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Accelerated motion corrected three ‐ dimensional abdominal MRI using total variation regularized SENSE reconstruction

View Article: PubMed Central - PubMed

ABSTRACT

Purpose: Develop a nonrigid motion corrected reconstruction for highly accelerated free‐breathing three‐dimensional (3D) abdominal images without external sensors or additional scans.

Methods: The proposed method accelerates the acquisition by undersampling and performs motion correction directly in the reconstruction using a general matrix description of the acquisition. Data are acquired using a self‐gated 3D golden radial phase encoding trajectory, enabling a two stage reconstruction to estimate and then correct motion of the same data. In the first stage total variation regularized iterative SENSE is used to reconstruct highly undersampled respiratory resolved images. A nonrigid registration of these images is performed to estimate the complex motion in the abdomen. In the second stage, the estimated motion fields are incorporated in a general matrix reconstruction, which uses total variation regularization and incorporates k‐space data from multiple respiratory positions. The proposed approach was tested on nine healthy volunteers and compared against a standard gated reconstruction using measures of liver sharpness, gradient entropy, visual assessment of image sharpness and overall image quality by two experts.

Results: The proposed method achieves similar quality to the gated reconstruction with nonsignificant differences for liver sharpness (1.18 and 1.00, respectively), gradient entropy (1.00 and 1.00), visual score of image sharpness (2.22 and 2.44), and visual rank of image quality (3.33 and 3.39). An average reduction of the acquisition time from 102 s to 39 s could be achieved with the proposed method.

Magn reson med 75:1484–1498, 2016. © 2015 the authors. magnetic resonance in medicine published by wiley periodicals, inc. on behalf of international society for magnetic resonance.: In vivo results demonstrate the feasibility of the proposed method showing similar image quality to the standard gated reconstruction while using data corresponding to a significantly reduced acquisition time. Magn Reson Med, 2015. © 2015 The Authors. Magnetic Resonance in Medicine published by Wiley Periodicals, Inc. on behalf of International Society for Magnetic Resonance in Medicine. This is an open access article under the terms of the Creative Commons Attribution License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited.

No MeSH data available.


Related in: MedlinePlus

Coronal (top), sagittal (middle) and axial (bottom) slices for volunteer 2 with maximum respiratory amplitude of 8.2 mm (including zoom‐in images, arrows point out some main differences). NMC (non‐motion corrected): 2× undersampled at 100% gating efficiency. Some blurring is visible in image structures and the liver–lung border. Gated: 2× undersampled at 77% gating efficiency. There is no significant improvement, as the gated reconstruction uses a 5 mm window. GMD: 4× undersampled at 96% gating efficiency. The high undersampling creates a strong noise‐like aliasing. TV‐GMD: 4× undersampled at 96% gating efficiency. The total variation regularization improves GMD undersampled reconstruction at the expense of some minor blurring, despite using only 128 radial profiles.
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mrm25708-fig-0006: Coronal (top), sagittal (middle) and axial (bottom) slices for volunteer 2 with maximum respiratory amplitude of 8.2 mm (including zoom‐in images, arrows point out some main differences). NMC (non‐motion corrected): 2× undersampled at 100% gating efficiency. Some blurring is visible in image structures and the liver–lung border. Gated: 2× undersampled at 77% gating efficiency. There is no significant improvement, as the gated reconstruction uses a 5 mm window. GMD: 4× undersampled at 96% gating efficiency. The high undersampling creates a strong noise‐like aliasing. TV‐GMD: 4× undersampled at 96% gating efficiency. The total variation regularization improves GMD undersampled reconstruction at the expense of some minor blurring, despite using only 128 radial profiles.

Mentions: Figure 5 shows multiple slice orientations for the nonmotion corrected, gated, GMD and TV‐GMD reconstructions for volunteer 1. In Figure 5, it can be seen that TV‐GMD and gated reconstructions yield images of similar quality, correcting most ghosting and blurring present in the non‐motion corrected (NMC). The gated and NMC reconstructions have an undersampling factor of 2×, while the GMD and TV‐GMD resulted in an undersampling of 3.5× for this volunteer. Remaining artifacts from undersampling and noise amplification can be observed in the GMD reconstruction (Fig. 5). This effect is consistent across all volunteers and increases for higher undersampling factors. Comparison between GMD and TV‐GMD highlights how TV regularization improves the conditioning of the reconstruction. Figure 6 shows multiple slice orientations for volunteer 2, where the GMD and TV‐GMD reconstructions resulted in an undersampling of 4×, compared with 2× for the gated and NMC. The TV‐GMD presents a sharper reconstruction than the gated (Fig. 6), due to the fact that the resulting binning windows were smaller (2.76 mm average) than the gating window (5 mm). Note that undersampling artifacts are stronger for this case, but still can be reduced by TV regularization.


