Imaging Characteristics of USPIO Nanoparticles (<5 nm) as MR Contrast Agent In Vitro and in the Liver of Rats

Abstract

Iron nanoparticles have an increasingly more and more important role in MR molecular imaging due to their novel magnetic and surface chemical properties. They provide new possibilities for noninvasive diagnosis and treatment monitoring, especially for tissues that are rich in macrophages. The smaller size and prolongation of the plasma half-life change the in vivo fate of ultrasmall superparamagnetic iron oxide (USPIO) nanoparticles captured by liver in reticuloendothelial system (RES) or mononuclear phagocytic system (MPS). However, there is still a lack of MR imaging studies on the liver assessing USPIO nanoparticles &lt;5 nm in size to reflect its absorption and clearance properties. In this study, we used MRI to study the in vitro phantom and in vivo rat liver imaging characteristics of USPIO nanoparticles (&lt;5 nm). The results showed that USPIO nanoparticles (&lt;5 nm) could potentially reduce longitudinal and transverse relaxation times and showed similar T1 relaxation rates compared with commercial gadolinium chelates. In addition, USPIO nanoparticles (&lt;5 nm) in vivo demonstrated both positive (T1) and negative (T2) liver contrast enhancement in healthy rats’ liver. Furthermore, USPIO nanoparticles showed relatively good in vitro biocompatibility and fast clearance (within 45.17 minutes after intravenous injection) in the normal liver. Taken together, these data might inspire a new personalized and precise diagnostic tool and stimulate new applications for specific targeted molecular probes.

Emodin-Conjugated PEGylation of Fe3O4 Nanoparticles for FI/MRI Dual-Modal Imaging and Therapy in Pancreatic Cancer

“…10,11 Magnetic nanoparticles (MNPs), especially iron oxide-based ones (magnetite Fe 3 O 4 ) are widely used in cancer theranostics due to their excellent stability, novel magnetic properties and surface chemistry for ligand binding and good biocompatibility. [12][13][14] Compared to gadolinium-based contrast agents (GBCA), MNPs showed stronger magnetic susceptibility effects, image features, and size-or surface chemistry-dependent pharmacokinetics. 15 It can be used to enhance the signals of T1-and T2-weighted images (T1WI and T2WI) while GBCA only provide contrast effects on T1WI images.…”

“…15 It can be used to enhance the signals of T1-and T2-weighted images (T1WI and T2WI) while GBCA only provide contrast effects on T1WI images. 12 By loading a wide range of functional materials such as fluorescent dyes and therapeutic agents, MNPs can achieve multiplexed imaging and targeted therapy.…”

Assessment of Fasudil on Contrast-Associated Acute Kidney Injury Using Multiparametric Renal MRI

“…The inversion recovery method was applied for T1 mapping, since it is insensitive to inaccuracies in excitation flip angles or imperfect spoiling and additional calibration measurements was usually not required ( Stikov et al, 2015 ). A 2D FSE multi-echo sequence was used for T2 mapping and eight echoes were acquired, which referred the method in reference ( Ma et al, 2019 ), where the T2 mapping method has been validated with the ultrasmall superparamagnetic iron oxide (USPIO) phantom. Parameters of data acquisition through ASL and T1/T2 mapping are shown in Table 1 .…”

Iron Oxide Nanoparticles in Bioimaging – An Immune Perspective

“…As such, they represent the counterpart to the classical Gadolinium (Gd)-based contrast agents which increase T 1 relaxation rates leading to positive (bright) image contrast ( 12 ). In recent literature, there is also evidence that ultra-small IONPs (<5 nm) can be used in both T 1 - and T 2 -weighted MRI ( 13 , 14 ). These findings could appear to be beneficial in the future since Gd-based contrast agents are known to be less biocompatible and can raise the possibility of nephrotoxicity, especially in patients with advanced acute or chronic kidney disease ( 15 , 16 ).…”