OBJECTIVETo compare the effect of ablations with pulsed and continuous high-intensity focused ultrasound (HIFU) on the target area containing large blood vessels in isolated perfused porcine liver.

METHODSAn isolated perfused liver model was established by perfusing the isolated porcine liver with autologous blood through the portal vein and hepatic artery using an cardiopulmonary bypass machine. With B-mode ultrasound guidance, a blood vessel about 4 mm in diameter was selected, and pulsed and continuous HIFU ablation at the same dose was delivered along the blood vessel at 3 mm to the vascular wall. After the ablation, the damages of the blood vessels as the acoustic channel and the target area were inspected, and the tissues at the interface of target volume and blood vessels were sampled for pathological examination.

RESULTSNeither pulsed nor continuous HIFU caused noticeable injuries of the acoustic channel vessels, but the volume of necrotic tissues in the target area differed significantly between the two groups (P<0.05). HE staining and vessel staining did not show any injuries of the blood vessels in the pathway of ultrasound ablation in neither of the groups (P>0.05).

CONCLUSIONWhen the target area contains large blood vessels in the pathway of ultrasound ablation, pulsed HIFU can have better therapeutic efficiency to effectively induce tissue damages without affecting the blood vessels.