A MRI system developed by Neoscan Solutions of Germany with PC cards from Spectrum Instrumentation is a quarter the size of the 8000kg scanners used for adults and so can be placed directly on a children’s ward in a hospital.
The system uses digitisers and arbitrary waveform generators (AWG) cards from Spectrum with sub-nanosecond resolution to generate the test signals and capture results, using a GPU in the PC to process the results.
“Having worked with MRI scanners for many years, I recognised the problem,” said Dr Stefan Roell, founder of startup Neoscan Solutions in Germany. “Scanning a sick child usually means a long journey out of the ward to the scanner and babies may need support equipment that is not easily transportable.”
“We have designed an MRI scanner specifically for new-borns and infants which means that the hole in the middle is only 30cm in diameter, not 60cm. As a result, the scanner is much smaller (170cm x 150cm x 110cm) and can go through standard doorways,” he said. “With a weight of only 2000 kg, it can be located on standard floors and, needing only ten square metres, it can be installed in a spare room directly on the children’s ward. Carrying a sleeping baby only a few metres to the MRI is a big advantage, saving a long journey through the building and the need for sedatives to keep the baby motionless for the scan.”
To shrink the size, the team developed a dry magnet that would create the standard 1.5 Tesla field inside the hole, but without requiring liquid helium. This is done by an inner, cylindrical magnet generating 2.5T and then an outer cylindrical magnet that counteracts the inner field to provide strong, active magnet shielding so that there are no stray magnetic field left beyond about 1m from the scanner.
For the control electronics, Neoscan uses a PC which runs the software that Neoscan has created plus the high-end measurement PC-cards from Spectrum Instrumentation. The signals for the MRI are generated by the M4i.6620-x8 and M2p.6546-x4 AWGs (Arbitrary Waveform Generators) and then analysed using an M2p.5968-x4 digitizer. The system uses Spectrum’s SCAPP software drivers that enable a graphics processor with 5000 cores to perform the parallel processing, instead of using the 8 or 16 cores in a mainstream processor.
“As a start-up, we could not afford to create specialized hardware and so we used this route of high quality, standard cards providing a platform to run our software on,” said Roell. “This meant that we could focus our skills on the software development with very fast development cycles in the knowledge that the hardware was already tried and tested.
“For MRI, it is vital that there is phase coherence in the 64MHz signals, otherwise there will be cancellation effects. In practice, that means that the AWG and matching digitizer have to have sub-nanosecond coherence precision, which the Spectrum cards achieve. During the research phase, it was hard to determine this from the specifications of the cards provided by the various suppliers that we contacted, as it is a rather unusual level of detail. However, Spectrum was outstanding in helping us with technical support both in the specification of the best cards to use and then again during the implementation. A rival proposal took weeks longer to arrive and was grossly over-specified and over-priced as they had not made the effort to understand the detail of our project.”
Neoscan will be shortly installing its first devices in German hospitals and the certification process with a CE mark is expected to be completed before the end of 2021.
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