The question always arises as to who truly needs an MRI. With routine headaches, and no neurological symptoms or signs, the usual dictum is that scans are not absolutely necessary. However, I would never fault any physician who does a scan on all headache patients. With newer onset headaches, new onset daily headache, neuro symptoms or signs, the ‘worst headache of my life‘, or a major change in pattern, MRI is often recommended. Whether you should have one (or a repeat) is a highly individualized decision between you and your doctor (I hope that you do have a doctor!).
…what do they show??…MRI scans are excellent at detecting tumors, multiple sclerosis, and similar pathology. They do NOT make the diagnosis of migraine, but rather they rule out significant pathology.