Three-vessel view. The main pulmonary artery, ascending aorta, and superior vena cava are arranged in a straight line from the left anterior to the right posterior aspect. The pulmonary artery is the largest in size, followed by the ascending aorta and the superior vena cava. The thymus is clearly visible anterior to the three vessels. Lt, left; Rt, right; MPA, main pulmonary artery; RPA, right pulmonary artery; DA, ductus arteriosus; Ao, aorta; SVC, superior vena cava; DAo, descending aorta.