Ionizing radiation like X-ray can be harmful. But to date no study has claimed that MRI is harmful. Instead of radiation a giant magnet is used to take image of body parts inside which may be your brain, heart or anything. One danger of MRI is its strong magnet attracts metal. So technicians ensure no one is entering with metal. Physics Girl explains how MRI works, whether it’s safe and scans some unusual objects like pineapples.