双期扫描法是指注入造影剂后于动脉期及门静脉期分别进行扫描 ,一般在螺旋ＣＴ机或高档型ＣＴ机上运用。肝脏普通增强ＣＴ扫描由于注射速度慢 ,开始扫描时间晚 ,扫描时间和间隔时间长 ,不能获得动脉期影像 ,无法了解病变的供血特征 ,常常造成定性诊断困难 ,且有一部分扫描层面 Double-phase scanning refers to the injection of contrast agent in the arterial phase and portal vein were scanned, generally in the CT or spiral CT machine use. General enhancement of liver CT scan due to slow injection, start the scan late, scan time and interval time, can not get the arterial phase imaging, can not understand the characteristics of the lesion blood supply, often resulting in qualitative diagnosis is difficult, and there is a part of the scan level