Question

which of the following statements is accurate in reference to the lungs vascular markings on a posteroanterior (pa) chest radiograph?
vascular markings are only visible when there is pulmonary pathology
vascular markings appear thinner in the superior portions of the lungs
the caliber of vascular markings should be the same from superior to inferior lung
vascular markings are only visible in the hilar regions near the heart

Explanation:

In a normal PA chest radiograph, the vascular markings in the superior portions of the lungs appear thinner due to normal physiological blood - flow distribution. Vascular markings are visible in normal lungs and not just in pathological conditions. The caliber of vascular markings is not the same from superior to inferior lung as there is more blood flow to the lower lobes. Vascular markings are not only visible in the hilar regions but throughout the lung fields.

Answer:

Vascular markings appear thinner in the superior portions of the lungs