The use of multimodal contrast agents can potentially overcome the intrinsic limitations of individual imaging methods. We have validated synthetic antiferromagnetic nanoparticles (SAF-NPs) as bimodal contrast agents for in vitro cell labeling and in vivo cell tracking using magnetic resonance imaging (MRI) and computed tomography (CT). SAF-NP-labeled cells showed high contrast in MRI phantom studies (r₂* = 712 s⁻¹ mM⁻¹), while pelleted cells showed clear contrast enhancement in CT. After intravenous SAF-NP injection, nanoparticles accumulated in the liver and spleen, as visualized in vivo by significant MRI contrast enhancement. Intravenous injection of SAF-NP-labeled cells resulted in cell accumulation in the lungs, which was clearly detectable by using CT but not by using MRI. SAF-NPs proved to be very efficient cell labeling agents for complementary MRI- and CT-based cell tracking. Bimodal monitoring of SAF-NP labeled cells is in particular of interest for applications where the applied imaging methods are not able to visualize the particles and/or cells in all organs.

中文翻译：

---

合成反铁磁性金纳米颗粒作为 MRI 和 CT 中的双峰对比剂——体外和体内实验研究

多模态造影剂的使用可以潜在地克服个别成像方法的内在局限性。我们已经验证合成反铁磁纳米粒子 (SAF-NPs) 作为双峰造影剂，用于使用磁共振成像 (MRI) 和计算机断层扫描 (CT) 进行体外细胞标记和体内细胞追踪。SAF-NP 标记的细胞在 MRI 体模研究中显示出高对比度 (r ₂ * = 712 s ^-1 mM ^-1)，而沉淀细胞在 CT 中显示出明显的对比度增强。静脉注射 SAF-NP 后，纳米颗粒在肝脏和脾脏中积累，通过显着的 MRI 对比度增强在体内观察到。静脉注射 SAF-NP 标记的细胞导致细胞在肺中积聚，使用 CT 可以清楚地检测到这一点，但使用 MRI 则无法检测到。SAF-NPs 被证明是非常有效的细胞标记剂，用于补充基于 MRI 和 CT 的细胞跟踪。SAF-NP 标记细胞的双模监测对于应用成像方法无法可视化所有器官中的颗粒和/或细胞的应用特别感兴趣。