CT angiogram sign | Radiology Signs

Answer:

The CT angiogram sign occurs when segments of pulmonary vessels are visible coursing through areas of alveolar consolidation or low-attenuation lung parenchyma, such as mucus-filled alveoli or tumor-infiltrated lung tissue. This sign is most often seen in conditions like bronchioloalveolar carcinoma (a subtype of lung adenocarcinoma) and other causes of alveolar consolidation where patent pulmonary vessels are preserved within the consolidated lung. Clinically, it suggests the presence of consolidated lung tissue without vascular obliteration, which can be useful in differentiating certain pulmonary masses or infiltrates.

Why is it called so?

It is named the “CT angiogram sign” because the pulmonary vessels within the consolidated lung enhance with intravenous contrast on CT angiography on CT imaging, resembling an angiogram—where blood vessels are contrasted and visualized clearly. The term reflects the visual appearance of contrasted vessels coursing through consolidated or non-aerated lung tissue, analogous to contrast-enhanced angiographic images.

Pathophysiology

In alveolar consolidation, lung tissue is replaced by fluid, cells, or tumor, which decreases aeration and attenuation on CT. However, the pulmonary vessels remain patent and fill with contrast material during CT angiography. Because the consolidated lung parenchyma has relatively lower attenuation compared to the enhanced vessels, the vessels stand out sharply within the consolidation, producing the characteristic appearance of an angiogram within the lung. This occurs because the intravascular contrast is not obscured or replaced by the pathological process affecting the alveoli.

Alternative names:

None commonly used.

Other associated named signs:

None specifically associated.