Radionuclide venography in the evaluation of superior vena cava syndrome.

Isotopic phlebography with Tc-99m-labeled microspheres was performed in 55 patients, 22 of whom presented with superior vena cava syndrome. The localization of the venous obstruction was visualized in each case, along with associated collateral views. Moreover, the transit times at different levels were markedly increased. In 11 patients, isotopic phlebography was repeated following treatment. Improvement, when it occurred, was largely due to diminished obstruction of the superior vena cava rather than to increased collateral supply. Therefore, isotopic phlebography of the upper extremities is a useful tool for the diagnosis of superior vena cava syndrome and for the evaluation of response to treatment.