In recent years, magnetic-resonance tomography or magnetic-resonance imaging (MRI) has become a leading diagnostic method [4]. Its speedy introduction into clinical practice was facilitated by such an advantage as the possibility of imaging of parts of the human body which are hardly accessible to other diagnostic methods (e.g., posterior cranial fossa). Although spatial resolution of X-ray tomography is better than in MRI, the latter provides much higher image contrast without injection of potentially toxic contrasting agents. The radiation background created by MRI is virtually safe because the frequency of the monitoring radiation used in MRI examination is 9-10 orders of magnitude less than the frequency of X-ray radiation, and it is regarded as biologically harmless.Dozens of magnetic resonance (MR) tomograph models are presently commercially available from foreign and domestic manufacturers. The problem of selection of the most appropriate model is rather difficult. Advertising brochures and leaflets provided by manufacturers of MR tomographs cannot solve this problem because they do not necessarily contain required technical information. It should also be taken into consideration that advertizing materials always contain only favorable information, which should be treated with caution.In this work we consider only technical and utility characteristics of MR tomographs. This does not mean that medical characteristics (e.g., availability of angiographic detection mode, synchronization with ECG or pulse signal, etc.) are less significant; they may have a decisive significance for the selection of a given model. However, the comparison of MR tomographs by medical characteristics is beyond the scope of this work and will be discussed elsewhere.A number of general aspects of the problem should be discussed before considering technical and utility characteristics of MR tomographs.There were several stages in the history of the development of MR tomography. These stages were distinguished by the methodology of data acquisition and processing, and thereby image quality. In the early stages, the method of reconstruction of projections (reverse projection) was used. Later, it was replaced by the method of measurement of phasing gradient (duration or amplitude of gradient pulse) and then, by the method of simple frequency coding. The method of two-dimensional Fourier transformation (two-dimensional spin tomography) followed. The models considered further in this work are based on this method.The majority of contemporary models of MR tomographs are based on the same technical principles, although their technological and circuitry implementations may differ in different models. For example, they may differ by the radio-frequency coil design. However, we assume that the technological capacity of the tomograph models considered in this work either have been implemented in full measure or will be implemented during further upgrade.In our opinion, tomographic image quality is not necessarily the main criterion of comparison...

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