12. November 2018 Augmented Reality Facilitates Aortic Repair

One of the major challenges associated with endovascular treatment of aortic aneurysms is the extraordinarily high exposure to radiation caused by continuous X-ray imaging during the operation. New 3D imaging technologies developed by scientists from the University of Lübeck aim to solve this problem. To treat aneurysms physicians usually use endovascular therapy: They put a stent graft via a delivery catheter inside the vessel which brings it back to its normal size and seals the aneurysm. "Endovascular therapy has resulted in huge improvements for patients, but there are two issues that create serious health hazards for patients and the surgical team," states Markus Kleemann, Head of Vascular and Endovascular Surgeryat University Hospital Schleswig-Holstein in Lübeck. To make patients' blood vessels visible, X-ray imaging is used. However, this leads to an extraordinarily high exposure to radiation and the administration of high doses of nephrotoxic contrast-agents. "Carcinogenic radiation in particular is a big problem for patients and the surgeons that carry out countless operations during their career," states Kleemann, "But with modern visualization technologies, contrast-agents and radiation are no longer needed for thei ntervention." Together with four different medical and technical partners in Lübeck, Kleemann established the Nav EVAR project (Navigated Contrast-Agent and Radiation Sparing Endovascular Aortic Repair) in 2017. The team aims at developing novel navigation systems for endovascular therapy to significantly reduce the X-ray burden. Unique infrastructure in Lübeck The project will receive funding of 4.2 million Euro by the German Federal Research Ministry until 2020. "The unique features of this project not only include disruptive research, but also excellent infrastructure here in Lübeck," says Floris Ernst from the Institute for Robotics and Cognitive Systems at the University of Lübeck (ROB). Clinicians and radiologists are only 200 meters away from their technical partners, including the ROB, Fraunhofer MEVIS and the Medical Laser Center Lübeck. "This environment creates synergistic effects and facilitates progress within the Nav EVAR project," Ernst points out. Thus far, the team has developed a patient specific vascular phantom model on the basis of CT angiography data from anonymous patients with real pathology by 3D rapid prototyping. "With this model we testand simulate our new tracking methods in a realistic environment and we avoid animal testing", states Ernst. To prevent exposure to radiation, the team wants to integrate a glassfiber with bragg grating for optical coherence tomography (OCT) into the stent placement system. The imaging technology can be used to verify the position of the catheter in the vessel and to later check whether the catheter is correctly placed. "OCT will improve accuracy and safety by continuously providing local feedback on the tip of the catheter with realtime visualization of the vessel. In combination with virtual angioscopy and other real-time visualizations, the OCT image can be displayed as a 3D projection through augmented reality," explains Ernst. By wearing a Microsoft HoloLens, doctors will be able to follow the catheter position at any time in a real-time navigation framework. "The HoloLens still has a very narrow viewing area. Also weight, accuracy and battery need to be improved. However, it is foreseeable that with our project the augmented technology will be mature enough to make it into the OR in the near future". Nav EVAR scientists currently use electromagnetic tracking systems to test the 3D printed phantom model for their navigation systems. "The latest challenge is to improve the accuracy of the fiber bragg navigation and to develop a stable catheter that incorporatesa fiber for both navigation and OCT." (Author: Helene Märzhäuser for LSN Magazine)

This text is from the latest LSN MAGAZINE 3_2018 - read more