The pulmonary circulation in patients with pulmonary atresia is dependent on a patent ductus arteriosus (Fig. 4.7). Therefore, the Blalock-Taussig (BT) shunt operation is necessary during the neonatal period to maintain pulmonary blood flow. For preoperative evaluation, precise characterization of the pulmonary artery, including presence of juxtaductal pulmonary artery coarctation, is necessary. If juxtaductal pulmonary artery coarctation is present or likely to develop after BT shunt, plasty of the pulmonary artery should be performed at the same time as BT shunt with the patient on cardiopulmonary bypass [13, 14]. In contrast, if juxtaductal pulmonary artery coarctation is not present, only the BT shunt operation is performed, and cardiopulmonary bypass is no longer necessary. Evaluation by MD-CT allows selection of the optimal surgical strategy. Some patients with pulmonary atresia have nonconfluent pulmonary arteries (Fig. 4.8). MD-CT, especially 3D reconstruction, can provide information about the distance separating the two pulmonary arteries and their spatial relation with the surrounding structures. Thus, MD-CT makes it easier for surgeons to develop a preoperative strategy for pulmonary artery plasty.

MD-CT is useful for noninvasive assessment of pulmonary arterial stenosis and growth after corrective surgery or BT shunt (Figs. 4.9 and 4.10). It can indicate the exact site length and severity of stenosis. Echocardiography does not always provide sufficient images because of a limited echo window. Therefore, precise characterization of target lesions by MD-CT allows optimal preparation for surgery or catheter intervention.

MD-CT is a very useful diagnostic tool in total anomalous pulmonary venous connection (TAPVC). Although TAPVC can only be diagnosed by echocardiography, it may be difficult to determine the precise structures of pulmonary veins, especially in mixed type (Fig. 4.11) or when TAPVC is associated with heterotaxy syndrome (Figs. 4.12 and 4.13). In such cases, MD-CT 2D images as well as 3D reconstruction can provide accurate anatomical information [2, 15, 16]. It is an excellent diagnostic tool for preoperative evaluation and for guidance of the surgical operation, because the drainage site of the pulmonary vein can be exactly determined. Furthermore, MD-CT can provide interventionalists with important information. In a neonate with TAPVC, stent implantation may be one of the treatment options to relieve stenosis, which is often found at the drainage site of pulmonary vertical veins [17]. Interventionalists must pay attention not only to the stenotic site but also to the surrounding structures (e.g., bronchi, coronary arteries, branches of the pulmonary vein, systemic veins, etc.) [18–20]. After repair of TAPVC, pulmonary vein stenosis may develop in some patients (Fig. 4.14), and MD-CT can give useful information about the site and severity of stenosis.

MD-CT can provide us with precise images concerning the origin of coronary arteries. In patients with anomalous origin of the left coronary artery from the pulmonary artery (ALCAPA), the diagnosis can often be made only by echocardiography; however, this is not always the case. The left coronary artery rarely originates from the right pulmonary artery in ALCAPA (Fig. 4.15) [21]. Such cases may be difficult to diagnose by echocardiography only, because the left coronary artery looks as if it originates normally from the left coronary cusp on echocardiography. MD-CT is a very useful tool for the diagnosis of such cases.

In the field of pediatric cardiology, echocardiography is a noninvasive and very useful tool to visualize the coronary arteries. Echocardiography is useful in the diagnosis of enlarged lesions; however, there are some limitations, such as the diagnosis of stenotic lesions in the coronary arteries. Furthermore, it is more difficult to obtain clear images in adolescents or patients with chest deformities such as pigeon chest. However, MD-CT can depict small structures such as the coronary arteries with improved spatial resolution because of increased numbers of detector rows [22–25]. Multiplanar reformatted (MPR), maximum-intensity projection (MIP), and 3D volume-rendered (VR) images are powerful tools that provide additional information on the nature and extent of disease and accurately illustrate anatomical relationships (Figs. 4.16, 4.17, 4.18, 4.19, and 4.20).

Anomalies of systemic venous return may be associated with congenital heart disease [26]. The general population without congenital heart disease may have a left superior caval vein (LSVC); however, it is more prevalent in individuals with congenital heart disease. The LSVC usually drains into the coronary sinus; however, it may drain into the left atrium or atrial roof (Fig. 4.21). It is very important to evaluate its drainage site and presence of the innominate vein for intracardiac repair. When the LSVC drains into the left atrium, atrial septation results in desaturation. MD-CT can illuminate the precise site of LSVC drainage.

In patients with congenital heart disease, anomalous vessels and previous surgical operations may cause airway obstruction [3, 6, 27, 28]. MD-CT can provide information on not only abnormal arteries or veins but also the structures of the trachea, bronchi, and coronary arteries. Pulmonary artery sling (anomalous origin of the left pulmonary artery from the right pulmonary artery) causes compression of the trachea by the anomalous origin of the left pulmonary artery (Fig. 4.22) [3, 6, 28]. 3D images superimposed on the obstructed airway show the spatial relationships. In patients with tetralogy of Fallot and absent pulmonary valve, the airway is compressed and obstructed by the dilated main and peripheral pulmonary arteries (Fig. 4.23) [3]. The site of airway obstruction can be clearly visualized with MD-CT, especially 3D images superimposed on images of the airway (Fig. 4.24). In patients with double aortic arch, the airways are surrounded and compressed by both aortic arches (Fig. 4.25).