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. Author manuscript; available in PMC: 2016 Jul 15.
Published in final edited form as: Neuroimage. 2015 Mar 27;115:269–280. doi: 10.1016/j.neuroimage.2015.03.050

Figure 8.

Figure 8

Performance of registration-based distortion correction in dataset-1. (a) The joint-histogram of the reference displacement (calculated from the fieldmap) and estimated displacement using (left) NMI and (right) INVERSION based method. (b) Box-and-whisker plots showing the absolute error in displacement estimated using NMI and INVERSION based distortion correction methods across (left) minimally distorted and (right) severely distorted voxels. The box extends from 25th to 75th percentile with the interior line representing the median and the whiskers extending from 10th to 90th percentile. (c) Qualitative comparison of distortion correction methods in (top) an axial and (bottom) a sagittal slice. Fieldmap based correction is shown as a reference for comparison. The distortion-corrected T2W-EPI images are shown overlaid with edge maps from the T1-weighted MPRAGE image in red. Arrows point to areas with inaccurate distortion correction in the NMI-based correction. (d) Visualization of the absolute errors (in mm) in displacement relative to the fieldmap estimated by INVERSION and NMI-based methods in (top) an axial and (bottom) a sagittal slice.