More than half of MRIs of the lower back that were ordered at two Canadian hospitals were either inappropriate or of questionable value for patients, researchers say.

Use of MRI to image the lumbar spine has increased in Canada and the United States despite a lack of a clear correlation between imaging findings and clinical signs and symptoms, Dr. Derek Emery wrote in Monday's online issue of the journal JAMA Internal Medicine.

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Eliminating inappropriate MRI scans could reduce harm from unneeded investigations, researchers say. (Jean-Paul Pelissier/Reuters)

"Our study has implications for management of MRI usage for the lumbar spine, which makes up approximately a third of all MRI in some regions," Emery, of the radiology and diagnostic imaging department at the University of Alberta, and his co-authors said.

"Eliminating inappropriate scans and some of uncertain value could reduce the harm that accrues from unneeded investigations and result in significant cost savings."

Last year, Canadians received 1.7 million MRI scans, according to the Canadian Institute for Health Information.

Of the requests from family doctors, about 34 per cent were considered appropriate versus less than 50 per cent for those ordered by neurologists and orthopedic surgeons.

Emery's team had a panel of specialists rate clinical requests for outpatient MRI for lumbar spine and headache on a nine-point scale for appropriateness.

'I think there's tremendous pressure on physicians to order imaging tests because that shows they are doing something and they're ruling out rare disease.' — Dr. Derek Emery, University of Alberta

Of the 1,000 requests for lumbar spine MRI, 443 were considered appropriate, the researchers said. The rest were split between inappropriate (28.5 per cent) or uncertain value (27.2 per cent).

"I think there's tremendous pressure on physicians to order imaging tests because that shows they are doing something and they're ruling out rare disease," Emery said.

Diagnostic value for low back pain

The only indication that was nearly uniformly considered appropriate was MRI for postoperative leg or back pain, which accounted for less than 17 per cent of all MRI lower back scans. 

Dr. Alan Poole, a radiologist at the regional hospital in Red Deer, Alta., said 90 per cent of Canadians suffer from low back pain at some point. He called getting an MRI valuable for many patients.

"The vast majority of doctors when they see their patients they're trying to get to the bottom of their problem and, you know, find out what's going on and get them on the appropriate therapy," Poole said.   

Many MRI requests for headache, 82.8 per cent, were considered appropriate. Most patients referred for MRI of the head for headache had been screened with a CT scan, which the researchers said likely explained the high appropriateness rating.

The researchers called on medical societies to show leadership in reducing overuse, which they said was driven by patient expectations, physician concerns about litigation and lack of physician accountability for cost.

Since the study, funded by the Canadian Institutes of Health Research, only looked at the University of Alberta Hospital and Ottawa Hospital, the findings may not apply in other health systems.

With files from CBC's Terry Reith