30-fold acceleration using sinogram-based system calibration for field free line MPI

Abstract

We propose a field-based calibration directly in the sinogram domain for a 3D field free line (FFL) dynamic sinusoidal trajectory. This approach involves performing calibration measurements with alternating magnetic field offsets for each offset and z-position in sinogram domain (covering a total of N_xy × N_z positions on a 2D grid), rather than calibration measurements for each MPI image voxel in 3D space (e.g., for N_xy × N_xy × N_z voxels). Using the sinogram-based calibration data, we synthesize the 3D system matrix (SM) in the image domain by exploiting the shift and rotation invariance of MPI systems. The proposed 2D sinogram-based calibration method for the 3D FFL trajectory achieved a 30-fold reduction in system calibration time due to reduced dimensionality, with less than 0.5% normalized RMS-error compared to 3D image-based calibration.