The number of MRIs being performed in Ontario every year has doubled since 2004, thanks to an infusion of cash to cut long wait times, a study has found. But wealthy patients are the one who are benefitting the most.

The for by the Institute for Clinical Evaluative Sciences (ICES) found that the access gap to MRI screening between wealthy and poor Ontarians has only widened.

When the study started in April 2002, patients living in the richest one-fifth of the province's neighbourhoods were 25 per cent more likely to receive MRIs than those living in the poorest one-fifth.

After five years and $118 million in new money buy more machines and operate them longer, wealthiest patients are now 38 per cent more likely to get an MRI than the poorest.

"It appears that individuals residing in wealthier neighbourhoods have benefited most, in terms of access, from Ontario's recent investments in MRI scanning," concludes the study led by Dr. John You, an assistant professor of medicine and clinical epidemiology and biostatistics at McMaster University.

The study, published in the journal Open Medicine, found a 112 per cent increase in the number of MRI scans performed in the province between 2002 and 2007. You says one would expect that increased funding would benefit all Ontarians, but his results suggest that hasn't been the case.

"It's well known that, on average, poor people have more health problems than the rich, so the trends go against what we would have expected," You said.

He offers a number of theories on why wealthier Ontarians are more likely to receive an MRI. First, wealthy patients are more likely to be aware of MRIs and to ask their doctors for one of the scans

"Wealthier individuals... are more adept at navigating the health system to gain access to the health services they desire," his study reads.

It's also possible that some doctors have negative perceptions of patients of lower socioeconomic status and are less likely to offer them the option of an MRI.

As well, You's study only looked at the number of MRIs that were performed - not how many were ordered. It's possible that patients of lower socioeconomic status were ordered MRI scans but couldn't get the tests done because of difficulties in paying for transportation or in booking time off work.

"However, it is unlikely that these barriers to accessing MRI services changed during the study period to a degree that would explain the increasing disparities in MRI use that we observed over time," the study notes.

Whether the gap in access to MRIs has translated into wealthier Ontarians getting better treatment is not clear. Many assume that better tests will mean better care or faster recovery but studies have not borne that out, You notes.

The study authors say more research is needed to determine why income seems to make a difference in getting an MRI before attempts can be made to close the access gap.