Magnetic Resonance Imaging (MRI), an important diagnostic test, has traditionally been off limits to more than 2 million people in the United States who have an implanted pacemaker to regulate heart rhythms or an implanted defibrillator to prevent sudden cardiac death. Now, in a study published in the October 4 issue of Annals of Internal Medicine, cardiologists at Johns Hopkins report that a protocol they developed has proved effective in enabling patients with implanted cardiac devices to safely undergo an MRI scan.