多层螺旋CT肝血管多期成像最佳时相方法选择

Choice of optimal phase for liver angiography and multi-phase scanning with multi-slice spiral CT

目的 探讨团注测试扫描（test bolus）技术在多层螺旋CT肝动脉（HA）-门静脉（PV）血管成像及肝脏多期一次成像联合扫描最佳时相设定的方法和意义。方法选取腹部CT扫描患者184例，根据扫描技术的不同分为两组，A组59例，采取经验值法设定HA-PV扫描延迟时间；B组128例，采取test bolus技术，选定腹主动脉和肠系膜上静脉作为目标血管，设强化阈值为50HU，先注射对比剂20m1，测得目标血管的时间一密度曲线，分别获得HA—PV两期的扫描延迟时间，评价两种方法所得CTA图像质量，结果并采用x^2检验进行比较。结果A组：HA血管成像期，图像质量优34例（58％）、良17例（29％）、差8例（13％）；PV血管成像期，图像质量优23例（39％）、良27例（46％）、差9例（15％）。B组，图像质量优128例（100％）、良0例（0％）、差0例（0％）；PV血管成像期，图像质量优96例（75％）、良28例（22％）、差4例（3％）。两组比较差异有统计学意义（x^2值分别为14．97、9．18，P值均〈0．05）。结论运用testbolus技术能准确地测得肝脏目标血管的时间一密度曲线，根据这一标准设定扫描延迟时间，能得到优质的CTA图像，有利于多层螺旋CT取得更好的肝脏三维血管重组图像。

Objective To evaluate the efficacy of test bolus technique with multi-slice spiral CT （MSCT） for determining the optimal scan delay time in CT Hepatic artery （HA）-portal vein （PV） angiography and multi-phase scanning. Methods MSCT liver angiography and multi-phase scanning were performed in 187 patients divided randomly into two groups. In group A （n =59）, the scan delay time was set according to the subjective experiences of operators ; in group B （ n = 128）, the scan delay time was determined by test bolus technique. Abdominal aorta and superior mesenteric, vein were selected as target blood vessels, and 50 HU was set as enhancement threshold value. 20 ml contrast agent was injected intravenously and time-density curve of target blood vessels were obtained, then HA-PV scanning delay time were calculated respectively. The quality of CTA images obtained by using these 2 methods were compared and statistically analysed using Chi-square criterion. Results For hepatic artery phase, the images of group A are： excellent in 34 （58%）, good in 17 （29%）, and poor in 8 （13%）, while those of group B are excellent in 128（ 100% ）, good in 0（0% ） ,and poor in 0（0% ）. For portal vein phase, the images of group A are ： excellent in 23 （ 39% ）, good in 27 （46%）, and poor in 9 （ 15% ）, while those of group B are excellent in 96 （ 75% ）, good in 28 （ 22% ）, and poor in 4 （ 3% ） respectively. There was statistically significant difference between the ratios of image quality in group A and group B （x^2 = 14. 97,9. 18, P 〈 0. 05）. Conclusion Accurate scan delay time was best determined by using test bolus technique, which can improve the image quality of liver angiography and multi-phase scanning.