THORACIC COLLATERAL VENOUS CHANNELS - NORMAL AND PATHOLOGICAL CT FINDINGS

Opacification of thoracic collateral venous channels (CVC) on chest CT is considered a useful sign of superior vena cava (SVC) obstruction, although its lack of specificity has occasionally been emphasized. We compared the degree of opacification of six various thoracic CVC in a group of 36 patients with SVC syndrome and in a control group of 50 patients; a dynamic incremental CT technique with bolus injection was used. Opacification of at least one CVC is inaccurate for the diagnosis of SVC obstruction, with a falsepositive and false-negative rate of 34 and 31%, respectively. Only the opacification of the subcutaneous anterior channel provides a good specificity (96%), significantly higher (p < 0.05) than that observed for the posterior collateral channels. In patients in whom the clinical records and other direct CT signs of vena cava obstruction are doubtful or absent, opacification of a subcutaneous anterior channel on chest CT should lead to a suspicion of obstruction of the SVC and cavography should be performed. © 1988 Raven Press, Ltd., New York.