Delayed systemic arterial-pulmonary arterial shunt simulating pulmonary embolism: An unusual case.

This case report describes the imaging findings of an older-aged male presenting with infectious respiratory symptoms. Evaluation with routine contrast-enhanced CT of the chest demonstrated pulmonary artery filling defects initially treated as a pulmonary embolism. However, short-term repeat imaging during pulmonary angiographic and delayed phases demonstrated retrograde filling through a systemic arterial-pulmonary arterial shunt. Given the high prevalence of pulmonary embolism which is also the leading cause of pulmonary angiographic filling defects, this case highlights the importance for clinicians to maintain a differential diagnosis and consider alternative etiologies.