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FDA Clears First 7T Magnetic Resonance Imaging Device

Siemens Magnetom Terra doubles available magnetic field strength

The FDA has approved the Magnetom Terra (Siemens Medical Solutions Inc.), a magnetic resonance imaging (MRI) device that more than doubles the static magnetic field strength available for clinical use in the United States.

The Magnetom Terra, which has a magnetic field strength of seven teslas (7T), was cleared under the 510(k) pathway. Before this clearance, clinical MRI systems were available in field strengths of 3T and below.

“The overall image quality of MRI improves with higher magnetic field strength,” said Robert Ochs, PhD, director of the Division of Radiological Health in the FDA’s Center for Devices and Radiological Health. “The added field strength allows for better visualization of smaller structures and subtle pathologies that may improve disease diagnosis.”

MRI is a medical imaging procedure that creates images of the internal structures of the body. MRI scanners use strong magnetic fields and radio waves (radiofrequency energy) to generate images. The signal comes mainly from the protons in fat and water molecules in the body. When interpreted by a trained physician, images from an MRI scan provide information that may be useful in determining a diagnosis. MRI scanners come in different magnet field strengths measured in tesla (T).

Under the the 510(k) premarket clearance pathway, a premarket submission is made to the FDA to demonstrate that a new device is substantially equivalent to a legally marketed predicate device. In this case, the FDA also reviewed sample clinical images and the safety of the radiofrequency subsystem through computational modeling, simulations, and rigorous experimental validation.

The manufacturer also provided data from a comparative study of 35 healthy patients that compared images of the patients using the 7T device and images using the 3T device. Board-certified radiologists reviewed the images and confirmed that the images acquired on the 7T device were of diagnostic quality and, in some cases, an improvement over imaging at the 3T.

The Magnetom Terra is for patients who weigh more than 66 pounds and is limited to examinations of the head, arms, and legs.

Source: FDA; October 12, 2017.

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