One Medos valve could no longer be programmed after being exposed four times to the static magnetic field. All Sophy valves exhibited paramagnetic behavior after the tests. All remained programmable. Observed changes always occurred within the safety area of the magnet. Subjective disturbances resulting from paramagnetic valve behavior are absent in Medos valves and are minor in Sophy valves.
Image artifacts require careful planning of valve position.
Artifacts observed in magnetic resonance imaging are less disturbing than those observed in computed tomography. Medos valves are more stable regarding disadjustment than are Sophy valves. Radiological control of valve setting after exposure to the magnetic field is mandatory in both. Failure of the programming mechanism of one Medos valve after several exposures to the magnetic field requires clarification. This was a prospective study.