CT evaluation of congenital and acquired abnormalities of the azygos system.

Abstract

Congenital and acquired abnormalities may alter the anatomy, size, or position of the azygos system. Computed tomography is often able to depict these abnormalities and in many cases indicate the cause. In this article, the normal anatomy of the azygos system is discussed and examples of congenital and acquired abnormalities are presented.

Reentrance of Azygos Vein into Azygos Fissure After Pneumothorax

“…[4]. In fetal growth, the right posterior cardinal and right supracardinal veins form the azygos vein [1]. The posterior cardinal vein takes a position medial to the right upper lobe.…”

“…An azygos fissure is observed in 0.4% of chest radiographs and 1.2% of thorax computed tomography (CT) scans as a normal anatomical variant [1,2]. It is developed as a result of the penetration of the azygos vein through the right upper lobe.…”

Congenital Thoracic Venous Anomalies in Adults: Morphologic MR Imaging

“…The hemiazygos vein (located on the left side of the spine) drains into the azygos vein (along the right side of the vertebral bodies), which in turn drains into the SVC (Fig 6). 14 …”

“…13 The hemiazygos continuation of the IVC is a less frequently seen abnormality, with 3 possible paths of drainage being described: (1) through the azygos vein; (2) into a persistent LSVC; and (3) into a normal right SVC (coursing through the accessory hemiazygos vein and LBCV). 14 Although previously thought to be associated with severe congenital heart disease and heterotaxy syndrome, 15 both these anomalies are being increasingly documented in asymptomatic patients since the advent of cross-sectional imaging. Awareness of these anomalies avoids misdiagnosing enlarged azygos or hemiazygos veins for retrocrural adenopathy.…”

“…These enlarged vessels should not be misinterpreted as lymphadenopathy. 14,16 Pulmonary Venous Anomalies…”