FDAnews Device Daily Bulletin


Nov. 18, 2005

Relatively minor manufacturing design modifications to implanted medical device leads can substantially decrease magnetic resonance imaging (MRI)-induced heating risks, according to a new study by Biophan Technologies.

In general, MRI is considered to be an extremely safe diagnostic modality, according to a paper co-authored by Robert Gray and W. Timothy Bibens, members of Biophan's research staff, and Frank Shellock of the University of Southern California in Los Angeles.

"However, under certain conditions, patients with electrically conducting implants may be seriously injured during MRI due to the generation of excessive heat," says the paper, published in the November issue of the scientific journal Magnetic Resonance Imagining. "This is particularly problematic for implants that have leads (e.g., spinal fusion stimulators, cardiac pacemakers, and neurostimulation systems), since MRI-induced heating tends to occur in extended wires that form resonant antennae."

The electromagnetic environment of MRIs can create safety problems in a wide range of medical devices. In some of the most dramatic cases, MRI's electromagnetic fields can cause the devices to heat or create induced voltages, or to malfunction, potentially causing serious harm to patients, the paper states. "It is obvious that there is a critical need for a means of reducing MRI-induced heating for implanted leads used with medical devices," the article concludes.

The authors propose the development of leads "that inherently minimize heating." Biophan has developed a portfolio of proprietary solutions consistent with the authors' findings, the firm said.

"Minor modifications to a wire form greatly reduce MRI-related heating. Because these modifications change the wire form's basic electrical characteristics, it is expected that similar results (i.e., reduction in MRI-induced heating) will apply to longer leads and to other physiological positions of lead wires. As such, these findings have important implications for implanted leads used in medical devices."