螺旋CT下肢深静脉间接血管成像合理延迟时间的选择

The optimal choice of scan delay time in indirect spiral CT venography of the lower extremeties

目的:探讨螺旋CT下肢深静脉间接血管成像合理的延迟时间。材料与方法:51例无心脏及下肢血管病变者,以3ml?s注射速率从周围静脉注入100mlOmnipaque300,在行增强扫描或血管成像后于大转子水平行同层动态扫描,每隔30秒扫描1次,连续扫描10次。测量每一层面股动脉和股静脉的强化CT值,并绘制时间-密度曲线。结果:股静脉的强化峰值为54～83Hu,平均67.7Hu;92%(46?51)股静脉的强化峰值大于60Hu。股静脉强化达峰值时间差异较大,为126～263秒,平均178.6秒。在180秒时间段股静脉平均强化CT值为63.1Hu,88%(45?51)股静脉的强化CT值超过其峰值的90%;在150秒及210秒时间段股静脉平均强化CT值分别为58.3Hu和59.4Hu,92%(47?51)和96%(49?51)股静脉的强化CT值超过其峰值的80%。结论:①150～210秒以峰值180秒为中心1分钟的时间段为ISCTV检查的适当扫描时间;②在扫描范围较长,1分钟的扫描时间无法完成ISCTV扫描时,扫描时间以向后延伸为宜。

Objective:To determine optimal time delay for indirect spiral CT venography(ISCTV)of the deep venous system of the lower extremities.Materials and Methods:In fifty-one individuals without vascular disease of the lower extremities,after standard spiral CT enhancement or angiography through injection of 100ml Omnipaque300at the rate of 3ml?s from peripheral veins,single-level dynamic CT scanning were performed at the level of the greater trochanter of femur.Ten scannings were obtained at30s intervals.The time-density curves(TDC)were plotted and the peak enhancement value and the delay time of the peak enhancement value were recorded.Results:The average peak enhancement value of the common femoral veins were67.7Hu (54～83Hu);92%(46?51)peak enhancement value of the common femoral veins were higher than60Hu.Time to peak enhancement was variable from126s to263s,mean178.6s.At 180s intervals,the average enhancement value of the common femoral veins was63.1Hu ,88%(45?51)patients were with in their90%peak enhancement value;At 150s and210s,the average enhancement value of the common femoral veins were58.3Hu and59.4Hu,respectively.92%(47?51)and96%(49?51)patients were with in their80%peak enhancement value.Conclusion:①The optimal scanning time of ISCTV were150～210s after bolus injection of contrast media from peripheral veins.②If the scanning range of ISCTV is too long to be scan in60s,the optimal scanning time had better to be prolonged after210s.