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. Author manuscript; available in PMC: 2015 Aug 1.
Published in final edited form as: Magn Reson Med. 2013 Sep 4;72(2):347–361. doi: 10.1002/mrm.24924

Figure 3.

Figure 3

Block diagram of the autofocus motion correction algorithm. (a) A normalized mutual information metric is used to estimate SI, AP, and RL displacements from sagittal and coronal iNAVs. (b) A set of motion basis waveforms is constructed by amplitude-scaling the measured SI, AP, and RL displacements. (c) For each set of motion basis waveforms, 3D translational correction is applied in k-space via phase modulation. (d) Motion-compensated images are reconstructed using 3D gridding followed by a 3D FFT. (e) A localized gradient entropy focusing metric is computed for each image. (f) Pixelwise minimization of the focusing metric yields the final image and SI, AP, and RL motion maps.