Magnetic resonance imaging (MRI) uses magnetic fields and radio waves to create images of organs and tissues in the human body, helping doctors diagnose potential problems or diseases. Doctors use MRI to identify abnormalities or diseases in vital organs as well as many other types of body tissue, including the spinal cord and joints.
Depending on what part of the body is being analyzed and how many images are required, an MRI scan can take up to an hour or more. Strengthening MRI from 1.5 tesla (T), the measurement for magnetic field strength, to 7.0 T can definitely improve images. But although higher-power MRIs can be done using stronger magnetic fields, they come with safety risks and even higher costs to medical clinics. The magnetic field of an MRI machine is so strong that chairs and objects from across the room can be sucked toward the machine — posing dangers to operators and patients alike.
A small ringlike structure made of plastic and copper was developed to amplify the already powerful imaging capabilities of MRI. The new magnetic metamaterial could be used as an additive technology to increase the imaging power of lower-strength MRI machines, increasing the number of patients seen by clinics and decreasing associated costs, without any of the risks that come with using higher-strength magnetic fields. It could also be used with ultra-low-field MRI, which uses magnetic fields that are thousands of times lower than the standard machines currently in use. This would open the door for MRI technology to become widely available around the world.
The magnetic metamaterial creates a clearer image that may be produced at more than double the speed of a current MRI scan. The metamaterial is made up of an array of units called helical resonators — three-centimeter-tall structures created from 3D-printed plastic and coils of thin copper wire. Put together, helical resonators can be grouped in a flexible array, pliable enough to cover a person’s kneecap, abdomen, head, or any part of the body in need of imaging. When the array is placed near the body, the resonators interact with the magnetic field of the machine, boosting the signal-to-noise ratio (SNR) of the MRI.