Abstract: Construction methods and techniques allow for a magnetic field of the field homogeneity required for the use in magnetic resonance imaging (MRI), in the order of 20 parts per million (ppm) in the area of interest (such techniques in the following will be indicated with the word “shimming”). The peculiarity of the constructive method is to obtain a homogeneous field region, usable for the MRI analysis, of linear dimensions equal to about 40% of the linear dimensions of the magnet. The shimming technique involves the use of conditioned magnetic material and allows accurate control of the magnetization of the corrective elements while using a material that inherently has a large spread in the magnetization value. The result is a low weight and small magnet suitable for MRI for dedicated clinical applications such as the analysis of the peripheral joint, the analysis of the ocular region, and veterinary applications.

Abstract: Construction methods and techniques allow for a magnetic field of the field homogeneity required for the use in magnetic resonance imaging (MRI), in the order of 20 parts per million (ppm) in the area of interest (such techniques in the following will be indicated with the word “shimming”). The peculiarity of the constructive method is to obtain a homogeneous field region, usable for the MRI analysis, of linear dimensions equal to about 40% of the linear dimensions of the magnet. The shimming technique involves the use of conditioned magnetic material and allows accurate control of the magnetization of the corrective elements while using a material that inherently has a large spread in the magnetization value. The result is a low weight and small magnet suitable for MRI for dedicated clinical applications such as the analysis of the peripheral joint, the analysis of the ocular region, and veterinary applications.

Abstract: The invention concerns an improved magnetic resonance apparatus and method for substantially reducing the dead time of the apparatus, in order to recover as much of the submicrosecond FID signals as quickly as possible. A double-channel, out-of-phase signal combination is employed. Two RF receiving coils are arranged with identical ringing characteristics, preferably mutually perpendicular to one another. The RF signal received by one coil is phase shifted by 180.degree., amplified, and combined with the amplified RF signal received by the other coil. The ringing components cancel, while the FID components in phase quadrature do not. The transmitter/receiver apparatus may be of duplex or crossed coil configuration. In the latter case, one of the receiver coils may be orientated parallel to the main field so that it receives no FID signal and operates only to reduce the dead time.