Which type of scan utilizes phagocytosis by the RES for localization?

• A. Bone scan
• B. Spleen scan
• C. Liver scan
• D. Both liver and spleen scan

Answer: (D)

The correct choice reflects the nature of both the liver and spleen scans, which are indeed utilized in the detection of phagocytosis by the reticuloendothelial system (RES). The RES comprises macrophages and other immune cells that are primarily involved in filtering the blood, removing foreign materials, dead cells, and pathogens.

In both liver and spleen scans, radioactively labeled compounds, such as those incorporating technetium, are administered. These radiopharmaceuticals are designed to target and be taken up by the cells of the RES, where the process of phagocytosis occurs. This allows for the visualization of these organs since the accumulated radiotracer emits gamma rays that can be detected by the imaging equipment. Therefore, these scans effectively highlight the functionality of the RES and are particularly useful in diagnosing conditions related to liver or spleen health.

While a bone scan is focused on areas of increased metabolic activity in the skeleton, and a spleen scan would primarily target splenic functions, only the liver and spleen scans utilize the phagocytic capabilities of the RES for localization, reinforcing the choice that includes both organs.