Cavernous Transformation of the Portal Vein

Cavernous transformation of the portal vein (CTPV) is the development of venous channels around a thrombosed portal vein to serve as portoportal collaterals. There are two accepted theories explaining the pathogenesis of CTPV: 1. congenital agenesis of the portal vein leads to periportal collateralization and 2. that it is a portal vein hemangioma.

The main causes of portal vein thrombosis in adults are hepatocellular carcinoma, pancreatitis, cirrhosis, liver transplantation, and splenectomy. CTPV may occur in as little as 6-20 days after the insult to the portal vein.

CECT will characteristically show a mass of veins with a beaded appearance at the porta hepatis. Intrahepatic extension of the cavernous transformation can occur. Hepatic arterial phase imaging will demonstrate heterogeneous, patchy areas of high attenuation along the liver periphery (collateral channels better supply the central regions of the liver causing increased peripheral arterial inflow).

Doppler ultrasound shows hepatopetal flow in the cavernoma lacking the respiratory undulation of a normal portal vein.

The images above are from a patient with a patent main portal vein but thrombosis of the left and segments of the right portal veins, with CTPV formation.

References

De Gaetano AM, Lafortune M, Patriquin H, et al. Cavernous transformation of the portal vein: patterns of intrahepatic and splanchnic collateral circulation detected with Doppler sonography. AJR Am J Roentgenol 1995; 165:1151–1155. 

Gallego C, Velasco M, Marcuello P, et al. Congenital and acquired anomalies of the portal venous system. Radiographics. 2002 Jan-Feb;22:141-159.

Posterior Dislocation of the Sternoclavicular Joint

Sternoclavicular joint dislocations are rare, with anterior types being most common. Posterior (or retrosternal) dislocations are usually secondary to a direct blow to the posterolateral shoulder and are associated with higher morbidity and fatal complications. They can effect structures in the thoracic outlet and anterior mediastinum causing damage to the trachea, great vessels and nerves (brachial plexus, recurrent laryngeal). Posterior dislocations are typically reduced in the operating room.

References

McCulloch P, Henlet BM, Linnau KF. Radiographic clues for high energy trauma: three cases of sternoclavicular dislocation. AJR Am J Roentgenol. 2001 June;176:1534.
Restrepo CS, Martinez S, Lemos DF, et al. Imaging appearances of the sternum and sternoclavicular joints. Radiographics. 2009 May-June;29:839-859.

New Beginnings

Please join me in welcoming Dr. Saba Gilani as the new editor of Roentgen Ray Reader. Dr. Gilani brings with her a collection of interesting cases of relevance to day-to-day practice, and, more importantly, will inject some much needed fresh energy into the blog.