Preliminary testing in laboratory animals has long been essential to the development of new pharmaceuticals and of new methods for the treatment of human disease. The current development of sophisticated transgenic animal models—coupled with a growing recognition of the importance of understanding of disease processes in the context of the living host—has extended the use of animal experimentation beyond safety and efficacy testing into the realm of mechanistic investigation.

Thanks to non-invasive imaging, researchers can now perform multiple measurements, over time, in the same animal. This development not only enhances data quality in studies of dynamic molecular and of physiologic processes—it greatly reduces the number of animals required for such studies.

During the last several years, scanners for small animals have become commercially available for all of the established modalities of medical imaging (X-ray, CT, MRI, SPECT, PET, and ultrasound), as well as for optical imaging. With the help of this extraordinary technology, the dynamic biodistribution of therapeutic agents (as well as vital processes, such as gene expression, cell trafficking, cell viability, cell proliferation, tissue hypoxia, and angiogenesis) can be monitored non-invasively in the intact animal.

Imaging of small animals has become indispensable to medical research and to scientific developments, as it helps investigators remain competitive for extramural funding.