Anatomy of the azygos vein examined by computerized tomography imaging

OBJECTIVE: To examine the anatomy of the azygos vein AV using different parameters. Therefore, the diameter of the AV at its opening into the superior vena cava, the opening level of the AV into the superior vena cava, and the position of the AV, with respect to the vertebral column and carina, were examined by CT.

METHODS: Chest CTs of 103 cases (42 female and 61 male) were reviewed at the Department of Radiology, Faculty of Medicine, Hacettepe University, Ankara, Turkey between July 2004 and February 2005. The CT examinations were performed with a Philips AU E1 spiral CT (Rotterdam, Netherlands) with the following parameters: 120 Hv; 200 mAs; slice thickness: 7 mm; pitch: 1; reconstruction index: 7 mm. The results were statistically analyzed.

RESULTS: The diameter of the AV at the opening into the superior vena cava ranged between 4.3 mm and 16 mm. The AV was in the midline in 41 cases. The arching and opening level of the AV was at the fifth thoracic vertebra in most cases. The opening level was most often at the same level as the carina. Hemiazygos veins were detected in 90 patients.

CONCLUSION: The parameters measured in this study may be useful in surgical procedures of the mediastinum and during the interpretation of chest radiographs.