Читать книгу Magnetic Resonance Microscopy - Группа авторов - Страница 65

Several additional geometries have been proposed to create uniform field volumes for MR. The approach of Manz et al. uses a variant of a Halbach sphere using a ring magnet (disk with hole), magnetized along the cylindrical axis and two simple cylinder magnets [117]. A yoked permanent magnet design was introduced for imaging cartilage in the knee at the magic angle, which requires the magnetic field to be rotated relative to the knee about two axes (the Halbach cylinder and conventional dipole are limited to a single rotation axis) [118]. The “Auberg ring” design uses radially magnetized rings on a cylinder to produce a field along the axis of the cylinder [119,120] and has seen increased interest for low-field MRI [25,121–123].