The sight of doctors walking around with stethoscopes slung round their necks is set to become a thing of the past as new technology becomes available, experts have predicted.The 200-year-old device could soon be replaced by handheld ultrasound equipment, according to an editorial in the medical journal Global Heart.Editor Jagat Narula and Professor Bret Nelson, from New York'sMount Sinai School of Medicine, said equipment using ultrasound - invented in Glasgow in the 1950s - is becoming smaller, more accurate and less expensive.They said portable ultrasound machines, which could be used to look at the heart and lungs, were becoming more accurate and therefore useful to doctors."Several manufacturers offer hand-held ultrasound machines slightly larger than a deck of cards, with technology and screens modelled after modern smartphones," the experts said.They predicted future medical students would use portable devices to "witness living anatomy and physiology previously only available through simulation".But engineer Tom Brown, who alongside Ian Donald pioneered ultrasound using equipment used in Glasgow's shipbuilding industry, insisted the stethoscope would continue have a place in hospitals alongside the technology he helped create.Mr Brown agreed ultrasound technology was moving on a par with mobile phone technology with everything becoming smaller, but said the majority of machines in hospitals were still large and used by specialists trained in their use."These pocket-sized machines aren't any better and are probably more limited in what they can do than bigger ones, but they can be carried to wards much like a stethoscope," he said."But they don't replace a stethoscope. A stethoscope relays sounds made within the body to the observer's ears. The ultrasound machines present the information in some pictorial form to the observer's eyes."