Skip to main page content
U.S. flag

An official website of the United States government

Dot gov

The .gov means it’s official.
Federal government websites often end in .gov or .mil. Before sharing sensitive information, make sure you’re on a federal government site.

Https

The site is secure.
The https:// ensures that you are connecting to the official website and that any information you provide is encrypted and transmitted securely.

Access keys NCBI Homepage MyNCBI Homepage Main Content Main Navigation
. 2010 Apr;63(4):1104-10.
doi: 10.1002/mrm.22254.

POCS-enhanced correction of motion artifacts in parallel MRI

Affiliations

POCS-enhanced correction of motion artifacts in parallel MRI

Alexey A Samsonov et al. Magn Reson Med. 2010 Apr.

Abstract

A new method for correction of MRI motion artifacts induced by corrupted k-space data, acquired by multiple receiver coils such as phased arrays, is presented. In our approach, a projections onto convex sets (POCS)-based method for reconstruction of sensitivity encoded MRI data (POCSENSE) is employed to identify corrupted k-space samples. After the erroneous data are discarded from the dataset, the artifact-free images are restored from the remaining data using coil sensitivity profiles. The error detection and data restoration are based on informational redundancy of phased-array data and may be applied to full and reduced datasets. An important advantage of the new POCS-based method is that, in addition to multicoil data redundancy, it can use a priori known properties about the imaged object for improved MR image artifact correction. The use of such information was shown to improve significantly k-space error detection and image artifact correction. The method was validated on data corrupted by simulated and real motion such as head motion and pulsatile flow.

PubMed Disclaimer

Figures

Figure 1
Figure 1
Block-diagram of the proposed motion correction algorithm.
Figure 2
Figure 2
Magnitude (a) and phase (b) of an MR image corrupted by motion.
Figure 3
Figure 3
Comparison of detection plots for different motion correction approaches (x-axis represents phase encode direction). Detection plots are formed using method of multiple k-space copies regeneration (13) and the proposed method without constraining, with object support, with phase constraint, and both constraints. Arrows point to unresolved k-space errors. Inclusion of more information gradually improves identification of corrupted lines. Note excellent resolution of continuous k-space errors when detection is attempted with phase constraint.
Figure 4
Figure 4
Correction of brain data corrupted by bulk motion. a: Corrupted image, b: Corrected image. c: Absolute value of difference between (a) and (b) (x4).
Figure 5
Figure 5
Correction of neck images corrupted by pulsatile motion of cerebrospinal fluid (CSF). Corrupted image (a) was corrected by the proposed method both without (b) and with support and phase constraints (c). The corresponding magnified ROIs are given in d, e, f, respectively. Note the increase in CSF intensity and its homogeneity around spinal cord from d to e to f. The mean values within the CSF ring are 0.901, 0.986, and 1.019 for uncorrected (d), POCSENSE-corrected (e), POCSENSE+support+phase corrected (f) cases, respectively. The differences between corrupted and corrected images (b, c) (x4) illustrating the removed artifacts are given in (g) and (h), respectively.

Similar articles

Cited by

References

    1. Pruessmann KP, Weiger M, Scheidegger MB, Boesiger P. SENSE: sensitivity encoding for fast MRI. Magn Reson Med. 1999;42:952–962. - PubMed
    1. Sodickson DK, Manning WJ. Simultaneous acquisition of spatial harmonics (SMASH): ultra-fast imaging with radiofrequency coil arrays. Magn Reson Med. 1997;38:591–603. - PubMed
    1. Bydder M, Larkman DJ, Hajnal JV. Generalized SMASH imaging. Magn Reson Med. 2002;47:160–170. - PubMed
    1. Kyriakos WE, Panych LP, Kacher DF, Westin CF, Bao SM, Mulkern RV, Jolesz FA. Sensitivity profiles from an array of coils for encoding and reconstruction in parallel (SPACE RIP) Magn Reson Med. 2000;44:301–308. - PubMed
    1. Griswold MA, Jakob PM, Heidemann RM, Nittka M, Jellus V, Wang J, Kiefer B, Haase A. Generalized autocalibrating partially parallel acquisition (GRAPPA) Magn Reson Med. 2002;47:1202–1210. - PubMed

Publication types