Medical NMR imaging

Interest in permanent magnets is increasing in non-medical NMR imaging. One reason is obviously the lower costs, permanent magnets do not need a power supply or cryogenic liquids. Only the temperature has to be kept very stable,... 

Medical NMR imaging is commonly called magnetic resonance imt i (MRI) to avoid the common fear of the word nuclear and the misconception that nuclear means radioactive. There is nothing radioactive about an NMR spectrometer. In fact, MRI is the least invasive, least hazardous method available for imaging the interior of the body. The only common side effect is claustrophobia from being confined within the ring of the wide-bore magnet. 

Of the many areas where NMR is applied these days, two can be considered as being established. The most important is certainly its use for structure elucidation, from small molecules up to medium-sized proteins in solution no university with an analytical lab can afford to be without a liquid-state, high-resolution NMR system. Most chemistry students will come into contact with NMR at least once during their courses. Second, is diagnostic medical imaging, which many of us may have experienced personally. From the first crude and blurred NMR images that were acquired over 30 years ago, incredible developments have been achieved by the efforts of researchers and industry alike. 

NMR imaging has been tested in a multitude of cases and many simple and sophisticated methods have been developed. The most successful applications of the method, however, are in the field of soft matter, because transverse relaxation times are compatible with current hardware technology. In the non-medical field, NMR imaging of elastomers shows great promise for genuine applications, and in addition to academic laboratories, the method is used in industry for product development and control. While academic efforts often strive towards the development more sophisticated measurement schemes and... 

Proper choice of tR and tE for suitable Ti and T2 weights is an important factor for determining image contrast in medical imaging. Due to less restrictions in measurement time and the use of rf power, a much wider variety of contrast parameters can be accessed in material applications of NMR imaging (cf. Chapter 7). 

Applications of NMR imaging outside the medical field have been published in a variety of books and journals [8-13, 21, 86, 108-115]. A rather important subject for applications of NMR imaging is polymer science, as polymers are rich in protons, the most sensitive, stable NMR nucleus, and many polymer materials are often soft, so that the homonuclear dipole-dipole interaetion among protons is partially averaged by molecular motion. Thus, polymers are far more suitable to NMR imaging than for instance ceramic materials. 

NMR imaging (MRI) techniques were developed in the 70s mainly in the medical and biological fields, using essentially the H nucleus but also He, F, P, and more recently hyperpolarized Xe nuclei, etc. 

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