Effect of neodymium doping to oleic acid coated gadolinium oxide nanoparticles on magnetic resonance imaging contrast

Abstract

Introduction: Magnetic resonance imaging (MRI) provides improvement of the anatomical and physiological studies in medical imaging field. Although new imaging techniques and sequences have been introduced and applied in MRI, using of MRI contrast media is essential to obtain better diagnosis and differentiation of the lesions. Gadolinium oxide nanoparticles (Gd2O3 NPs) have attracted much attention due to their appropriate magnetic properties and excellent relaxivity. One of the most desirable features of these NPs is the ability of doping with other lanthanides. Doping means creation of impurities in matter to upgrade the NPs properties. Neodymium doped Gd2O3 NPs have shown photoluminescence and optical properties, but the characteristics of the NPs in MRI has been not investigated yet. The aim of this study is investigation of the effect of neodymium doping to oleic acid coated Gd2O3 NPs in MRI.

Material and method: Gd2O3 and Nd doped Gd2O3 (1 and 3%: Nd1Gd2O3 and Nd3Gd2O3) NPs were purchased from Tabriz university. The physicochemical properties of the NPs were investigated using X-ray diffraction (XRD) and scanning electron microscopy (SEM). Besides, the cytotoxicity of the NPs was investigated in the cell culture. MR relaxivity properties of the NPs were studied with a 1.5 tesla MRI system. T1W and T2W MR images were prepared using spin echo sequence. After measuring signal intensities in the images, plotting the curves of T1 and T2 relaxation times was done using MATLAB software. Relaxivity values for each NPs were obtained from relaxation rate versus concentration curve.

Results: XRD patterns showed peaks of Gd2O3 and neodymium. The average size of the NPs was measured 125 nm. According to the threshold of 50%, the cell viability for all concentrations was more than the threshold for all nanoparticles. The longitudinal relaxivity (r1) for Gd2O3 NPs was higher than Nd doped Gd2O3 in T1W images. On the other hand, in T2W MR Images, the transverse relaxivity (r2) for Nd doped Gd2O3 was higher. Between doped NPs, the Nd3Gd2O3 NPs showed higher r2.

Conclusion: The effectiveness of Gd2O3 NPs for positive MRI contrast agent is higher than Nd doped Gd2O3 NPs. Doping the neodymium increases the r2 relaxivity and decreases the positive contrast enhancement of the NPs.