Radiologic Technologist Practice Exam

What sign is described when the right heart border is not visible due to right middle lobe consolidation?

1. Silhouette sign

2. Cardiac sign

3. Pneumonia sign

4. Halo sign

The correct answer is: Silhouette sign

The silhouette sign is a radiologic term that describes the loss of the normal borders between adjacent structures that have similar radiographic densities, which can occur when one structure becomes obscured due to consolidation or fluid. In this case, right middle lobe consolidation can cause the right heart border to become indistinct or disappear on a chest X-ray. When the right middle lobe is consolidated, it blends in with the adjacent structures, like the right heart border, because both have similar radiographic densities. The presence of the silhouette sign indicates that there is a pathological process—like pneumonia—affecting the lung lobe adjacent to the area of interest. This sign is helpful for radiologists and healthcare providers in determining the location of a disease process, as it suggests that the consolidation is likely within the right middle lobe rather than the heart or aortic arch. The other choices do not accurately describe this phenomenon. The cardiac sign is not a recognized term in the context of radiographic findings. The pneumonia sign is a general term and does not specifically refer to the identification of structures on a radiographic image. The halo sign typically refers to the appearance of an area of ground-glass opacity surrounding a nodule, which is unrelated to the visibility of the