An implantable medical device comprises a sensing device for sensing a magnetic field, and a processing device configured to detect a presence of an MRI device based on measurement values obtained from the sensing device. The processing device is configured to conclude that an MRI device is present if a multiplicity of measurement values indicates an increase of a strength of the magnetic field. Further, the sensing device is configured to conduct measurements at a specified frequency in between 1 Hz and 50 Hz, in particular at 4 Hz, and to provide measurement values at a predefined sampling rate.