Systemic-to-pulmonary venous shunt in superior vena cava obstruction: depiction on computed tomography venography.

PURPOSE: To describe computed tomography (CT) venographic appearances of systemic-to-pulmonary venous shunts with CT venography and three-dimensional reconstruction images from patients with superior vena cava obstruction.

MATERIAL AND METHODS: From January 1994 to April 2002, CT venography was performed in 45 patients with superior vena cava obstruction using a single-detector helical CT scanner (n=38) and four-detector row CT scanner (n=7). Analysis of CT scan data included the cause and degree of venous obstruction, the presence of pleural thickening and enhancement, and the attenuation of pulmonary veins. The causative factor for systemic-to-pulmonary venous shunt was evaluated using the Fisher exact test.

RESULTS: Systemic-to-pulmonary venous shunts were observed in four patients (9%) who had high-attenuated pulmonary veins and pleural enhancement on CT venography. Pleural thickening (P=0.01) and a history of pulmonary tuberculosis (P=0.034) are statistically significant risk factors.

CONCLUSION: CT venography showed strong pleural enhancement and high-attenuated pulmonary veins indicating systemic-to-pulmonary venous shunts. Radiologists should study the earlier enhancement of pulmonary veins in patients with superior vena cava obstruction.