Comparison of Superparamagnetic and Ultrasmall Superparamagnetic Iron Oxide Cell Labeling for Tracking Green Fluorescent Protein Gene Marker with Negative and Positive Contrast Magnetic Resonance Imaging. - Zhuoli Zhang; Dharmakumar, Rohan; Mascheri, Nicole; Zhaoyang Fan; Shengyong Wu; Li, Debiao (Molecular Imaging, 2009)