What is a characteristic of the localization mechanism for Tc RBCs?

• A. Concentration in fatty tissues
• B. Sequestration in the liver
• C. Compartmental distribution
• D. Active passing through membranes

Answer: (C)

The characteristic of the localization mechanism for Technetium-99m (Tc) labeled red blood cells (RBCs) is compartmental distribution. This refers to the way in which the labeled RBCs are distributed within the vascular compartments of the body, primarily within the circulatory system. When Tc is bound to the RBCs, it allows visualization of blood flow and volume dynamics in various organs or tissues during imaging studies.

In the case of Tc RBCs, the radiotracer will remain within the bloodstream, and the imaging reflects the perfusion and blood pool within the cardiovascular system. This compartmental distribution is particularly useful for assessing conditions like myocardial perfusion or detecting blood volume and flow in specific organs.

The other options do not accurately describe the mechanism of localization for Tc labeled RBCs. Concentration in fatty tissues, sequestration in the liver, and active passing through membranes do not reflect the behavior of Tc RBCs in circulation, as their primary function is to remain within the blood vessels rather than distributing to other types of tissue or organs.