To investigate the blocking effect on microcirculation of rabbits VX2 tumors by low-intensity pulsed ultrasound combined with intravenous microbubble injection. Methods Thirty-six rabbits bearing subcutaneous VX2 tumors were randomly divided into 3 groups. For ultrasound combined with microbubbles group, pulsed ultrasound was delivered to the tumor surface for 10 min following intravenous infusion with microbubbles as ultrasound and microbubbles. For microbubbles group, only microbubbles were injected, while for ultrasound group, only exposure under pulsed ultrasound was performed. The tumor perfusion areas in CEUS were measured at 0, 30 min, 60 min. After treatment, 6 rabbits in each group were taken randomly to sacrifice for pathological observation. Results The contrast perfusion of tumors immediately vanished after treatment in ultrasound combined with microbubbles group, then recovered gradually at 30 min and 60 min. Pathological examination showed significant swell and hemorrhage, damages in the endothelia, abundance intercellular fluid, and in situ thrombosis in ultrasound combined with microbubbles group. There was no obvious change in CEUS and pathology in microbubbles group, nor in ultrasound group. Conclusion The tumor microcirculation can be blocked by microbubble associated with low energy ultrasound. The mechanism may be related to vessel wall injury caused by ultrasound cavitation, and tissue edema increases the resistance to the blood circulation of tumor areas.%目的 探讨低能量脉冲式超声联合微泡对兔VX2肿瘤微循环的阻断作用及其病理机制.方法 将36只皮下VX2荷瘤兔随机平均分成3组:超声微泡组注入0.2 ml/kg体质量微泡5ml,并辅以超声辐照10 min;单纯超声组注入生理盐水5 ml,辐照10 min;单纯微泡组仅注入0.2 ml/kg体质量微泡5 ml,不进行超声辐照.CEUS观察各组治疗前、治疗后0.30 min、60 min时血流灌注情况,比较各时间点的灌注面积.治疗后即刻随机选取各组6只荷瘤兔处死,完整切取肿瘤,行病理学检查.结果 超声微泡组治疗后即刻肿瘤血流灌注完全消失,灌注面积为0,但30 min及60 min后灌注有所恢复,各时间点治疗后灌注面积显著大于治疗前(均P＜0.05)；大体病理检查见肿瘤微血管扩张、管壁结构崩解,弥漫性充血、出血和肿瘤组织水肿,局部血肿,形成血栓等.单纯超声组及单纯微泡组治疗前、后造影剂灌注面积无差异,肿瘤内部未见出血、水肿等.结论 低能量超声联合微泡能够阻断肿瘤微循环,可能是由于空化效应导致血管壁损伤,组织水肿对局部肿瘤血液循环产生阻力,从而阻断肿瘤血液循环.
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