Which of the following radionuclides is used for performing venography?

The chosen radionuclide, Technetium-99m-macroaggregated albumin (99mTc MAA), is widely utilized for venography due to its properties and the type of imaging it facilitates. In venography, a contrast agent is injected into the venous system to visualize veins and detect conditions such as thrombosis.

99mTc MAA is particularly effective because it has a suitable half-life of about 6 hours, which allows ample time for imaging while minimizing patient exposure to radiation. Additionally, the macroaggregated albumin particles are large enough to predominantly lodge in pulmonary capillaries, providing clear delineation of blood flow when injected intravenously. This is crucial for assessing the patency and perfusion of veins.

Other radionuclides listed do not offer the same advantages for venography. For instance, Iodine-123 is more commonly used for thyroid scans and certain types of brain studies. Gallium-68 is typically employed in PET imaging, focusing on oncological applications. Iodine-125 has a longer half-life and is used in different contexts, such as brachytherapy and certain types of organ imaging, but not venography. Hence, 99mTc MAA is the most appropriate