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Virtual Mirror: Interaction Paradigm for Augmented Reality ApplicationsAugmented Reality offers a higher degree of freedom for the programmer than classical visualization of volume data on a screen. The existing paradigms for interaction with 3D objects are not satisfactory for particular applications since the majority of them rotate and move the object of interest. The classic manipulation of virtual objects cannot be used while keeping real and virtual spaces in alignment within an AR environment. This project introduces a simple and efficient interaction paradigm allowing the users to interact with 3D objects and visualize them from arbitrary viewpoints without disturbing the in-situ visualization, or requiring the user to change the viewpoint. We present a virtual, tangible mirror as a new paradigm for interaction with 3D models. The concept borrows its visualization paradigm in some sense from methodology used by dentists to examine the oral cavity without constantly changing their own viewpoint or moving the patients head. The virtual mirror improves the understanding of complex structures, enables completely new concepts to support navigational aid for different tasks and provides the user with intuitive views on physically restricted areas. |
Reconstruction and Registration of Histology and Phase Contrast Images for Clinical Validation of Imaging ModalitiesBefore its introduction into the hospital, a new imaging modality has to be validated. In other words, appearing structures need to be correlated to the imaged tissues. Such a cross validation is only meaningful when performed against the gold standard which is histology. Currently, cross validation is performed by qualitative comparison of 3D datasets to 2D histology slices. Since the acquisition of a consistent 3D histology volume is a challenging task, its comparison to the corresponding dataset always remained qualitative.The classic histology procedure can be divided in four steps: pre processing, cutting, post processing and imaging of the tissues. In the first step, the sample is chemically processed to preserve the tissues and is then embedded in a paraffin block. By using a microtome, it is cut in very thin slices, and put on a glass slide. During post processing the sample is stained to enhance the structures of interest. The imaging is performed with a camera mounted in a microscope, or with a dedicated scanner. Several difficulties inherent to this process can have a dramatic influence on the quality of the reconstructed histology volume. For instance, since the cutting process is done manually, problems like flipping, bending or ripping of the slides may happen. If the knife starts to wear off, some banding will appear over the slices. Moreover, a few slices could be missing. Finally since the staining color is time dependent, variation in the color of the slices can occur. In this project, we propose to improve the histology procedure and to develop methods towards a consistent reconstruction of 3D histology volumes. |
Endovascular Stenting of Aortic AneurysmsEndovascular stenting is a minimally invasive treatment technique for aortic aneurysms or dissections. Thereby, a certain aortic prosthesis (stent graft) is placed inside the aortic aneurysm in order to prevent a life-threatening rupture of the aortic wall. Prior to the intervention, a computed tomography angiography (CTA) is acquired on which the surgical staff can measure the parameter of the desired stent graft and finalize the intervention workflow. The entire interventional catheter navigation is done under 2D angiography imaging where the physician is missing the important 3D information. The purpose of our project is two-fold:1. In the planning phase, a modified graph cuts algorithm automatically segments the aorta and aneurysm, so the surgical staff can choose an appropriate type of stent to match the segmented location, length, and diameter of the aneurysm and aorta. By visualizing the defined stent graft next to the three-dimensionally reconstructed aneurysm, mismeasurements can be detected in an early stage. Our main goal is the creation of an interactive simulation system that predicts the behaviour of the aortic wall and the movement of the implanted stent graft. 2. During implantation of the stent graft, after an intensity based registration of CTA and angiography data, the current navigation can be visualized in the 3D CT data set at any time. This includes solutions for electro-magnetic tracking of catheters as well as guide wires and stent grafts. Eventually, Our main goal is the creation of solutions that enable the surgeon to enhance the accuracy of the navigation and positioning, along with a minimum use of angiography, leading to less radiation exposure and less contrast agent injection. |
