Hepatic pseudolesion in SVC obstruction - 99mtechnetium sulfur colloid scan equivalent of quadrate lobe hot spot sign on computerized tomography

An area of increased activity in segment IV of liver (quadrate lobe) on 99m Tc-sulfur colloid (TSC) scans has been well documented in patients with superior vena cava obstruction. Similarly intense enhancement of the quadrate lobe in the arterial phase may be seen on computed tomography in patients of superior vena cava syndrome. We present this imaging finding in a case of malignant thymoma causing superior vena cava syndrome and discuss the physiological cause and importance of this sign.