Abdominal Aortic Aneurysm

Description

An abdominal aortic aneurysm (AAA) is a bulge in the wall of an artery. It is estimated that 1.5 million Americans have an AAA, although only approximately 200,000 are diagnosed each year. AAA’s are almost always caused by arteriosclerosis. As a plaque accumulates, the pressure of the blood flowing through the weakened section of the artery causes the artery to balloon, forming an aneurysm. If the aneurysm is not detected in time, the weakened aorta will rupture, often causing death.

AAA planning software

/webdav/site/vrai-group/shared/projects/nccr/images/stent-tool.pngWe are currently developing a visualization system to improve the choice and placement of AAA prostheses. Our system works by processing preoperative CT angio-scanner data, automatically extracting the aorta, iliac arteries and the aneurysm in order to build a 3D model.

With this 3D model our system will enable surgeons to examine possible prosthesis locations and catheter trajectories. In addition, the system will offer advanced measurement tools to assist with evaluation of the surgical area.

Once the surgeon has identified a target position and the position stent is defined, the system will automatically suggest a set of candidate prostheses to allow the surgeon to validate his choice by simulating the prosthesis contact.

AAA navigation system

/webdav/site/vrai-group/shared/projects/nccr/images/aorta-projective.pngWhen a C-Arm is used for stent placement, the catheter, prosthesis and bones can easily be seen in the X-ray image. By injecting a contrast product into the blood stream, the arteries will also become visible. The aneurysm however cannot be viewed by contrast.

X-ray images have numerous limitations; for example, the imagery is not real-time and because surgeons must wait for images, it is often difficult to achieve the level of accuracy required for good stent placement. Additionally, the curvature of a deformed aorta may not be visible on 2D projective images.

To address these problems, we have begun to develop a navigation system to assist with prostheses placement. The system registers and overlays 3D graphical models (based on preoperative CT scans) on the X-ray images. We believe these enhanced images will help the surgeon to achieve better placement accuracy.