The future

Within the next 20 years, nuclear medicine could become a major focus of medical practice and biomedical research as medicine enters a new age of certainty, in which surgery, radiation, and chemotherapy will only be used when a benefit is certain to result from the treatment. Not only in neuropsychiatric disease, but also in other diseases, such as cancer, disease will be viewed as molecular dissonance, or, a communication disorder. Cells become cancerous and people become anxious, neurotic, or even psychotic because specific tissue cells or neurons either do not get the right messages because of a deficiency in DNA transcription and wrong messages are produced, or because of a failure in reception of the correct messages carried to cells. Nuclear medicine makes it possible to characterize these transmitters and receptors as they are distributed throughout various parts of the living human body. No field of clinical medicine is better equipped to transfer the advances in molecular biology and genetics to the care of the sick. Nuclear medicine takes a physiological and biochemical, rather than an anatomical or ontological, view of disease. Disease is characterized as a statistically defined deviation of one or more functions or regional biochemical processes from those of healthy people under circumstances as close as possible to those of a person of the same sex and age as the patient. The emission of photons from radioactive tracers that can penetrate from the inside of the body to external radiation detectors is what makes it possible to examine molecular interactions involving picomolar concentrations of molecules involved in biochemical interactions between macromolecular recognition sites, enzymes, and substrates within different parts of the living body. Perturbations (stress tests) will be increasingly used to detect abnormal responsiveness to external forces early in the course of a disease. Movement of the diagnostic process from an orientation toward anatomy to a more fundamental level, the molecular level, will be the hallmark of medicine in the next millennium. Gross or histopathologic changes will no longer suffice. Radiotracers will be able to characterize plasma membrane and intracellular recognition sites and will also provide in vivo probes, making it possible to identify changes in specific genes, as well as their molecular expression, even before the disease or disorder has manifest itself by symptoms and physical signs. Such molecular characterization of disease in situ will make it possible to treat the patient as an individual and not just as a representative member of a group of patients who have similar problems and have been labeled as having a particular disease. Diagnosis will become increasingly specific despite the heterogeneity of the present diagnostic labels.