Which radiopharmaceutical is used to image deep vein thrombus in the lower extremities?

The radiopharmaceutical used to image deep vein thrombus in the lower extremities is technetium-99m macroaggregated albumin (Tc99-MAA). This agent is particularly effective in the evaluation of pulmonary perfusion and is utilized in nuclear medicine for imaging because of its properties that allow visualization of blood flow and distribution within the vascular system.

In the context of venous imaging, Tc99-MAA can help identify areas where perfusion is altered due to the presence of a thrombus. In cases of deep vein thrombus, the affected areas may show changes in perfusion patterns, which can be detected and interpreted through scintigraphy. The use of macroaggregated albumin allows for the retention of the radiolabeled particles within the vascular bed, making it effective for such imaging applications.

The other options provided are not suitable for imaging deep vein thrombus. For instance, F-18 FDG is primarily used in oncology for metabolic imaging and to evaluate tumors rather than thrombus. I-123 MIBG is used for imaging certain neuroendocrine tumors and assessing cardiac sympathetic innervation, while Ga-67 citrate is employed in detecting infections and certain malignancies. These agents have different mechanisms and applications that do not align with