Ductus Arteriosus and its Remnants in Adults

The ductus arteriosus involutes during infancy, sometimes leaving a small remnant called the ductus bump or diverticulum. It can also remain patent into adulthood or form into an aneurysm.

A ductus bump or diverticulum is a focal outpouching of the proximal descending aorta and is a normal variant, not to be confused with either a patent ductus arteriosus, aneurysm, or pseudoaneurysm.

Aneurysm of the ductus diverticulum is rarely seen in adults . Patients may present with hoarseness, dyspnea, hemoptysis, and/or cough. The aneurysm can erode into a bronchus, the esophagus, pericardium, or pleural cavity, with disastrous consequences. Risk of rupture increases when the aneurysm is larger than 3 cm. The main differential consideration for a ductus aneurysm is just a regular aortic arch aneurysm. Three dimensional reconstructions help by showing ductus aneurysms pointing toward the left pulmonary artery.

A traumatic pseudoaneurysm is also a consideration. They tend to occur in the region of the isthmus and usually form an acute angle with the aorta, unlike the more gentle obtuse angle of the ductus bump.

On the axial images, we see a rounded structure (pink arrow) arising from the aortic arch (blue arrow) and heading toward the left pulmonary artery. At this point, we could be dealing with a patent ductus arteriosus or a diverticulum. The fact that the study was done without intravenous contrast limits our evaluation of this incidental finding in a 70-year-old woman, but coronal and sagittal oblique maximum intensity projections help a bit. In the case of a diverticulum, we'd expect to see a plane between the structure and the left pulmonary artery, but we don't see one here.

References

• Goitein O, Fuhrman CR, Lacomis JM. Incidental finding on MDCT of patent ductus arteriosus: use of CT and MRI to assess clinical importance. AJR Am J Roentgenol. 2005 Jun;184(6):1924-31.
• Lee EY, Boiselle PM, Cleveland RH. Multidetector CT evaluation of congenital lung anomalies. Radiology. 2008 Jun;247(3):632-48
• Sugimoto T, Takahashi T, Inui K, Minowa T, Watanabe T, Shimazaki Y. Aneurysm of the ductus diverticulum in adults: the diagnostic value of three-dimensional computed tomographic scanning. Jpn J Thorac Cardiovasc Surg. 2003 Oct;51(10):524-7.