Preoperative Estimation of Microvascular Invasion in Hepatocellular Carcinoma

The Aplio SSA-770A or Aplio 500 (Toshiba Medical Systems, Tokyo, Japan) equipped with a 375BT convex transducer (frequency range, 1.9 to 6.0 MHz). CHI is used with a mechanical index that ranged from 0.06 to 0.10. After activating CHI mode, a bolus injection of 2.4 ml of SonoVue (Bracco, Milan, Italy) is administered intravenously via an antecubital vein, followed immediately by a flush of 5 ml of normal saline solution. The targeted lesion should be observed continuously for 5 minutes, and the entire arterial and portal venous phases and several repetitions of the late phase are stored on the hard disk. The arterial, portal venous and late phases are defined as 0-30 s, 31-120 s and 121-360 s after the injection, respectively.

The Aquilion 64-slice helical CT machine (Tokyo, Japan) is used. The imaging protocol for CT examinations is as follows: 0.5 mm × 64 mm collimation, 120 kV, 150-200 mAs for 64-slice helical CT examination. The standard triphasic scan procedure is used. An unenhanced helical sequence scan through the liver will be performed first; thereafter nonionic iodinated contrast material (Ultravist, Schering, Berlin, Germany) (1.5 mL/kg) will be administered via antecubital vein with power injection at a rate of 4 mL/s for 64-slice helical CT. The arterial phase sequence is obtained 25-32 s after contrast material administration, followed by a portal venous phase sequence 70 s after contrast agent administration.