螺旋CT门静脉造影延迟时间的合理选择

应用时间－密度曲线选择螺旋ＣＴ门静脉造影的合理扫描延迟时间。材料与方法１４例正常人和１２例重度肝硬化患者于第一门水平行同层动态增扫描。造影剂量为２ｍｌ／ｋｇ体重，注射速率３ｍｌ／ｓ。经外周静脉注射造影剂后１５ｓ开始扫描，以后每隔５ｓ扫描１次，持续至１２０ｓ。分别测同一层面门静脉，肝脏，脾脏的ＣＴ值，并计算各时间各时点民肝脏的密度差，描绘时间－密度曲线，结果正常组与肝硬化组门静脉平均强化峰值和达到时

The Optimal Choice of Scan Delay Time in Spiral CT Portography

Objective: To investigate the optimal scan delay time in spiral CT portography (SCTP) by using timedensity curves. Materials and Methods: Fourteen individuals without liver lesions and 12 patients with severe hepatic cirrhosis were involved in this study. Singlelevel dynamic CT scanning was performed at the level of the first liver hilus, starting at 15s after nonionic contrast injection (dose 2ml/kg, injection rate 3ml/s), and the scanning was repeated every 5s for 2min. Using ROI, CT value of the portal vein, liver and spleen was measured. The density differences between the portal vein and liver were calculated and the timedensity curves were drawn. Results: The average maximum enhancement value and the time for peak enhancement of the portal vein in normal group and cirrhotic group were 208.6HU (60s) and 166.0HU (65s), respectively. And the same measurements of the liver in two groups were 122.3HU (70s) and 99.8HU (80s), respectively. The maximum density differences between the portal vein and liver (PL) were 106.5HU and 72.8HU in two groups, respectively ( P <0.001), and the time reaching was 55s and 65s in average ( P >0.05). The time for peak enhancement of spleen was 55s in both groups and there was no significant difference between them regarding the time reaching the maximum value of PL, respectively. Conclusion: (1) The optimal delay time in SCTP in both groups can be decided by making the 60th second as the middle point of total scanning time when the contrast dose is 2ml/kg and injection rate is 3ml/s. (2) With the same contrast dose and the same injection rate, there is difference in PL CT value between normal group and hepatic cirrhotic group, which may interfere with the quality of SCTP image in hepatic cirrhotic group.