Principles of CT imaging

Abstract

The traditional imaging modality for the pre- and postoperative evaluation of patients with congenital heart disease (CHD) had been catheter angiography but had been replaced by echocardiography for most conditions. However, several anatomical structures including the pulmonary vasculature, the aortic arch, and the right ventricle are sometimes difficult to evaluate with transthoracic echocardiography. Albeit these structures are better visualized with transesophageal echocardiography, the method is limited in patients with pulmonary enlargement. Moreover, the diagnostic quality and interpretation of echocardiography highly depends on the operator and the presence of an adequate acoustic window. In recent years, magnetic resonance imaging (MRI) has been introduced in the diagnostic armamentarium for patients with CHD because of its noninvasiveness, the accurate morphological and functional information provided, and that neither iodinated contrast agent nor ionizing radiation is required. Therefore, MRI is considered an excellent diagnostic tool particularly for the evaluation of young children with CHD, because they may require several follow-up examinations during their lifetime. As a drawback, the utilization of MRI may be limited in the many patients who have undergone surgical corrections of CHD and those who have implanted pacemakers or cardioverter-defibrillator. In addition, the long examination time of MRI often requires lengthy period of patient sedation.