In ultrasonography, ultrasound contrast agents (UCAs) that possess high acoustic impedance mismatch with the bulk medium are frequently employed to highlight the borders between tissues by enhanced ultrasound scattering in a clinic. Typically, the most common UCA, microbubble, is generally close in size to a red blood cell (<∼10 μm). These microscale UCAs cannot be directly entrapped into the target cells but generate several orders of magnitude stronger echo signals than the nanoscale ones. And their large containment and high ultrasound responsiveness also greatly facilitate to perform combined treatments, e.g., drug delivery and other imaging techniques. So multifunctionalized microscale UCAs appear on this scene and keep growing toward a promising direction for precise theranostics. In this review, we systematically summarize the new advances in the principles and preparations of multifunctionalized microscale UCAs and their medical applications for malignant tumors.

中文翻译：

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用于恶性肿瘤精确治疗诊断的多功能化微型超声造影剂。

在超声检查中，临床上经常使用与体介质具有高声阻抗不匹配的超声造影剂（UCA）来通过增强超声散射来突出组织之间的边界。通常，最常见的 UCA（微泡）的大小通常接近红细胞（<∼10 μm）。这些微米级 UCA 不能直接捕获到靶细胞中，但会产生比纳米级 UCA 强几个数量级的回波信号。它们的大容量和高超声响应性也极大地促进了联合治疗，例如药物输送和其他成像技术。因此，多功能微型 UCA 出现在这个场景中，并朝着精确治疗诊断学的有希望的方向不断发展。本文系统总结了多功能微型UCA的原理、制备及其在恶性肿瘤医学应用方面的新进展。