With magnetic resonance imaging Magnetic Resonance Imaging (MRI) In magnetic resonance imaging (MRI), a strong magnetic field and very high frequency radio waves are used to produce highly detailed images. MRI does not use x-rays and is usually very safe... read more 
(MRI), a powerful magnetic field and radio waves are used to produce detailed images of the heart and chest. This expensive and sophisticated procedure is used predominantly for the diagnosis of complex heart disorders that are present at birth (congenital) and to differentiate between normal and abnormal tissue.
MRI has some disadvantages. It takes longer to produce MRI images than computed tomography Computed Tomography (CT) of the Heart Computed tomography (CT) may be used to detect structural abnormalities of the heart, the sac that envelops the heart (pericardium), major blood vessels, lungs, and supporting structures in... read more (CT) or echocardiography Echocardiography and Other Ultrasound Procedures Ultrasonography uses high-frequency (ultrasound) waves bounced off internal structures to produce a moving image. It uses no x-rays. Ultrasonography of the heart (echocardiography) is one of... read more 
images. Because of the movement of the heart, the images obtained with MRI are fuzzier than those obtained with CT. However, newer MRI scans that are timed to match specific parts of the electrocardiogram (ECG—called gated MRI) are much clearer than conventional MRI scans. MRI cannot be used when people have certain types of implanted metal objects, such as pacemakers, cochlear implants, implanted drug pumps or neural stimulators, clips in the brain used to treat aneurysms, or shrapnel.
Magnetic resonance angiography Magnetic resonance angiography (MRA) In magnetic resonance imaging (MRI), a strong magnetic field and very high frequency radio waves are used to produce highly detailed images. MRI does not use x-rays and is usually very safe... read more (MRA) is a type of MRI that focuses on blood vessels rather than organs. MRA produces images of blood vessels and blood flow similar in quality to those produced by conventional angiography Angiography In angiography, x-rays are used to produce detailed images of blood vessels. It is sometimes called conventional angiography to distinguish it from computed tomography (CT) angiography and magnetic... read more but is not an invasive procedure. MRA can be used to detect bulges (aneurysms Aortic Aneurysms The aorta, which is about 1 inch (2.5 centimeters) in diameter, is the largest artery of the body. It receives oxygen-rich blood from the left ventricle of the heart and distributes it to all... read more ) in the aorta, narrowing of the arteries supplying the kidneys (renal stenosis), and a narrowing or blockage in the arteries that supply blood to the heart (coronary artery disease Overview of Coronary Artery Disease (CAD) Coronary artery disease is a condition in which the blood supply to the heart muscle is partially or completely blocked. The heart muscle needs a constant supply of oxygen-rich blood. The coronary... read more 
) or the arms and legs (peripheral artery disease Overview of Peripheral Arterial Disease Peripheral arterial disease results in reduced blood flow in the arteries of the trunk, arms, and legs. Most often, doctors use the term peripheral arterial disease to describe poor circulation... read more 
). Some MRA techniques require injection of a contrast agent Magnetic resonance angiography (MRA) (a substance that makes organs and structures easier to see on MRI) into a vein in the arm. However, people with kidney problems should not receive MRA contrast due to the risk of a serious side effect that affects the skin, joints, eyes, and internal organs (nephrogenic systemic fibrosis). Newer contrast agents, which do not carry this risk, may make the test available to people with kidney problems.
