RAD CT Guide

CTCA (CT Coronary Angiography) is a minimally invasive imaging test to facilitate visualisation of the coronary arteries. It is a targeted examination performed only looking at coronary anatomy and pathology and does not include comprehensive visualisation of other pulmonary structures. It typically involves a coronary artery calcium score to assess the burden of calcified plaque on the coronary arteries.  It is usually performed to evaluate the coronary arteries in patients where there is not a high pretest probability of coronary artery disease.  It is not appropriate for highly suspicious acute coronary syndrome.

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ECG monitoring is used throughout the scan to allow the images to be taken at periods of minimal cardiac motion (typically late diastole).  Beta blocking medication may be administer prior to the scan or on the table to facilitate the required heart rate.  Those with high heart rates or irregular rhythms (such as AF) are generally unsuitable for CTCA as the images are degraded by motion artefact and radiation doses are often high.

 

As with other CT angiograms an injection of intravenous iodinated contrast is required.  Risk factors for contrast allergy, thyroid dysfunction and renal impairment should be considered.  In addition to this medication may be required to lower the heart rate.  Ideally all patients for CTCA should have normal sinus rhythm and heart rate 55-75 bpm.  Patients should avoid stimulant medications as well as caffeine and smoking for 12 hours.  Patients should be well hydrated and require administration of GTN prior to contrast administration to reduce the impact of coronary spasm.

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