Mouse genomic imaging laboratories: An opportunity for radiology to move from the bedside to the bench

An opportunity is upon us. It is an opportunity for the imaging world to move itself beyond the more traditional bedside role and the role of providing research support and out into the world of primary bench research—research that will contribute significantly to the research endeavors of the entire biomedical field in the 21st century. This opportunity is a real one, because not only is the biomedical world ready for us and we for them, but, crucially, the funding has now arrived as well. This opportunity to move from bedside to bench is arising from a confluence of advances in imaging technology, molecular biology, and informatics. Key understanding of biological systems is now being derived from molecular biological techniques applied to small animal models, particularly the mouse (the next mammalian species to be genotyped), yielding thousands of different genotypes of these animals through induced mutation and other genetic manipulations. The problem is that current molecular genetic understanding currently does not allow the ability to produce a predictable phenotypic model, so that researchers truly have no reliable way to predict what kind of phenotype they will produce in these animals. The only realistic way to crack the code is to work backward, by manipulating the genes and identifying what phenotypic effects result. Here is where imaging can make its mark: by developing and applying in vivo and ex vivo imaging techniques for mouse models in order to better understand basic developmental and pathophysiological processes under highly controlled experimental conditions. The fundamental goal is to develop and apply imaging techniques that can help describe mouse phenotypes for correlation with the corresponding genotypes in order to fully understand genotypic expression. Current imaging techniques pose a limitation to studying smaller animals. Many, if not most, in vivo imaging devices have been optimized for human studies and have inadequate spatial resolution for small animals. Fortunately, most contemporary imaging techniques can be scaled down to yield very high resolution and signal-sensitive in vivo and ex vivo images of mouse-sized samples. Better yet, these scaled-down machines are much cheaper to build and run than human-sized machines, making this research opportunity available to a much greater number of institutions, and particularly to basic scientists. Furthermore, there are some imaging techniques that are able to provide valuable information about small animals that are not easily applicable to human subjects, for example, optical imaging and electron paramagnetic resonance (EPR) imaging. We radiologists are uniquely poised to develop these techniques into an array of research modes for investigating biological systems through small animals. Currently there are four established imaging techniques that can be applied to living (or dead) mice—magnetic resonance (MR) imaging, positron emission tomography (PET)/single photon emission computed tomography (SPECT), x-ray computed tomography (CT), and ultrasound (US)—and at least two newer, developing imaging modalities. MR imaging provides the state of the art in structural imaging of soft tissues, as well as numerous physiological parameters (1). Currently MR imaging studies can be routinely performed on mice, collecting data comparable in signal and anatomic resolution to that in humans. The Acad Radiol 2001; 8:295–298