Axially unlimited elongation of a volume-covering sampling trajectory for a novel 3D MPI scanner with cylindrical field-of-view

• Applicant: Professor Dr. Thorsten Buzug
• Subject Area: Medical Physics, Biomedical Technology
• Term: from 2014 to 2020
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 264145401

The aim of this proposal is the development, simulation, and technical validation of an innovative data acquisition method for Magnetic Particle Imaging (MPI), reducing the technical complexity of the coil topology to a 2D setup combined with a continuous translation of the measuring object, in order to achieve an axially unlimited cylindrical measuring field by a linear elongation of the sampling trajectory. Essential criteria for an imaging system are a high spatial resolution, a high sensitivity, and real-time capability. Combining these criteria, MPI has the potential to set new standards. The procedure is based on visualizing the concentration of nanoparticles with cores made of superparamagnetic iron oxide (SPIO). The most important physical characteristics of the SPIOs are a non-linear magnetization and saturation behavior. The non-linearity of the particle magnetization, excited by a sinusoidal magnetic field, contributes to the signal generation, responding with a non-sinusoidal variation of the magnetization, from which harmonics can be measured. Although the criteria of high spatial resolution, high sensitivity and real-time capability are fulfilled in an excellent way using MPI, the realized prototype systems suffer from a very small measuring field. Due to this, the measuring field is extended in axial direction in this proposal. This is achieved by a two-dimensional, symmetrical arrangement of gradient coils and excitation coils in conventional geometry, enclosing the measuring field resulting in cylindrical access. The two-dimensional measuring field is sampled by a planar trajectory, while translating the measuring object with a continuous feed through the measuring field. The resulting linear axial elongated and volume covering path of the sampling point leads to a subsampling in the transversal plane. A key element of the data acquisition strategy is to research suitable interpolation strategies to complete the sampling in the transversal plane. Performing a simulation and measuring based evaluation of three currently implemented MPI scanner topologies (FFP scanner with cylindrical measuring field, single-sided FFP scanner with asymmetric coil topology, and FFL scanner with cylindrical measuring field) will be a fundamental step towards the realization of three-dimensional real-time MPI, paving the way for human full-body MPI.

• DFG Programme: Research Grants