What anatomical position is most likely to show the presence of a small pleural effusion in the upright chest radiograph?

Question

Quizplus · Accepted Answer

In an upright chest radiograph, the presence of a small pleural effusion is most likely to be seen in the costophrenic angles where the lungs meet the diaphragm. This is because as fluid accumulates, it tends to settle in the dependent regions of the thorax, which in the upright position is the bottom-most part of the lung. The apical regions, fissures, and subdiaphragmatic region are less likely to show the presence of a small pleural effusion.

What Anatomical Position Is Most Likely to Show the Presence