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MR/Ultrasound Integration for NeurosurgeryBecause the brain shifts position when a craniotomy procedure is performed, image-guided surgery systems that rely on the assumption that a pre-operative MR image accurately reflects the shape of the brain during surgery are insufficient for a broad range of neurosurgical tasks. We are developing techiques that use ultrasound images of the brain, collected during the surgery, to track the distortion of the brain tissue. Once the distortion has been measured, it is used to warp the pre-operative MR images such that they accurately reflect the shape of the brain during surgery. |
Electrophysiology AtlasesStereotactic functional neurosurgery is a technique that must rely on multiple electrode trajectories to characterize the functional properties of approximated surgical targets within the brain. With each passage of the electrode carrying a risk of intracranial hemorrhage, decreasing the total number of required trajectories to locate a target would be highly advantageous. This goal of this project is to increase initial targeting accuracy through direct localization of indistinguishable anatomy such as the thalamic nuclei or sub-regions of the globus pallidus internus or subthalamic nuclei. A database of intraoperative electrophysiologic observations recorded during microelectrode recording and micro- and macrostimulation has been created to accomplish this goal. |
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Optimization of Brain MRI ImagesWe are developing innovative imaging methods and analysis techniques to optimize the contrast of brain MRI images. This will enable us to see differences between area of the brain that are structurally similar but functionally distinct. |
Image Guided Cardiac SurgeryRobot-assisted microsurgical systems have been recently introduced to minimally invasive cardiac surgery. We are involved in developing a 3-D virtual cardiac surgical planning platform for robot-assisted cardiac surgical systems to further reduce risks and trauma to patients. |
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Stereotactic Surgical PlanningFrame based stereotaxy is the method of choice for deep brain functional procedures where high accuracy, patient immobilization and rigid instrument fixation are required.Yves Starreveld
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Anatomic Brain Atlas VisualizationBrain atlases are popularly used in current image-guided neurosurgery operations. For the purpose of developing an atlas-based image-guided neurosurgery system, an anatomic brain atlas visualization using digitized and color-coded atlases is introduced which operates on a simple but powerful registration scheme based on the proportional grid system(PGS). |
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EndoscopyIn minimally invasive surgery, endoscopes and surgical instruments are passed through small access ports in the body cavity. Endoscopes provide high resolution 2D images of the surgical site. They have been used as a surgical tool, mostly in orthopedics and abdominal surgery, and more recently in the brain. Since the endoscopic field-of-view is limited, the biggest limitation with the use of endoscopes is the lack of relative context between the endoscope and its surroundings. The purpose of my research is to map endoscopic images, acquired during surgery, to object surfaces obtained from 3D pre-operative MR or CT images, for assistance in surgical planning and guidance. |
Poly(Vinyl Alcohol) Cryogel (PVA-C) PhantomsWe have developed techniques to make multi-modality phantoms from a common industrial material, powdered poly(vinyl alcohol) (PVA), which , in one form, is simply white glue. When a 10-20% acqueous solution of PVA is twice frozen (to -18°C) and thawed, a rubbery solid forms which has good imaging characteristics. For MRI, T1 and T2 values are around 1230 ms and 160 ms, respectively. For ultrasound imaging, speed of sound and acoustic attenuation are 1510 m/s and 3.8 dB/cm at 3.3 MHz. The figure shows a three-dimensional ultrasound image of a phantom that had two bifurcated vessels in it. These vessels were formed by pouring the liquid PVA solution around y-shaped mandrels, which could be pulled out in pieces from the solid phantom. |
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Atamai - Surgical Planning SoftwareAtamai is a corporation that has been formed as a partnership between the Robarts Research Institute, London Health Sciences Centre, the University of Western Ontario, Kirk Finnis, David Gobbi, Terry Peters, and Yves Starreveld. It was formed to ensure the widespread free availability of software developed in the Image Guided Surgery Lab to all interested academic parties, and to foster the commercialization of some portions of that software without limiting academic access to it. Atamai also performs contract development to create new software compontents which are subsequently added to the existing framework. |
Research at the Montreal Neurological InstituteThe following projects are ongoing or have recently been completed at the former location of this laboratory in the McConnell Brain Imaging Centre of the Montreal Neurological Institute. |
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Image Guidance for Thalamotomy and PallidotomyThalamotomies and Pallidotomies are used most frequently in the treatment of Parkinson's disease and involve lesioning parts of the thalamus and the globus pallidus. To assist the surgeon in identifying the structures of interest in the patients brain a MRI image of the patients brain is automatically mapped to a model brain and displayed using the VIPER platform.Abbas Sadikot
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Ultrasound Guidance for NeurosurgeryImage guided neurosurgery allows the surgeon to use image information from a variety of sources as an interactive guide during surgery. Most image guided neurosurgery systems are based on preoperative image information to act as the guide for the surgeon. One of the most important considerations in image guided neurosurgery is that of accuracy. During surgery the soft tissues of the brain can move rendering preoperative images inaccurate. The use of intraoperative ultrasound is a solution to this problem. |
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Use of Finite Element Techniques in IGNSFinite element analysis and modelling (FEA/FEM) has been used for years as a numerical solution technique for systems of differential equations in the engineering problems of a structural analysis and stress analysis. More recently these techniques have been utilized in a biomedical engineering context, for modelling parts of the human body using realistic biomechanical data for the revelant tissues/materials. |
Intra-operative Tracking for Cortical Shift in the BrainWe propose a method for estimating intrasurgical brain shift for image-guided surgery. This method consists of five stages: the identification of relevant anatomical surfaces within the MRI volume, range-sensing of the skin and cortex in the OR, computation of the range-MRI rigid transformation based on a calibration procedure and sensor-base tracking, non-rigid motion tracking over time of cortical range images, and lastly, interpolation of this surface displacement information over the whole brain volume via a realistically valued finite element model of the head. |
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