Electron Paramagnetic Resonance Imaging

Electron paramagnetic resonance imaging is a spectroscopy technique used by scientists to study chemical and nuclear samples that potentially have unpaired electrons in their electron field. Spectroscopy is the study of interactions between radiation, matter, and frequency. Spectroscopy has many sub fields such as EPR, although it is traditionally associated with the visual study of light. Spectroscopy is used extensively in physics, astronomy, and analytical chemistry for substance identification by emitted or absorbed spectrum wavelength. Electron paramagnetic resonance imaging is widely used in biology to detect free radicals – pathogenic atoms, ions, or molecules that are believed to cause degenerative diseases and cancers. Since they have free or unpaired electrons, free radicals are highly reactive. Electron paramagnetic resonance imaging or EPR imaging is very similar to nuclear magnetic resonance imaging. NMR imaging is used for detecting nuclei, whereas EPR is used to detect electrons. As most stable molecules and macromolecules have paired electrons, EPR is a very specialized branch of spectrophotometry and is not widely used even in most commercial laboratories. EPR is most often used in biochemical research labs. Individuals must be highly qualified to perform EPR analysis – these specialists are called EPR spectroscopists. EPR spectroscopists have a thorough understanding of modern physics, chemistry, and biology.

EPR, when compared to other forms of spectroscopy such as visual, flame, x-ray, or infrared, is rather technical. EPR, also known as electron spin resonance or ESR, uses an applied external magnetic field to detect the movements of unpaired electrons. Electrons, like protons, have spin - thus giving them movement while under a magnetic field. This spin causes electrons to behave like very small magnets. When a magnetic field is applied, the unpaired electrons in a questioned substance, due to their spin, are oriented between parallel or perpendicular regions according to the direction of the magnetic field as they rotate. These regions of parallel and perpendicular regions create two energy levels that allow EPR spectroscopists to measure and identify unpaired electrons as they are driven between the two distinct levels.

High resolution electron paramagnetic resonance imaging is the only definitive unpaired electron test. Other well known tests such as the florescence test, serve only as indicators are are not always certain. EPR imaging is currently being used in the medical science field in conjunction with free radical and cancerous cell studies. Biochemists have been studying the role free radicals play in pathogenic and toxic substances as well as the role free radicals play in contracting cancer. Non reactive radicals have been developed to be absorbed and to attach to certain points in cells. These markers allow EPR spectra tests to give information about the marker's environment within the cell. This development has been used in cancer treatment studies and has given valuable information to medical scientists about the conditions within a cancerous cell. Cancer patients are associated with increased levels of free radicals present in the body. EPR has several other non medical uses. It has been used by anthropologists to date teeth. Ionizing radiation releases free radicals in tooth enamel. When calibrated properly, the free radicals can be measured to date a subject's level of radiation damage and age. EPR has also been used agriculturally to measure dosages of radiation-sterilized produce. High radiation dosages can cause various diseases and radiation poisoning if they are ingested.