International Journal on Magnetic Particle Imaging
Vol 3 No 1 (2017): Int J Mag Part Imag

Research Articles

Comparison of System-Matrix-Based and Projection-Based Reconstructions for Field Free Line Magnetic Particle Imaging

Main Article Content

Serhat Ilbey (Advanced Sensing Research Program Department, ASELSAN A. Ş.), Can Barış Top (Advanced Sensing Research Program Department, ASELSAN A. Ş.), Alper Güngör (Advanced Sensing Research Program Department, ASELSAN A. Ş.), Tolga Çukur (Department of Electrical and Electronics Engineering, Bilkent University, Ankara, Turkey National Magnetic Resonance Research Center (UMRAM), Bilkent University, Ankara, Turkey), Emine Ulku Saritas (Department of Electrical and Electronics Engineering, Bilkent University, Ankara, Turkey National Magnetic Resonance Research Center (UMRAM), Bilkent University, Ankara, Turkey), H. Emre Güven (Advanced Sensing Research Program Department, ASELSAN A. Ş.)

Abstract

In magnetic particle imaging (MPI), system sensitivity can be enhanced by scanning the sample along a field free line (FFL) instead of a field free point (FFP). FFL MPI data can then be processed via system-matrix or projection-based reconstructions. Here, we compare the relative performance of these two approaches. We assume an ideal FFL (straight and homogeneous), which is translated and rotated in a two-dimensional field-of-view. We simulate the acquired data from a numerical vessel phantom for a broad range of noise levels. For the system-matrix reconstruction, we propose Alternating Direction Method of Multipliers (ADMM) to solve a constrained convex optimization problem. We also analyze the results of the nonnegative fused lasso (NFL) model to compare the performance of ADMM with one of the state-of-the-art system-matrix-based methods. For the projection-based reconstruction, we use the inverse Radon transform formulation with x-space reconstruction. System-matrix-based methods resulted in a higher structural similarity index and contrast compared to the x-space reconstruction method at the expense of longer reconstruction time. Artifacts occurred due to gridding errors for the x-space reconstruction. As expected, ADMM and NFL reconstructions yielded similar image quality. 

Article Details