Positron emission tomography (PET): a powerful molecular imaging technique

Non-invasive, in vivo molecular imaging will assume an increasing role in the diagnosis and management of patients with cancer in the future. During the past decade, there has been a revolution in our basic understanding of human disease and cancer in particular. This has been made possible from the rapid development of basic molecular techniques. Associated with the developments in molecular biology, the imaging sciences have made remarkable advances in technology and methodologies. Recently, spectroscopic MRI techniques and positron emission tomography (PET) became available and used routinely in clinical practice. The molecular function of a tumor can be assessed rather than just visualizing the mass on an anatomic imaging study, which may not necessarily change with newer cytostatic therapies. Monitoring the effect of directed therapy is now possible eliminating the need for repeat biopsy or tissue sampling to assess viable tumor. FDG has shown its power as a very important molecular imaging probe in patients with cancer. However, there are many other aspects of malignancy that can be explored and understood by the use of the appropriately labeled radiopharmaceutical using PET technology. Other important aspects of malignancy include determination of proliferative activity; hypoxia; tumor blood flow and perfusion; and in-vivo non-invasive determination of certain tumor receptor densities. With the synthesis and characterization of more targeted radio-pharmaceuticals it will be possible to characterize tumors and assist the oncologist in selecting the appropriate individualized therapy best for treatment of a particular malignant disease in each and every patient.