Purpose or Case Report: Hepatic sinusoidal obstruction syndrome (SOS) - previously termed hepatic veno-occlusive disease (VOD) - is a serious cause of acute liver failure in patients undergoing hematopoietic cell transplantation (HCT).

Hepatic SOS results from injury to the hepatic venous endothelium during intensive myelopablative chemotherapy or radiation therapy prior to HCT. Endothelial injury eventually leads to fibrous obliteration of the terminal hepatic venules with sinusoidal obstruction, hepatocyte necrosis, and hemorrhage, typically seen in the first 3-6 weeks post-transplant.

Early identification of this disease process is critical given high incidence of multi-organ failure and significant morbidity and mortality. Ultrasound is extremely valuable in accurate early diagnosis as imaging findings often precede clinical signs of disease. Spectrum of findings on gray-scale ultrasound includes hepatomegaly, heterogeneous hepatic parenchymal echotexture, ascites, and gallbladder wall thickening. Findings on Doppler ultrasound - increased mean hepatic artery resistive index (RI) and decreased or reversed portal venous flow - are highly sensitivie for hepatic SOS.

In this education exhibit we will review the epidemiology and pathophysiology of hepatic sinusoidal obstruction syndreom (SOS) and discuss imaging findings that aid in accurate diagnosis. Special attention will be given to Doppler ultrasound findings and additional diagnostic information provided by B-flow Doppler ultrasound.
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