Gene reporters can be used to track viable cells in vivo and their patterns of gene expression. There have been numerous attempts to develop gene reporters for magnetic resonance imaging (MRI) but these give only modest image contrast and often this is negative, which can be difficult to detect. Kevin Brindle and collaborators have developed a dual-imaging modality reporter that gives intense and positive contrast in magnetic resonance images (up to eight-fold increase in signal), which can also be used with radionuclide imaging. This allows the combination of the sensitivity of radionuclide imaging with the spatial resolution of MRI. The contrast obtained is directly related to the degree of gene expression and is readily reversible, thus allowing longitudinal studies of changes in expression. The work has been published in PNAS.