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3 - Principles of magnetic resonance imaging and spectroscopy
- from Section I - Physics, safety, and patient handling
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- By Nicola J. Robertson, Senior Lecturer in Neonatology and Honorary Consultant Neonatologist, University College London Hospitals, London, Enrico de Vita, Magnetic Resonance Physicist, Department of Medical Physics and Bio-Engineering, University College London Hospitals, NHS Foundation Trust, London, UK, Ernest B. Cady, Clinical Scientist and Section Head MR Physics UCLH NHS Trust; Director, Bloomsbury Centre for Magnetic Resonance Spectroscopy; Honorary Lecturer UCL, Department of Medical Physics and Bioengineering, UCLH, NHS Foundation Trust, London, UK
- Edited by Janet M. Rennie, University College London, Cornelia F. Hagmann, University College London, Nicola J. Robertson, University College London
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- Book:
- Neonatal Cerebral Investigation
- Published online:
- 07 December 2009
- Print publication:
- 29 May 2008, pp 22-44
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- Chapter
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Summary
Nuclear magnetic resonance – a historical perspective
Magnetic resonance imaging (MRI) is the most important medical diagnostic development since the discovery of X-rays by Roentgen in 1895. Professor Paul Lauterbur obtained the world's first MRI scan in the USA in 1973, but many techniques empowering the modality were invented in the UK at Aberdeen, Nottingham, and Oxford Universities. The main historical highlights are summarized in Fig. 3.1 and Table 3.1.
In 1952 Felix Bloch of Stanford and Edward Purcell of Harvard Universities shared the Nobel Prize for observing nuclear magnetic resonance (NMR) [1, 2] (see below). Following this, the imaging applications of NMR evolved independently of metabolic uses and the terms MRI and magnetic resonance spectroscopy (MRS) came into use (clinical MRI primarily detects hydrogen (1H) nuclei (protons) in water and MRS detects protons and other nuclei in more complicated metabolites).
Magnetic resonance imaging
In 1971 Raymond Damadian showed differences in NMR water characteristics between normal and abnormal tissues as well as between different types of normal tissue [3]. Contemporaneously, Paul Lauterbur superimposed small magnetic field gradients on the highly uniform magnetic field required for NMR spectroscopy: the NMR resonant frequency, of water for example, is directly proportional to the local magnetic field strength and thus location can be encoded. Signal intensity at a particular radio frequency (RF) was then proportional to the water concentration at the corresponding location.