From the article Small Animals, Big PromiseIn vivo small-animal imaging offers unique advantages. It is minimally or entirely non-invasive, examines biological processes in their native environments, uses clinical modalities and allows longitudinal studies. Those compelling advantages are driving medical and biological researchers to consider incorporating small-animal imagers into their research protocols. What is most important for them to keep in mind?Bradley Smith suggested a first conversation might revolve around the selection of a labeling method. The experimenter must choose between ligand-bound probes that stick to the target and the activated probes that emit, for example, when they’re presented with their complementary enzyme. Mark Does noted that new users are used to thinking in terms of what they can look at with a confocal microscope. “You can’t possibly get the same level of detail in vivo as you can observing excised tissue on a slide.” New users often don’t appreciate that in vivo imaging is generally on the macroscopic scale, and the challenge is to relate macroscopic contrast to microscopic characteristics. For Christopher Flask the issue involves “who” as much as “how.” Often the expectations of the biologists are not realistic. “Cultivating imaging experts is good.” He suggests consulting with an MR physicist, an optical imaging expert or whoever is appropriate to convey the capabilities of the imaging modalities in question.But even with the limitations and the experimental protocol design concerns, Yingqiu Yvette Liu summarized the promise of small-animal imaging: “The trend toward translational research is designed to enable a lot of applications to quickly move from the preclinical to the clinical stage, and many applications are only a small step away from achieving this transition.”