Migration of the azygos vein from the azygos fissure to the mediastinum.

We report a case of migration of the azygos vein from an azygos fissure into the mediastinum following a large right pleural effusion.

CT of the paraumbilical and ensiform veins in patients with superior vena cava or left brachiocephalic vein obstruction.

The purpose of this study was to elaborate on the anastomoses between the paraumbilical and systemic veins, particularly the ensiform veins. The connections with the ensiform veins have received little attention in the anatomical and radiological literature, and remain incompletely described. Too small to be reliably traced in normal CT scans, the paraumbilical veins can dilate in response to increased blood flow from systemic veins in superior vena cava obstruction (SVCO), allowing a study of their arrangement and connections. Collateral paraumbilical veins were therefore analyzed retrospectively in 28 patients with SVCO using CT. We observed inferior and superior groups of collateral vessels in 23/28 (82%) and 17/28 (61%) patients, respectively. Inferior veins ascended towards the liver and drained into portal veins (19/28, 68%) or the umbilical vein (8/28, 29%); superior veins descended and drained into portal veins. The inferior veins (N = 27) could be traced to ensiform veins in almost all of the cases (26/27, 96%), and a little over half (14/27, 52%) were also traceable to subcutaneous and deep epigastric veins. They were opacified by ensiform (25/27, 93%), deep epigastric (4/27, 15%) and subcutaneous (4/27, 15%) veins. The superior veins (N = 17) were supplied by diaphragmatic (13/17, 76%) and ensiform veins (4/17, 24%); the diaphragmatic veins were branches of collateral internal thoracic, left pericardiacophrenic and anterior mediastinal veins. Collateral ensiform veins were observed in 22 patients and anastomosed with internal thoracic (19/22, 86%), superior epigastric (9/22, 41%), diaphragmatic (4/22, 18%), subcutaneous (3/22, 14%) and anterior mediastinal veins (1/22, 5%). These observations show that the paraumbilical veins communicate with ensiform, deep epigastric, subcutaneous and diaphragmatic veins, joining the liver to the properitoneal fat pad, anterior trunk, diaphragm and mediastinum. In SVCO, the most common sources of collateral flow to the paraumbilical veins are the ensiform and diaphragmatic branches of the internal thoracic veins.

CT of the bronchopulmonary veins in patients with superior vena cava or left brachiocephalic vein obstruction.

OBJECTIVE: The purpose of this study was to show the arrangement and connections of the bronchopulmonary veins (i.e., vessels draining the bronchi, bronchioles, and pleura in patients with chronic superior vena cava (SVC) or left brachiocephalic vein (LBCV) obstruction using CT. MATERIALS AND METHODS: Contrast-enhanced CT scans of the chest of 16 patients with chronic SVC or LBCV obstruction were analyzed retrospectively. Scans were acquired using various standard protocols. The mean age of the patients (10 men and six women) was 63 years (range, 41-86 years). The causes of obstruction were malignancy (7/16, 44%), catheter-related thrombosis (7/16, 44%), chronic fibrosing mediastinitis (1/16, 6%), and unknown (1/16, 6%). RESULTS: The following sites were obstructed: SVC (9/16, 56%), SVC below the azygos vein (4/16, 25%), and lower LBCV (3/16, 19%). The bronchopulmonary veins were opacified via the brachiocephalic, azygos, or accessory hemiazygos veins or their branches. We observed long vessels that could be traced along the lateral mediastinum or alongside the trachea and central bronchi to their termination in the central pulmonary veins from the level of the ostia to segmental divisions. These vessels intercommunicated and gave rise to smaller veins contiguous with the walls of the bronchi and pulmonary arteries. The pulmonary venous connections of the bronchopulmonary veins were more frequent with the lower lobe pulmonary veins. Pericardial and esophageal veins were also opacified through the brachiocephalic or azygos veins and anastomosed commonly with the bronchopulmonary veins. CONCLUSION: The arrangement and connections of the bronchopulmonary veins in patients with chronic SVC or LBCV obstruction can be depicted by CT; these vessels form an intricate network connecting the systemic and pulmonary venous circulations and can act as systemic-pulmonary shunts.

Reversed halo sign in acute pulmonary embolism and infarction.

BACKGROUND: The reversed halo sign, originally described in cryptogenic organizing pneumonia, has been observed in a variety of pulmonary diseases, including pulmonary embolism (PE). PURPOSE: To describe the computed tomographic (CT) findings in patients with the reversed halo sign and acute PE at initial presentation and in subsequent scans. MATERIAL AND METHODS: Contrast-enhanced CT examinations of 12 patients with the reversed halo sign and acute PE were analyzed retrospectively. The diagnosis of pulmonary embolism was made by CT angiography in 11 cases and by a routine contrast-enhanced scan of the chest in the other case. Follow-up scans of seven patients and follow-up radiographs of two patients were also examined retrospectively. The average age of the patients was 49 years (range, 21-80 years). Seven (58%) patients were women. Six patients had no significant medical history, and six patients had deep venous thrombosis initially. RESULTS: The reversed halo sign was observed as a single lesion in 10 patients; in two patients, two lesions were found. The lesions, all pleural-based, occurred more frequently in the lower lobes and were associated with acute thromboemboli in segmental and subsegmental pulmonary arteries of the corresponding segment. Ten (10/14, 71%) lesions displayed an ellipsoid configuration, two (2/14, 14%) had a pyramidal shape, and two involved an almost entire pulmonary segment. The average largest dimension was 3.9 cm (range, 2.1-6.7 cm). All lesions subtended one or more bronchovascular bundles; three (3/14, 21%) showed air-bronchograms, and a thromboembolus was identified in the subtended arteries in nine (9/14, 64%) lesions. In succeeding CT scans (eight lesions) and follow-up radiographs (three lesions), the lesions became smaller, and the majority evolved into pleural-based linear scars by 7 months. CONCLUSION: The reversed halo sign very likely corresponds to pulmonary infarction in patients with acute PE. Its recognition may have important clinical implications.

CT demonstration of the extracardiac anastomoses of the coronary veins in superior vena cava or left brachiocephalic vein obstruction.

CT scans in four cases of chronic superior vena cava or left brachiocephalic vein obstruction demonstrate a systemic-to-cardiac collateral venous pathway through anastomoses between the pericardial branches of systemic veins and the presumed adventitial veins of the ascending aorta and pulmonary trunk. These adventitial veins then drain into tributaries of the anterior cardiac veins or ventricular coronary veins.