Once those protons are lined up, coils in the scanner emit a short burst of radio-frequency waves that cause the protons’ magnetic fields to wobble. The heart of the MRI is still a tube-like superconducting magnet, which generates a static electromagnetic field that realigns a small fraction of the hydrogen protons inside water molecules. The nuts and bolts of MRI technology have not changed much since the first human scanner was developed in the mid-1970s. “This is a window we’ve just never had in the intact human brain,” says Ravi Menon, a neuroimaging scientist at Robarts Research Institute at Western University in London, Canada. The scanners offer detail that was once seen only in thinly sliced postmortem samples imaged by powerful microscopes. But work at 7 T has already resulted in gains, researchers say, for both neuroscience and clinical applications: clinicians can guide electrodes for deep-brain-stimulation treatments more accurately, and might also be able to detect osteoarthritis at an earlier stage than was possible before. They also require more attention to safety. The scanners are bigger, more expensive and more technically demanding. The push to achieve higher field strengths presents a range of challenges. The University of Minnesota’s 10.5-T magnet is delivered and moved into the institution’s Center for Magnetic Resonance Research in this timelapse series. Scanners with even higher field strengths are expected to have resolving power that is at least double that of the 7-T devices. That resolution can be as fine as 0.5 millimetres in a 7-T machine - enough to discern the functional units inside the human cortex and perhaps see for the first time how information flows between collections of neurons in a live human brain. At 3 T, MRI machines can resolve details of the brain as small as 1 millimetre. The stronger the magnetic field, the greater the signal-to-noise ratio, which means the body can be imaged either at greater resolution, or at the same resolution, but faster. The appeal of ultra-high-field scanners is clear. Germany, China and South Korea are considering building 14-T human scanners. In addition to the University of Minnesota’s machine, researchers are readying two 11.7-T devices for their first tests on people: a gargantuan one for whole-body scanning at the NeuroSpin Centre at CEA Saclay outside Paris, and a smaller one for head scans at the US National Institutes of Health (NIH) in Bethesda, Maryland. At the extreme end are three scanners designed for humans that reach beyond 10 T. There are already dozens of 7-T machines in research labs around the world, and last year, the first 7-T model was cleared for clinical use in both the United States and Europe. But ultra-high-field scanners are on the rise. Today, hospitals routinely use machines with field strengths of 1.5 T or 3 T. The US$14-million scanner is one of a handful around the world that are pushing MRI to new limits of magnetic strength. “It was extremely exciting and very rewarding,” Ugurbil says. But it was worth the wait: when the scan materialized on screen, the fine resolution revealed intricate details of the wafer-thin cartilage that protects the hip socket. Even then, they didn’t quite know what they’d see. After the machine was finally delivered, on a below-freezing day in 2013, it took four years of animal testing and ramping up the field strength before Ugurbil and his colleagues were comfortable sending in the first human. The magnet faced long delays because the liquid helium needed to fill it was in short supply. The centre’s director, Kamil Ugurbil, had been waiting for years for this day. In the MRI room at the University of Minnesota’s Center for Magnetic Resonance Research, he lay down inside a 4-metre-long tube, surrounded by 110 tonnes of magnet and 600 tonnes of iron shielding, for an hour’s worth of imaging of his hips, whose thin cartilage would test the limits of the machine’s resolution. Days earlier, he had passed a check-up that included a baseline test of his sense of balance to make sure that any dizziness from exposure to the magnets could be assessed properly. #STRONGEST MAGNET IN THE WORLD FULL#Any metal could be ripped out by the immensely powerful, 10.5-tesla magnet - weighing almost 3 times more than a Boeing 737 aeroplane and a full 50% more powerful than the strongest magnets approved for clinical use. On a cold morning in Minneapolis last December, a man walked into a research centre to venture where only pigs had gone before: into the strongest magnetic resonance imaging (MRI) machine built to scan the human body.įirst, he changed into a hospital gown, and researchers made sure he had no metal on his body: no piercings, rings, metal implants or pacemakers.
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