New research suggests $1 billion is spent on brain scans in the U.S. every year; many of these examinations are unnecessary. 

About one in eight patients that visit the doctor with a headache receive an MRI or CT scan, a University of Michigan Healthcare System news release reported. 

Many national guidelines for U.S. doctors discourage brain scans for patients who complain of migraine or headaches. This has not seemed to stop doctors from doing so as the rate of brain scans has risen since these guidelines were released. 

The researchers suggest better education for the public and insurance plans that require patients to pay part of the costs for brain scans. 

About half of all headache related visits between 2007 and 2010 were migraine-related; 12.4 percent of these headache related visits resulted in a brains scan. The U.S. is estimated to have spent $3.9 billion on the brain scans that were prescribed over those four years. 

"This is a conservative cost estimate based on what Medicare would pay for these tests. CTs and MRIs are commonly ordered for headache and migraine, and increasing over time, despite the fact that there are rare circumstances where imaging should be used," Brian Callaghan, M.D., M.S., the U-M neurologist who led the research team, said in the news release. "Lots of guidelines say we shouldn't do this - including ones from neurology and radiology groups - but yet we still do it a lot. This is a source of tremendous cost in health care without a lot of evidence to justify the cost."

Researchers estimate only about one to three percent of brain scans of patients with recurring headaches find an abnormality in the growth or blood vessels of the brain. 

"There's solid research showing that the number of times you find serious issues on these scans in headache patients is about the same as that for a randomly chosen group of non-headache patients and a lot of the things we find on such scans aren't necessarily something we will do something about." Callaghan said.