Wei Liu1,2, Julien Senegas3, Melissa Smith2, Joseph A. Frank2
1Clinical Sites Research Program, Philips Research North America, Briarcliff Manor, NY, USA; 2Clinical Center, National Institutes of Health, Bethesda, MD, USA; 3Phlips Research Europe, Hamburg, Germany
The quantitation of SPIO labeled cells by MRI is often confounded by the need to account for the possible existence of extracellular SPIOs that are present as a result of cell labeling with incomplete washing of cells or cell death following direct injection of labeled cells into tissues. This study investigated quantitative approaches for differentiation of intracellular and extracellular SPIOs using both R2 and R2* mapping. Experiment with phantoms containing mixtures of free SPIOs and SPIO labeled cells demonstrated a very good linear correlation between the estimated ratios of intracellular and extracellular SPIOs and the theoretical values.
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