About half of 500 lower-back scans studied were either inappropriate or of questionable value.
Doctors are ordering needless MRI scans for patients with low-level pain, lengthening wait times for others, a new study indicates.
"In Canada, MRIs are a limited resource," explained the lead author of the study, Dr. Derek Emery, a neuroradiologist and researcher in the faculty of medicine and dentistry at the University of Alberta. "And by using MRI time for patients who may not benefit, it is preventing someone else from getting one of those time slots."
Magnetic resonance imaging machines use powerful magnets to create detailed images of soft tissues, including organs, nerves and veins. Without the radiation risks associated with CT scans, MRIs can be extremely valuable for spotting problems that do not show up on traditional X-rays.
For the study, expert panels analyzed physician requests for MRI scans at the University of Alberta Hospital and the Ottawa Hospital. At each medical centre, 1,000 MRI imaging requests were reviewed – 500 for the spine and 500 for the head. The scans were performed in the period from 2008 to 2010.
The study revealed that about half of the lower-back scans were either inappropriate or of questionable value for patients, according to the findings published on Monday in the journal JAMA Internal Medicine.
But doctors did a better job when it came to ordering MRI scans for headache pain. The requests were deemed appropriate about 83 per cent of the time. In these cases, the main concern is that headache may be the result of a brain tumour.
In some parts of the country, MRI tests of the lower back account for a significant portion of all MRI requests. "We perform about 25,000 lumbar spine MRIs every year in Alberta. So up to 7,000 might be inappropriate and another 7,000 of uncertain value," Emery said.
He noted that back pain is extremely common. "Almost all of us have back pain at some point. And generally, it is agreed in the medical literature and by the experts, imaging will not help in most cases," he said.
"Most of the time, the treatment is the same – proper exercise and control of your weight," he said. "Imaging helps only if we have something that might be surgical, like a true disc protrusion that is compressing a nerve route and it may benefit for patients to have that disc protrusion taken out."
Still, primary-care physicians are often under pressure to order an MRI scan for back pain. "A lot of patients expect something to be done. And one of the things the physician can do is order an imaging test. It also give them more confidence that they are not missing something."
In fact, it can be difficult for family doctors to identify those cases that need a closer look. "We don't have really good tools to help them decide if the patient would benefit from imaging," Emery said.
The study showed the MRI back-scan requests from family doctors were appropriate only about a third of the time. That figure is in start contrast to specialists, such as neurosurgeons, whose requests were considered appropriate about 75 per cent of the time.
The needless tests are adding to health-care costs and lengthening wait times. "If you rush out to get an MRI because of back pain, you are going to put our health-care system at major risk because we just won't be able to afford them all," said one of the study authors, Dr. Alan Forster, scientific director of performance measurement at the Ottawa Hospital.
The researchers hope that their finding will help lead to a better allocation of limited health-care resources. "There are many patients who would benefit from MRIs who are not being imaged due to a lack of access," Emery said. Some people with knee pain are waiting up to 222 days for a scan, he said.
However, it will be a challenge to train family doctors to make the proper referrals for scanning related to back pain, Foster acknowledged. "I don't want to tell you this is going to be easy to solve because, for us [the expert panel], to figure out what was appropriate and inappropriate was a big job. To operationalize that in the system will take some significant investment," he explained.
"Basically, we need a feedback mechanism," Emery said, envisioning a computer system in which the doctor would provide the patient's symptoms along with the MRI request and get an immediate response about the merits of testing. "Given the best evidence that we have about patients with these signs and symptoms, doctors would be told then and there if the patient is unlikely to benefit. And unless they have some other compelling reasons, they probably shouldn't be ordering the imaging."
On a positive note, the researchers were encouraged that doctors were not far off the mark when making requests for brain scans. "It shows that you can't assume there is inappropriateness throughout the imaging world. You have to look at each specific area individually," Emery said.
He added that many doctors may be referring brain-scan cases – where a tumour is suspected – first to CT scanners, which are more readily available than MRIs. "If the CT scan is normal, they tend not to get more imagining," he said.