Superior vena cava obstruction, Hot Quadrate sign | Figure 1

CincyKidsRad

Cincinnati Children's Radiology

Superior vena cava obstruction, Hot Quadrate sign

Axial contrast-enhanced CT of the abdomen shows a rectangular area of increased early hepatic parenchymal enhancement (arrow) within segment IV of the liver. This finding is termed the hot quadrate sign and is a finding of superior vena cava obstruction. Small venous collateral vessels (arrowhead) are shunting blood between the superior vena cava and the left portal vein via internal mammary and paraumbilical veins. This finding is termed the hot quadrate sign and is a finding of superior vena cava obstruction. Coronal contrast-enhanced CT of the chest (image 2) shows lymphoma (arrow) causing obstruction of the superior vena cava (arrowhead).

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Coronal (Image 1) and axial (Images 2 and 3) contrast-enhanced CT reveal the 'hot quadrate' sign (arrow) due to superior vena cava occlusion (arrowhead). In this patient, the thrombus extends into the right atrium (arrowhead, image 3). The hot quadrate sign occurs due to collateral venous flow around the obstructed superior vena cava. In this setting, contrast passes from the upper extremity to the inferior vena cava via collateral veins such as the internal thoracic, superior and inferior epigastric, and paraumbilical veins.