Pulmonary congestion and pulmonary stasis refer to the arterial and venous systems, respectively, with different anatomic locations. Pulmonary arteries tend to run vertically in a longitudinal direction. The venous system is mostly horizontal. It can be identified as a disease of the arterial and venous systems by whether the vessels are blurred horizontally or vertically. Pulmonary congestion is defined as increased blood flow in the pulmonary arteries. In the posteroanterior view, the pulmonary artery segment is enlarged and the hilar shadow is enlarged with clear margins; the hilar pulsation is enhanced on fluoroscopy, which is known as hilar “dancing. The pulmonary texture extends towards the outer band and is significantly thickened with clear margins. Long-term pulmonary congestion can lead to spasm and constriction of small pulmonary arteries, followed by intimal hyperplasia and narrowing of the lumen, and finally cause pulmonary hypertension. Pulmonary congestion is commonly seen in congenital heart disease with left-to-right shunts, such as atrial septal defect and patent ductus arteriosus. It can also be seen in increased circulating volumes, such as hyperthyroidism and anemia. Pulmonary stasis refers to obstruction of pulmonary venous return and stagnation of blood in the lungs. With prolonged elevated pulmonary venous pressure, reflex spasm, constriction and narrowing of the small pulmonary arteries will occur. Over time, elevated pulmonary artery pressure and increased right heart burden cause hypertrophy and dilation. The posterior anterior position shows a generalized dilatation of the pulmonary veins in the form of blurred striped shadow, which is heavier in the middle and lower lung fields. The hilar shadow is enlarged and blurred i In the presence of reflex vasospasm, the upper pulmonary veins are dilated and thickened and the lower pulmonary veins are constricted and thinned, which is known as pulmonary streak inversion. In severe pulmonary stasis, interstitial pulmonary edema appears, and a septal line shadow perpendicular to the lateral chest wall (KedeyB line), about 2-3em long and lmm wide, can be shown near the angle of the rib diaphragm, as a result of pulmonary venous hypertension causing fluid retention in the lobular septum. Common causes of pulmonary stasis are mitral stenosis and left heart failure, etc.