Question 2:  What is the structure that is circled in this patient?

Diagnosis: Patent Ductus Arteriosus

The structure connects the pulmonary artery and the aorta and is nicely seen on the 3D VRT and MIP images.

Patent Ductus Arteriosus (PDA): Facts

• Isolated Patent Ductus Arteriosus accounts for up to 10-12% of all congenital heart anomalies
• Most incidentally discovered PDAs in adult are asymptomatic
• Diagnosis on CT is based on defining a vessel connecting the main pulmonary artery and the aorta that is patent

Patent Ductus Arteriosus (PDA): CT Findings

• Calcification at the site of the PDA is common
• Communication best seen on MPR and 3D images
• Flow may be from aorta to pulmonary artery or pulmonary artery to aorta

"The daily use of MDCT studies for the evaluation of pulmonary embolic disease or aortic abnormalities can reveal incidental PDAs. Small incidental PDAs can be identified on chest MDCT angiography timed for either the pulmonary arteries or the aorta."

Incidental Finding on MDCT of Patent Ductus Arteriosus: Use of CT and MRI to Assess Clinical Importance
Goitein O et al.
AJR 2005;184:1924-1931

"MDCT represents a novel method of noninvasively assessing patent ductus arteriosus in adults that provides detailed anatomic information."

Morphologic Assessment of Patent Ductus Arteriosus in Adults using Retrospectively ECG-Gated Multidetector CT
Morgan-Hughes GJ et al.
AJR 2003; 181:749-754