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First Image Taken With an Ultra Low Field MRI
KentuckyFC writes "MRI machines are about to get smaller, much smaller. Most of their bulk is taken up by the huge superconducting magnets required to generate fields of a few Teslas. Now a team at the Los Alamos National Lab in New Mexico has built a machine that can produce images using a field of only a few microTesla (PDF, abstract here). So giant superconducting magnets aren't necessary, a development that has the potential to make MRI machines much smaller, perhaps even suitcase-sized. The one-page paper shows sections of the first 3D brain image taken with the device."
The summary is VERY incorrect.
This isn't an ultra low field MRI, it's a DUAL field MRI. In a normal scanner you have a big, static magnetic field that polarizes the sample and remains for readout. In one of these dual field scanners you use the big field (or a bigger field, it's usually a resistive electromagnet so it can't be anywhere near as strong as a superconductor) to polarize the sample then you shut it off and use a much smaller field for readout. There are a few advantages, the one the abstract focuses on is that you can do things like MEG in a very low field. The other is that energy deposition is related to the field strength so by using a small field you can use imaging sequences that would otherwise pump too much energy into the subject.
One of the guys working on this technology visited my lab last year. It was a very interesting presentation.
I believe someone has produced an MR image using the Earth's magnetic field. They've certainly done nMR in the Earth's field. You can't get much lower than that on this planet.