History of Magnetic Resonance Imaging (MRI)
Getting an MRI scan may someday become as common as getting an X-ray. - Davis Meltzer, 1987
According to Gould (2004), on July 3, 1977, an event took place that would forever alter the landscape of modern medicine, although outside the scientific research community, this event hardly attracted any notice at all. The event in question was the first MRI exam ever performed on a human being. The procedure required almost five hours to produce one image, and the images were, by today's standards, very primitive (this first MRI machine now occupies a special niche in the Smithsonian); however, its successors number if the thousands today (Gould, 2004). The advent of the MRI clearly represented the beginnings of a new standard in noninvasive radio imaging that continues to be refined. This paper provides the background and history of magnetic resonance imaging, including its discovery and evolution, as well as newly identified applications for the technique. A summary of the research is provided in the conclusion.
Review and Discussion
Background and Overview. According to an early report by Howard Suchurek (1987), "Like the director of a chorus, an MRI scanner conduct the 'singing' of hydrogen atoms within the human body. The scanner surrounds the body with powerful electromagnets. Supercooled by liquid helium, they create a magnetic field as much as 60,000 times as strong as that of the earth" (16).
Magnetic resonance imaging (MRI) is an imaging technique that is used primarily in medical settings to produce high quality images of the inside of the human body (Gould 2004). MRI is based on the principles of nuclear magnetic resonance (NMR), a spectroscopic technique used by scientists to obtain microscopic chemical and physical information about molecules (Gould, 2004).
The technique was called magnetic resonance imaging rather than nuclear magnetic resonance imaging (NMRI) because of the negative connotations associated with the word nuclear in the late 1970's. MRI began as a tomographic imaging technique; in other words, it produced an image of the NMR signal in a thin slice through the human body. Since those early efforts, MRI has advanced beyond such tomographic imaging techniques to a more sophisticated volume imaging technique. This improved approach provides a comprehensive picture of the basic principles of MRI (Gould, 2004).
Today, magnetic resonance imaging is an imaging modality that is used primarily to develop pictures of the NMR signal from the hydrogen atoms contained within an object. In medical MRI applications, for example, radiologists are most interested in looking at the NMR signal from water and fat, the major hydrogen containing components of the human body (Gould, 2004).
Brief History of MRI. Any investigation of the science of MRI must review its history to understand how the technology evolved to its state today. According to Dr. Hornak (2002), Felix Bloch and Edward Purcell (both of whom were awarded the Nobel Prize in 1952), discovered the magnetic resonance phenomenon independently in 1946. During the period between 1950 and 1970, NMR was developed and used for chemical and physical molecular analysis. In 1971, Raymond Damadian demonstrated that the nuclear magnetic relaxation times of tissues and tumors differed, thus motivating scientists to consider magnetic resonance for the detection of disease (Gould, 2004).
In 1973 the x-ray-based computerized tomography (CT) was introduced by Hounsfield. This date is important to the MRI timeline because it demonstrated conclusively that hospitals were amenable to investing large amounts of money for medical imaging hardware. Magnetic resonance imaging was first demonstrated on small test tube samples in 1973 by Paul Lauterbur; this scientist employed a back projection technique similar to that used in CT. According to Gould, in 1975, Richard Ernst first proposed magnetic resonance imaging using phase and frequency encoding, as well as the Fourier Transform.
This technique became the foundation for current MRI techniques. In 1977, Raymond Damadian first demonstrated an MRI field-focusing nuclear magnetic resonance; also that year, Peter Mansfield developed the echo-planar imaging (EPI) technique. This technique was expected to be refined in the future to produce images at video rates (30 ms / image) (Gould, 2004).
In 1980, Edelstein and his coworkers demonstrated imaging of the body using Ernst's technique; using this approach, a single image could be acquired in approximately five minutes. The imaging...
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