Molecular Imaging: a Short Review

Molecular Imaging may be broadly defined as the in-vivo characterization and measurement of biologic processes at the cellular and molecular level. In contradistinction to “classical” imaging, it sets forth to probe the molecular abnormalities that are the basis of the disease rather than to image the end results of these molecular alterations. Recent advancements in molecular sciences and medicine shows how imaging modalities can be explored to assess specific molecular targets. In the future, specific imaging of such targets will allow earlier detection and characterization of disease, earlier and direct molecular assessment of treatment effects and a more fundamental understanding of the disease process.

With the advancement in molecular and cell biology techniques, much research attention has been rightfully directed toward understanding the molecular mechanism of the diseases, but efforts have also been directed toward the development of non-invasive, high-resolution, in-vivo imaging technology. Specifically over the past 2 years, in-vivo molecular imaging has been identified by the National Cancer Institute, Massachusetts USA as an extraordinary opportunity for studying diseases non-invasively and quantitatively at the molecular level in some cases.

Molecular imaging is a growing research discipline aimed at developing and testing novel tools, reagents and methods to image specific molecular pathways in vivo, particularly those that are key targets in disease process. While certain nuclear imaging techniques may be defined as “molecular” were developed decades ago (e.g. imaging with monoclonal antibodies MOAB, receptor imaging with nuclear techniques), it is only recently that a host of needed adjunct basic research tools have become routinely available. Some of the tools include – molecular cloning, microfabrication, chip arrays, robotics, X-ray crystallo-graphy, fast mass spectrometry and sophisticated computer analysis systems.

Our current assessment of disease is based on anatomic changes or in some specialized cases, the physiologic changes that are a late manifestation of the molecular alterations that truly underlie the disease. Whereas, Direct Imaging of these molecular changes will directly affect patient care by allowing much earlier detection. We may potentially image those states what we define now as “pre-disease states” which would allow intervention at a time when the outcome is most likely to be affected. In addition, we may be able to directly image the effects of therapy.

Research on molecular imaging potentially includes vast arenas, out of which most “hot” topics are –
· How best to image molecular targets in vivo;
· Efficient “amplification” strategies i.e. increase in number of copies of specific DNA fragment (PCR), (increasing the imageable signal), study of genes, DNA, mRNA, Human Genome Project;
· Imaging efforts in Gene Therapy;
· Using Angiogenesis and Apoptosis as examples on how to image at molecular level;
· Phenotypic imaging of Transgenic and Knock-out mice.