CT Angiography is a test for diagnosing the various types of heart or lung diseases that is undiagnosed or difficult to diagnose by echocardiography. It is a non-invasive test and involves X-ray radiation.
In this we give a contrast by intravenous route (IV) and then scan the heart and related structures. It gives a better delineation of pulmonary veins and arteries, vascular rings, collaterals etc.
Cardiac MRI is a non-invasive test and does not involve X-ray radiation (unlike CT scan). It is a superior modality for diagnosing few cardiac problems like assessment of myocardium in dilated cardiomyopathy and then better planning of its treatment.
It is a very useful test in post-operative cases of tetralogy of Fallot in which we need to assess right ventricle function and its volume. It can also be used for diagnosing other cardiac diseases.