A method for operating a mobile magnetic resonance tomography system having magnets and/or coils generating a magnetic field and a shield surrounding the magnets and/or coils is intended to enable an optimal image quality during the examination and at the same time have a small space requirement. For this purpose, a temperature is measured at a plurality of points on the shield by a temperature measuring system, where measured data of the temperature measuring system is sent to a compensation system, and where effects of temperature differences on the homogeneity of the magnetic field are compensated by the compensation system.

A method for operating a mobile magnetic resonance tomography system having magnets and/or coils generating a magnetic field and a shield surrounding the magnets and/or coils is intended to enable an optimal image quality during the examination and at the same time have a small space requirement. For this purpose, a temperature is measured at a plurality of points on the shield by a temperature measuring system, where measured data of the temperature measuring system is sent to a compensation system, and where effects of temperature differences on the homogeneity of the magnetic field are compensated by the compensation system.

Systems and methods for designing and fabricating three-dimensional objects with precisely computed material compositions for use in enhancing electromagnetic fields for magnetic resonance imaging (MRI) are provided. As examples, the fabricated object can be designed to reduce magnetic field inhomogeneities in the main magnetic field of an MRI system, or to reduce inhomogeneities in a transmit radio frequency (RF) field (i.e., a B.sub.1 field). As examples, the object can be a shim; a housing or other part of an RF coil; a medical device, such as a surgical implant; or component used in a medical device, such as a housing for an implantable medical device.

Systems and methods for designing and fabricating three-dimensional objects with precisely computed material compositions for use in enhancing electromagnetic fields for magnetic resonance imaging (MRI) are provided. As examples, the fabricated object can be designed to reduce magnetic field inhomogeneities in the main magnetic field of an MRI system, or to reduce inhomogeneities in a transmit radio frequency (RF) field (i.e., a B.sub.1 field). As examples, the object can be a shim; a housing or other part of an RF coil; a medical device, such as a surgical implant; or component used in a medical device, such as a housing for an implantable medical device.

A magnetic resonance imaging configuration, system and method to straighten and otherwise homogenize the field lines in the imaging portion, creating improved image quality. Through use of calibrated corrective coils, magnetic field lines can be manipulated to improve uniformity and image quality. Additionally, when the apparatus is composed of non-ferromagnetic materials, field strengths can be increased to overcome limitations of Iron-based systems such as by use of superconductivity. A patient positioning apparatus allows multi-positioning of a patient within the calibrated and more uniform magnetic field lines.

A magnetic resonance imaging configuration, system and method to straighten and otherwise homogenize the field lines in the imaging portion, creating improved image quality. Through use of calibrated corrective coils, magnetic field lines can be manipulated to improve uniformity and image quality. Additionally, when the apparatus is composed of non-ferromagnetic materials, field strengths can be increased to overcome limitations of Iron-based systems such as by use of superconductivity. A patient positioning apparatus allows multi-positioning of a patient within the calibrated and more uniform magnetic field lines.

To suppress eddy current generation by a gradient magnetic field while an RF shield has a function of reducing magnetic coupling of an RF coil with a gradient magnetic coil, the RF shield must be formed of a conductive material of a tiled or slitted strip-shaped thin plate. On the other hand, cooling must be performed to suppress temperature rise due to heat generation by the eddy current. Furthermore, to enlarge an opening through which a patient is inserted, the gradient magnetic coil, the RF coil, and the RF shield, which are located in a static field magnet and have roughly concentrically cylindrical shapes, are required to be reduced in thickness. To solve the above problem, the present invention provides a structure, where an RF shield, which is obtained by forming a tiled or slitted thin-plate conductive material into a sheet, is adhered or attached to an inner cylindrical surface of the gradient magnetic coil, where the RF shield is configured to be adhered or attached to a region including the vicinity of each of turn centers of an X-gradient magnetic coil pattern and a Y-gradient magnetic coil pattern, or is adhered or attached along a pattern on or a slit in the thin plate conductive material of the RF shield.

To suppress eddy current generation by a gradient magnetic field while an RF shield has a function of reducing magnetic coupling of an RF coil with a gradient magnetic coil, the RF shield must be formed of a conductive material of a tiled or slitted strip-shaped thin plate. On the other hand, cooling must be performed to suppress temperature rise due to heat generation by the eddy current. Furthermore, to enlarge an opening through which a patient is inserted, the gradient magnetic coil, the RF coil, and the RF shield, which are located in a static field magnet and have roughly concentrically cylindrical shapes, are required to be reduced in thickness. To solve the above problem, the present invention provides a structure, where an RF shield, which is obtained by forming a tiled or slitted thin-plate conductive material into a sheet, is adhered or attached to an inner cylindrical surface of the gradient magnetic coil, where the RF shield is configured to be adhered or attached to a region including the vicinity of each of turn centers of an X-gradient magnetic coil pattern and a Y-gradient magnetic coil pattern, or is adhered or attached along a pattern on or a slit in the thin plate conductive material of the RF shield.

A superconducting magnetic field generating device includes: a superconductor including an outer superconductor formed with a high temperature superconducting material in a cylindrical shape and generating a trapped magnetic field, and an inner superconductor formed with a high temperature superconducting material in a cylindrical shape and coaxially disposed with the outer superconductor on the inner circumferential side; and a cooling device cooling the outer and inner superconductors to a temperature equal to or lower than the superconducting transition temperature, wherein the inner superconductor is formed so that a ratio (Jc1/Jcz1) of a critical current density (Jc1) of the inner superconductor in the circumferential direction to a critical current density (Jcz1) of the inner superconductor in the axial direction is closer to 1 than a ratio (Jc2/Jcz2) of the critical current density (Jc2) in the circumferential direction to a critical current density (Jcz2) of the outer superconductor of the outer superconductor in the axial direction.

A superconducting magnetic field generating device includes: a superconductor including an outer superconductor formed with a high temperature superconducting material in a cylindrical shape and generating a trapped magnetic field, and an inner superconductor formed with a high temperature superconducting material in a cylindrical shape and coaxially disposed with the outer superconductor on the inner circumferential side; and a cooling device cooling the outer and inner superconductors to a temperature equal to or lower than the superconducting transition temperature, wherein the inner superconductor is formed so that a ratio (Jc1/Jcz1) of a critical current density (Jc1) of the inner superconductor in the circumferential direction to a critical current density (Jcz1) of the inner superconductor in the axial direction is closer to 1 than a ratio (Jc2/Jcz2) of the critical current density (Jc2) in the circumferential direction to a critical current density (Jcz2) of the outer superconductor of the outer superconductor in the axial direction.