Fast Sinogram-Based System Calibration for Field Free Line Magnetic Particle Imaging

In this study, we propose a novel calibration method for magnetic particle imaging (MPI), in which a field-based calibration procedure is employed directly in the sinogram domain for a dynamic 3D field free line (FFL) sinusoidal trajectory. Unlike the conventional voxel-wise calibration in the image-domain, our approach involves performing calibration measurements in sinogram domain with alternating magnetic field offsets. The resulting sinogram-based calibration data are then used to synthesize the 3D system matrix (SM) in the image domain by exploiting the shift invariance property of MPI systems. With the proposed method, frequency mixing terms originating from the simultaneous translation and rotation of the FFL can be acquired without the use of an external calibration device, such as a precise 3D-axis robot. The proposed sinogram-based calibration method for the 3D FFL trajectory with 100 ms duration achieved acquisition of a 57<inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$\times 57\times$</tex-math></inline-formula>11 SM in approximately 1 minute with minimal image degradation. In contrast, the conventional system calibration method requires about 1 hour for the same spatial resolution.