Optimization of the scan delay-time of multi-slice spiral CT portography in patients with liver cirrhosis

Objective:To optimize the scan delay time of multi-slice spiral CT portography (MSCTP).Methods:30 patients with liver cirrhosis were divided into Group A (Child A 15 cases) and Group B (Child B 12 cases and Child C 3 cases) according to Child-Pugh liver function classification.The patients received 30 ml and 1.5ml/kg contrast media at a rate of 3.0ml/s in the CT examination using Smart Prep techniques.The peak times of portal vein were recorded and compared.20 patients with liver cirrhosis were randomly divided into Group C and Group D,and received respectively CTP using Smart Prep techniques and empirical 55~65s scan delay time,the image quality was estimated.Results:With 1.5ml/kg contrast media dose,the peak times of Group A and Group B were 52.07s and 54.33s (P=0.098) respectively,being 7.93s and 8.2s (P=0.701) later than with 30ml contrast media dose.The density difference between portal vein and hepatic parenchyma was significantly higher in Group C (67.27HU) than in Group D (46.18HU)(P=0.000).By the maximum intensity projection reconstruction,the points of the branches and the vascular edges were 4.83 and 3.33 in Group C,better than in Group D,which were 3.85 and 2.5.Conclusion:At the injection rate of 3ml/s,the optimum scan delay time is 8s delayed in patients with liver cirrhosis according to the peak time of the test bolus.