Details about Molecular Imaging Principles and Practice
Molecular imaging (MI) of living subjects is an emerging field that aims to study molecular and cellular events in the intact living animal and human. These events can be as simple as the location(s) of a specific population of cells or levels of a given protein receptor on the surface of cells. In addition, it is possible to study more complex events such as the interaction of two intracellular proteins, cellular metabolic flux, or transcription of a set of genes when one cell type comes into contact with another cell type. In contrast to molecular processes studied in intact cells outside the living subject (eg, with light microscopy techniques), it is much more difficult to longitudinally study the same processes in intact living subjects where most cells are located within deep tissues. It is the hope of many MI researchers that most of the biology will eventually be able to be studied in the intact living subject instead of having to remove tissues/cells for further analysis, as is no w commonly done. This will allow the study of simple and complex processes while cells reside in their native environment with all molecular feedback loops fully intact. The reasons for monitoring/imaging various molecular targets are usually related to characterizing a disease process that may correlate with concentrations of one or more of these molecular targets. For example, the presence of relatively high levels of the somatostatin receptor type 2 (located on cell membranes) in the lungs of a subject may be indicative of the presence of cancer cells in the lung. This may then help guide medical management of the subject in which such a molecular signal is detected. Another very important reason to study various cellular/molecular targets is to help dissect complex underlying biology. For example, one might be able to study the migration of a specific subset of T-cells (or T lymphocytes) into a tumor and subsequent activation of these T-cells by a T-cell receptor to better understand the details of the interaction of the tumor with the immune system.