Demonstration of collateral pathways in superior vena cava syndrome by means of radionuclide venography.

Radionuclide venography was used to study lesions producing obstruction in the superior vena caval system. This procedure is a simple and safe diagnostic method; it offers precise information regarding the site and degree of venous obstruction and the extent of the collaterals. It is useful not only in diagnosis, but also in radiotherapy planning and follow-up evaluation.