Budd-Chiari Syndrome: Update on Classification and Intravascular US.

Budd-Chiari syndrome (BCS) results from the obstruction of hepatic venous outflow and can occur anywhere from the level of the small hepatic veins (HVs) to the junction of the inferior vena cava (IVC) and the right atrium. The obstruction of the HVs can be global or segmental. This results in sinusoidal congestion, which leads to portal hypertension and subsequent centrilobular fibrosis, nodular regenerative hyperplasia, and ultimately cirrhosis. Treatment is aimed at restoring HV or IVC outflow by angioplasty, stent placement, or creating a portosystemic shunt, which in turn drastically reduces hepatic sinusoidal pressure. Thus, treatment strategies should be based on detailed knowledge of the underlying causal factors, lesion classification, clinical presentation, and baseline liver function. The BCS classification system is divided into types and subtypes that can guide interventional therapy, with the aim of standardizing the imaging diagnosis and interventional therapy of BCS. Intravascular US (IVUS) aids in BCS lesion characterization as described by the BCS classification system. It can help determine the need for stent placement following angioplasty and is helpful in portosystemic shunt creation. Additionally, IVUS can reduce radiation dose, contrast agent volume, and procedure time and increase the technical success rate of procedures. It is essential for the radiologist to understand the BCS classification system as a useful tool to guide interventional therapy. ©RSNA, 2025 Supplemental material is available for this article.