"The superior vein of Sappey traverses the upper falciform ligament, connecting the phrenic, internal thoracic, and superior epigastric veins to the portal veins of the left hepatic lobe, especially segment 4A. In the setting of increased systemic venous pressure, this vein can serve as a conduit for systemic blood to enter the liver, resulting in focal hyperenhancement ("hot spots") on imaging, which may mimic pathology."
"The epigastric-paraumbilical venous system (EPVS) includes the inferior vein of Sappey and the ensiform veins. These veins drain the lower falciform ligament and round ligament, entering the liver parenchyma or peripheral portal branches of the left lobe, particularly segment 4. The EPVS descends to the umbilicus, where it communicates with the inferior epigastric veins. In collateralization, these veins can be traced to the ensiform, deep epigastric, and subcutaneous veins, providing an alternative hepatopetal flow 1,2."
"The vein of Burow is the third vein around the falciform ligament, but it does not enter the liver directly. It terminates in the middle portion of the round ligament and connects via small intercalary veins to the inferior vein of Sappey, thus participating indirectly in collateral flow."
"Cystic veins in the gallbladder bed drain into intrahepatic portal vein branches or directly into hepatic sinusoids, contributing to the third inflow in segments 4B and 5. These veins are relevant in portal hypertension and can be a source of focal perfusion anomalies."
"Aberrant gastric venous drainage to either right or left gastric veins can cause pseudolesions in posterior segment 4 or posterior segments 2/3 respectively."
"SVC obstruction (early intense quadrate segmental contrast enhancement - quadrate hot spot)"