Which finding on imaging would indicate parallel great arteries suggestive of TGA?

• A. Normal cross relation of the great arteries
• B. Dextrocardia with situs inversus
• C. Aorta arising from the right ventricle
• D. Parallel arrangement of the great arteries on 3VT/3V views

Answer: (D)

Parallel arrangement of the great arteries on the three-vessel/trachea views is the imaging hallmark of transposition of the great arteries. In this condition, the aorta arises from the right ventricle and the pulmonary artery from the left ventricle, so the two great vessels run side by side rather than crossing as they do in normal anatomy. The 3VT/3V views best display this relationship, making the vessels appear parallel instead of forming the usual crossing pattern. This direct visualization is the most specific indicator of TGA on fetal imaging. Normal cross relation argues against TGA, while dextrocardia with situs inversus is a different configuration, and seeing the aorta arising from the right ventricle is supportive but not as definitive as the parallel arterial arrangement seen on these views.