Angiographic documentation of systemic-portal venous shunting as a cause of a liver scan ""hot spot'' in superior vena caval obstruction.

Four patients with superior vena caval obstruction were evaluated with contrast venography and radiocolloid liver scans to investigate systemic-portal venous shunting as a cause of a liver scan "hot spot". In two of the cases a hot spot due to systemic-portal venous shunting was documented by angiography. The venous anatomy and pathophysiology related to hot spot formation on the liver scan is discussed. To develop a liver scan hot spot it appears necessary to have considerable systemic-portal venous flow through anterior parietal and periumbilical venous channels.