Ultrasound Contrast Agents (UCAs) consisting of gas-filled-coated Microbubbles (MBs) with diameters between 1 and 10 µm have been used for a number of decades in diagnostic imaging. In recent years, submicron contrast agents have proven to be a viable alternative to MBs for ultrasound (US)-based applications for their capability to extravasate and accumulate in the tumor tissue via the enhanced permeability and retention effect. After a short overview of the more recent approaches to ultrasound-mediated imaging and therapeutics at the nanoscale, phase-change contrast agents (PCCAs), which can be phase-transitioned into highly echogenic MBs by means of US, are here presented. The phenomenon of acoustic droplet vaporization (ADV) to produce bubbles is widely investigated for both imaging and therapeutic applications to develop promising theranostic platforms.

中文翻译：

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从微米到纳米多功能治疗诊断平台：有效的超声成像不仅仅是规模问题。

超声造影剂 (UCA) 由直径在 1 至 10 µm 之间的充气涂层微泡 (MB) 组成，已在诊断成像中使用了数十年。近年来，亚微米造影剂已被证明是基于超声 (US) 应用的 MB 的可行替代品，因为它们能够通过增强的渗透性和保留效应在肿瘤组织中外渗和积聚。在简要概述了纳米级超声介导成像和治疗的最新方法后，本文介绍了相变造影剂 (PCCA)，它可以通过超声相变为高回声 MB。声学液滴汽化（ADV）产生气泡的现象在成像和治疗应用中得到了广泛研究，以开发有前景的治疗诊断平台。