Creation of images of objects such as the body by use of the nuclear magnetic resonance phenomenon. The immediate practical application involves imaging the distribution of hydrogen nuclei (protons) in the body. The image brightness in a given region depends on the spin density and the relaxation times, with their relative importance determined by the particular imaging technique employed. Image brightness is also affected by motion such as blood flow.
For the wide uses of NMRspectroscopy (from mineralogy to medicine) there is a variety of different spectroscopic imaging techniques available.
A short listing of the most frequent variations:
'Two-dimensional NMRSpectroscopy' (2D NMR) is based on pulse spectroscopy. This technique is mostly used for the study of chemical interactions accompanied by magnetization transfer. Examples for more diversified spectroscopy techniques are based on homonuclear (COSY, TOCSY, 2D-INADEQUATE, NOESY, ROESY) or heteronuclear correlation (HSQC, HMQC, HMBC).
•
'Solid State NMR Spectroscopy' analyzes samples with little or no molecular mobility. Dipolar coupling and chemical shift anisotropy are the dominating nuclear physical effects here. Used for example in pharmaceutical analysis.
•
'Solution State NMR Spectroscopy' is a technique to analyze the structure of samples with a high degree of molecular mobility as polymers, proteins, nucleic acids etc.
The NMR, MRI relevant nuclear spin is the rotational movement of a subatomic particle (proton or neutron) around its axis. Whether a nucleus has an overall spin, depends on its amount of protons and neutrons. Nuclei with an identical number of protons and neutrons cancel out their overall spins. Nuclei with an odd number of protons or an odd number of neutrons or both have an overall spin. This spin is measured with a nuclear spin quantum number (I). The nuclear spin quantum number of a nuclei depends on the protons/neutrons which are not paired, and is a positive integer multiple of 0.5. 1H, 19F, 13C, 31P and 15N are examples of nuclei with an nuclear spin quantum number of 0.5, 2H and 14N have a nuclear spin quantum number of 1.
•
] and 41 definitions [
]
Further Reading:
Random Page
top
