Prominent Right 3rd Intercostal-Bronchial Artery Trunk; No Vascular Injury

Contrast-enhanced chest CTA axial (Fig. 1A-1D), coronal (Fig. 2A-2B), and sagittal oblique (Fig. 3A-3D) images reveal a well-defined contour anomaly projecting posteromedially off the descending thoracic aorta. The contour anomaly is conical and triangular in nature and vessels emanate from its apex and course to the spaces (Fig. 1C; 2B; 3A-3D). The aorta is otherwise unremarkable.     Diagnosis: Prominent Right 3rd Intercostal-Bronchial Artery Trunk; No Vascular Injury

Discussion:

The infundibulum of the right 3^rd intercostal artery is referred to by various terms including the right intercostal -bronchial trunk; superior intercostal; uppermost intercostal;  or highest thoracic intercostal artery. The infundibulum and its adjacent branches are often seen on Multiplanar chest CTA, MRA, and conventional transcatheter aortograms supplying the 2^nd and 3^rd intercostal spaces. The right infundibulum is usually more prominent than its counterpart and can mimic the appearance of an acute traumatic aortic injury or pseudoaneurysm. Other anatomic variants that can mimic acute vascular injuries include the brachiocephalic artery infundibulum, the aortic spindle, and a prominent ductus diverticulum (see Cardiopulmonary Pulmonary Imaging Correlation Conference Case of the Week from 9-24-2009).

Imaging Findings

CTA/ MRA / Aortography

• Arise at the origin of the right 3^rd intercostal artery (Fig. 1-3)
• Conical, symmetrical, bulge (Fig. 1-3)
• Smooth, uninterrupted margins (Fig. 1-3)
• Vessel)s) emanate from its apex and course to the intercostal space(s) (Fig. 1C; 2B; 3A-3D)

Caveats

• The characteristic appearance distinguishes this infundibulum from that of a true traumatic injury or pseudoaneurysm
• Variations in the morphology of the infundibulum do occur; sometimes appearing more rounded than conical or triangular

 

Selected Readings

• 1. Fisher RG, Sanchez-Torres M, Whigham CJ, Thomas JW. "Lumps" and "Bumps" that Mimic Acute Aortic and Brachiocephalic Vessel Injury. RadioGraphics 1997; 17: 825-834.
• 2. Steenburg SD, Ravenel JG. Acute Traumatic Thoracic Aortic Injuries: Experience with 64-MDCT. AJR 2008; 191: 1564-1569.
• 3. Scaglione M, Pinto A, Pinto F, et al. Role of Contrast-enhanced CT in the Evaluation of Acute Thoracic Aortic Injuries after Blunt Chest Trauma. Eur Radiol 2001; 11(12): 2444-2448.