In a medical MRI apparatus, it is often desirable to have electronic
devices 62, 64 for communicating with or monitoring the patient 58 in the
imaging volume 29 of the apparatus. Such electronic devices should not
interfere with the MRI electromagnetic fields because of the high
sensitivity of such apparatus to field disturbances. According to the
invention, a shielding housing for such devices is proposed, which is
formed from customary printed circuit board (PCB). Such shielding does
not influence the MRI fields if the shielding layer 98 is made of a
material having a resistivity below 0.05 .OMEGA.m, a thickness below 40
.mu.m and the overall surface area of the shielding layer is less than
100 cm.sup.2.
