by Uten Yarach, Yi-Hang Tung, Kawin Setsompop, Myung-Ho In, Itthi Chatnuntawech, Renat Yakupov, Frank Godenschweger, Oliver Speck
Abstract:
Purpose To develop a reconstruction pipeline that intrinsically accounts for both simultaneous multislice echo planar imaging (SMS-EPI) reconstruction and dynamic slice-specific Nyquist ghosting correction in time-series data. Methods After 1D slice-group average phase correction, the separate polarity (i.e., even and odd echoes) SMS-EPI data were unaliased by slice GeneRalized Autocalibrating Partial Parallel Acquisition. Both the slice-unaliased even and odd echoes were jointly reconstructed using a model-based framework, extended for SMS-EPI reconstruction that estimates a 2D self-phase map, corrects dynamic slice-specific phase errors, and combines data from all coils and echoes to obtain the final images. Results The percentage ghost-to-signal ratios (\%GSRs) and its temporal variations for MB3Ry2 with a field of view/4 shift in a human brain obtained by the proposed dynamic 2D and standard 1D phase corrections were 1.37 ± 0.11 and 2.66 ± 0.16, respectively. Even with a large regularization parameter λ applied in the proposed reconstruction, the smoothing effect in fMRI activation maps was comparable to a very small Gaussian kernel size 1 × 1 × 1 mm3. Conclusion The proposed reconstruction pipeline reduced slice-specific phase errors in SMS-EPI, resulting in reduction of GSR. It is applicable for functional MRI studies because the smoothing effect caused by the regularization parameter selection can be minimal in a blood-oxygen-level–dependent activation map.
Reference:
Dynamic 2D self-phase-map Nyquist ghost correction for simultaneous multi-slice echo planar imaging (Uten Yarach, Yi-Hang Tung, Kawin Setsompop, Myung-Ho In, Itthi Chatnuntawech, Renat Yakupov, Frank Godenschweger, Oliver Speck), In Magnetic Resonance in Medicine, volume 80, 2018.
Bibtex Entry:
@article{yarach_dynamic_2018,
title = {Dynamic 2D self-phase-map {Nyquist} ghost correction for simultaneous multi-slice echo planar imaging},
volume = {80},
url = {https://onlinelibrary.wiley.com/doi/abs/10.1002/mrm.27123},
doi = {10.1002/mrm.27123},
abstract = {Purpose To develop a reconstruction pipeline that intrinsically accounts for both simultaneous multislice echo planar imaging (SMS-EPI) reconstruction and dynamic slice-specific Nyquist ghosting correction in time-series data. Methods After 1D slice-group average phase correction, the separate polarity (i.e., even and odd echoes) SMS-EPI data were unaliased by slice GeneRalized Autocalibrating Partial Parallel Acquisition. Both the slice-unaliased even and odd echoes were jointly reconstructed using a model-based framework, extended for SMS-EPI reconstruction that estimates a 2D self-phase map, corrects dynamic slice-specific phase errors, and combines data from all coils and echoes to obtain the final images. Results The percentage ghost-to-signal ratios (\%GSRs) and its temporal variations for MB3Ry2 with a field of view/4 shift in a human brain obtained by the proposed dynamic 2D and standard 1D phase corrections were 1.37 ± 0.11 and 2.66 ± 0.16, respectively. Even with a large regularization parameter λ applied in the proposed reconstruction, the smoothing effect in fMRI activation maps was comparable to a very small Gaussian kernel size 1 × 1 × 1 mm3. Conclusion The proposed reconstruction pipeline reduced slice-specific phase errors in SMS-EPI, resulting in reduction of GSR. It is applicable for functional MRI studies because the smoothing effect caused by the regularization parameter selection can be minimal in a blood-oxygen-level–dependent activation map.},
number = {4},
journal = {Magnetic Resonance in Medicine},
author = {Yarach, Uten and Tung, Yi-Hang and Setsompop, Kawin and In, Myung-Ho and Chatnuntawech, Itthi and Yakupov, Renat and Godenschweger, Frank and Speck, Oliver},
year = {2018},
keywords = {Nyquist ghost, self-phase map, slice-specific phase correction, SMS-EPI},
pages = {1577--1587}
}