Many MRI scans for people with lower back pain are not medically necessary, according to a study in JAMA Internal Medicine. Experts used widely accepted criteria to decide, after the fact, if MRI scans ordered for back pain or headaches were really necessary to diagnose or treat the problem effectively. Sometimes a scan is not likely to reveal anything especially useful.

The study found only 44 percent of scans of the lumbar spine (the lower back) were appropriate. Of the remaining scans, 56 percent were deemed either inappropriate or of "uncertain value." The study also looked at MRIs for headache, but found the clear majority, 83 percent, were deemed medically valuable.

Most people endure back pain sometime in their lives, but before you undergo diagnostic scanning, make sure it's really needed. MRI scans of the lumbar spine could pick up suspicious-looking features nearby that can cause you anxiety, follow-up testing, and medical visits, but turn out to be nothing.