IN BRIEF, WHAT ARE NMR AND MRI? 
HOW MANY MR MACHINES ARE THERE? 
ARE THERE OTHER THAN MEDICAL APPLICATIONS OF MR?
IS MR IMAGING A SAFE PROCEDURE OR ARE THERE SIDE EFFECTS? 
HOW DID MAGNETIC RESONANCE IMAGING DEVELOP?
I DO NOT UNDERSTAND ALL THE ACRONYMS USED FOR 
CAN YOU PROVIDE AN OVERVIEW OF MR CONTRAST AGENTS?
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Paul C. Lauterbur
The first magnetic resonance images (from Nature) |
Spatial Encoding All the experiments up to now had been one-dimensional and lacked spatial information. Nobody could determine exactly where the NMR signal originated within the sample. After MR imaging had first been described, several individuals and companies claimed that they had achieved imaging earlier, but their machines were not conceived of as imagers. In roentgenology, the times of conventional imaging ended in September 1971, when the world's first axial x-ray computed tomograph was installed in England. In the same month, Paul Lauterbur of the State University of New York at Stony Brook had the idea of applying magnetic field gradients in all three dimensions and the computerized axial tomography (CAT)-scan back-projection (= projection-reconstruction) technique to create NMR images. He published the first images of two tubes of water in March 1973 in the journal Nature [35]. This was followed later in the year by the picture of a living animal, a clam, and in 1974 by the image of the thoracic cavity of a mouse [36]. Lauterbur called his imaging method zeugmatography, a term which was later replaced by (N)MR imaging.
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Richard Ernst
The first two-dimensional Fourier-transformed images. |
Field gradients had been used before. They are an essential feature of the study of molecular diffusion in liquids by the spin-echo method developed by Erwin L. Hahn in 1950 [22]; his group used a gradient approach also to create a storage memory [2]. In 1951, Roger Gabillard from Lille in France had imposed one-dimensional gradients on samples [16, 17]. Carr and Purcell described the use of gradients in the determination of diffusion in 1954 [7]. However, Lauterbur's idea revolutionized NMR because it opened the field to imaging. Many of today's innovations were thought of and developed in his laboratory in the late 1970s and 1980s [3, 15, 34, 37-39, 46, 52]. When he presented his approach to NMR imaging at the International Society of Magnetic Resonance (ISMAR) meeting in January 1974 in Bombay, Raymond Andrew, William Moore, and Waldo Hinshaw from the University of Nottingham, England, were in the audience and took note. As a result, Hinshaw developed his own approach to MR imaging with their sensitive point method [26, 27]. In April 1974, Lauterbur gave a talk at a conference in Raleigh, North Carolina. This conference was attended by Richard Ernst from Zurich, who realized that instead of Lauterbur's back-projection one could use switched magnetic field gradients in the time domain. This led to the 1975 publication, 'NMR Fourier Zeugmatography' by Anil Kumar, Dieter Welti, and Richard Ernst [33], and to the basic reconstruction method for MR imaging today.
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Peter Mansfield | A second NMR group in Nottingham got also involved in MR imaging. Its leader, Peter Mansfield, worked on studies of solid periodic objects, such as crystals. At a Colloque Ampère conference in Cracow in September 1973, Mansfield and his collaborator Peter K. Grannell presented a one-dimensional interferogram to a resolution of better than 1 mm [43]. This, however, cannot be considered an MR image. However, one year later, Alan Garroway and Mansfield filed a patent and published a paper on image formation by NMR [19]. By 1975, Mansfield and Andrew A. Maudsley proposed a line technique which, in 1977, led to the first image of in vivo human anatomy, a cross section through a finger. In 1978, Mansfield presented his first image through the abdomen [44, 45]. In 1977, Hinshaw, Paul Bottomley, and Neil Holland, succeeded with an image of the wrist [28]. Damadian and collaborators created a cross section of a human chest [12]. More human thoracic and abdominal images followed, and by 1978, Hugh Clow and Ian R. Young, working at the British company EMI, reported the first transverse NMR image through a human head [8]. Two years later, William Moore and colleagues presented the first coronal and sagittal images through a human head. In the research group of John Mallard at the University of Aberdeen, Jim Hutchison, Bill Edelstein, and coll. developed the spin-warp technique. They published a first image through the body of a mouse in 1974 [14, 30]. Margaret Foster contributed much to this work.
The prototype MR equipment in Aberdeen with Jim Hutchison. |
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