Open MRI: Doctors Weigh the Trade-Offs

For nearly a decade, doctors have used a technique called magnetic resonance imaging, or MRI, to help find tiny tumors and to diagnose joint conditions and other problems. As a patient lies quietly in a closed cylindrical tunnel, radio waves directed into a powerful magnetic field within the tunnel help obtain detailed cross-sectional images of the body.

But the tunnel so frightens some patients--in particular claustrophobics and children--that they refuse to complete or even begin the test.

For these patients, there is now a so-called “open” MRI. Rather than lie in a tunnel-like unit, a patient is placed on a bed-like gurney with magnetic plates above and below, says Jerry Tsutsumi of Toshiba in South San Francisco, which manufactures a unit that resembles a four-poster bed.

At least seven of these units are in operation in Southern California. (For information on locations, call (800) 477-4674.)

As promising as the new technique sounds, doctors familiar with both models caution that the open scan might not be best for everyone. “With the open unit, patients don’t have claustrophobia,” says Dr. Stanley Baum, a University of Pennsylvania radiologist and chairman of the American College of Radiology Commission on MRI. But the images might “not be as sharp” because the magnetic fields are weaker, he adds.

Also, scanning with the open unit usually requires more time, says Dr. Alexander Margulis, a radiologist at the UC San Francisco School of Medicine. “You trade time for comfort,” he says. Closed scans generally require 45 minutes, while open scans can take 60 minutes or longer.

Whether open or closed MRI is better, Margulis says, depends partly on what the doctor is looking for. A closed scan, for instance, is better at finding a brain tumor less than a centimeter in size. But doctors who use open MRI claim that the technique is getting better at finding even tiny abnormalities.

With a little preparation, even apprehensive patients might find it easier to endure a closed MRI scan, Baum and Margulis say. Here are their suggestions to reduce nervousness:

* Wear headsets and listen to music.

* If the unit has a mirror, watch the technician at work.

* Have a family member accompany you, if permitted, and talk to you during the scan.