Diagnostic image quality of magnetic resonance imaging (MRI) is fundamentally determined by the ratio of the observed values ​​of contrast fabric and the noise level. While the absolute magnitude of the signal decreases monotonically with decreasing field strength, the contrast, defined as the relative difference inintensity of adjacent tissue, in contrast, increases because of the divergence of relaxation times. On the other hand, the observed noise includes terms that are generated by the object under study (the patient's body) and radio-electronic components of the device. At low fields, the noise contribution of the object is negligible, which helps to reduce overall noise levels by improving the electronic scanner. The combined effect of these patterns leads to the fact that the optimum contrast ratio S / N (in the study of central nervous system) is observed in magnetic fields below 0.5 Tesla.

At low fields are applied and the small gradient field switching have spent most of the energy power sources. Thus, in the fields of the order of 0.1 T the total energy consumption of all elements of the imager on a permanent magnet can be only about 500 watts.

Number of technical problems encountered in high field scanner, less manifest themselves in low fields. These include artifacts associated with the movement of the patient with the changes of the magnetic susceptibility, the presence of foreign metal objects. For example, the presence of non-removable dentures can be bulky to do technically impossible to conduct high field scanner, while the low field can get good quality images.

Value of RFID on the patient load varies as the square of the field. At low fields, the problems associated with restriction of the RF load, are virtually absent. Also other aspects of patient safety, impose less stringent requirements. Stray field of the magnet is usually low-floor is negligible, which allows you to place these systems in a confined space.

Initial cost and cost of ownership low floor MR system is much lower than for vysokopolnoy. The absence of a superconducting magnet and associated cryogenic technology significantly reduces the requirements for the qualification of technical staff, allowing for adequate maintenance in a medical institution.

RZ Sagdeev, Academician, Director of the International Tomography Center, Novosibirsk

Yu.A. Pirogov, Professor, Director Center for Magnetic Tomography and Spectroscopy, Moscow State University. MV Lomonosov Moscow

AA Saveliev, Ph.D., senior researcher at the International Tomography Center, Novosibirsk