Molecular and cellular imaging techniques answer questions about
normal biochemical activities of cells and their molecules, and
how these are altered by disease, injury and their treatments,
but they do so at a much higher resolution in space and time
than do PET, SPECT and MRS. Cellular and molecular imaging
techniques use several types of light microscopes, and various
types of “optical probes,” which are molecules that have been
specially labeled to emit light of various wavelengths, to
“contrast” the target cells of interest from other cells.
Molecular imaging, therefore, exploits specific molecules for
image contrast. This refers to the ability to measure and
characterize cellular and molecular activities in living animals
or humans, or in their tissues, by using contrast to identify
and follow actions of only the specifically labeled molecules.
While “intravital” light microscopy—used to visualize live
organisms—was developed more than 170 years ago, the development
in recent times of many types of hig