Patent ID: 8604794
Filing Date: 2013-12-10
Classification: G01R

Abstract:
1. A method of providing a homogeneous magnetic field within an active volume located in an air gap between a permanent magnet grouping and a facing plate within a permanent magnet structure of non-enclosed structure of Magnetic Resonance Imaging (MRI), said method comprising: providing a permanent magnet arrangement comprising: a yoke of shape selected from (i) generally C-shaped and (ii) generally U-shaped, formed from magnetically permeable material, said yoke having two ends defining an air gap therebetween; a single mobile permanent magnet grouping secured to a back plate mechanically connected to one end of said yoke; said mobile permanent magnet grouping comprising: a one-piece, disk-shaped central permanent magnet; at least one permanent magnet of substantially annular cross-section arranged substantially concentrically with respect to said central permanent magnet; each of said permanent magnets having a front surface and a rear surface, each said front surface facing said air gap; moving means for individually laterally and longitudinally moving said permanent magnets in said magnet grouping along an axis within said air gap; and, a facing plate constructed from ferromagnetic material mounted to the second end of said yoke, said facing plate disposed opposite to said mobile permanent magnet grouping and parallel to said back plate; thereby providing a magnetic field within an active volume located in said air gap between said mobile permanent magnet grouping and said facing plate, wherein said magnetic field is sufficiently homogeneous for performance of Magnetic Resonance Imaging (MRI) and further wherein said permanent magnet structure enables performance of MRI on a patient in a non-enclosed structure.