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目的制备乳酸羟基乙酸共聚物(polylactic-co-glycolicacid,PLGA)微泡声学造影剂,考察其理化及声学特性。方法复乳法制备不同聚乳酸/聚羟基乙酸(PLA/PGA)的微泡,考察其理化特性;体内外显影评价不同剂量、不同机械指数条件下微泡造影剂的声学密度(AD)变化规律。结果 PLGA微泡成品呈白色粉末状,以生理盐水或PBS稀释溶解后为乳白色混悬液,pH为6.5±0.3;光镜显示微泡大小均匀,分散程度好;微泡平均粒径1.2μm;Coulter计数显示0.01g多聚体微泡冻干粉溶于10ml蒸馏水中的浓度为(2～4)×109/ml;4℃与常温干燥储存的PLGA微泡10周后再分散其浓度、粒径、pH值无明显差异;体外显影显示声学密度随微泡浓度的升高而增大,同浓度下声学密度与机械指数(mechanicalindex,MI)呈直线相关关系;兔心脏造影检查可观察到PLGA微泡造影剂能顺利通过肺循环实现左心显影,当MI为0.2时,左室内声学密度值较其他3组(MI为0.6、1.0、1.2)均有非常显著性差异。结论 PLGA微泡造影剂具有较高的可控性和稳定性,微泡共振频率较高,可以顺利通过肺循环实现左心室显影。
OBJECTIVE To prepare polylactic-co-glycolic acid (PLGA) microbubble contrast media and investigate its physico-chemical and acoustic properties. Methods The PLA / PGA microbubbles were prepared by double-emulsion method and their physical and chemical properties were investigated. The changes of acoustic density (AD) of microbubble contrast medium under different dosages and different mechanical indexes were evaluated in vitro and in vivo. . Results The finished PLGA microbubbles showed a white powdery milky white suspension after dilution with physiological saline or PBS, and the pH value was 6.5 ± 0.3. The light microscopy showed that the microbubbles were uniform in size and dispersed well. The average diameter of the microbubbles was 1.2μm. Coulter counting showed that the concentration of 0.01g polymer micro-vesicle lyophilized powder dissolved in 10ml distilled water was (2 ~ 4) × 109 / ml; Diameter and pH. There was a linear correlation between acoustics density and mechanical index (MI) at the same concentration, PLGA Microvesicle contrast agent can achieve left ventricular imaging smoothly through the pulmonary circulation. When the MI was 0.2, the left ventricular acoustical density was significantly different from the other three groups (MI 0.6, 1.0, 1.2). Conclusion The PLGA microbubble contrast agent has high controllability and stability. The microbubble resonance frequency is high, and the left ventricle can be successfully developed through pulmonary circulation.