应用64层螺旋CT智能触发技术优化肝脏双动脉期扫描

目的 探讨64层螺旋CT对比剂追踪智能触发技术(ABT)在肝脏双动脉期扫描中的技术优化.方法 将200例接受64层螺旋CT肝脏平扫加增强扫描的患者随机分为四组各50例;其中三组患者采用ABT技术启动动脉早期扫描,触发监测点设为腹腔干层面的降主动脉,CT触发阀值分别采用110、140、170 HU,触发后延时5 s开始动脉早期扫描,延时20 s开始动脉晚期扫描;另一组患者动脉早期扫描用固定延时(注射对比剂后)20 s,动脉晚期延时35 s.测量肝实质的强化CT值及腹腔干层面的降主动脉、肝固有动脉的CT值作为评判动脉早期成像质量的指标.结果 ABT三组中,140 HU触发组符合优化的动脉早期成像(43/50,86.00%)高于110 HU触发组(35/50,70.00%)及170 HU触发组(32/50,64.00%);固定延时扫描组符合率最低(28/50,56.00%),四组之间优化的动脉早期成像的符合率差异有显著统计学意义(P<0.01).结论 在触发阀值为140 HU时,64层螺旋CT肝脏智能触发增强扫描技术可获取最佳双动脉期增强效果.

Application of automatic bolus tracking in optimizing dual arterial phase scanning of liver with 64-slice helical CT

Objective To investigate the optimal protocol of automatic bolus tracking (ABT) in dual hepatic arterial phase scanning of liver with 64-slice helical CT. Methods Two hundred consecutive patients who underwent hepatic contrast-enhanced examination with 64-slice helical CT were randomized devided into four different groups (each n=50). Determination of the scanning delay for arterial phase imaging was achieved using ABT in 3 groups with the level of the trigger threshold set at 110, 140, and 170 HU respectively in the aorta at the origin of the celiac artery, and the early and late arterial phase scanning began automatically at 5 and 20 seconds, respectively after trigger threshold was reached. In the other group, the beginning of the early and late arterial phase scanning was determined by a standard time delay of 20 and 35 seconds respectively. For the quantitative analysis, the measurements of HU values in hepatic parenchyma, inherent hepatic artery, and aorta at the origin of the celiac artery were used for assessing the degree of contrast enhancement and image quality during the early arterial phase. Results The number of patients with optimal enhancement (HU values) and higher image quality in the group of 140 HU trigger threshold was higher than those in all the rest groups, especaily that in the group of standard scanning time delay (P<0.01). Conclusion A trigger threshold of 140 HU in ABT demonstrated optimal contrast enhancement and image quality in dual arterial phase scanning of liver using 64-slice helical CT.