Siemens Aktiengesellschaft

Zhong You Ren

Cheng Ni

Chao Wang

Jin Chen

Jing Gao

Xing En Yu

Hui Cao

Xi Yang Du

Huai Yu Pan

A current lead for the superconducting magnet of a magnetic resonance system, the superconducting magnet being refrigerated by a cold head, has a positive current lead and a negative current lead electrically connected to the superconducting magnet for magnetization thereof. The cold head is electrically connected to the superconducting magnet and is used as one of the positive and negative current leads. The cold head is used as the positive current lead or the negative current lead so as to reduce the number of current leads as well as the heat conducted by the current lead, therefore it maintains a stable superconducting environment more efficiently. Furthermore, the cold head and the current lead can be provided in the same conduit without the need to design a separated turret tube and side tube, and the structure of the current leads of the superconducting magnet of the magnetic resonance system is simplified.

Current lead of superconducting magnet of magnetic resonance system

A method for reducing eddy currents caused by the gradient magnetic field in a magnetic resonance system employs an anti-eddy current device formed by a number of laminated metallic plates, and includes the steps of calculating the distribution of the main magnetic field of the magnetic resonance system in the anti-eddy current device, calculating the distribution of the main magnetic field and the gradient magnetic field in the anti-eddy current device, subtracting the calculated distribution of the main magnetic field in the anti-eddy current device from the calculated distribution of the main magnetic field and the gradient magnetic field in the anti-eddy current device, to obtain the distribution of the gradient magnetic field in the anti-eddy current device, and adjusting the setting of the metallic plates of the anti-eddy current device based on the distribution of the gradient magnetic field in the anti-eddy current device, so as to reduce the eddy current. The adjustment in the metallic plates of the anti-eddy current device should be such that the gradient magnetic field is parallel to or substantially parallel to the plane of the metallic plates. The metallic plates can be further divided into a number of areas, or the laminating direction of the metallic plates in different areas can be adjusted according to the specific distribution of the gradient magnetic field to obtain the optimum effect of eddy current reduction.

Method of reducing eddy currents caused by a gradient magnetic field in a magnetic resonance system

In a shimming method for an irregular object to be examined by magnetic resonant equipment magnetic field parameters are measured at measurement points located on the surface of an irregular object to be examined. Based on the measured magnetic field parameters, the positions and number of shims for adjusting magnetic field homogeneity are calculated when a passive shimming is to be performed, or the current value in a shimming coil are calculated when an active shimming is to be performed, or at the same time both the positions and number of shims and current value in the shimming coil are calculated when active shimming and passive shimming are to be performed at the same time. Shimming is then performed according to the calculated results. These above steps are repeated until achieving required magnetic field homogeneity. Since the homogeneous region is designed to have an irregular shape, it can provide a better coverage of the irregular object to be examined, and at the same time it reduces the shimming constraints to the unnecessary regions outside the irregular object to be examined, therefore avoiding shimming in those unnecessary regions.

Shimmed magnetic resonance imaging apparatus and shimming method therefor

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Shenzhen, China

Zhong You Ren