What imaging findings are indicative of a vascular occlusion?

• A. Excessive blood flow
• B. Uniform vessel diameter
• C. Absence of blood flow and focal filling defects
• D. Increased collateral circulation

Answer: (C)

The presence of absence of blood flow and focal filling defects is a key indicator of vascular occlusion. When a blood vessel is occluded, it means that blood is not able to pass through that vessel, leading to a lack of flow in the area that the occlusion affects. This can be visualized in various imaging modalities, such as angiography, where the blocked area will appear as a region without contrast enhancement, indicating that the blood is not flowing through that vessel.

Focal filling defects refer to specific areas within a vessel where the contrast agent does not fill the expected lumen, often due to the presence of a clot or other obstruction within the vessel. These defects, combined with the complete absence of blood flow in the images, provide strong evidence of an occlusive process, allowing for accurate diagnosis and timely treatment.

In contrast, excessive blood flow, uniform vessel diameter, and increased collateral circulation do not directly indicate an occlusion. Excessive blood flow might suggest hyperemia or increased perfusion, while uniform vessel diameter indicates normal vascular conditions, and increased collateral circulation often develops as a compensatory mechanism in response to chronic occlusion but does not directly state the presence of an obstruction. Therefore, the identification of absent blood flow and focal filling defects is