interactive 3D visualization of co-registered magnetic resonance images (MRI), computed tomography (CT) scans, 3D brain atlases, neurophysiological microelectrode recording (MER) data, and deep brain stimulation (DBS) electrode(s) with the volume of tissue activated (VTA) as a function of the stimulation parameters. The software can be used in pre-operative planning to help select the optimal position on the skull for burr hole (in humans) or chamber (in monkeys) placement to maximize the likelihood of complete microelectrode and DBS coverage of the intended anatomical target. Intra-operatively, Cicerone allows entry of the stereotactic microdrive coordinates and MER data, enabling real-time interactive visualization of the electrode location in 3D relative to the surrounding neuroanatomy and neurophysiology. In addition, the software enables prediction of the VTA generated by DBS for a range of electrode trajectories and tip locations. In turn, the neurosurgeon can use the combination of anatomical (MRI/CT/3D brain atlas), neurophysiological (MER), and electrical (DBS VTA) data to optimize the placement of the DBS electrode prior to permanent implantation. <s> BIB003 </s> Stereotactic implantation of deep brain stimulation electrodes: a review of technical systems, methods and emerging tools <s> Intraoperative data visualisation <s> The placement of deep brain stimulator leads requires a great deal of technology and equipment. We describe our 25-month experience with an integrated platform system, the StimPilot (Medtronic Inc., Minneapolis, MN), for the placement of deep brain stimulator leads. The platform consists of a neuronavigation station, microdrive control, and microelectrode recording display and control. This platform is run from a laptop-sized portable control unit. The unit was used in 147 patients for the placement of 262 leads. Leads were placed into the subthalamic nucleus, ventral intermediate nucleus, globus pallidus interna, and anterior thalamic nucleus. One patient required replacement of one lead during this time frame, with successful reimplantation. No system failures occurred. <s> BIB004 </s> Stereotactic implantation of deep brain stimulation electrodes: a review of technical systems, methods and emerging tools <s> Intraoperative data visualisation <s> Objective: Deep brain stimulation (DBS) surgeries commonly rely on brain atlases and microelectrode recordings (MER) to help identify the target location for electrode implantation. <s> BIB005
In Sect. 3.2, we show the quantity of existing data that has to be analysed intraoperatively in order to take a decision on the final surgical target. Most of the clinical groups base their decision on taken notes and the ''mental combination'' of all these data. Only BrainLab has proposed very recently a software module that allows for processing of intraoperatively acquired micro electrode recording/stimulation data to support the optimum DBS treatment decision through graphical representations. None of the other existing navigation and planning systems seems currently to propose an intraoperative ''intuitive visualisation'' interface. The StimPilot Software (Medtronic Inc., Minneapolis, MN, USA) BIB004 allowed a combined visualisation of short MER recordings together with the anatomical information, but it is only commercialised in the US. Only few groups use homemade software for online data collection and visualisation BIB001 BIB002 BIB005 . Most of them use electrophysiological databases of several patients taking into account MER and rarely as well test stimulation results which are non-rigidly registered to the patient's MRI in order to predict preoperative target points. Miocinovic et al. BIB003 have added a feature predicting the volume of tissue activated for a given electrode position and stimulation parameter setting. The aim in the future should be to set up an interface that supports management and visualisation of all data achieved during planning and surgery, including new emerging technologies (Fig. 5) . 