MRIs and Implanted Devices - New Research at Johns Hopkins

Approximately 2 million people in the United States have implanted pacemakers and/or defibrillators. Experts estimate that nearly 3/4 of these people will at some time need an MRI. As it stands, people with implanted pacemakers or defibrillators, cannot safely have an MRI test. The radiofrequency energy from the MRI can have life threatening effects on these patients via their implanted device.

All this is poised to change with the results of research led by Henry R. Halperin, M.D., M.A., of Johns Hopkins Hospital, in September 2006 and published in Circulation. Halperin and his team developed protocol that would allow MRIs on people with modern pacemakers and/or defibrillators to be performed safely and effectively. The key phrase here is modern. The researchers limited their study to pacemakers made in 1996 or later and defibrillators made in 2000 or later. The reason is that these newer devices are made of titanium alloy, a material which protects them from the radiofrequency emitted by the MRI machine. Older pacemakers and defibrillators are made from a different material and it is already established that this material is not safe inside the patient during an MRI.

While the results of the study were encouraging enough to for Johns Hopkins Hosptial to implement routine MRIs for patients with implanted devices, there are still many questions and restrictions:

• First, this was a very small study of 31 patients. Since the research was conducted, Johns Hopkins has given MRIs to a total of approximately 100 patients with pacemakers/defibrillators, still a very small number of individual successes.
• The study was done with only 1 type of MRI machine, the 1.5 Tesla by General Electric. One of the research team members has had a professional relationship with General Electric, as well.
• The lead author of the study, Dr. Saman Nazarian, a cardiac electrophysiology specialist, said that giving MRIs to people with pacemakers and/or defibrillators is an extremely specialized business, and requires advanced safety training on the part of the administering physician. He also cautioned that because it is still early, it would be best if MRIs were restricted to the same types of implanted devices and the same type of MRI used in this research study.
• Other than for research, the FDA has not approved any MRIs to be done on patients with implanted cardiac devices.
• Several of the research team members have professional relationships with defibrillator and pacemaker manufacturers. The Radiological Society of North America predicts that manufactures of implanted devices will soon produce MRI-safe products, as a result of this study.

The good news for back pain sufferers is that study found 100% accuracy in MRIs taken outside the chest area.

See Also:

• Types of Diagnostic Imaging Tests
• MRI
• MR neurography - MRN
• Positional MRI
• MRIs Don't Mix with Implanted Neurostimulators
• Spinal Cord Stimulation - FAQs