Researchers at the Martinos Center for Biomedical Imaging at Massachusetts General Hospital have developed a new technology that may allow more patients with pacemakers, defibrillators and spinal cord stimulators to undergo MRI exams.

The radiofrequency (RF) energy used in MRI can increase the electrical current induced in the lead's nonmagnetic metallic wires and generate heat that can damage tissues. The FDA has approved a group of “MR conditional” devices but those can only be used with low-power scanners, instead of the new, more powerful MRI systems, according to the researchers.

"Clinical electrical stimulation systems such as pacemakers and deep-brain stimulators are increasingly common therapies for patients with a large range of medical conditions, but a significant limitation of these devices is restricted compatibility with MRI," Giorgio Bonmassar, senior and corresponding author of the paper, said in a statement.
The resistive tapered stripline (RTS) technology works by reducing the generation of heat when wires are exposed to RF energy. It disrupts the RF-induced current increase by abruptly altering the electrical conductivity of wires made from conductive polymers.

The researchers developed a deep-brain stimulation device with an RTS lead and tested it on a gel model that resembled an adult human head and torso. They found that the RTS lead generated less than half the heat produced by exposure to a powerful MRI-RF field compared to the commercially available leads.

For epilepsy patients, brain MRI exams can reveal more accurate information about where seizures originate and their relation to other brain structures. In addition, the MR-compatible leads will enable patients with brain implants to undergo MRI exams of their knee, spine and breast, which are currently not allowed.

The researchers are currently pursuing an FDA Investigational Device Exemption so they can start clinical trials to test the RTS leads.

MRI Homepage