MRI (magnetic resonance imaging) has traditionally been used to assess anatomy and cardiac muscle function, as well as to identify the presence of any scar tissue in the musculature. MRI scanning can distinguish between muscle that is impaired but can be improved through medical therapies, surgery, or angioplasty, and muscle that has undergone necrosis, or tissue death, and has turned permanently into scar tissue. Since scar tissue no longer retains the muscular characteristics required to contract, improving blood flow will not improve its function. Thallium scanning and PET scanning—types of nuclear scans— as well as echocardiography can also distinguish between reparable and permanently damaged tissue.

MRI can diagnose arrhythmogenic right ventricular dysplagia (ARVD) which may present with potentially lethal arrhythmias in young people without prior symptoms. Another use of MRI as diagnostic tool, known as MRA or magnetic resonance angiography, at present lags behind CT in helping identify the individual coronary arteries that feed the heart.

CT scanning exposes patients to X-irradiation, while MRI and MRA use a magnet to generate images and do not involve X-ray radiation exposure. However gadolinium is often injected to enhance the clarity of MR images and must be monitored to verify that it has been expelled through the kidneys.