A number of diseases can affect the aorta, and endovascular (minimally invasive) techniques can be used to treat many of these conditions. During endovascular aortic repair, different instruments, such as catheters (plastic tubes), metal wires and balloons are visualized by X-rays. Intermittent aortic injections of contrast medium improve the depiction of the aorta; however, contrast medium may damage kidney function in some patients, radiation can be harmful and X-ray images are 2- dimensional, i.e., the impression of depth is missing. To reduce the use of X-rays and contrast medium, as well as to provide physicians with a better spatial understanding of a patient's vascular anatomy, one can use a navigation system with 3-dimensional images. The use of 3-dimensional visualization and navigation during the endovascular repair of aortic diseases is a subject of research at the Norwegian University of Science and Technology (NTNU), SINTEF Dept. of Medical Technology and St. Olav's Hospital. A navigation system for blood vessels has similarities to the GPS systems used in cars. Such a navigation system can provide the position of different instruments in a 3-dimensional image of a patient’s vascular system without using X-rays and contrast medium. The use of a navigation system may improve precision and simplify future minimally invasive treatment of the aorta. The purpose of this thesis was to investigate the applicability of a navigation system with 3-dimensional images of the vascular system for guidance in endovascular aortic treatment, and to assess the reliability of such a navigation system. The assessment was conducted in four sub-studies. First, we used the navigation system to insert an endoprosthesis (artificial blood vessel) into a model of the abdominal aorta. With specially developed software, the navigation system can use 3-dimensional images (CT scans) of the patient acquired before the procedure as a roadmap. In phantom and animal experiments, the navigation system specified the position of instruments with a high degree of accuracy. Finally, we used the navigation system during the insertion of aortic endoprostheses in patients. In this thesis, we demonstrate that a navigation system that enables visualization of instruments in a 3-dimensional image can be a useful tool during minimally invasive treatment of the aorta. The navigation system is accurate and easy to use.

PhD i medisinsk teknologi

PhD in Medical Technology