![]() In addition, a large thymus overlies the larger vessels in the medial lung areas. Consequently, the lungs appear hyperlucent and the pulmonary vascularity less prominent. Normally newborns and young infants have a deeper thoracic cage and therefore an increased ratio between the air-filled lung and soft tissue. It is also considered to be due to a difference in shape of the thoracic cage. This is partly due to the small vessel size in normal newborns. ![]() Pulmonary vascularity appears less prominent in newborns and younger infants than in older children ( Fig. The changing pattern of pulmonary vascularity is more obvious on the lateral images. A large thymus overlies the cardiac silhouette and central pulmonary vessels. Pulmonary vascularity appears diminished in the early neonatal period and becomes more prominent with age. 9.2 Normal frontal and lateral radiographs in a series of young infants. 2 In the peripheral lungs, the pulmonary vessels and adjacent bronchial lumina are equally sized.įig. Normally, the diameter of the descending branch of the right pulmonary artery is equal to the diameter of the trachea in the thorax ( Fig. When the vascularity is symmetric, the descending branch of the right pulmonary artery can be used as a reference vessel for determination of pulmonary vascular prominence. When the left hilum is uncovered on a chest radiograph obtained in a slight left anterior or right posterior oblique view, the vascularity of the left lung appears mistakenly increased. As a significant part of the left lower lung is overlain by the cardiac silhouette, the pulmonary vascularity of this area is perceived as less obvious than the vascularity of the opposite right lower lung. It is common to perceive the vascularity of the left lower lung as being slightly less prominent than that of the right lower lung. The symmetry of the peripheral pulmonary vascularity should be assessed region by region. Although the pulmonary vessels show some asymmetric anatomy in the lung hila, the pulmonary vascularity in the lungs is normally symmetric. The apical parts of the lungs are devoid of sizable vascular markings in most normal individuals. Vascular markings are more prominent in the lower lungs than in the upper lungs, especially when the chest radiograph is obtained in an upright position. The normal pulmonary vascular markings show gradual tapering toward the periphery of the lungs ( Fig. These findings in conjunction with a reduced volume of the right lung are highly suggestive of unilateral absence of the right pulmonary artery.” The right lung is diffusely reticular, which suggests systemic-to-pulmonary arterial collaterals. The right lung hilum is not only overlain by the displaced heart but also inconspicuous. Uneven, unequal, or asymmetric vascularityįor example, this part of the report in a patient with unilateral absence of the right pulmonary artery can read as follows: “The pulmonary vascularity is asymmetric with the vascularity of the right lung markedly reduced and that of the left lung increased.Pulmonary arterial hypertension pattern.The pulmonary vascular patterns can be classified into six categories 1: The fourth step in chest radiographic interpretation is to assess the pulmonary vascular patterns.
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