Dual contrast enhancement method using contrast agents for cellular magnetic resonance imaging

Abstract

This thesis analyses the effect of mixed usage of positive and negative contrast agents in cellular magnetic resonance imaging and proposes a method to enhance dual contrast using composite method. Paramagnetic gadolinium (Gd) chelates and superparamagnetic iron oxide particles (SPIOs) are widely used contrast agents for enhancing longitudinal and transverse relaxation in magnetic resonance imaging (MRI). Assuming the minimal mutual interactions between these two agents in vitro, this study examined the potential utility of combining these two contrast agents for the cell labeling and subsequent MRI visualization. Aqueous solution containing various concentrations of the two contrast agents were prepared as well as different concentration mixture of Gd- and SPIO-labeled glioma cells, suspended in Ficoll solution. Based on the examination of the relaxation properties, glioma cells that are co-labeled with varying amount of both Gd and SPIO, were prepared and subsequently characterized in terms of $T_1$ and $T_2$ relaxation time. In the experimental result, the composite MR contrast from the cells can be created by simultaneous labeling of the two distinct contrast agents. Consequently, the proposed method shows more diverse contrast conditions for the labeled cells can be expected and demonstrates the attainable dual contrast characteristics according to concentration of each contrast agent.