Correlation of Signal Intensity and ICP/OES-Related Concentration of Gadolinium-based Nanomagnetic Particles in Molecular MRI: In Vitro Study

Imaging methods have an important role in the management of patient’s health care. Some of the advantages made magnetic resonance imaging (MRI) as an exclusive modality. Gd-DTPA is one of the most common contrast agents in clinical applications. In this study, the concentrations of three gadolinium-based MRI contrast agents were measured and quantification accuracy of these contrast agents by MRI method was investigated. Different concentrations from the Gd-DTPA, Gd₂O₃–DEG and paramagnetoliposome nanoparticles (encapsulated Gd₂O₃–DEG nanoparticles in liposome) samples were prepared. Physical characteristics of the contrast agents were investigated by DLS and TEM methods. The T₁-weighted images of the prepared samples were recorded using MRI scanner. For each sample, gadolinium concentrations were determined using the relaxation rates and relaxivities. Determined concentrations by the experimental and ICP/OES methods were compared and the standard errors of the results were determined. Morphology, dimension and hydrodynamic diameter of the contrast agents were investigated. The hydrodynamic diameter of Gd₂O₃–DEG and PML nanoparticles were 90 ± 7.2 nm (with PdI = 0.328) and 96.8 ± 6.5 nm (with PdI = 0.299), respectively. In assessment of gadolinium concentrations, standard deviations of the experimental and ICP/OES data were ranged from 0.007 to 0.04. P values of all data points were higher than 0.05 that confirm there is no significant difference between the experimental and ICP/OES measurements. From the results, it could be concluded that MR systems could be used as an accurate and available method to estimate gadolinium concentrations.