微泡激励的超声空化阻断正常肝血流灌注的初步研究

目的探讨采用脉冲式超声激励微泡空化阻断兔正常肝脏血流的可行性及阻断的病理改变。方法健康新西兰大白兔24只随机分成3组,分别是超声微泡组、单纯超声组、假照组。经兔耳缘静脉注射脂质微泡,剂量0.1 ml/kg;同时超声治疗头垂直辐照兔肝脏300 s,超声能量以脉冲式发射,频率1.2 MHz,平均声强0.89 W/cm~2。靶区治疗前后进行超声造影检查和定量分析。最后,获取该区域肝组织标本,行病理学检查。结果超声微泡组治疗后肝组织血流灌注基本消失,而单纯超声组、假照组治疗前后无明显变化。超声微泡组治疗前后肝实质平均灰阶值(GSV)分别为115.27±3.8和1.16±0.7,治疗后肝实质GSV显著低于治疗前(P0.01),单纯超声及假照组治疗前后GSV无显著差别。病理检查,超声微泡治疗组肝组织出现大片充血、出血、血栓形成等。结论微泡增强的脉冲式超声空化可以造成正常肝的血流灌注暂时性阻断或者显著下降,阻断机制可能是肝实质出血、水肿和血栓形成。

Obstruction of Normal Hepatic Blood Perfusion by Microbubble-enhanced Ultrasound Cavitation

Objective To explore the feasibility of blood perfusion obstruction of normal rabbit liver by microbubbles mediated ultrasound cavitation and the related pathology.Methods Twenty-four healthy New Zealand rabbits were randomly divided into 3 groups,including the ultrasound plus microbubbles group (US+MB),the ultrasound (US) group and the control group.Lipid microbubbles at 0.1 ml/kg were injected via auricular marginal vein,while the left lobe of liver was insonated by pulsed focused ultrasound at 1.2 MHz and 4.6 MPa of the peak negative pressure.Contrast ultrasonography was performed before and after the treatment.The pathological examination was performed at last.Results The visual blood perfusion of liver almost vanished in the US+MB group but it remained in the US and the control groups.The average gray scale values (GSV) of liver contrast imaging of the US+MB group was higher before insonation (115.27±3.8) than that of the post (1.16±0.7) (P<0.01),but there was no significant difference in the US and control groups.The pathological examination showed significant hemorrhage,edema of hepatocytes and intravascular thrombosis in the the US+MB group.Conclusions Microbubble-mediated ultrasound cavitation can produce temporary obstruction of liver blood perfusion.The mechanism could be hemorrhage,edema and thrombosis.