Objective: To investigate the feasibility of labeling endothelial progenitor cells (EPCs) with a novel dual modal contrast agent Molday ION^TM EverGreen(MIEG) and its performance in vitro MRI.Methods: EPCs were isolated from rat bone marrow and labeled with 10, 20, 50 μg/mL MIEG, respectively. The labeling rates were identified by Prussian blue staining and fluorescence microscopy. The vitality of EPCs labeled with 20 μg/mL MIEG was detected by trypan blue exclusion test at 1 d, 1 w, 2 w, and 6 w after labeling. EPCs labeled with different concentrations of MIEG were scanned by 3.0T MRI with T₁ weighted and T₂ weighted imaging.Results: The labeling rates for EPCs labeled with different concentrations of MIEG were greater than 98%,and the cytoplasm of labeled EPCs was present with Prussian blue staining. Although the green lighting level went down, the labeling rate at 6 w after labeling was greater than 90%. Trypan blue exclusion test showed that there was no significant difference in the vitality between EPCs labeled with MIEG at 1 d, 1 w, 2 w and 6 w after labeling and EPCs without labeling (all P>0.05). There was no difference in signal intensity on T₁ weighted image among EPCs labeled with different concentrations of MIEG. However, the signal intensity on T₂ weighted image was reduced in all labeled groups, and the signal reduction became more apparent with increased concentration of MIEG. Conclusions: EPCs can be effectively labeled by MIEG without interference on the cell viability at the labeled concentration of 20 μg/mL. The signal intensity change of labeled cells can be detected sensitively by T₂ weighted imaging at 3.0T MRI.