Local compression of the magnetic particle imaging system matrix for efficient image reconstruction

Magnetic particle imaging (MPI) is a quantitative method for determining the spatial distribution of magnetic nanoparticles, which can be used as tracers for cardiovascular imaging [1,2,3]. For reconstructing a spatial map of the particle distribution, the system matrix describing the magnetic particle imaging equation has to be known. Due to the complex dynamic behavior of the magnetic particles, the system matrix is commonly measured in a calibration procedure. In order to speed-up the reconstruction process, in [4], a matrix compression technique has been proposed that makes use of a basis transformation in order to sparsify the MPI system matrix. By thresholding the resulting matrix and storing the remaining entries in compressed row storage format, only a fraction of the data has to be processed when reconstructing the particle distribution. The purpose of this work is to improve the compression rate for this technique.