实时阈值手动触发技术在下肢动脉CT血管成像中的临床应用价值

摘要

目的：探讨实时阈值手动触发技术在多排螺旋C T下肢动脉成像中的临床应用价值。方法：70例临床疑有下肢动脉病变的患者接受下肢动脉CT检查，患者被随机分为两组。自动触发组（n＝35）患者采用自动阈值触发技术，阈值到达150 Hu后延迟6 s启动扫描；手动触发组（n＝35）患者通过实时观察时间密度曲线图至峰值稳定后手动即刻启动扫描。分析两组的延迟扫描时间，评价两组的图像质量。图像质量的评价包括显示动脉的最远分支级别、动脉边缘光滑度、静脉干扰情况、动脉节段的CT值。结果：两种触发方式的启动扫描延迟时间有明显差异（P＝0．002），自动触发组早于手动触发组；两种触发扫描方式对腹主‐髂动脉及股动脉‐腘动脉区域血管的远端分支及血管边缘显示能力差异无统计学意义（P＞0．05）；手动触发组患者小腿动脉的远端分支及血管边缘的图像质量较自动触发组高，差异有统计学意义（ P值分别为0．004、0．003）；同样，手动触发组患者的足部动脉的远端分支及血管边缘的图像质量较自动触发组高（ P值分别为0．003、0．003）；两组的图像在整个下肢静脉干扰评分中差异均无统计学意义（P＞0．05）。腹主‐髂动脉、股‐腘动脉和小腿动脉3个层面的CT 值在两组间的差异均无统计学意义（P＞0．05），而两组在足背动脉层面的CT值差异有统计学意义（P＝0．006），手动触发组在4个层面的CT值均高于自动触发组。结论：实时阈值手动触发技术考虑了患者的个体差异，可以更好地把握患者的延迟扫描时间，能获得更高质量的下肢动脉图像。%Objective: To investigate the clinical avalue of real time threshold manual triggering technique in the lower extremity arterial CT angiography .Methods :A total of 70 patients with clinically suspected lower extremity arterial disease underwent lower extremity arterial CT examination ,and the patients were randomly divided into two groups .In the first group 35 patients ,the automatic threshold triggering technique was used .After the threshold reached to 150 Hu ,6 s was delayed before scanning .The other group of 35 patients with manual triggering was used to observe the time density curve .When the peak value was stable ,scanning was started at once .The delay time of the two groups was analyzed and the image quality of the two groups was evaluated .The image quality evaluation included the branch level ,the smooth degree of the arterial edge , the interference of the vein and the CT value of the arterial segment .Results:There were significant differences in the starting delay time of the two trigger modes (P=0 .002 ,P<0 .05) ,and the auto trigger group was earlier than the manual triggering group .Between the two trigger modes ,there was no significant difference in the distal branches and vessel edge of abdominal‐iliac artery and femoral popliteal artery display ability .In the lower limb artery ,the image quality of manual triggering group was higher than that of the automatic trigger group ,the two groups had statistical significance (P=0 .004 , P=0 .003) .The same as to the distal branch and the edge of the vessel of the foot (P=0 .003 ,P=0 .003) .Two sets of images in the lower limb vein interference score had no significant difference ( P> 0 .05 ) .CT value had no significant difference in abdominal‐iliac artery ,femoral‐calf and popliteal arteries between the two groups ,while that in the dorsalis pedis artery had statistical significance between the two groups (P=0 .006) .Four levels of CT values in manual triggering group were higher than those in the automatic trigger group .Conclusions :Real time threshold manual triggering technique takes into account the individual differences of patients ,so the patient's delay scan time can be evaluated better and higher quality of lower extremity arterial images can be acquired .