Accelerated motion corrected three ‐ dimensional abdominal MRI using total variation regularized SENSE reconstruction
Coronal (top), sagittal (middle) and axial (bottom) slices for volunteer 2 with maximum respiratory amplitude of 8.2 mm (including zoom‐in images, arrows point out some main differences). NMC (non‐motion corrected): 2× undersampled at 100% gating efficiency. Some blurring is visible in image structures and the liver–lung border. Gated: 2× undersampled at 77% gating efficiency. There is no significant improvement, as the gated reconstruction uses a 5 mm window. GMD: 4× undersampled at 96% gating efficiency. The high undersampling creates a strong noise‐like aliasing. TV‐GMD: 4× undersampled at 96% gating efficiency. The total variation regularization improves GMD undersampled reconstruction at the expense of some minor blurring, despite using only 128 radial profiles.
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Related In: Results  -  Collection

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mrm25708-fig-0006: Coronal (top), sagittal (middle) and axial (bottom) slices for volunteer 2 with maximum respiratory amplitude of 8.2 mm (including zoom‐in images, arrows point out some main differences). NMC (non‐motion corrected): 2× undersampled at 100% gating efficiency. Some blurring is visible in image structures and the liver–lung border. Gated: 2× undersampled at 77% gating efficiency. There is no significant improvement, as the gated reconstruction uses a 5 mm window. GMD: 4× undersampled at 96% gating efficiency. The high undersampling creates a strong noise‐like aliasing. TV‐GMD: 4× undersampled at 96% gating efficiency. The total variation regularization improves GMD undersampled reconstruction at the expense of some minor blurring, despite using only 128 radial profiles.
Mentions: Figure 5 shows multiple slice orientations for the nonmotion corrected, gated, GMD and TV‐GMD reconstructions for volunteer 1. In Figure 5, it can be seen that TV‐GMD and gated reconstructions yield images of similar quality, correcting most ghosting and blurring present in the non‐motion corrected (NMC). The gated and NMC reconstructions have an undersampling factor of 2×, while the GMD and TV‐GMD resulted in an undersampling of 3.5× for this volunteer. Remaining artifacts from undersampling and noise amplification can be observed in the GMD reconstruction (Fig. 5). This effect is consistent across all volunteers and increases for higher undersampling factors. Comparison between GMD and TV‐GMD highlights how TV regularization improves the conditioning of the reconstruction. Figure 6 shows multiple slice orientations for volunteer 2, where the GMD and TV‐GMD reconstructions resulted in an undersampling of 4×, compared with 2× for the gated and NMC. The TV‐GMD presents a sharper reconstruction than the gated (Fig. 6), due to the fact that the resulting binning windows were smaller (2.76 mm average) than the gating window (5 mm). Note that undersampling artifacts are stronger for this case, but still can be reduced by TV regularization.

View Article: PubMed Central - PubMed

ABSTRACT

Purpose: Develop a nonrigid motion corrected reconstruction for highly accelerated free‐breathing three‐dimensional (3D) abdominal images without external sensors or additional scans.

Methods: The proposed method accelerates the acquisition by undersampling and performs motion correction directly in the reconstruction using a general matrix description of the acquisition. Data are acquired using a self‐gated 3D golden radial phase encoding trajectory, enabling a two stage reconstruction to estimate and then correct motion of the same data. In the first stage total variation regularized iterative SENSE is used to reconstruct highly undersampled respiratory resolved images. A nonrigid registration of these images is performed to estimate the complex motion in the abdomen. In the second stage, the estimated motion fields are incorporated in a general matrix reconstruction, which uses total variation regularization and incorporates k‐space data from multiple respiratory positions. The proposed approach was tested on nine healthy volunteers and compared against a standard gated reconstruction using measures of liver sharpness, gradient entropy, visual assessment of image sharpness and overall image quality by two experts.

Results: The proposed method achieves similar quality to the gated reconstruction with nonsignificant differences for liver sharpness (1.18 and 1.00, respectively), gradient entropy (1.00 and 1.00), visual score of image sharpness (2.22 and 2.44), and visual rank of image quality (3.33 and 3.39). An average reduction of the acquisition time from 102 s to 39 s could be achieved with the proposed method.

Magn reson med 75:1484–1498, 2016. © 2015 the authors. magnetic resonance in medicine published by wiley periodicals, inc. on behalf of international society for magnetic resonance.: In vivo results demonstrate the feasibility of the proposed method showing similar image quality to the standard gated reconstruction while using data corresponding to a significantly reduced acquisition time. Magn Reson Med, 2015. © 2015 The Authors. Magnetic Resonance in Medicine published by Wiley Periodicals, Inc. on behalf of International Society for Magnetic Resonance in Medicine. This is an open access article under the terms of the Creative Commons Attribution License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited.

No MeSH data available.


Related in: MedlinePlus