Which of the following should be demonstrated on appropriately positioned, posteroanterior hand radiographs?

When evaluating posteroanterior (PA) hand radiographs, one of the key aspects that should be observed is the equal concavity of the metacarpal bodies. This feature is important as it indicates proper positioning of the hand during the radiographic study. In a well-positioned PA view, the metacarpal shafts should exhibit a symmetrical appearance, showing equal concavity on both sides. This symmetry suggests that the hand is positioned correctly, with the fingers extended and the palm against the film plate, allowing for an accurate representation of the anatomy.

The absence of equal concavity, or asymmetrical appearances, could suggest improper hand positioning, potential pathology, or distortion caused by factors such as rotation of the hand. Therefore, observing the equal concavity of the metacarpal bodies ensures confidence in the interpretation of the radiograph and aids in identifying any possible abnormalities.

The other aspects mentioned, such as equal thickness of the metacarpal bodies or spacing between carpals, do not directly pertain to the fundamental criteria for evaluating alignment and positioning in PA views of the hand, making them less relevant in this context. In addition, distorted alignment of the phalanges would indicate an error in positioning or a pathological condition, which would