Manganese(III) porphyrins (Mn^IIIPs) as MRI contrast agents (CAs) have drawn particular attention due to their high longitudinal relaxivity (r₁) and unique biodistribution. In this work, two Mn^IIIP-based oligomers, MnPD and MnPT, were designed to further improve the relaxivity with ease of synthesis. The two compounds were fully characterized and their nuclear magnetic relaxation dispersion (NMRD) profiles were acquired with a fast field cycling NMR relaxometer. Both of the compounds exhibited extended high molar r₁ at high fields, higher than that of Gd-DTPA, the first clinical gadolinium(III)-based MRI CA. The r₁ value of per manganese atom increased with the increasing number of Mn^IIIP building blocks, suggesting rotational correlation time (τ_R) played dominant role in the r₁ dispersion. The toxicity of the two Mn^IIIPs and the imaging effectiveness were estimated in vitro and in vivo. With good biocompatibility, significant contrast enhancement, and complete excretion in 24 h, MnPD and MnPT are both promising for high field clinical applications. The applied strategy also potentially provided a facile approach for creation of more Mn^IIIP oligomer as efficient T₁ MRI CAs.

锰 (III) 卟啉 (Mn ^III Ps) 作为 MRI 造影剂 (CA) 因其高纵向弛豫率 ( r ₁ ) 和独特的生物分布而受到特别关注。在这项工作中，设计了两种基于Mn ^III P 的低聚物 MnPD 和 MnPT，以在易于合成的情况下进一步提高弛豫率。对这两种化合物进行了充分表征，并使用快速场循环 NMR 弛豫仪获得了它们的核磁弛豫色散 (NMRD) 分布图。这两种化合物在高场下均表现出扩展的高摩尔r ₁，高于 Gd-DTPA，这是第一个基于钆 (III) 的临床 MRI CA。在[R ₁每个锰原子的值随着 Mn ^III P 结构单元数量的增加而增加，表明旋转相关时间 ( τ _R ) 在r ₁色散中起主导作用。在体外和体内估计了两种 Mn ^III Ps的毒性和成像效果。MnPD 和 MnPT 具有良好的生物相容性、显着的对比度增强和 24 小时内的完全排泄，在高场临床应用中都有希望。所应用的策略还可能为创建更多 Mn ^III P 寡聚体作为有效的T ₁ MRI CA提供了一种简便的方法。