Sunday, November 24, 2019

The Invention of Magnetic Resonance Imaging (MRI)

The Invention of Magnetic Resonance Imaging (MRI) Magnetic resonance imaging or scanning (also called an MRI) is a method of looking inside the body without using surgery, harmful dyes or x-rays. The MRI scanner uses magnetism and radio waves to produce clear pictures of the human anatomy. Foundation MRI is based on a physics phenomenon discovered in the 1930s, called nuclear magnetic resonance or NMR, in which magnetic fields and radio waves cause atoms to give off tiny radio signals. Felix Bloch, working at Stanford University, and Edward Purcell, from Harvard University, discovered NMR. NMR spectroscopy was then used as a means to study the composition of chemical compounds. Paul Lauterbur and Peter Mansfield The 2003 Nobel Prize in Physiology or Medicine was awarded to Paul C Lauterbur and Peter Mansfield for their discoveries concerning magnetic resonance imaging. Paul Lauterbur, a Professor of Chemistry at the State University of New York at Stony Brook wrote a paper on a new imaging technique which he termed zeugmatography (from the Greek zeugmo meaning yoke or a joining together). Lauterbur imaging experiments moved science from the single dimension of NMR spectroscopy to the second dimension of spatial orientation- the foundation of MRI. Peter Mansfield of Nottingham, England, further developed the utilization of gradients in the magnetic field. He showed how the signals could be mathematically analyzed, which made it possible to develop a useful imaging technique. Peter Mansfield also showed how extremely fast imaging could be achievable. This became technically possible within medicine a decade later. Raymond Damadian- First Patent in the Field of MRI In 1970, Raymond Damadian, a medical doctor and research scientist, discovered the basis for using magnetic resonance imaging as a tool for medical diagnosis. He found that different kinds of animal tissue emit response signals that vary in length, and that cancerous tissue emits response signals that last much longer than non-cancerous tissue. Less than two years later he filed his idea for using magnetic resonance imaging as a tool for medical diagnosis with the U.S. Patent Office, entitled Apparatus and Method for Detecting Cancer in Tissue. A patent was granted in 1974, it was the worlds first patent issued in the field of MRI. By 1977, Dr. Damadian completed construction of the first whole-body MRI scanner, which he dubbed the Indomitable. Rapid Development within Medicine The medical use of magnetic resonance imaging has developed rapidly. The first MRI equipment in health was available at the beginning of the 1980s. In 2002, approximately 22 000 MRI cameras were in use worldwide, and more than 60 million MRI examinations were performed. Water constitutes about  two-thirds  of the human body weight, and this high water content explains why magnetic resonance imaging has become widely applicable to medicine. There are differences in water content among tissues and organs. In many  diseases, the pathological process results in changes  of  the water content, and this is reflected in the MR image. Water is a molecule composed of hydrogen and oxygen atoms. The  nuclei of the hydrogen atoms  are able to act as microscopic compass needles. When the body is exposed to a strong magnetic field, the nuclei of the hydrogen atoms are directed into order- stand at attention. When submitted to pulses of radio waves, the energy content of the nuclei changes. After the pulse, a resonance wave is emitted when the nuclei return to their previous state. The small differences in the oscillations of the nuclei are detected with advanced computer processing, it is possible to build up a three-dimensional image that reflects the chemical structure of the tissue, including differences in the water content and in movements of the water molecules. This results in a very detailed image of tissues and organs in the investigated area of the body. In this manner, pathological changes can be documented.

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