Abstract: A local shimming device and a method for compensation of non-uniformity of a main magnetic field are disclosed, wherein the local shimming device comprises: a local coil, arranged to cover a local region of an examination subject, to receive a magnetic resonance signal from the local region; multiple shim coils, wherein the multiple shim coils are integrated in the local coil or arranged to surround at least a part of the local coil; and a shimming controller, configured to control at least one shim coil of the multiple shim coils, according to a strength distribution of a main magnetic field in the local region, to provide a field distribution for compensating a component of the main magnetic field in the local region.

Abstract: A radio-frequency system for a magnetic resonance apparatus has a local coil, a body coil, and an impedance adjusting shield. The body coil is wirelessly power-coupled with the local coil such that the body coil serves as a transmitting coil for radio-frequency signals and the local coil serves as a receiving coil for magnetic resonance signals. The local coil is disposed in an internal cavity of the impedance adjusting shield. An impedance of the local coil is adjusted by the impedance adjusting shield so as to match the impedance of the local coil and the body coil. The impedance adjusting shield has a frequency modulation element that adjusts the resonance frequency of the local coil. The body coil couples power to the local coil, and the impedance adjusting shield effectively reduces energy transmission efficiency loss caused by reflection, thereby improving energy transmission efficiency.

Abstract: A radio-frequency system for a magnetic resonance apparatus has a local coil, a body coil, and an impedance adjusting shield. The body coil is wirelessly power-coupled with the local coil such that the body coil serves as a transmitting coil for radio-frequency signals and the local coil serves as a receiving coil for magnetic resonance signals. The local coil is disposed in an internal cavity of the impedance adjusting shield. An impedance of the local coil is adjusted by the impedance adjusting shield so as to match the impedance of the local coil and the body coil. The impedance adjusting shield has a frequency modulation element that adjusts the resonance frequency of the local coil. The body coil couples power to the local coil, and the impedance adjusting shield effectively reduces energy transmission efficiency loss caused by reflection, thereby improving energy transmission efficiency.

Abstract: A body coil includes a first end ring and a second end ring provided at two ends thereof. The first end ring and the second end ring are connected to each other with a plurality of legs. The first end ring or the second end ring has a structure with the current flow width in a direction parallel to the axis thereof being greater than that in a direction perpendicular to the axis thereof. Since the effective action width of the current is increased in the axial direction and the centralized flow of the current in the end ring is reduced, the local specific absorption rate of radio frequency induced by the magnetic field is therefore reduced.

Abstract: A body coil includes a first end ring and a second end ring provided at two ends thereof. The first end ring and the second end ring are connected to each other with a plurality of legs. The first end ring or the second end ring has a structure with the current flow width in a direction parallel to the axis thereof being greater than that in a direction perpendicular to the axis thereof. Since the effective action width of the current is increased in the axial direction and the centralized flow of the current in the end ring is reduced, the local specific absorption rate of radio frequency induced by the magnetic field is therefore reduced.