By Andrew M. Seaman
NEW YORK (Reuters Health) - Magnetic resonance imaging (MRI) is often needed for patients plagued by headaches, but the scans are overused when back pain is the chief complaint, according to a new study from Canada.
An expert panel that reviewed 1,000 requests for lower back MRI at Canadian hospitals considered less than half of them appropriate - meaning the scans might help doctors care for the patients. In contrast, the panel found 83 percent of requested head MRIs to be potentially useful.
Dr. Derek Emery, the study's lead author from the University of Alberta in Edmonton, said the results show that most lower back pain does not need to be imaged.
"We have to look at our resources carefully. MRI - like all medical tests - should be used carefully," he said.
MRI scans use magnetic fields and radio waves to create detailed images of the body and therefore don't carry a risk of radiation exposure like X-rays and CT scans, but there are other concerns about their overuse.
"The biggest concern is cost. By far MRIs are way more expensive than X-rays and CT scans. I think that is the main realistic concern," said Dr. Frederick Korley, who has researched imaging use but wasn't involved in the new study.
In the U.S., for example, a CT scan of the stomach costs about $400 versus about $1,000 for a MRI of the stomach.
Emery said unnecessary MRI scans also inconvenience patients and may put them at risk for more aggressive or invasive tests.
He told Reuters Health that his team wanted to get a better sense of the number of MRI scans that were being ordered inappropriately.
For the new study, the researchers recruited two panels of experts to determine when ordering a MRI of the lower back for a patient with back pain, or of the head for a patient with headaches, would be appropriate for a doctor to do.
Those two conditions, according to Emery, are the most common reasons for requesting MRI scans.
His team then collected 1,000 requests for MRI scans of the lower back and 1,000 requests for head scans at two hospitals, one in Alberta, the other in Ottawa, between 2008 and 2010.
Overall, the expert panel found 443 of the 1,000 requests for lower back MRI scans to be appropriate. Another 272 were of "uncertain appropriateness" and 285 were considered inappropriate, which meant the test would not help the doctors care for their patients.
The majority of head MRI scans, however, were considered appropriate by the panel.
Emery said he was surprised by how many head scans were deemed appropriate. But those, he added, may be the result of headache patients having suspicious CT scans before their doctors ordered a MRI to investigate further.
For lower back pain, however, he said he was not surprised that many MRI scans were unnecessary, because that kind of pain usually clears up on its own in about six weeks.
Korley, from Johns Hopkins Medicine in Baltimore, also said the findings show there needs to be more discussion about imaging use.
"We definitely have to have a lot more dialogue about diagnostic testing and what the implications are and how that would affect management before we go ahead and order these tests. We need to make smart and educated choices about diagnostic tests," he said.
SOURCE: http://bit.ly/MbBLb9 JAMA Internal Medicine, online March 25, 2013.