Method of determining a spatial distribution of magnetic particles

A method of determining a spatial distribution of magnetic particles (102) in an examination area, comprising the steps

• a) generating a first, temporally constant magnetic field with a spatial course of the magnetic field strength such that in the examination area there is a first part-region (301) having a relatively low magnetic field strength and a second part-region (302) having a relatively high magnetic field strength,
• b) changing the spatial position of the two part-regions (301, 302) in the examination area so that the magnetization of the particles (102) changes locally,
• c) recording real measured values which depend on the magnetization in the examination area, said magnetization being influenced by the change in position of the two part-regions (301, 302),
• d) reconstructing the spatial distribution ({right arrow over (c)}) of magnetic particles in the examination area from the real measured values, by means of the following steps:
• providing a transfer function which, applied to a dependence distribution which depends on a spatial distribution ({right arrow over (c)}) of magnetic particles, supplies fictitious measured values, and also providing a regularization parameter (λ) and a regularization functional (F) which can be applied to a dependence distribution which depends on a spatial distribution ({right arrow over (c)}) of magnetic particles,
• determining a dependence distribution which depends on a spatial distribution ({right arrow over (c)}) of magnetic particles, such that a sum which comprises as summands
• i) the difference of the real measured values ({right arrow over (V)}) from fictitious measured values which are determined by applying the transfer function to the dependence distribution, and
• ii) the product of the regularization parameter (λ) and of a regularization value which is determined by applying the regularization functional (F) to the dependence distribution, is minimized,
• e) determining using a processor, the spatial distribution ({right arrow over (c)}) of magnetic particles from the determined dependence distribution.