An apparatus for influencing and/or detecting magnetic particles in a field of view, which apparatus comprises: i) selection-and-focus means for generating a magnetic selection-and-focus field having a pattern in space of its magnetic field strength such that a first sub-zone having a low magnetic field strength where the magnetization of the magnetic particles is not saturated and a second sub-zone having a higher magnetic field strength where the magnetization of the magnetic particles is saturated are formed in the field of view and for changing the position in space of the field of view within an examination area, said selection-and-focus means comprising at least one set of selection-and-focus field coils (114; 113, 115-119) and a selection-and-focus field generator unit for generating selection-and-focus field currents to be provided to said at least one set of selection-and-focus field coils (114; 113, 115-119) for controlling the generation of said magnetic selection-and-focus field, wherein said at least one set of selection-and-focus field coils comprises: - at least one inner selection-and-focus field coil (113, 115) being formed as a closed loop about an inner coil axis, - a group of at least two outer selection-and-focus field coils arranged at a larger distance from said inner coil axis than said at least one inner selection-and-focus field coil (113, 115) and at different angular positions, each being formed as a closed loop about an associated outer coil axis (116a-119a), and ii) drive means comprising a drive field signal generator unit and drive field coils (124; 125, 126, 127) for changing the position in space and/or size of the two sub-zones (52, 54) in the field of view by means of a magnetic drive field so that the magnetization of the magnetic material changes locally; characterized in that said at least one set of selection-and-focus field coils further comprises at least one pole shoe (310, 320; 510, 520) having a number of pole shoe segments carrying the various selection-and-focus field coils and a pole shoe yoke connecting said pole shoe segments. i) selection-and-focus means for generating a magnetic selection-and-focus field having a pattern in space of its magnetic field strength such that a first sub-zone having a low magnetic field strength where the magnetization of the magnetic particles is not saturated and a second sub-zone having a higher magnetic field strength where the magnetization of the magnetic particles is saturated are formed in the field of view and for changing the position in space of the field of view within an examination area, said selection-and-focus means comprising at least one set of selection-and-focus field coils (114; 113, 115-119) and a selection-and-focus field generator unit for generating selection-and-focus field currents to be provided to said at least one set of selection-and-focus field coils (114; 113, 115-119) for controlling the generation of said magnetic selection-and-focus field, wherein said at least one set of selection-and-focus field coils comprises: - at least one inner selection-and-focus field coil (113, 115) being formed as a closed loop about an inner coil axis, - a group of at least two outer selection-and-focus field coils arranged at a larger distance from said inner coil axis than said at least one inner selection-and-focus field coil (113, 115) and at different angular positions, each being formed as a closed loop about an associated outer coil axis (116a-119a), and - at least one inner selection-and-focus field coil (113, 115) being formed as a closed loop about an inner coil axis, - a group of at least two outer selection-and-focus field coils arranged at a larger distance from said inner coil axis than said at least one inner selection-and-focus field coil (113, 115) and at different angular positions, each being formed as a closed loop about an associated outer coil axis (116a-119a), and ii) drive means comprising a drive field signal generator unit and drive field coils (124; 125, 126, 127) for changing the position in space and/or size of the two sub-zones (52, 54) in the field of view by means of a magnetic drive field so that the magnetization of the magnetic material changes locally;