While conventional x-ray methods, including computed tomography (CT), visualize varying degrees of x-ray absorption in different tissues, magnetic resonance imaging (MRI) is based on a completely different principle. There are some excellent reviews explaining the physical aspects of this technique  to which we refer. Very briefly we can say here that nuclei containing an unpaired number of protons rotate on their own axis (Spin) and in doing so produce a discrete magnetic field. By means of static and electromagnetic fields we can temporarily influence these nuclei and their reactions can be measured and finally transformed to images with the help of a computer. These depend on the quantity of nuclei influenced in a given area, on their motion and on the biological properties of the tissue examined, expressed by T1 and T2 relaxation times.
KeywordsToxicity Iodi Peri Meningioma Gadolinium
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