What is one of the primary concerns when using MAA particles in pulmonary imaging?

The concern regarding the blocking of too many capillaries pertains to the use of macroaggregated albumin (MAA) particles in pulmonary imaging. When these radiolabeled particles are injected into the bloodstream, they are designed to lodge in the capillaries of the lungs for imaging purposes. However, if the particles are too large or if too many particles are injected, there is a risk of occluding a significant number of capillaries, which can lead to complications such as pulmonary hypertension or localized ischemia.

The overarching goal in pulmonary imaging is to ensure that the MAA particles distribute appropriately within the pulmonary vasculature to provide clear and accurate imaging of lung perfusion. An optimal number of particles must be used to achieve this balance without significantly impairing blood flow, ensuring safety while still obtaining useful diagnostic information.

The other choices, while they may relate to various aspects of MAA use, do not capture the primary concern regarding their use in pulmonary imaging as effectively as the risk of blocking too many capillaries does.