The Technical Study Of Helical CT Phlebography Of The Superior Vena Cava And Its Clinical Application

Part one : The technical study of helical CT phlebography (HCTP) of the superior vena cava (SVC)Object: The purpose of this study was to select the best injection program of contrast medium and related parameters of HCTP of the SVC.Materials and Methods: HCTP was performed in 70 volunteers who have normal SVC. They were divided into 7 groups by injection site, method and concentration of contrast medium while each group contains 10 cases. The first group were injected 300mgl/ml contrast medium at a rate of 2ml/s in single anterior elbow veins, scan delay was 5 second after injection finished. The second group were injected 300mgl/ml iodinated contrast medium in lower extremity veins at 3ml/s, scan delay depended on smartprep software (GE). The total dose of contrast medium depended on weight (1.5ml/kg) in the first and second group. The third to sixth groups were simultaneous injected low concentration contrast medium (150mgl/ml, lOOmgl/ml, 75mgl/ml, 50mgl/ml respectively) during the scanning process in bilateral anterior elbow veins at 2ml/s, scan delay was 25s. The seventh group injected the best concentration of the third tovsixth groups with other parameters same of the third group. Axial, MPR, MIP and SSD reconstruction was used for all patients. Combined analysis the degree of opacification, stripes artifacts, flow artifacts of the SVC and total quality of images and selected the best program of contrast medium injection with excellent image quality.Results: Excellent images were obtained in the group which using injection program of simultaneous bilateral anterior elbow veins injection of 75mgl/ml contrast medium at 2ml/s with a delay time of 25s, the images quality were significant difference between other groups (P>0.05). The degree of opacification, stripes artifacts and total images quality were best in all groups, only flow artifacts were worse than the second group which of injection through lower extremity veins, the difference were no significant. But the degree of opacification of this group was bad, could not perform three-dimension reconstniction of SVC in two cases.Conclusion: The best injection program is of simultaneous bilateral anterior elbow veins injection of 75mgl/ml contrast medium at 2ml/s with a delay time of 25s .VIpart two: Clinical application of helical CT phlebography of the superiorvena cava in the superior vena cava abnormalitiesObject: To analyze the image quality and to evaluate clinical application of HCTP of the SVC in SVC abnormalities.Materials and Methods: HCTP were performed in 22 patients with SVC abnormalities. The best injection program seeing part one was used. Analyze the degree of opacification, stripes artifacts, flow artifacts of the SVC and total quality of images. The images quality and its capabilities of display and diagnosis SVC abnormalities was evaluated.Results: HCTP was performed successfully in all 22 paients. The degree of opacification is good in all cases. Slight Stripes artifacts showed in two cases. Flow artifacts of the SVC beside the enter of azygos v. were found in one case. The quality of three-dimension reconstruction images was optimal in 19 cases. In all these patients, HCTP showed the double SVC malformation and SVCO. The site, extent, cause and collateral pathway of SVCO displayed clearly. The diagnosis of HCTP was conformed in all cases.Conclusion: HCTP can provide all the information necessary to diagnose and treat SVC abnormalities, it is a useful non-invasion technique for imaging the SVC .