根据细胞外囊泡 (EV) 的起源和形成过程，可以识别不同类别的细胞外囊泡 (EV)。其中，外泌体（EXO）源自与质膜融合的内体区室，形成小脂质囊泡，运输一系列分子货物，例如核酸、蛋白质和脂质。 EXO 的组成因其细胞来源而异，涵盖各种细胞类型，包括中性粒细胞、树突状细胞，甚至肿瘤细胞。值得注意的是，EXO 具有固有的稳定性、低免疫原性和相容性，使其成为有效的药物输送纳米载体。生物发光、荧光和核成像等成像技术对于非侵入性追踪生物体内的 EXO 至关重要。这个过程需要将放射性核素附着到 EXO 的结构上，而不改变其基本特征。 EXO 的实时成像对其临床应用至关重要，标记和跟踪方法的最新进展提供了对 EXO 介导的药物输送的生物分布、功能和潜在途径的见解。这篇综述介绍了 EXO 在各种模式的靶向成像中的不同应用的最新进展，它们作为造影剂促进组织可视化和疾病追踪。因此，EXO 成为医疗诊断和成像领域有前途的实体。版权所有 © 2024。由 Elsevier Inc. 出版。

Different categories of extracellular vesicles (EVs) are identified based on their origin and formation processes. Among these, exosomes (EXOs) originate from endosomal compartments merging with the plasma membrane, forming small lipid vesicles that transport a range of molecular cargo such as nucleic acids, proteins, and lipids. The composition of EXOs varies depending on their cellular source, encompassing various cell types, including neutrophils, dendritic cells, and even tumor cells. Remarkably, EXOs possess inherent stability, low immunogenicity, and compatibility, making them efficient nano vectors for drug delivery. Imaging techniques like bioluminescence, fluorescence, and nuclear imaging are crucial in non-invasively tracking EXOs within living organisms. This process requires the attachment of radionuclides to the EXO's structure without altering its essential characteristics. Real-time imaging of EXOs is vital for their clinical application, and recent advancements in labeling and tracking methodologies provide insights into biodistribution, functionality, and potential pathways for EXO-mediated drug delivery. This review presents updated progress in the diverse applications of EXOs in targeted imaging across various modalities, where they function as contrast agents facilitating tissue visualization and disease tracking. Consequently, EXOs emerge as promising entities in medical diagnostics and imaging.Copyright © 2024. Published by Elsevier Inc.