An imaging apparatus, such as an MRI system, contains at least one layer of soft magnetic material between the yoke and each permanent magnet. This imaging apparatus may be operated without pole pieces due to the presence of the soft magnetic material. The permanent magnets may be fabricated by magnetizing...http://www.google.ca/patents/US7023309?utm_source=gb-gplus-sharePatent US7023309 - Permanent magnet assembly and method of making thereof
