The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Oct. 03, 1995
Filed:
Oct. 26, 1993
Johannes P Groen, Eindhoven, NL;
Peter Van Der Meulen, Eindhoven, NL;
Gerrit H Van Yperen, Eindhoven, NL;
Antoon F Mehlkopf, Eindhoven, NL;
U.S. Philips Corporation, New York, NY (US);
Abstract
In an MRI device operating according to a spin-echo method, switched gradient magnetic fields are applied in the form of slice selection, phase encoding and read gradients. The switching of the gradients causes eddy currents in metal parts of the apparatus. The eddy currents disturb the applied magnetic fields, thereby changing the phases of the precessing nuclear spins of a body to be examined and causing artefacts in a reconstructed image. The disturbing effects of the eddy currents is compensated for by supplementing a sequence of switched gradient magnetic fields with additional gradient fields. These additional fields have zero net effect but induce further eddy currents which compensate for the disturbing effects of the eddy currents generated by the regular switched gradient magnetic fields. The additional gradient fields are chosen such that the total time-integrated strength of a gradient in any interval between two RF-pulses is substantially equal to the desired value.