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newscientist 00058.txt

#Mini MRI to check bone health on space station Astronauts may soon have a portable MRI machine to keep an eye on their muscles and bones during a spell on the International space station. The custom-built lightweight MRI should be ready to fly by 2016. Bone and muscle loss in microgravity is a major health issue in orbit astronauts are checked usually before and after missions. But we don't know how bone and muscle density change with time during a mission says Gordon Sarty at the University of Saskatchewan in Canada. You can only guess with the before and after data we have today. Hospital MRI machines can weigh more than a tonne thanks to their strong superconducting magnets making them impractical for the ISS. So Sarty and his colleagues at MRI manufacturer MRI-Tech Canada of Calgary Alberta and space flight hardware maker Com Dev International of Cambridge Ontario have developed a technique called Transmit Array Spatial Encoding or TRASE which uses fluid as a proxy for bone and muscle mass. Conventional MRIS found in hospitals work by inducing a magnetic field gradient across your entire body. Additional radio signals cause the protons in your body's liquids to resonate with the magnetic field and send out signals that allow their positions to be imaged. This helps medical technicians localise and examine tissues inside your body but requires bulky equipment. To shrink down TRASE uses a novel radio wave timing technique that requires much smaller magnets. Instead of creating a magnetic field across the entire body the device sends superfast radio pulses into a small area of the body like a wrist. The pulses make protons in the body spin in a precise way that sends signals that can be interpreted as the location and density of fluid in the bones and muscle. At just 50 centimetres wide and with a mass of 50 kilograms it is small enough to fit on an ISS experiment rack. Astronauts need only place their wrists inside to have checked their bones. Sarty presented the technology at the International Astronautical Congress in Toronto Canada on 3 october. All this significantly reduces the hardware complexity of an MRI which saves us considerable weight making it suitable for space flight Sarty told New Scientist. It also leaks very little magnetism outside of its enclosure so it won't interfere with other experiments on the ISS. Sarty and colleagues have tested the technology and scanned wrists with it successfully. They are now waiting to see if the Canadian space agency selects their ISS-MRI for a life science berth on a rocket flight in 2016. The decision should be made before the end of the year. The mini MRI technology may also find applications in far-flung places On earth. Five years down the road I expect really portable MRIS based on TRASE to be everywhere Sarty says. You'll see new applications in the ER in surgery with telehealth in remote communities and even in ambulances. While a system based on permanent magnets sounds perfect for use in space where power is scarce the Canadians will have their work cut out expanding the technology On earth predicts David Taylor founder of scanner-maker MR Solutions in Guildford UK. We tried to make one that would do a wrist and it was like trying to put together a thousand bar magnets most of which were trying to repel each other. You can do it but that repulsion is a big manufacturing challenge e

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