In America, a whopping 12 percent of visits to primary care doctors for headaches result in brain scans, despite the results more often than not pointing to a simple headache.

Overeager patients and doctors often flout guidelines, which advise to exercise restraint in recommending brain scans. However, data from a recent study shows that the number of scans has been increasingly steadily each year, accounting for 5 percent of patient visits in 1995 to 15 percent in 2010. The study, titled Headaches and Neuroimaging: High Utilization and Costs Despite Guidelines, was published in JAMA Internal Medicine, and notes that just one to three percent of brain scans conducted on patients with regular headaches reveal 'significant abnormalities.'

The cost of unnecessary scans runs at around $1 billion per year, according to Dr. Brian Callaghan, lead researcher of the study and an assistant professor of neurology at the University of Michigan Health System. "During headache visits, brain scans are ordered an incredible amount of the time," said Dr. Callaghan."There are a lot of MRIs and a lot of CTs and that adds up to a lot of money. It's about $1 billion a year."

Those with chronic headaches are far more likely to be suffering from migraines or tension headaches - painful and inconvenient, though conditions that don't necessarily warrant a CT scan. Neurologists instead advise that scans are only conducted when a severe headache advances out of the blue, or if the headache in question is noticeably distinct from previous headaches.

Indeed, when the total number of headache-related doctor's visits amounts to around 51 million in a four-year period, 12 percent is nothing to be scoffed at. Further, Callaghan warns against excessive scanning not just to cut gratuitous costs, but to avoid false positives (a common consequence of MRIs) and exposure to radiation (a potentially dangerous side effect of CT scans). "Most headaches are not caused by something bad," said Callaghan to NPR's Shots. "Even people with brain tumors rarely have headaches."

Callaghan also adds that it's worthwhile for primary care doctors to explain the process to their patients, particularly when a scan isn't necessary. "I actually find that most patients are quite reasonable if you're willing to explain all the things that went into deciding why not to get a scan."