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:
Jan. 29, 2002
Filed:
Nov. 22, 2000
Labros S. Petropoulos, Solon, OH (US);
Heidi A. Schlitt, Chesterland, OH (US);
Michael R. Thompson, Cleveland Heights, OH (US);
Philips Medical Systems (Cleveland), Highland Heights, OH (US);
Abstract
A magnetic resonance apparatus includes a main magnet ( ) which generates a main magnetic field through and surrounding an examination region ( ). The main magnetic field contains inhomogeneities which affect image quality. A gradient coil assembly ( ) generates gradient magnetic fields across the examination region, which contain higher order harmonics causing inhomogeneities in the gradient magnetic field. A multi-axis shim set ( ) is selectively excited in order to cancel both the main magnetic and gradient magnetic field inhomogeneities. More particularly, DC currents are applied by a shim coil power supply ( ) to cancel the main magnetic field inhomogeneities. AC current pulses are superimposed on the DC currents by the shim coil power supply ( ) in order to correct the gradient magnetic field inhomogeneities. The existence of correctable higher order gradient magnetic field harmonics provides for fast switching, high duty cycles, and high peak gradients, without adding distortions to the resulting magnetic resonance images.