cardiac CT

Cardiac CT uses X-rays taken from many angles around the chest, which a computer reconstructs into detailed cross-sectional slices and three-dimensional pictures of the heart and its arteries. Where a plain chest film gives one flat shadow, CT delivers a sharp, sliceable anatomy that can be rotated and re-cut on screen. The challenge is that the heart is always moving, so modern scanners are fast and synchronized to the ECG to freeze it between beats.

Its standout application is the CT coronary angiogram, in which contrast dye is injected into a vein and the scanner pictures the coronary arteries non-invasively. This shows narrowings and, importantly, the composition of plaque in the artery wall. Because a clear scan reliably excludes significant coronary disease, CT angiography has become a leading first test for chest pain in patients at low-to-intermediate risk, sparing many an invasive procedure. CT also evaluates structures before procedures such as valve replacement, and the great vessels for aneurysm or dissection.

Cardiac CT is excellent at anatomy but, in its basic form, shows the plumbing rather than whether flow is functionally limited — though newer techniques add flow information. It uses ionizing radiation and iodine-based contrast, which constrains use in pregnancy and impaired kidneys, and heavy calcium or fast, irregular heart rhythms can blur the coronary images. It is most informative when patient selection and heart-rate control are optimized.