If you’ve ever wondered how much energy it takes to perform a full body scan, consider this: a new MRI designed to probe the deep structure of the brain uses a magnet more powerful than the ones inside theLarge Hadron Collider. This magnet could pick up a 60-metric-ton tank. It could create a field strong enough to affect the weak diamagnetism of blood, even levitating small animals. Or, if used properly, it could align a good portion of the protons in your body, turning your atomic structure into the most powerful musical instrument of all time. In an MRI, applying the magnetic field puts tension on the atomic strings, and sudden removal of the field plucks them — the hydrogen-rich water molecules in your body snap back to their lowest energy state, and in the process give off radio waves that can be collected to show how those molecules were arranged.
A regular MRI brain scan. Booooooring.
So the resolution of an MRI is directly related to, among other things, field strength. Most medical imaging machines produce fields between 0.5 and three teslas in strength — that’s enough to align a good portion of the hydrogen nuclei (protons) in the body, enough to see large scale structures like tumors or loss of brain mass. However, for research purposes it’s often necessary to dramatically increase the strength of the magnetic field, aligning nuclei even more densely and thus creating more data points per cubic centimeter. Newer research MRI machines can produce fields of around nine teslas, but this upcoming machine, called INUMAC, can reach strengths of almost 12. It creates this field using coils made of more than 200 kilometers of superconducting cable.
INUMAC stands for Imaging of Neuro disease Using high-field MR And Contrastophores — even with all those skipped words and a price tag in excess of $250 million, they still couldn’t come up with a meaningful acronym. It is at least descriptive, however: INUMAC will use a high-powered magnetic resonance field to image neurological disease. To add to this field, it’s necessary to start looking at the brain on a much more detailed level than ever before. Where normal hospital scanners can see down to resolution of about a cubic millimeter (roughly 10,000 neurons per pixel), INUMAC will be able to see roughly ten times more acutely, with a resolution of 0.1 mm, or 1000 neurons. The brain also functions at an incredible pace, and the standard MRI “time resolution” of one second can lead to smudged images, almost like leaving the shutter open too long on a camera. INUMAC will be able to capture information across just one tenth of a second, which will dramatically reduce noise in its measurements.
Powerful electromagnets use coils of superconducting cable to carry huge currents and create enormous magnetic fields.
There’s no telling what researchers might learn from watching the progression of neurological disease on this scale. There is still much to discover about how Alzheimer’s disease eats away at the tissue of the brain — and a higher resolution scanner could detect the onset of disease much earlier than currently possible. Functional imaging, which follows brain activity by watching neuron excitation, could be taken to a whole new level of detail and reveal structural complexities we currently cannot see. (See: Easy cloaking with superconductors and magnetic tape.)
In fact, INUMAC’s field is so strong it could even allow new forms of imaging. As mentioned, modern MRI machines look for the RF signals of realigning hydrogen nuclei, but a sufficiently powerful magnet could look with other elements like sodium or potassium. This could potentially reveal a whole new array of evidence about the brain, new tissues that incorporate few freely aligning hydrogen atoms and are thus underrepresented on “1H-MRI” scans. INUMAC’s super-magnet must be kept at a chilly -271 degrees Celsius or else lose its superconductivity, though, and the liquid helium required to do this makes an economy model impossible to imagine. Until we learn to make cheap, readily availablesuperconductors that operate at or near room temperature, there’s no way to get this kind of functionality to the masses.
The team hopes to have INUMAC producing working research images by 2015.
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