不同扫描触发阈值技术在256层CT头颈动脉成像中的应用

Application of different scan trigger threshold preset value in head and neck angiography by 256-slice CT

目的探讨256螺旋CT头颈动脉成像中不同触发阈值对图像质量影响。方法选择接受256层螺旋头颈动脉成像的120例的患者随机分为3组,每组40例。将激发层面感兴趣区均设在主动脉弓下缘降主动脉内。A、B、C组触发阈值分别设为150、120、90 HU。并测量3组图像中颈总动脉及大脑中动脉处CT值。记录3组不同触发扫描阈值的延迟时间及图像质量评价情况。结果 A组颈总动脉及大脑中动脉CT值分别为(420.28±46.02)、(421.34±45.16)HU;B组颈总动脉及大脑中动脉CT值分别为(408.83±52.84)、(413.21±58.78)HU;C组颈总动脉及大脑中动脉CT值分别为(311.22±39.22)、(339.08±33.21)HU,C组与A、B组颈总动脉及大脑中动脉CT值比较差异均有统计学意义(P<0.05)。A组与B组头颈动脉图像质量评分差异无统计学意义,但C组与A、B组比较差异均有统计学意义(P<0.05)。A、B、C组从对比剂开始注射到机器自动触发扫描所用时间分别为(12.26±1.57)、(10.23±2.24)、(7.76±3.49)s,每2组间比较差异有统计学意义(P<0.05)。结论在256层螺旋CT头颈动脉成像中将120 HU作为监测触发阈值时,可以在保证图像质量的前提下缩短从对比剂开始注射到触发扫描前延迟时间,并相应减少了对比剂用量。

Objective To explore different scan trigger threshold preset value in head and neck angiography in 256-slice CT.Methods A total of 120 patients who underwent CT intracranial and cervical angiography were randomly divided into 3 groups,with 40 cases per group.The threshold preset value in A,B and C groups were 150,120,90 HU,respectively.Measuring the CT value of common carotid artery and middle cerebral artery.The CT values of arch of common carotid artery,cerebral artery were measured.The mean prolonged time of trigger threshold preset value and imaging quality were recorded.Results The CT value of common carotid artery and cerebral artery in group A were(420.28±46.02)and(421.34±45.16)HU,respectively,and(408.83±52.84),(413.21±58.78)HU in group B,respectively,(311.22±39.22),(339.08±33.21)HU,respectively in group C.There were statistically significant differences between group C,and group A,B in CT value of common carotid artery and cerebral artery(P<0.05).There was no significant difference between group in image quality scores between head and neck arteries in group A and group B,but the differences between group C and group A,B were observed(P<0.05).The time from contrast agent injection to the automatic triggering of the machine in group A,B and C were(12.26±1.57),(10.23±2.24)and(7.76±3.49)s respectively,and significant differences were seen in every two groups(P<0.05).Conclusion When using 120 HU as a monitoring trigger threshold in 256-slice spiral CT head-and-neck arterial imaging,it is possible to shorten the delayed time from injection of the contrast agent to triggering of the scan,and to correspondingly reduce the amount of contrast agent.