Kumar Tushar,  Elhussein Wala,  Kim Helen Hr

Final Pr. ID: Poster #: EDU-040

Sinusoidal obstruction syndrome (SOS), also known as veno-occlusive disease (VOD), is a potentially life-threatening hepatic complication that occurs primarily following hematopoietic stem cell transplantation (HSCT). It is characterized by obstruction of hepatic sinusoids and venules due to accumulation of cellular debris and red blood cells, leading to impaired hepatic outflow. The incidence in pediatric patients can be as high as 40%, resulting from toxic injury or activation of liver sinusoidal endothelial cells (LSECs). Common etiologic factors include myeloablative conditioning regimens for HSCT, chemotherapeutic agents such as oxaliplatin, and total body irradiation. SOS/VOD is classified into acute (80%, within 21 days post-HSCT) and late-onset forms (20%, beyond 21 days). Histopathologically, late-phase SOS shows peri-sinusoidal fibrosis and hepatocyte atrophy in addition to sinusoidal obstruction. Clinically, the disease manifests with painful hepatomegaly, conjugated hyperbilirubinemia, and rapid weight gain or ascites. While the modified Seattle and Baltimore criteria are traditionally used for adults, the European Society for Blood and Marrow Transplantation (EBMT) 2019 criteria have been specifically developed for the pediatric population, incorporating both clinical and radiologic parameters. Ultrasonography remains the first-line imaging modality, including gray-scale, color Doppler, and spectral analysis. Ultrasound elastography can detect SOS as early as 2–12 days before clinical criteria are met by quantifying increased hepatic stiffness due to portal hypertension; a ≥ 30% rise in stiffness from baseline has demonstrated high sensitivity and specificity. Characteristic sonographic findings include hepatomegaly, gallbladder wall thickening, increased portal vein diameter, ascites, paraumbilical vein visualization with altered flow, reduced portal venous velocity, and elevated hepatic artery resistive index—imaging parameters that are incorporated into the newer Hok-US scoring system (maximum 14 points). Additionally, MR elastography and hepatobiliary MRI using Eovist have shown promise for early, noninvasive detection. Early diagnosis is critical, as severe SOS carries mortality rates up to 80%, and the only approved therapy remains defibrotide, emphasizing the need for vigilant imaging surveillance and prompt management. Read More

Authors:  Kumar Tushar , Elhussein Wala , Kim Helen Hr

Keywords:  Abdominal Imaging, Venoocclusive Disease, Sinusoidal Obstruction Syndrome

Shore Matthew,  Riedesel Erica

Final Pr. ID: Poster #: EDU-128

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. Read More

Authors:  Shore Matthew , Riedesel Erica

Keywords:  Hepatic Sinusoidal Obstruction Syndrome, Doppler Ultrasound, B-flow Ultrasound, Educational Exhibit

Reddivalla Naresh,  Opfer Erin,  Robinson Amie,  Reid Kimberly,  Chan Sherwin

Final Pr. ID: Poster #: SCI-053

Sinusoidal obstruction syndrome (SOS) is a potentially fatal disease affecting children following bone marrow transplantation (BMT). SOS diagnosis is clinical because traditional ultrasound has poor sensitivity and specificity with portal vein flow reversal occurring well after the disease is clinically evident. Ultrasound elastography is a newer technology that measures liver stiffness, which should increase in SOS due to passive hepatic congestion. Our hypothesis is that quantitative shear wave ultrasound elastography will be more accurate in detecting this disease compared with conventional ultrasound parameters. Read More

Authors:  Reddivalla Naresh , Opfer Erin , Robinson Amie , Reid Kimberly , Chan Sherwin

Keywords:  Sinusoidal Obstruction Syndrome, Veno-Occlusive Disease, Ultrasound Elastography