Endovascular aortic repair procedures are commonly guided using X-rays, which cause side effects to patients and the surgical team. Researchers now present an interdisciplinary approach that includes navigation, imaging techniques and augmented reality to reduce radiation exposure and optimise visualisation during these procedures.
By Verónica García-Vázquez
Abdominal aortic aneurysms, defined as an enlargement of the aorta greater than 1.5 times the normal size, are a relatively common and potentially lethal disease. Endovascular aortic repair (EVAR) is a minimally invasive technique for the treatment of aortic aneurysms and consists of the implantation of a stent graft along the aneurysm, via a delivery catheter inside the vessel, to avoid the rupture of the aorta. This endovascular procedure is commonly guided using X-rays and administering contrast-agents to the patient in order to highlight their vessel anatomy. Both have potential side effects: X-rays are carcinogenic and the contrast agent may cause kidney damage.
A recent study, published in Innovative Surgical Sciences, reviews the current state of the ongoing research project Nav EVAR (funded by the German federal ministry for education and science, BMBF) and its further research, describing the potential and limitations of each technology involved. This project focuses on guiding EVAR procedures following an interdisciplinary approach to reduce its current disadvantages, namely radiation exposure and contrast agent administration.
The approach includes tracking the endovascular tools, such as the delivery catheter, inside the patient and reconstructing their shape by combining an electromagnetic tracking system and fibre Bragg grating sensors. Catheter-based imaging modalities such as intravascular ultrasound or optical coherence tomography would allow the acquisition of intraoperative cross-sectional images of the vessel in order to update navigation with the patient’s current anatomy.
Augmented reality technology, specifically Microsoft HoloLens glasses, is incorporated to enable a more intuitive visualisation of the navigation data (namely, 3D models of vascular structures, preoperative computed tomography [CT] images, virtual angioscopies built from CT studies, intraoperative images and the current position of endovascular tools). Its hands-free manipulation with interaction built on hand gestures and voice commands makes HoloLens suitable for surgical environments. The Nav EVAR project also includes 3D printing of patient-specific phantoms for generating realistic test environments, avoiding animal experiments. According to the researchers, “The combination of these techniques is a promising approach to overcome the problems with x-ray imaging in the EVAR procedures”.
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Verónica García-Vázquez, Felix von Haxthausen, Sonja Jäckle, Christian Schumann, Ivo Kuhlemann, Juljan Bouchagia, Anna-Catharina Höfer, Florian Matysiak, Gereon Hüttmann, Jan Peter Goltz, Markus Kleemann, Floris Ernst, Marco Horn: Navigation and visualisation with HoloLens in endovascular aortic repair, 04.10.2018.