Abstract:Objective: By compare the inferior vena cava diameters,CT value,image quality of direct and indirect 64-slice spiral CT angiography , analysis whether there is an advantage of direct. Method: Collecting 30 cases which were underwent direct inferior vena cava phlebography; and collecting 30 cases of whole abdominal contrast enhanced CT, get the venous phase image. Original datas were transferred to GE adw4.6 workstation for post-processing. The major axis、minor axis 、CT value were individually measured, at the levels of its entrance to the right atrium, the portahepatis, the renal pelvis, above the junction of iliac vein. The image quality of inferior vena cava (IVC) was evaluated by two physicians with more than 5 years experience. The results of the two groups were compared and statistically analyzed. Result: At the levels of its entrance to the right atrium, the portahepatis, the renal pelvis, above the junction of iliac vein, the major axis, minor axis of direct CT phlebography individually were (3.02±0.44, 2.06±0.32), (2.29±0.49, 1.39±0.52), (2.46±0.44, 1.73±0.45), (2.30±0.38, 1.66±0.46), of indirect phlebography individually were (2.88±0.43, 1.95±0.31), (2.37±0.59, 1.17±0.37), (2.28±0.32, 1.63±0.31), (2.25±0.21, 1.47±0.34), there is no obviously difference between them. The CT values of direct CTP were (232.57±59.45)、(278.10±80.00)、(360.32±92.13)、(466.78±100.71)HU, much higher than the indirect CTP (122.45±16.10)、(107.10±13.32)、(92.46±12.93)、(88.23±12.62)HU. Image quality better than good of direct CTP is 93.3%, much higher than indirect CTP 56.6%. Conclusion: Multi slice spiral CT direct CTP of IVC is feasible and superior to indirect CTP. It can obtain better image quality and can be used to diagnose the IVC diseases.