<<返回上一页

Stereo eye

发布时间:2019-03-08 09:06:12来源:未知点击:

By Duncan Graham-Rowe BRAIN surgeons will soon be able to operate with more confidence thanks to a microscope imaging technique that allows them to “see” beneath the surface of the brain they are working on. The Microscope Assisted Guided Intervention technique (MAGI), developed at Guy’s Hospital in London, lessens the risk of damage to critical structures and helps ensure complete extraction of tumours. Brain surgery is a delicate business. Cut a little bit too deep and a surgeon could pierce a blood vessel or sever a nerve. So knowing what lies beneath the surface of tissue can be a life-saver. But the only way to do this at present is to look away from the surgical microscope and examine brain scans of the patient that were taken before the operation. MAGI addresses this problem by marrying data from two types of scan: magnetic resonance imaging (MRI), which shows proton density, and computerised tomography (CT), which integrates cross-sectional X-ray images. The two image types are combined to form a three-dimensional computerised model of the patient’s brain that is then fed into the microscope and appears as an overlay on the microscope image. “The advantage of viewing the image through the microscope is that it is stereo. You have a different image for each eye,” says Philip Edwards, a computer scientist working on the project. The overall effect is what he calls augmented reality: a 3D model of the parts of the brain laid over the top. To avoid having to hold the patient’s head stationary with a clamp, MAGI shifts the computer image with every tiny movement of the patient’s head, so that it always exactly corresponds to where the surgeon is looking. To achieve this, markers are placed on the patient’s upper teeth and these are monitored by cameras. Movements as small as 0.9 millimetres can be detected and compensated for. One of the main difficulties in developing the tool was matching the size of the computer model from the scans with the microscope’s image of the actual organ. The researchers are currently testing different formats for the stereo image to discover which one surgeons find most helpful. Options include outlines, silhouettes and wire-frame overlays. “In a way, the MAGI project is ahead of its time,” says Michael Gleeson, a senior surgeon at Guy’s, “because many of the ways of treating these skull-based tumours are still in their infancy.” Gleeson has operated several times using MAGI in its various stages of development. “It’s comforting to be able to see where the tumour is,” he says. So far the system has been tested on seven patients undergoing procedures such as skull-based surgery and ear,