Periumbilical Uptake of Tc-99m MAA on Lung Perfusion Scanning in a Patient With Superior Vena Cava Obstruction

Abstract

A 25-year-old woman with severe parenchymal lung disease of unknown etiology and existing for more than a decade was referred for ventilation-perfusion scintigraphy because of suspicion of pulmonary embolism. Both ventilation and perfusion images showed, apart from perfusion defects from her severe lung disease, a left apical pneumothorax and signs of recurrent pneumonia of the left lower lobe. Noteworthy was the periumbilical uptake of the Tc-99m macroaggregated albumin (MAA). Her medical history revealed iatrogenic superior vena cava (SVC) obstruction. In this case, the main collateral pathway of portosystemic shunting is probably, after recanalization of the left umbilical vein, a network of smaller paraumbilical veins.

Portosystemic Shunting in Superior Vena Cava Obstruction by Tumor Demonstrated on Ventilation-Perfusion Lung Scan

“…Hepatic uptake of 99m Tc-macroaggregated albumin has been reported in both superior and inferior vena cava obstructions (1)(2)(3)(4) and is caused by shunting of venous blood flow through collateral pathways to the portal system. Superior vena cava obstructions are usually due to malignancy (2-4) but are also seen infrequently in benign conditions such as inflammation, trauma, coagulopathies, and indwelling catheters with insidious progression allowing various collateral pathways to develop (5).…”