Magnetic resonance imaging apparatus with regulator for reducing eddy current effects

US5200701A · kind A · utility

Assignee

• Siemens Aktiengesellschaft · DE

Inventors

• Horst Siebold · Erlangen, DE
• Ralph Oppelt · Uttenreuth, DE
• Guenter Ries · Erlangen, DE

Key dates

• Filing date: Sep 18, 1991
• Grant date: Apr 6, 1993
• Expiry date: Sep 18, 2011

Classification

• Technology area (CPC G): Physics
• CPC primary: G01R33/385
• WIPO field: Measurement
• WIPO sector: Instruments

Abstract

A magnetic resonance imaging apparatus for producing tomograms has a C-magnet with substantially planar pole faces for generating a magnetic field in the direction of the z-axis of a Cartesian coordinate system, for examining a human body having a body axis extending in the direction x-axis, the region to be examined being disposed between the pole pieces, gradient coils substantially parallel to the pole pieces, and a regulator for controlling the gradient currents of the gradient coils using the magnetic flux associated with each gradient coil as the measure value effecting such control. The gradient currents are adjusted dependent on disturbances in the magnetic flux which are caused by eddy currents and saturation effects in the ferromagnetic material in the proximity of the pole faces. Such a regulator can also be used in combination with gradient coils for generating a gradient in the z-direction for compensating for transient inhomogeneities in the main magnetic field.