In Vivo Evaluation of 64Cu-Labeled Magnetic Nanoparticles as a Dual-Modality PET/MR Imaging Agent

A novel nanoparticle-based dual-modality positron emission tomograph/magnetic resonance imaging (PET/MRI) contrast agent was developed. The probe consisted of a superparamagnetic iron oxide (SPIO) core coated with PEGylated phospholipids. The chelator 1,4,7,10-tetraazacyclo-dodecane-1,4,7,10-tetraacetic acid (DOTA) was conjugated to PEG termini to allow labeling with positron-emitting 64Cu. Radiolabeling with 64Cu at high yield and high purity was readily achieved. The 64Cu-SPIO probes produced strong MR and PET signals and were stable in mouse serum for 24 h at 37 °C. Biodistribution and in vivo PET/CT imaging studies of the probes showed a circulation half-life of 143 min and high initial blood retention with moderate liver uptake, making them an attractive contrast agent for disease studies.