低声压超声调控微泡空化对大鼠Walker-256肿瘤血管效应的初步研究

Vascular effect of rat Walker-256 tumor induced by low-pressure-amplitude ultrasound with microbubbles

目的探讨低声压超声调控的微泡空化对大鼠Walker-256肿瘤产生的血管效应。方法健康雄性SD大鼠26只,双侧大腿内侧细胞接种法移植Walker-256肿瘤52个,利用随机数字表法进行分组后,分别给予不同强度的治疗声压,即假照组（n=6）、200 k Pa组（n=12）、400 k Pa组（n=10）、600 k Pa组（n=12）、800 k Pa组（n=12）。超声治疗占空比1%,治疗时间5 min。各不同声压治疗组中半数肿瘤在超声辐照同时经尾静脉注射0.1 m L脂质微泡。治疗前后分别进行超声造影,利用Adobe Photoshop软件对图像进行灰阶定量分析,得到肿瘤造影峰值平均灰阶值。治疗结束后获取肿瘤标本行病理检查。结果假照组和各实验组在治疗前后的超声造影分析结果显示,肿瘤造影峰值平均灰阶值差异无统计学意义（P〉0.05）,但病理检查发现600 k Pa组肿瘤组织血浆外渗和轻度水肿,800 k Pa组肿瘤组织明显出血、水肿。结论低声压超声联合微泡对大鼠Walker-256肿瘤的血流灌注影响不大,但600-800 k Pa声压可引起血管通透性的增加。

Objective To investigate the vascular effect of rat Walker-256 tumor induced by lowpressure-amplitude ultrasound（ US） with microbubbles. Methods Fifty-two Walker-256 tumors in 26 male SD rats were treated with therapeutic ultrasound at 4 different acoustic pressures： 200 k Pa（ n = 12）,400 k Pa（ n = 10）,600 k Pa（ n = 12）,800 k Pa（ n = 12） or sham exposure（ n = 6） for 5 min. The duty cycle was set at 1%. For half of the tumors in every treatment group,0. 1 m L microbubbles were administered intravenously during US exposure. The tumor blood perfusion was imaged with contrast-enhanced US（ CEUS） before and after treatment. The gray scale value（ GSV） of tumor CEUS was quantified with Adobe Photoshop. All tumors were harvested for histological examination. Results There was no significant difference in GSV before and after treatment in all the groups（ P〉0. 05）. Plasma extravasation and slight tissue edema were observed in the tumors treated with 600 k Pa US,and significant hemorrhage and tissue edema were found in the tumors treated with 800 k Pa US,with or without microbubble administration during US exposure. Conclusion Lowpressure-amplitude US cannot induce significant changes of blood perfusion in rat Walker-256 tumor,but the tumor microvascular permeability is increased at the acoustic pressure of 600 - 800 k Pa.