A SOFTWARE fix for improving the quality of aircraft-mounted radar images could also correct blurred MRI scans and save hospitals the cost of repeating them.
MRI scans can take up to 10 minutes and even a slight twitch on the part of the patient can ruin the image. As a result, up to 10 per cent of images must be repeated, costing as much as 拢750 a scan. Children, the elderly and people in pain are particularly fidgety, says David Atkinson, an MRI researcher at Guy鈥檚 Hospital in London. 鈥淪ome children have to be scanned under anaesthetic to keep them still.鈥�
Now a team led by Armando Manduca at the Mayo Clinic in Rochester, Minnesota, has developed a software fix called 鈥渁utocorrection鈥�, which factors out the patient鈥檚 motion. The software is based on a device developed by British defence research company Qinetiq of Farnborough for sharpening images collected by aircraft-mounted radar.
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Such images are sometimes distorted by the movement of the plane itself and subtracting this from the data can correct the problem. The software does not need to know precisely what movements it is correcting for in advance. Instead, it tries a series of educated guesses until the image improves.
Qinetiq and Atkinson began applying this approach to MRI, but the crucial advance by the Mayo team was to find a measure of image quality that works for a wide variety of MRI scans. Their program effectively works out the difference in brightness between each pixel in the image and its neighbours, then adds these up to give a global 鈥渟harpness鈥� measure.
The program next tries to subtract a variety of possible movements by the patient from the original data to see if this improves image sharpness. A three-dimensional object can move in any one of six ways (see Graphic) or combinations of these. But by eliminating movements that the body part being scanned is unable or unlikely to make, the processing takes only 2 minutes on an ordinary PC. For a shoulder scan, for example, movements along the body鈥檚 head-to-toe axis are most likely, as the patient breathes or gradually relaxes. The technique will undergo its first tests in hospitals in January.
