Comparison of Phase Estimation Methods for Quantitative Susceptibility Mapping Using a Rotating-Tube Phantom

Figure 2

(a) An example magnitude GRE image showing both the tube ROI (small black box in center) used for the analysis and the placement of the 13 background ROIs. (b) Example frequency images in tube 3 (0.5 mM GdCl3) obtained with the single GRE sequence (1 mm, TR 45 ms) and reconstructed with MEDI.RG phase estimation method. (c) Also using SEGE + MEDI.RG, the field difference between two angles () showing that this difference is attributable to the spatially invariant component (in homogeneous areas) and a spatially variant component (in areas close to material boundaries). The spatially invariant component of the field difference is removed with frequency referencing (FR). (d) A plot of the frequency against the angle of rotation (modulo 180°) is shown for each of the data without frequency referencing (in green (x), data after frequency referencing using the frequency reference ROI #9 (blue circles), and the model’s prediction of the frequency (solid red line).

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