OTTAWA - The number of magnetic resonance imaging and computed tomography scanners in Canada has increased significantly over the last four years but still lags the median for developed countries.

A new report from the Canadian Institute for Health Information released Thursday said there were 419 CT scanners and 222 MRI machines in Canada in 2007, up from 325 and 149, respectively, in 2003.

That represents 12 CT scanners and six MRI machines per million population, while the median for nations in the Organization for Economic Co-operation and Development was 15 CT scanners and seven MRI machines in 2005, the most recent year for which figures were available.

But the fact that many of Canada's machines were installed fairly recently is good news because they are using the latest technology to aid in diagnoses, noted Francine Anne Roy, director of Health Resources Information at CIHI.

"Increases in the number of imaging scanners over the last few years mean that the majority currently installed and in use in Canada are less than six years old," she said.

"These newer machines are using the latest technology to produce more detailed scans."

The rate of MRI exams rose by 43 per cent and CT exams by 28 per cent in the four years between 2003 and 2007.

The newest CT scanners offer improved images, greater imaging speed and more coverage, enabling advances in non-invasive cardiac imaging and virtual colonoscopy.

The report noted that while the number of machines has increased, the number of people who can operate them has not changed much in the last four years.