Imaging defines a number of technologies based on the generation and evaluation of images that provide information on the status of a physiological process in health and disease either in isolated cells, tissues or whole organisms. In pharmaceutical research, imaging is a powerful tool to study drug distribution, target-drug engagement, protein expression, tissue perfusion and a variety of other parameters. Functional imaging is a non-invasive method to assess these factors in a living organism. The imaging technologies available to Roche scientists both within Roche as well as through collaborations include Nuclear Magnetic Resonance (NMRI), Positron Emission Tomography (PET) and Autoradiography. In the area of cell-based assays, imaging is used in combination with immunoassays to give information on cellular phenotypes.