Arrangement and method for detecting and/or locating a magnetic material in a region of action

An arrangement (10) for detecting and/or locating a magnetic material (100) in a region of action (300), which arrangement comprises:

• selection means (210) for generating a magnetic selection field (211) having a pattern in space of its magnetic field strength such that a first sub-zone (301) having a low magnetic field strength and a second sub-zone (302) having a higher magnetic field strength are formed in the region of action (300),
• drive means (220) for changing the position in space of the two sub-zones (301, 302) in the region of action (300) by means of a magnetic drive field (221) so that the magnetization of the magnetic material (100) changes locally,
• receiving means (230) for acquiring detection signals, which detection signals depend on the magnetization in the region of action (300), which magnetization is influenced by the change in the position in space of the first and second sub-zone (301, 302),
• storage means (75) for storing a subset of system function data of the arrangement's system function, said system function comprising a system function data set describing the relation between spatial position of the magnetic material and the system response for said arrangement and the trajectory along which said first sub-zone (301) is moved for the acquisition of said system function data, and
• reconstruction means (74) for reconstructing the spatial distribution of the magnetic material (100) in the region of action (300) from the detection signals and the stored subset of the system function data, using additional knowledge about the structure of the system function.