多排螺旋CT的肝脏灌注时间的研究

目的利用多层螺旋CT观察肝脏在不同条件下的血流灌注情况。方法45个健康志愿者分三组,A组:速率2ml/s,剂量30ml;B组:速率4ml/s,剂量30ml;C组:速率4ml/s,剂量60ml。注射后10s在肝门区行8排螺旋容积扫描,间隔2s,至120s。分别测肝门区同一解剖层面主动脉、肝动脉、门静脉和肝实质的增强前后的CT值,将每组内各时间点的强化CT值平均,得到它们强化的平均峰值及到达峰值的平均时间和肝实质平衡时的平均CT值及到达的时间。并绘出它们的时间—强化曲线图。结果主动脉、肝动脉、门静脉、肝实质平均到达峰值时间分别为22.5s,25s,37.5s,45s在A组和C组,20s,22.5s,30s,35s在B组。肝实质到达平衡期的平均时间A组、B组、C组时分别为60s,40s,60s。结论肝及血管强化程度受对比剂量正比影响;剂量相等时,肝、血管强化到达的峰值时间与注射速率成反比;注射时间相等,强化峰值与注射速率成正比,但到达的峰值时间不变;注射速率相同时,注射时间的延长,峰值时间随之落后。建议在4ml/s速率下,多排螺旋CT肝脏检查,动脉期、门脉期及平衡期时间窗的选择设定在注射对比剂后25,40,65s为宜。

Study of liver perfusion time with multi-detector spiral CT

Objective To study the perfusion time for hepatic scan w it h multi-slice spiral CT. Methods In total 45 volunteers with no history of liv er disease were divided into three groups, candidates in group A recieved a volu me of 30ml contrast medium at a injection rate of 2ml/sec,respectively, in group B a volume of 30ml contrast medium was given individually at a injection rate o f 4ml/sec and for group C a volume of 60ml contrast medium at a injection rate o f 4ml/sec was utilized. Axial 8-slice CT scans through the hepatic portal was performed in 10 seconds after the injection was started. The scan duration was 0 .5s and the scan interval was 2s. Total dynamic scan took 120s. CT numbers at ab dominal aorta, hepatic artery, portal vein and hepatic parenchyma were measured before and after the contrast material administration .The time-density curves were constructed, and time to peak (Tpeak) , time to equilibration (Teq) were o btained. Results The mean Tpeak of aorta, hepatic artery, portal vein, hepatic p arenchyma were 22.5s,25s,37.5s,45s in group A and C, and 20s,22.5s,30s,35s in gr oup B. The mean Teq were 60s, 40s, and 60s in A-C group respectively. Meanwhil e, with increasing rate or the volume of injection, the intensity of the enhance ment increased. Conclusions At the same volume of contrast medium, with a increa sed rate of injection, the time to peak enhancement and equilibration will be ad vanced, Meanwhile, the intensity of the enhancement follows the volume of contra st medium proportionally. At a 4ml/sec injection, the recommended delay time of liver scan was 25s, 40s, 65s for arterial, portal vein and hepatic parenchyma phase respectively.