According to one embodiment, a magnetic resonance imaging apparatus includes: a cylindrical magnetic pole for generating a static magnetic field in an imaging region; a cylindrical gradient magnetic field coil arranged on a radially inner side of the magnetic pole, coaxially with the magnetic pole to generate a dynamic magnetic field having a linear magnetic field strength in the imaging region; a cylindrical high frequency coil arranged on a radially inner side of the gradient magnetic field coil, coaxially with the magnetic pole and the gradient magnetic field coil to generate a high frequency magnetic field in the imaging region; and a computer system for processing signals to obtain images. The magnetic resonance imaging apparatus further includes at least two loop-shaped additional coils arranged on the radially outer side of the gradient magnetic field coil and having different electric current circulating direction.

The present invention provides a radiation shield (204), in particular for shielding main coils (202) of a magnetic resonance imaging system (110), whereby the radiation shield (204) comprises a cavity (214) for housing at least one main coil (202), whereby the cavity (214) is formed between an inner cylindrical wall (206), an outer cylindrical wall (208), which are arranged essentially concentrically to each other, and two ring-shaped base walls (212), which interconnect the inner cylindrical wall (206) and the outer cylindrical wall (208), wherein at least one out of the inner cylindrical wall (206), the outer cylindrical wall (208), and the two ring-shaped base walls (212) is provided at least partially with an inner layer (216), which faces the cavity (214), and an outer layer (218), wherein the inner layer (216) is a layer comprising carbon fiber reinforced plastic, and the outer layer (218) comprises a metal, which is paramagnetic or diamagnetic. The present invention also provides a shielded main magnet (200) comprising at least one main coil (200) for generating a static main magnetic field in a magnetic resonance imaging system (110), and a radiation shield (204) as specified above, wherein the at least one main coil (202) is housed in a cavity (214) of the radiation shield (204).

A portable magnetic resonance imaging (MRI) system and methods, involving a magnet configured to generate a magnetic field, the magnet being a portable magnet transportable on a cart, and at least one coil assembly disposed in relation to the magnet, the at least one coil assembly having at least one gradient coil.

Gradient coil assemblies for horizontal magnetic resonance imaging systems (MRIs) and methods of their manufacture. Some embodiments may be used with open MRIs and can be used with an instrument placed in the gap of the MRI. In general, concentrations of conductors or radially oriented conductors may be moved away from the gap of the MRI so as to reduce eddy currents that may be induced in any instrument placed within the gap. Systems for directly cooling primary gradient and shield coils may be utilized and various coil supporting structures may be used to assist in coil alignment or to facilitate use of an instrument in the MRI gap.

According to some aspects, a portable magnetic resonance imaging system is provided, comprising a magnetics system having a plurality of magnetics components configured to produce magnetic fields for performing magnetic resonance imaging. The magnetics system comprises a permanent B.sub.0 magnet configured to produce a B.sub.0 field for the magnetic resonance imaging system, and a plurality of gradient coils configured to, when operated, generate magnetic fields to provide spatial encoding of emitted magnetic resonance signals, a power system comprising one or more power components configured to provide power to the magnetics system to operate the magnetic resonance imaging system to perform image acquisition, and a base that supports the magnetics system and houses the power system, the base comprising at least one conveyance mechanism allowing the portable magnetic resonance imaging system to be transported to different locations. According to some aspects, the base has a maximum horizontal dimension of less than or equal to approximately 50 inches. According to some aspects, the portable magnetic resonance imaging system weighs less than 1,500 pounds. According to some aspects, the portable magnetic resonance imaging system has a 5-Gauss line that has a maximum dimension of less than or equal to five feet.

According to some aspects, a portable magnetic resonance imaging system is provided, comprising a magnetics system having a plurality of magnetics components configured to produce magnetic fields for performing magnetic resonance imaging. The magnetics system comprises a permanent B.sub.0 magnet configured to produce a B.sub.0 field for the magnetic resonance imaging system, and a plurality of gradient coils configured to, when operated, generate magnetic fields to provide spatial encoding of emitted magnetic resonance signals, a power system comprising one or more power components configured to provide power to the magnetics system to operate the magnetic resonance imaging system to perform image acquisition, and a base that supports the magnetics system and houses the power system, the base comprising at least one conveyance mechanism allowing the portable magnetic resonance imaging system to be transported to different locations. According to some aspects, the base has a maximum horizontal dimension of less than or equal to approximately 50 inches. According to some aspects, the portable magnetic resonance imaging system weighs less than 1,500 pounds. According to some aspects, the portable magnetic resonance imaging system has a 5-Gauss line that has a maximum dimension of less than or equal to five feet.

A Magnetic Resonance Imaging (MRI) system, including: two separate static magnetic field generators, which are each cylindrical, are axially aligned, and are separated by a rotary load-bearing structure arranged to freely rotate about an axis of a static magnetic field generated by the static magnetic field generators, wherein the rotary load-bearing structure is mounted on thrust bearings which take an axial load between the static magnetic field generators.

In some aspects, a method of operating a magnetic resonance imaging system comprising a B.sub.0 magnet and at least one thermal management component configured to transfer heat away from the B.sub.0 magnet during operation is provided. The method comprises providing operating power to the B.sub.0 magnet, monitoring a temperature of the B.sub.0 magnet to determine a current temperature of the B.sub.0 magnet, and operating the at least one thermal management component at less than operational capacity in response to an occurrence of at least one event.

A magnetic resonance imaging system is provided. The system includes a solenoid magnet configured to generate a static magnetic field and an annular coil assembly housed within at least a portion of the solenoid magnet. The coil assembly includes a gradient coil, wherein the annular coil assembly has an aperture formed therein.

The gradient coil assembly is designed to address a neck-shoulder clearance problem by configuring the coil holder housing with a cylindrical portion modified with a slanted surface and positioning current return elements of the coil pattern at the slanted surface, while positioning the active electrical elements on the cylindrical surface, thus eliminating influence of an undesired magnetic field generated by the current return elements, shortening the coil, and moving the homogeneous field gradient region toward the end of the cylindrical portion of the bore in the coil holder housing. The subject assembly operation is further improved by the direct external cooling approach, where a coolant flows in direct contact with electrical wires of the gradient coil inside the cooling channels in the surface of the coil holder housing.