Patent ID: 6621267
Filing Date: 2003-09-16
Classification: A61B,G01R

Abstract:
Magnetic resonance imaging apparatus comprising:a C-shaped ferromagnetic yoke defining a ferromagnetic flux path for magnetic flux and having a patient-receiving gap for receiving a patient to be studied by magnetic resonance, and said C-shaped ferromagnetic yoke having a pair of facing and spaced pole surfaces for defining the patient-receiving gap therebetween; a source of magnetic flux for generating magnetic flux flowing from one to the other of said pole surfaces through the patient-receiving gap; and means for reducing magnetic field asymmetry within the gap induced by asymmetry of said C-shaped yoke including at least one auxiliary gap devoid of ferromagnetic material in said C-shaped ferromagnetic yoke at a position sufficiently close to the patient-receiving gap to homogenize the magnetic field crossing said pole surfaces and reduce magnetic field asymmetry within the patient-receiving gap.