This test is a lot like the Cardiac MRI except you will not need an injection (fluids put in your hand or arm). You will change into a gown and lie on a table. The table will slide into the big tube. At times, the person testing you may ask you to hold your breath for a few seconds. The test will take about 15 minutes to one hour. Your parent(s) will probably be allowed to be in the MRI room with you. It does not hurt.