| Abstract [eng] |
Magnetic resonance imaging (MRI) is a widely used method for clinical diagnosis. To improve the diagnostic value of MR images, MRI contrast agents are often required. The most commonly used contrast agents are gadolinium-based compounds. Unfortunately, these contrast agents have several disadvantages such as high toxicity or sometimes too low contrast. That leads to investigation of novel MRI contrast agents. The aim of this study was to evaluate the newly synthesized negative contrast superparamagnetic Fe3O4 nanoparticles and positive contrast NaGdF4:Yb,Er nanoparticles as an efficient MRI contrast agents. The MRI results of superparamagnetic nanoparticles in vitro and in vivo revealed that the Fe3O4 gives a negative contrast in the T2*-weighted MR images. In vivo MRI studies showed that the nanoparticles are slowly removed from the injection site. It was concluded that the Fe3O4 nanoparticle clearance rate from the injection site depends on the concentration of the injected contrast agent. In vitro and in vivo studies of the upconverting nanoparticles showed that NaGdF4:Yb,Er nanoparticles provide significant positive contrast on the T1-weighted MR images. The upconverting nanoparticles enhanced MR signal was increasing with the concentration until it reaches a critical value and the signal begins to decrease. The obtained MR signal enhancement of the NaGdF4:Yb,Er nanoparticles in liver and kidneys of a rat was rather weak. These findings indicate that superparamagnetic Fe3O4 nanoparticles and upconverting NaGdF4:Yb,Er nanoparticles could be applied as an efficient MRI contrast agent. Nevertheless, further investigation is required. |
