Satnav for surgeons: accurately navigating the body’s arterial highways
3D overlay of blood vessels.
The scientists behind this exhibit have produced a system, similar to a car's satnav, but for key-hole surgery.
The "map" in this case is a high-quality 3D image taken before the operation. The scientists have developed methods to link this "map" to the x-rays used to guide the surgery.
X-rays clearly show surgical instruments, but not blood vessels. Also, x-rays are only 2D, shadow-projections, of real 3D anatomy. This link has been used to overlay computer-generated 3D blood vessels, from the high-quality image, onto the x-rays. This overlay, called a "road-map", shows blood vessels and surgical instruments all on the same image, helping surgeons navigate to their target.
How does it work?
The core technology underpinning this research is known as "image registration". Essentially this just means matching images together. It is used to form the link between the high-quality 3D image and the 2D x-rays used to guide the operation.
The computer program takes the 3D image and produces lots of 2D images (which look like x-rays) from different view directions. Over half a million images are produced and each is compared to the real x-ray using a statistical measure. The image which best matches the real x-ray image tells the system how the 3D image and x-ray are spatially linked. Once this information is known, the 3D vessel surfaces can be overlaid onto the x-ray images. All this needs to be done very quickly, within a few minutes and ideally a few seconds, so fast computing techniques (graphics-card programming) are used to speed up the program.