AIM: To assess the value of computed tomography during arterial portography (CTAP) in portal vein-vena cava shunt,and analysis of the episode risk in encephalopathy.METHODS: Twenty-nine patients with portal-systemic encephalopathy due to portal hypertension were classified by West Haven method into grade Ⅰ(29 cases), gradeⅡ(16 cases), grade Ⅲ(10 cases), grade Ⅳ( 4 cases). All the patients were scanned by spiral-CT. Plane scans, artery phase and portal vein phase enhancement scans were performed, and the source images were thinly reconstructed to 1.25 mm. We reconstructed the celiac trunk, portal vein,inferior vena cava and their branches and subjected them to three-dimensional vessel analysis by volume rendering(VR) technique and multiplanar volume reconstruction(MPVR) technique. The blood vessel reconstruction technique was used to evaluate the scope and extent of portal vein-vena cava shunt, portal vein emboli and the fistula of hepatic artery- portal vein. The relationship between the episode risk of portal-systemic encephalopathy and the scope and extent of portal vein-vena cava shunt,portal vein emboli and fistula of hepatic artery- portal vein was studied.RESULTS: The three-dimensional vessel reconstruction technique of spiral-CT could display celiac trunk, portal vein,inferior vena cava and their branches at any planes and angles and the scope and extent of portal vein-vena cava shunt, portal vein emboli and the fistula of hepatic artery- portal vein. In twenty-nine patients with portal-systemic encephalopathy, grade Ⅰ accounted for 89.7% esophageal varices, 86.2% paragastric varices; grade Ⅱ accounted for68.75% cirsomphalos, 56.25% paraesophageal varices,62.5% retroperitoneal varices and 81.25% dilated azygos vein; grade Ⅲ accounted for 80% cirsomphalos, 60%paraesophageal varices, 70% retroperitoneal varices, 90%dilated azygos vein, and part of the patients in grades Ⅱand Ⅲ had portal vein emboli and fistula of hepatic arteryportal vein; grade Ⅳ accounted for 75% dilated left renal vein, 50% paragallbladder varices, all the patients had fistula of hepatic artery- portal vein.CONCLUSION: The three-dimensional vessel reconstruction technique of spiral-cT can clearly display celiac trunk, portal vein, inferior vena cava and their branches at any planes and angles and the scope and extent of portal vein-vena cava shunt. The technique is valuable for evaluating the episode risk in portal-systemic encephalopathy.