During normal biodistribution, where do Tc MAA particles eventually break down after being in the lungs?

During normal biodistribution, where do Tc MAA particles eventually break down after being in the lungs?

• A. Brain and kidney
• B. Heart and pancreas
• C. Liver and spleen
• D. Muscles and skin

Answer: (C)

The correct choice indicates that Technetium-labeled macroaggregated albumin (Tc MAA) particles primarily break down in the liver and spleen after their passage through the lungs. This is consistent with the biodistribution characteristics of Tc MAA, which are designed to mainly be trapped in the pulmonary capillaries. Once these particles are trapped, they are gradually cleared by macrophages in the lungs, but they can later be transported to the liver and spleen for further processing. The liver plays a key role in metabolism and the clearance of various substances, including particles, while the spleen is involved in filtering blood and recycling components from aged or damaged red blood cells. The other potential locations for breakdown mentioned in the incorrect options, such as the brain and kidney, heart and pancreas, or muscles and skin, do not align with the expected radiopharmaceutical behavior. The redistribution of the particles after they have been deposited in the lungs would primarily involve the liver and spleen, making this the most accurate and relevant answer based on the known mechanisms of biodistribution and clearance of technetium-labeled compounds.

The correct choice indicates that Technetium-labeled macroaggregated albumin (Tc MAA) particles primarily break down in the liver and spleen after their passage through the lungs. This is consistent with the biodistribution characteristics of Tc MAA, which are designed to mainly be trapped in the pulmonary capillaries.

Once these particles are trapped, they are gradually cleared by macrophages in the lungs, but they can later be transported to the liver and spleen for further processing. The liver plays a key role in metabolism and the clearance of various substances, including particles, while the spleen is involved in filtering blood and recycling components from aged or damaged red blood cells.

The other potential locations for breakdown mentioned in the incorrect options, such as the brain and kidney, heart and pancreas, or muscles and skin, do not align with the expected radiopharmaceutical behavior. The redistribution of the particles after they have been deposited in the lungs would primarily involve the liver and spleen, making this the most accurate and relevant answer based on the known mechanisms of biodistribution and clearance of technetium-labeled compounds.