Method of determining a gradient impulse response function during execution of a magnetic resonance imaging or spectroscopy sequence

A method of determining an actual gradient impulse response function during execution of a magnetic resonance (MR) imaging or spectroscopy sequence, wherein a main magnetic field is generated in a sample region of an MR apparatus by means of a main magnet and wherein superimposed time dependent gradient fields and radiofrequency fields in a first RF band are generated in the sample region according to a first MR sequence for forming images or spectra, the gradient fields being generated by gradient forming means of the MR apparatus operated according to a gradient forming sequence part of said first MR sequence, the MR apparatus further comprising at least one magnetic field probe, each one of said magnetic field probes being located at a pre-determined position and comprising a magnetic resonance (MR) active substance, means for pulsed MR excitation of said substance and means for receiving a probe MR signal generated by said substance, wherein said pulsed MR excitation and said probe MR signal is in a second RF band that does not overlap said first RF band, the method comprising the steps of:

• operating said at least one magnetic field probe according to a second sequence, whereby a time dependent probe signal is repeatedly acquired from each magnetic field probe during a probe acquisition time window, thus providing at least one time dependent probe signal;
• obtaining said actual gradient impulse response function by calculating an impulse response function from said at least one time dependent probe signal and from said gradient forming sequence part.