Advances in emission tomography and magnetic resonance

This paper will review recent technical improvements in emission tomography (PET and SPECT) as well as new approaches in magnetic resonance in vivo studies (MRI and MRS). These advances now enable more detailed studies of dementia and heart disease as well as improved methods to diagnose and treat cancer. Forms of dementia (Parkinson´s and Alzheimer´s disease) can now be quantitatively accessed using PET and SPECT probes that target dopamine brain chemistry, inflammatory reactive receptors on glial cells and amyloid plaques. In addition there are advances that allow early detection of cardiovascular disease through the rapid analysis of heart muscle perfusion changes due to mental or physiologic stresses. Quantitative flow changes with stress cannot be easily done clinically with PET due to the need for a dedicated supply of accelerator-produced positron emitters, but this problem is solved with use of the well known but expensive rubidium-82 generator (strontium-82 decay product) and with the renewal of the iodine-122 generator (xenon-122 decay product). These technologies provide a means for detection of individuals who will eventually develop congestive heart failure that kills more than frac12 million people per year in the U.S.A. and is the most fatal of all cardiovascular diseases. A major limitation of positron tomography is the limited availability of carbon-U, nitrogen-13, and oxygen-15. The concept of a table-top accelerator using the helium-3 fusion reaction with deuterium will be presented as a possible new technology. Magnetic resonance instrumentation and contrast probes improvements can also help define heart disease leading to heart failure, and in addition provides a potential guide (i.e., late enhancement quantitation) to heart failure treatment using surgical left ventricular reconstruction. Advances in MRI field strength, gradient coil design and contrast agents (e.g. hyperpolarization) will allow for the first time the measurement of individua- - l differences in metabolism through the use of high field magnets and hyperpolarized substrates where the movement of carbons from single molecules and can be traced through the body´s metabolic processes. This ability has the potential to give information that can reverse the major epidemic of obesity in the world.