In vivo imaging is the non-invasive visualization of living organisms for research or diagnostic purposes. Generally speaking, this method can be divided in two key areas: anatomical/morphological imaging and molecular imaging. In molecular imaging cellular function or molecular processes are visualized, normally using biomarkers. While in anatomical imaging no marker is used and visualization is based on the intrinsic properties of the tissues and organs being observed, such as the attenuation of X-rays in the case of computed tomography, molecular imaging very often uses biomarkers labeled with bioluminescence or fluorescence.
By using in vivo molecular imaging, multiple molecular events can be monitored simultaneously, for example, to visualize drug effects, to optimize drug and gene therapy, to monitor tumor growth or to study disease progression in both, living animals and plants. By providing insights into transcription–translation feedback loops, which are entrained by environmental signals such as light or temperature, even circadian clocks in plants can be monitored. Compared to other methods of measuring molecular processes, in vivo imaging has several important advantages:
- It provides the spatial location of the process or molecule.
- It is dynamic: changes in time can be followed.
- It can be repeated several times in the same individual.
- It allows the observation of a (mostly) undisturbed process: that means, results are physiologically relevant.
These advantages make in vivo imaging a very useful technology in many research and diagnostic fields.