Fig. 1

Multiplanar slicing of a fetus with normal cardiac structure of 19 gestational weeks. Panels a, b, and c represent three orthogonal planes (A, transverse; B, sagittal; and C, coronal). The cardiac apex in the 4CV was oriented upwards and the reference point (indicated by the green arrow) was placed in the crux of the heart in Panel a (A). Move the reference point to the left ventricle in Panel a. By adjusting the position of the reference point in Panel a, near the position of the outflow tract (at the basal part of the left ventricle, near the crux of the heart), a great artery with clear course could be visualized in Panel b (B). Moving the reference point to this artery and then navigating along the course of the artery in Panel B, we could demonstrate a round (transverse) cross section of one great artery and a longitudinal section of the other great artery (characterized by the short trunk with bifurcation) (C). They were aorta and the pulmonary artery. As the reference point was located at the aorta, it could be confirmed that aorta was originated from the left ventricle. Back to the initial state in Panel a (A). Move the reference point to the right ventricle in Panel a. By adjusting the position of the reference point in Panel A, near the position of the outflow tract (at the basal part of the right ventricle, near the crux of the heart), a great artery with its valve could be clearly visualized in Panel b (D). Moving the reference point to the valve in Panel b, two great arteries with cross section and longitudinal section respectively could be visualized in Panel a (E). As the reference point was located at the pulmonary artery, it could be confirmed that the pulmonary artery was originated from the right ventricle. AO, aorta; LV, left ventricle; PA, pulmonary artery; RV, right ventricle