Which patient should receive fewer particles than typically administered for lung perfusion imaging?

For lung perfusion imaging, the administration of particles is typically adjusted based on certain patient characteristics and conditions. In the case of a patient with a right-to-left cardiac shunt, the rationale for administering fewer particles is primarily related to the risk of delivering a higher concentration of particles to areas of the body where they could cause harmful effects, like the systemic circulation.

In a right-to-left shunt, blood bypasses the lungs and goes directly into systemic circulation. If standard doses of particles are administered, there is a chance that a significant number of these particles will enter systemic circulation instead of being trapped in the pulmonary vessels. This could lead to potential complications, such as embolic events in areas outside the lungs where those particles can lodge.

Therefore, appropriate practice dictates that patients with a right-to-left cardiac shunt should receive a reduced amount of particles to minimize the risk of these undesired effects while still allowing the imaging of lung perfusion to be effective and safe. This consideration is crucial to ensure patient safety and optimal imaging results.