Real-time fusion of ultrasound and gamma probe for navigated localization of malignancyIntra-operative localization of non-superficial cancerous lesions in non-hollow organs like liver, kidney, etc is currently facilitated by intra-operative ultrasound (IOUS) and palpation. This yields a high rate of false positives due to benign abnormal regions and thus unnecessary resections with increased complications and morbidity. In this project we integrate functional nuclear information from gamma probes with IOUS, to provide a synchronized, real-time visualization that facilitates the detection of active tumors and metastases intra-operatively. The bet of this project is that the inclusion of an advanced, augmented visualization provides more reliability and confidence on classifying lesions prior to the resection. |
Magneto-Optic Tracking of a Flexible Laparoscopic Ultrasound TransducerIn abdominal surgery, a laparoscopic ultrasound transducer is commonly used to detect lesions such as metastases. The determination and visualization of position and orientation of its flexible tip in relation to the patient or other surgical instruments can be of much help to (novice) surgeons utilizing the transducer intraoperatively. This difficult subject has recently been paid attention to by the scientific community. Electromagnetic tracking systems can be applied to track the flexible tip. However, the magnetic field can be distorted by ferromagnetic material.We present a new method based on optical tracking of the laparoscope and magneto-optic tracking of the transducer, which is able to automatically detect and correct field distortions. This is used for a smooth augmentation of the B-scan images of the transducer directly on the camera images in real time. |
Port Placement in Minimally Invasive Endoscopic SurgeryOptimal port placement is a delicate issue in minimally invasive endoscopic surgery. A good choice of the instruments' and endoscope's ports can avoid time-consuming consecutive new port placement. We present a novel method to intuitively and precisely plan the port placement. The patient is registered to its pre-operative CT by just moving the endoscope around fiducials, which are attached to the patient's thorax and are visible in its CT. Their 3D positions are automatically reconstructed. Without prior time-consuming segmentation, the pre-operative CT volume is directly rendered with respect to the endoscope or instruments. This enables the simulation of a camera flight through the patient's interior along the instruments' axes to easily validate possible ports. |
Laparoscope Augmentation for Minimally Invasive Liver ResectionIn recent years, an increasing number of liver tumor indications were treated by minimally invasive laparoscopic resection. Besides the restricted view, a major issue in laparoscopic liver resection is the precise localization of the vessels to be divided. To navigate the surgeon to these vessels, pre-operative imaging data can hardly be used due to intra-operative organ deformations caused by appliance of carbon dioxide pneumoperitoneum and respiratory motion.Therefore, we propose to use an optically tracked mobile C-arm providing cone-beam computed tomography imaging capability intra-operatively. After patient positioning, port placement, and carbon dioxide insufflation, the liver vessels are contrasted and a 3D volume is reconstructed during patient exhalation. Without any further need for patient registration, the volume can be directly augmented on the live laparoscope video. This augmentation provides the surgeon with essential aid in the localization of veins, arteries, and bile ducts to be divided or sealed. Current research focuses on the intra-operative use and tracking of mobile C-arms as well as laparoscopic ultrasound, augmented visualization on the laparoscope's view, and methods to synchronize respiratory motion. |
| UsersForm | |
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| Title: | Dr. |
| Firstname: | Marco |
| Middlename: | |
| Lastname: | Feuerstein |
| Picture: | |
| Birthday: | |
| Nationality: | Bavaria |
| Languages: | English, German, Bavarian, Japanese |
| Groups: | Registration/Visualization, Segmentation, Medical Imaging, Computer-Aided Surgery, Medical Augmented Reality |
| Expertise: | Registration/Visualization, Segmentation, Medical Imaging, Computer-Aided Surgery, Medical Augmented Reality |
| Position: | External Collaborator |
| Status: | Alumni |
| Emailbefore: | marco.feuerstein |
| Emailafter: | micro-dimensions.com |
| Room: | microDimensions GmbH |
| Telephone: | |
| Alumniactivity: | COO of microDimensions |
| Defensedate: | 15 October 2007 |
| Thesistitle: | Augmented Reality in Laparoscopic Surgery - New Concepts for Intraoperative Multimodal Imaging |
| Alumnihomepage: | |
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