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Abstract #5130

Liposome-Loaded Microspheres as a Magnetic Susceptibility Agent for PH Sensing

Kannie W. Y. Chan1,2, April M. Chow1,2, Ed X. Wu1,2

1Laboratory of Biomedical Imaging and Signal Processing, The University of Hong Kong, Pokfulam, Hong Kong SAR, China; 2Department of Electrical and Electronic Engineering, The University of Hong Kong, Pokfulam, Hong Kong SAR, China

MR susceptibility contrast agents have been used for imaging of vasculature and tumors, such as microbubbles and iron oxides. We have developed a susceptibility agent for pH sensing, especially for acidic tumor environment, increasing sensitivity around physiological pH using liposome-loaded microspheres. Our in vitro data showed that both R2 and R2* decreased at low pH, and the percentage change in R2* is larger when compared to controls at pH 6.8-7.2. Liposome-loaded microspheres showed a substantial increase in pH-dependence of R2*, which favoured by localization of liposomes on microspheres, and is first demonstrated to an improve pH sensitivity at 7T.