Pediatric CT Angiography

Traditional invasive angiography remains the “gold standard” for the diagnosis of congenital heart defects (CHDs) in children, but it is an invasive method of examination, with approximately 1% of complications even in large cardiology centers, and the multiple angles of exposure can generate high doses of radiation. Therefore, an increasing number of noninvasive methods are gradually replacing traditional invasive angiography in pediatric patients. Transthoracic echocardiography (TTE) is usually the first noninvasive examination method; it can dynamically display the cardiovascular system in real time and provide the information on cardiac structure and function. It is inexpensive and available. However, TTE has several limitations, such as being easily affected by the acoustic window, a limited spatial resolution, and heavy dependence on the operator’s technical proficiency. Recently, multislice spiral CT (MSCT) has been increasingly used in the diagnosis of pediatric cardiovascular diseases due to the continuous improvements in its temporal and spatial resolution. There are three types of CT angiography in children according to ECG-gated use: non-ECG-gated spiral scan, retrospective ECG-gated scan, and prospective ECG-gated scan. Each of them has its own advantages and disadvantages. It is very important to understand the principles and methods of their application for pediatric cardiovascular CT imaging. In short, non-ECG-gated spiral scans are mainly suitable for the observation of extracardiac great vessel malformations. However, due to the existence of motor and respiratory artifacts, intracardiac structures and coronary artery malformations are often not displayed. Retrospective ECG-gated scans are mainly suitable for the observation of intracardiac and paracardiac structures, including aortic, pulmonary arteriovenous malformations, and coronary malformations, as well as the observation of heart valves and evaluation of cardiac function. Prospectively ECG-gated scanning can further reduce the radiation dose of CT examination effectively by emitting rays at a specific location during the heart cycle and can comprehensively evaluate intracardiac and extracardiac malformations, being the most potential new technique under development.