PURPOSE: To determine the clinical usefulness of spiral computed tomographic (CT) venography for theevaluation of central venous obstruction. MATERIALS AND METHODS: The authors prospectively performed a total of29 spiral CT venography procedures in 25 consecutive patients with suspected central venous obstruction. Dilutedcontrast media were directly injected into the peripheral veins of the hand or the foot. Scan parameters were 3 mmX-ray beam collimation, table speed of 4-6 cm/sec, scan time of 32-40 sec, and injection delay of 20 sec. Axialimages were reconstructed at 2-mm intervals, and using shaded surface display (SSD), maximum intensity projection(MIP), and multiplanar reformation (MPR), 3-D reconstruction was performed. In all cases, ascending venograp-hy(n=13) and/or direct catheter venography (n=21) was performed within 2 days of CT venography. With regard to site,extent, extent, severity, and cause of obstruction and collateral circulation, we compared the results of CT andcontrast venography. RESULTS: In 24 patients, a total of 56 sites of central venous obstruction or stenosis(>50%) were demonstrated. The causes of obstruction were venous thrombosis (n=6), malignant tumors (n=4),arteriovenous fistula for hemodialysis (n=5), extrinsic compression (n=2), coincidence of extrinsic compressionand arteriovenous fistula (n=1), pacemaker (n=1), mediastinal inflammatory pseudotumor (n=1), spinal tuberculosis(n=1), membranous obstruction of the hepatic inferior vena cava (n=1), Behcet's disease (n=1), or unknown cause(n=1). When compared with ascending venography (n=13), CT venography was superior for evaluation of the extent andcause of obstruction and collateral circulation in two, four and one case(s), respectively. For the evaluation ofsite and severity of obstruction, CT venography was equal to ascending venography. In two cases, direct cathetervenography (n=21) was superior to CT venography for evaluating the obstruction site, but in three, five and onecase(s) respectively, CT venography was superior to direct catheter venograp-hy for evaluating the extent andcause of obstruction and collateral circulation. For the evaluation of severity of obstruction, CT and directcatheter venography were equal. CONCLUSION: In patients with suspected central venous obstruction, spiral CTvenography can be an alternative to replace not only conventional CT but also direct contrast venography.