A Powerful Attraction: FDA Approves New 7 Tesla MRI Technology
In magnetic resonance imaging, the stronger the magnet, the better the image.
Most MRI machines in medical use today have a static field strength of 3 Tesla. On Oct. 12, the Food and Drug Administration approved a new MRI technology with a strength of 7T for brain and limb imaging. Manufactured by Siemens, the Magnetom Terra has more than twice the field strength of 3T devices. According to the company’s press release, the Terra can provide contrast at submillimeter scales. This enables considerably finer resolution and offers the hope of detecting tumors and brain lesions at very early stages.
Another advantage, according to Siemens, is the “hyper-fast” image reconstruction computer software, making the images available up to 20 times faster than previous 7T scanners.
The FDA approved the Terra based on its substantial equivalence to devices already on the market, including comparable safety and effectiveness. The safety data supplied by the manufacturer was based on “computational modeling, simulations, and rigorous experimental validation,” according to the FDA announcement.
MRIs are generally considered safe for the patient except for the risk of metallic objects such as implants and iron-bearing tattoo inks responding to intense magnetic fields. There have also been recent reports of one ingredient of a common contrast media, gadolinium, accumulating in patients’ bodies. The FDA Medical Imaging Drugs Advisory Committee met in September to discuss the latter and develop a research agenda to clarify the issue. The European Medicines Agency suspended the use of three gadolinium contrast agents last July.
The Terra does alleviate another concern: loss of the helium used to cool MRI magnets. Global supplies of helium are dwindling. The Siemens press release noted that the Terra has a “zero helium boil-off feature” that reduces evaporation of the gas.