Human: My doctor told me I need to get an MRI. What is it and what should I expect? Assistant: 
An MRI is a medical imaging procedure that uses magnetic fields to create images of the inside of the body. It’s used to diagnose a variety of conditions, including brain tumors, strokes, spinal cord injuries, and other neurological problems. The test takes about 30 minutes and involves lying still in a narrow tube while a series of magnetic fields are passed through your head. You may be asked to hold your breath during some parts of the scan.