CAMRT Radiography Practice Exam

Why is a CT study for PE scanned from the abdomen to just above the shoulders?

1. To minimize radiation exposure

2. To reduce contrast artifact during initial injection

3. To allow for better image quality of the abdomen

4. To ensure all organs are covered in one scan

The correct answer is: To reduce contrast artifact during initial injection

The correct answer focuses on the need to reduce contrast artifact during the initial injection. In a CT study for pulmonary embolism (PE), the dynamic behavior of the contrast medium is crucial for optimal imaging. As contrast is injected, it needs to be visualized effectively as it travels through the vasculature, particularly in the chest where many structures are closely packed. By scanning from the abdomen to just above the shoulders, the imaging can capture the flow of the contrast agent in the vessels leading to the lungs and ensure that any potential artifacts caused by premature contrast arrival or uneven distribution are minimized. This practice not only enhances the visibility of blood vessels in the pulmonary circulation but also aids in accurately assessing potential emboli without interference from artifacts that might obscure critical diagnostic information. The other options, while they do relate to considerations in CT imaging, are not the primary rationale for this scanning range. Minimizing radiation exposure is important, yet the scope of scanning is determined more by the diagnostic requirements rather than just radiation concerns. Similarly, improving image quality in the abdomen or ensuring that all organs are covered do play a role in CT protocol design but do not specifically address the mechanics of contrast transit and imaging necessary for evaluating PE.