Photoacoustic imaging (PAI) is a noninvasive hybrid imaging modality offering rich optical contrast and high depth-to-resolution ratio deep-tissue imaging. Endogenous chromophores present in the body such as hemoglobin, lipid, melanin, and so on provide strong photoacoustic contrast due to their strong light absorption in certain optical window. To enhance the performance of PAI further, researchers have developed several exogenous contrast agents such as metallic nanoparticles, carbon-based nanomaterials, quantum dots, organic small molecules, semiconducting polymer nanoparticles, and so on. These exogenous contrast agents not only help improving the imaging contrast, but also make targeted molecular imaging possible. In this review article, we first discuss the state-of-the-art PAI techniques with endogenous contrast mechanism. Later, we provide an overview of recent progress in the development of exogenous photoacoustic contrast agents for in vivo imaging applications. Finally, we present the pros/cons of the existing PA contrast agents along with future challenges of contrast agent-based PAI for biomedical applications. This article is categorized under: Diagnostic Tools > Diagnostic Nanodevices Diagnostic Tools > In Vivo Nanodiagnostics and Imaging.

中文翻译：

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用于体内成像的光声造影剂的最新进展。

光声成像（PAI）是一种非侵入性混合成像方式，可提供丰富的光学对比度和高深度分辨率的深层组织成像。人体中存在的内源性发色团（例如血红蛋白，脂质，黑色素等）由于在某些光学窗口中的强光吸收性，因此具有很强的光声对比度。为了进一步提高PAI的性能，研究人员开发了几种外源性造影剂，例如金属纳米颗粒，碳基纳米材料，量子点，有机小分子，半导体聚合物纳米颗粒等。这些外源性造影剂不仅有助于改善成像对比度，而且使靶向分子成像成为可能。在这篇评论文章中，我们首先讨论具有内在对比机制的最新PAI技术。后来，我们概述了用于体内成像应用的外源光声造影剂的最新进展。最后，我们介绍了现有PA造影剂的优缺点，以及针对生物医学应用的基于造影剂的PAI的未来挑战。本文归类于：诊断工具>诊断纳米设备诊断工具>体内纳米诊断和成像。