assembling magnetic circuitry for an mri system is disclosed . the mri system comprises two permanent magnets provided within a yoke structure such as to face each other for generating magnetic field in the space defined therebetween , and two pole pieces respectively provided on opposing surfaces of the permanent magnets . each of the pole pieces is installed at a predetermined position of the corresponding permanent magnet by sliding the pole piece on the corresponding permanent magnet in a direction parallel with a main surface of the corresponding permanent magnet on which the pole pieces is to be installed .