Systemic to pulmonary venous shunting in superior vena cava obstruction. Unusual myocardial and thyroid visualization.

Obstruction of the superior vena cava is commonly associated with the development of several collateral venous pathways. Right-to-left systemic to pulmonary venous shunting, however, rarely has been reported. This paper describes a case in which a previously unsuspected shunt, manifested by the striking visualization of myocardial and thyroid tissue in addition to other findings, was discovered on a routine lung perfusion scan. Imaging, as well as radiologic studies are presented in the investigation of this phenomenon.