超声造影剂(UCAs)是微米量级的由脂类体或者蛋白膜包裹可溶性气体形成的微气泡.其最初在临床上的应用是为了增强超声显影图像的对比度,以提高医学诊断的准确性.随着其临床应用范围的不断扩大以及生命科学的发展,超声造影剂微泡在恶性肿瘤治疗、基因/药物输运或转染、超声止血、骨骼及肌肉系统疾病治疗等方面的临床治疗作用也日益得到广泛关注.造影剂微泡在超声作用下会发生膨胀、塌缩乃至剧烈破裂等动力学行为,这一过程被称为超声瞬态空化(IC).空化微泡在剧烈破裂过程中会产生高温、高压、发光发热等物理现象,而与之相关的声学响应和散射效应在一些诊断和治疗应用上也是非常重要的.为了更好的控制和优化超声造影剂微泡瞬态空化所产生的临床疗效,必须对其声学响应有更深的了解,其中尤为重要的是瞬态空化阈值.一般情况下IC阈值取决于其内部的气体成分和包膜的性质.在目前的工作中,瞬态空化导致的瞬态散射声信号在破裂过程中通过宽带噪声来表征,它被用来作为决定超声造影剂的瞬态空化阈值的表征量.在不通过的超声造影剂浓度和超声脉冲宽度条件下,通过实验测量了两种超声造影剂(Optison和SonoVue)的瞬态空化阈值.结果表明蛋白包膜的超声造影剂(Optison)比脂质包膜的超声造影剂(SonoVue)有更高的瞬态空化阈值.
Destruction of ultrasound contrast agents(UCAs) and the associated emissions are very important in some diagnostic and therapeutic applications.The UCA's acoustic response,especially their inertial cavitation(IC) thresholds,depends on gas content and shell properties of the UCA.In the present work,transient acoustic emissions induced by IC activities are characterized by broadband noise in the destruction process,which is used as an indicator to determine the IC threshold for UCAs.Experiments were performed to measure the IC thresholds for two kinds of UCAs(Optison and SonoVue) as a function of the UCAs' concentration and acoustical pulse length.The results show that albumin-shelled UCAs(Optison) might have higher IC threshold than lipid-shelled ones(SonoVue).