Magnetic resonance imaging or MRI, is primarily a medical imaging technique used in radiology to visualize detailed internal structure and limited function of the body. Stargate Command used MRI's to detect infestation by a Symbiote. When Colonel Everett Young was injured exiting the Stargate on the Destiny, Lt. Tamara Johansen told him he could have internal or concussive injuries and he needed an MRI and a qualified Doctor to read it. (SGU: "Air, Part 2")