1. Department of Chemistry, University of Georgia, Athens, Georgia 30602, USA
2. Department of Nuclear Medicine, China-Japan Union Hospital of Jilin University, 126 Xiantai Street, ErDao District, Changchun 13033, China
3. Center for Molecular Imaging and Translational Medicine, State Key Laboratory of Molecular Vaccinology and Molecular Diagnostics, School of Public Health, Xiamen University, Xiamen 361102, China
4. College of Chemistry and Molecular Sciences, Wuhan University, Wuhan, Hubei 430072, China
5. Bio-Imaging Research Center, University of Georgia, Athens, Georgia 30602, USA
*These authors contributed equally to this work.
Magnetic resonance imaging (MRI) is one of the most widely used diagnostic tools in the clinic. To improve imaging quality, MRI contrast agents, which can modulate local T1 and T2 relaxation times, are often injected prior to or during MRI scans. However, clinically used contrast agents, including Gd3+-based chelates and iron oxide nanoparticles (IONPs), afford mediocre contrast abilities. To address this issue, there has been extensive research on developing alternative MRI contrast agents with superior r1 and r2 relaxivities. These efforts are facilitated by the fast progress in nanotechnology, which allows for preparation of magnetic nanoparticles (NPs) with varied size, shape, crystallinity, and composition. Studies suggest that surface coatings can also largely affect T1 and T2 relaxations and can be tailored in favor of a high r1 or r2. However, the surface impact of NPs has been less emphasized. Herein, we review recent progress on developing NP-based T1 and T2 contrast agents, with a focus on the surface impact.
Keywords: nanoparticle, magnetic resonance imaging, relaxivity, contrast agents, surface modification