Which radiopharmaceutical is used to label white blood cells with Technetium-99m?

The correct choice is Technetium-99m-Pertechenate, which is commonly utilized to label white blood cells for diagnostic imaging, particularly in infections and inflammatory processes. This radiopharmaceutical functions effectively because it binds to the leukocytes due to its ability to penetrate cell membranes, thus allowing the imaging of the radionuclide within the circulating white blood cells.

In the context of nuclear medicine, mapping the distribution of white blood cells helps in diagnosing conditions such as infections, abscesses, and certain types of cancers, allowing healthcare providers to assess the site and extent of various pathologies.

The other options listed do not serve the same purpose. For example, Technetium-99m-DTPA is primarily used for renal imaging as it is taken up by the kidneys to evaluate glomerular filtration rate. Similarly, Technetium-99m-MAG3 is used in renal studies too, especially for evaluating renal tubular function. Technetium-99m-Sulfur Colloid is utilized in liver and spleen imaging, particularly for imaging in cases of portal hypertension and to assess liver function, which does not involve the labeling of white blood cells. Thus, none of these alternatives fulfill the specific requirement of labeling white blood