In vivo MRI isolates single cells

The ability to image single cells with MRI is analogous to Lindbergh's transatlantic flight to Paris. Just as it is hard to imagine commercial aviation without transoceanic travel, molecular imaging cannot realize its full potential without in vivo imaging of individual cells.

Erik M. Shapiro, Ph.D., has demonstrated that it is possible to characterize individual cells in mice with MRI. Primary mouse hepatocytes were double-labeled with 1.63-micron-diameter, polymer-coated iron oxide particles (MPIOs) and a fluorescent cell tracker agent and were then transplanted into the spleens of mice. Optical microscopy showed that most labeled cells contained more than 50 MPIOs. Previous research had demonstrated that the MPIO-labeled cells migrated to the liver and engraft as single cells.

Confocal fluorescent microscopy and in vivo gradient-echo MRI acquired at 100 x 100 x 300-micron resolution were performed a month after transplantation.

Shapiro, now an assistant professor of radiology at New York University School of Medicine, conducted the study in the Laboratory of Functional and Molecular Imaging at the National Institute for Neurological Disorders and Stroke. He presented his findings in May at the International Society for Magnetic Resonance in Medicine meeting in Miami.