Bronchial artery collateral inflow artifact is a flow-related artifact, seen as pulmonary artery smoke in patients with a background of bronchiectasis and chronic lung disease. It is often overdiagnosed as pulmonary embolism and requires CT aortic angiogram to be confirmed1.
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Pathology
Bronchiectasis and chronic lung diseases induce the development of microscopic systemic arterial anastomoses and collaterals that connects the bronchial arteries and the pulmonary arteries, which create a retrograde arterial inflow from the high-pressure systemic arteries, into the lower-pressure pulmonary arteries1,2.
Radiographic features
CT
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on pulmonary angiogram
the opacification of pulmonary arteries is higher than that of the bronchial arteries and aorta, so the systemic flow will be seen as a low-density pseudo-filling defect or "pulmonary artery smoke" in the region of the anastomoses
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on aortic angiogram
the opacification of the aorta and bronchial arteries is higher than that of the pulmonary arteries, so a retrograde inflow, seen as contrast filling of the pulmonary arteries from the bronchial arteries in the site of the previous pseudo-filling defects.
there is complete reversal of the pulmonary angiogram findings in this case
enlargement of the bronchial arteries supplying the diseased region
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on venous phase
the pulmonary artery smoke will disappear in this phase, but the the retrograde inflow from the bronchial arteries will not be seen
Tips
To create the best negative contrast between bronchial arteries and pulmonary arteries, the aortic angiogram should be1 :
under cardiac gating - for optimal bronchial artery collateral resolution and for less artefacts.
high contrast medium concentration (e.g. 5.5 ml/s)
immediate saline bolus flush after the iodinated contrast bolus
Differential diagnosis
pulmonary artery smoke from regional pulmonary hypertension
pulmonary embolism - the venous phasae is usually sufficient to rule it out
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