Apparatus and method for influencing and/or detecting magnetic particles

An apparatus (100) for influencing and/or detecting magnetic particles in a field of view (28), which apparatus comprises:

• selection means comprising a selection field signal generator unit (110) and selection field elements (116) for generating a magnetic selection field (50) having a pattern in space of its magnetic field strength such that a first sub-zone (52) having a low magnetic field strength where the magnetization of the magnetic particles is not saturated and a second sub-zone (54) having a higher magnetic field strength where the magnetization of the magnetic particles is saturated are formed in the field of view (28),
• drive means comprising a drive field signal generator unit (130) and drive field coils (136a, 136b, 136c) for changing the position in space of the two sub-zones (52, 54) in the field of view (28) by means of a magnetic drive field so that the magnetization of the magnetic particles changes locally,
• wherein said drive field signal generator unit (130) is adapted to provide a time-dependent oscillating drive field current per drive field coil for driving the respective drive field coil, each drive field current having one or more individual oscillating frequencies and one or more individual current amplitudes and being generated by a corresponding drive field voltage per drive field coil (136a, 136b, 136c), each drive field voltage being generated by a superposition of a number of drive field voltage components including a drive field voltage component per drive field coil, wherein a drive field voltage component corresponding to a particular drive field coil comprises one or more sub-components, a sub-component having an individual voltage amplitude and having the same individual oscillating frequency as the respective drive field current of said particular drive field coil.