June 2010

Is That Safe in an MRI?
By Jim Knaub
Radiology Today
Vol. 11 No. 6 P. 4

Frank G. Shellock’s e-mail led to a phone discussion and a review copy of the Reference Manual for Magnetic Resonance Safety, Implants and Devices: 2010 Edition making its way to my desk. An adjunct clinical professor at the University of Southern California and the driving force behind the Web site www.mrisafety.com, Shellock edits the annual reference manual. While the title has no snap, the book is filled with the kind of detailed information that professionals entering an MRI suite (or those sending patients there) should have in their offices. For example, this edition evaluates more than 200 aneurysm clips for safety in an MR environment. After briefly pondering the notion of more than 200 aneurysm clips, I did a quick count and found that about one half are considered “safe” in a 1.5T MR environment, while the remaining hundred or so were deemed either unsafe or conditionally safe. It’s a good thing someone writes down all this information in one place.

In addition to the clips, Shellock’s list includes evaluations of pacemakers, access ports, radioactive seed implants, and a host of other common (and uncommon) medical devices. What Shellock calls “The List” is evolving because implants and other devices are changing and MRI technology is changing. If a device is evaluated as safe in a 1.5T environment, what does that mean for a 3T environment? It means the device needs to be evaluated in a 3T environment. That testing is underway; some is included in the 2010 edition and more will be included in subsequent years’ editions.

The manual underscores the important idea that MRI safety is an ongoing, evolving process. Even if you knew everything about the topic a few years ago, you could be behind the times today. Kathy Hardy’s article on that topic appears on page 16. Also in this edition, Beth W. Orenstein writes on a catheter-based technique for imaging and evaluating plaque inside patients’ arteries—another example of how things change in imaging.
Enjoy the issue.