National Engineering Research Center for Biomaterials, Sichuan University, Chengdu, 610065, China.
Department of Radiology, West China Hospital, Sichuan University, Chengdu, 610041, China.
Adv Healthc Mater. 2021 Mar;10(5):e2001091. doi: 10.1002/adhm.202001091. Epub 2020 Sep 2.
Magnetic resonance imaging (MRI) has been widely used for disease diagnosis because it can noninvasively obtain anatomical details of various diseases through accurate contrast between soft tissues. Over one-third of MRI examinations are performed with the assistance of contrast agents. Traditional contrast agents typically display an unchanging signal, thus exhibiting relatively low sensitivity and poor specificity. Currently, advances in stimulus-responsive contrast agents which can alter the relaxation signal in response to a specific change in their surrounding environment provide new opportunities to overcome such limitation. The signal changes based on stimulus also reflects the physiological and pathological conditions of the site of interests. In this review, how to design stimulus-responsive nanoparticle MRI contrast agents from the perspective of theory and surface design is comprehensively discussed. Key structural features including size, clusters, shell features, and surface properties are used for tuning the T and T relaxation properties. The reversible or non-reversible signal changes highlight the contrast agents have undergone structural changes based on certain stimulus, as an indication for disease diagnosis or therapeutic efficacy.
磁共振成像（MRI）因其能够通过对不同疾病的软组织进行精确对比，无创地获取解剖细节，已被广泛用于疾病诊断。超过三分之一的 MRI 检查都需要借助造影剂的帮助。传统造影剂通常呈现出不变的信号，因此灵敏度相对较低，特异性也较差。目前，刺激响应型造影剂的发展为克服这一局限性提供了新的机会，这些造影剂能够根据周围环境的特定变化改变弛豫信号。基于刺激的信号变化也反映了感兴趣部位的生理和病理状况。在这篇综述中，我们从理论和表面设计的角度综合讨论了如何设计刺激响应型纳米颗粒 MRI 造影剂。关键结构特征包括大小、团簇、壳特征和表面性质，用于调节 T1 和 T2 弛豫特性。可逆或不可逆的信号变化突出了造影剂根据特定刺激发生了结构变化，可作为疾病诊断或治疗效果的指示。
