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Scientists at Stanford University in California have come up with a way to
slash the cost of MRI scanners from the $3 million they now cost to
around $150,000. They propose replacing expensive superconducting magnets
with a pair of much cheaper copper-wire magnets. Superconductors are used
because they produce fields that are strong enough to align molecules in the
body and uniform enough for the alignment this creates to be measured. The
Stanford trick is to use different magnets for each job: one strong but not very
homogeneous magnet for the alignment, and a second weak but homogenous magnet to
do the measuring.