What is CT triple rule out?

What is CT triple rule out?

CT Triple rule out is an ECG gated multi detector computed tomographic scan which can be used in patients coming to the emergency department with severe chest pain. Three important potential causes: aortic dissection, pulmonary embolism and coronary artery disease constitute the ‘triple’ rule out.

Aortic dissection is a break in the inner layer of the aorta, the largest blood vessel in the body carrying oxygenated blood. Pulmonary embolism is blockage of blood vessels of the lungs by clots carried by circulation from elsewhere, usually from the legs. Coronary artery disease is blocks in blood vessels of the heart which may cause a heart attack.

CT triple rule out can be done rapidly in potentially life threatening cases of acute chest pain and has high negative predictive value. High negative predictive value means that if the test is negative, the probability of disease is remote. Though CT triple rule out is good for assessing the initial part of the blood vessels to the heart, it is not as good as conventional coronary angiography in visualizing finer details. Coronary angiography is done by injecting radiocontrast medications to the blood vessels of the heart directly using long tubes introduced through blood vessels of wrist or groin.

A regular CT coronary angiogram is also superior to CT triple rule out in visualizing details of blocks in blood vessels of the heart. This is because regular CT coronary angiogram uses time consuming software and three dimensional reconstructions, which are out of question in an emergency setting. CT coronary angiogram is obtained by injecting radiocontrast medications in the blood vessel of the arm and obtaining advanced CT imaging with specialized equipment and software.

CT triple rule out can pick up significant pulmonary embolism very well. Some errors are possible in diagnosing aortic dissection, which have been mostly eliminated by ECG gating. ECG gating selects images during a particular part of the contraction or relaxation of the heart, guided by the ECG waves, avoiding movement artefacts. Movement artifacts blur the images as we see in the photograph of a moving object.