He wanted to study whether it is safe for patients to undergo lumbosacral MRI and what actually happens to the device. How much heat or temperature change occurs in the device? He discusses studies from his institution, Cleveland Clinic, where they performed phantom model using a plexiglass outline of a body and filled with an acrylic gel matrix and implanting the sacral neuromodulation device and putting it through a MRI. They analyzed the changes in temperature. Tested intact system, a fragmented lead, and intact lead. He found that in an intact system there was none or minimal heating of the device that were turned off. In a broken lead there was none or minimal heating. Intact lead at the IPG site the temperature changed slightly.
Now he questions what happens in a live person. He had an IRB approved in vivo study to assess safety in patients undergoing lumbosacral MRI. A prospective study with 11 patients who needed MRI. Devices were interrogated before and after lumbar/spine MRI. 1 patient felt discomfort. 2 felt warmth and no one felt paresthesias. There was no changes in symptom scores or changes in impedance/IPG activity.
This research was stimulated by his curiosity of how brain activity changes during SNM.
Other fields have studied devices and MRI safety. In particular cardiac devices have been studied. No long-term clinically significant effects were seen.
In summary, Dr. Goldman found that 1.5T MRI is safe in patients who have the Interstim II device implant with a caveat this was done at his institution, in their machine and location. There is no or minimal risk of heating to the device, especially intact or fractured lead. He advises that surgeons should still weigh risks and benefits and radiology departments still may not allow for MRI in patients with Interstim devices. More research is needed to create devices that are MRI compatible.
Presented by: Howard B. Goldman, MD, FACS, Department of Urology, Cleveland Clinic, Cleveland, Ohio
Written by: M Lira Chowdhury, DO, Fellow, Female Urology, Pelvic Reconstructive Surgery & Voiding Dysfunction, The University of California Irvine, Department of Urology, @lirachowdhury at the Society of Urodynamics, Female Pelvic Medicine & Urogenital Reconstruction Winter Meeting, SUFU 2019, February 26 - March 2, 2019, Miami, Florida