The present invention relates to an apparatus and a method for influencing and/or detecting magnetic particles in a field of view (28), in particular for examination of human patients. The apparatus comprises i) selection-and-focus means (120) for generating a magnetic selection-and-focus field (50), 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 (115a),first inner selection-and-focus field coil (115) -a group of at least two outer selection-and-focus field coils (116-119) arranged at a larger distance from said inner coil axis (115a) 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 (120) comprising a drive field signal generator unit (122) 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 (28) by means of a magnetic drive field so that the magnetization of the magnetic material changes locally.La presente invención se relaciona con un aparato y método para alterar y/o detectar partículas magnéticas en un campo de visión (28), en particular para examen de pacientes humanos. El aparato comprende: i) un medio de selección y enfoque (120) para generar un campo de selección y enfoque magnético (50), en donde por lo menos un conjunto de bobinas de campo de selección y enfoque comprenden: - por lo menos una bobina de campo de selección y enfoque interna (113, 115) que está conformada como un circuito cerrado alrededor de un eje de bobina interno (115a), primera bobina de campo de selección y enfoque interna (115) - un grupo de por lo menos dos bobinas de campo de selección y enfoque externas (116 a 119) distribuidas a una distancia más grande de los ejes de bobina internos (115a) e
