In some cases, it is necessary to have a coronary CT followed by a cardiogram. If the CT result is negative, no further imaging is needed; if the CT result is positive, a cardiac imaging may be necessary. Specific tests should be ordered by your doctor. If coronary artery disease is not detected by CT examination of the coronary arteries, there is no need to do another cardiac imaging, but if coronary artery stenosis is detected, it is necessary to continue to do cardiac imaging to clarify the location and extent of coronary artery stenosis, in order to guide the diagnosis and further treatment. Cardiac imaging is an invasive procedure that requires the injection of a contrast medium into the body of the subject through a vein, which is required to meet the indications for performing cardiac imaging. Coronary CT, as a commonly used imaging non-invasive test, can be used for the diagnosis of cardiovascular diseases, such as coronary artery stenosis and aneurysm, and can be used for coronary heart disease screening.