Multi-detector Row Spiral CT Portography And Its Evaluation Of Portal System And The Collaterals In Portal Hypertension

Objective: (1) To discuss the feasibility of dual flow rates ( 3.5ml/s ,1.0 ml/s )injection method in reducing the dosage of contrast agent without compromise to the resulted image quality.,compared to single flow rate( 3.5ml/s) injection method(2) compare the display of the collaterals by VR,MIP , referring to the axial source and MPR images. Material and Methods: 30 patients with documented portal hypertension in clinics underwent MDCTP, who were divided into group A(n=15) and B(n=15) randomly.Prior to scanning , 600ml of plain water were administered orally as a negative contrast to distend the stomach and duodenum. scanning was performed at dual flow rates of 3.5ml/s for 16-18s and 1.0 ml/s until portal phase started in group A .a flow rate of 35.ml/s in group B, injection contrast dosage was 1.5-2.0 ml/kg. Portal phase scanning was started 45-50s after injection。Technical parameters were as follows: collimation 0.75mm, table feed 15mm/360。,pitch 15,120kv,250mAs. Post-processing techniques such as MIP,MPR and VR were applied to display the collaterals . Paired t-test was carried out between group A and B, concerning on 2 indexes (density difference between portal vein and liver parenchyma at same slice, distal branches display). Referring to the display of thin axial and MPR images, counting the numbers of collaterals visualized by post-processing methods, compared the visualization capability between VR and MIP using paired- x2 test.Results: (1)No significant differences were indicated between 2 indexes(PV-L density difference, and portal branches display) of group A and B(t values were 1.632 and 1.578, respectively,P >0.05),the dosage contrast in group A was less than that in group B .(2) the visualization rates of MIP and VR were 87.6 % and 72.3%,respectively, significant difference was indicated(x2=6.13 P<0.05) Conclusion: (1) Method of dual flow rates( 3.5ml/s ,1.0 ml/s )injection reduced the dosage of contrast agent without compromise to image quality.(2) VR and MIP were preferred in MDCTP visualization of collaterals , MIP provided better reconstructed images, combined with VR ,referring to axial and MPR images when necessary diagnosis Part two Evaluation of Portal System and its Collateral in Portal Hypertension using Multi-detector row Spiral CT PortographyObjective: To evaluate the value of multi-detector row spiral CT portography(MDCTP) findings in demonstrating portal system and its collaterals in portal hypertension. Material and Methods: MDCTP was performed in 31 patients with documented portal hypertension in clinics, prior to scanning , 600ml of plain water were administered orally as a negative contrast to distend the stomach and duodenum. scanning was performed at dual flow rates of 3.5ml/s for 16-18s and 1.0 ml/s for portal inflow phase in 15 cases , single flow rate of 3.5ml was applied in 16 cases. Technical parameters were as follows: collimation 0.75mm, table feed15mm/360。, pitch 15,120kv, 250mAs. Post-processing techniques such as MIP,MPR and VR were applied to display the collaterals . Findings of MDCTP in 10 patients were compared with those from DSA direct portography.Results: MDCTP simultaneously depicted fourth or fifth branches of the intrahepatic portal veins and entire portosystemic collaterals. on MDCTP images ,left gastric varicose were seen in 28 patients, esophageal and paraesophageal varicose in 27, splenic varicose in 21 , short gastric veins or posterior gastric veins in 7,splenorenal shunts in 1,abdominal wall and umbilical varicose in 2, portal venous thrombosis in 4,SMV thrombosis in 2 .With demonstration of portosystemic collaterals in 10 cases ,MDCTP showed results similar to those of DSA direct portogaphy, on portal vein, proximal intrahepatic branches and collaterals, except 2 umbilical varicose displayed by MDCTP were ignored in DSA direct portography, and also provided the similar results of emboli zed or recanalized collaterals to DSA direct portography in 2 interventional therapy cases.Conclusion: MDCTP provide the accurate information of the collateral circulations and the post-operative follow-up examination in patients with portal hypertension, It becomes an alternative method for non-invasive and valuable portography.