Understanding Phase Combine Artifact

Oct 13, 2025 by wbrum.org 68 views

Introduction

Phase combine artifact sometimes occurs in medical imaging, particularly in the context of quantitative susceptibility mapping (QSM) and susceptibility-weighted imaging (SWI). This issue can lead to incomplete phase unwrapping, resulting in artifacts at the borders of the phase wrap. In this article, we will delve into the possible causes of this problem and explore potential solutions.

Understanding Phase Combine Artifact

Phase combine artifact is a common issue in QSM and SWI, where the phase information from multiple images is combined to produce a final image. However, when the phase unwrapping process is incomplete or inaccurate, it can lead to artifacts at the borders of the phase wrap. This can result in a distorted or incomplete image, which can be challenging to interpret.

Causes of Phase Combine Artifact

There are several possible causes of phase combine artifact, including:

Incomplete phase unwrapping: When the phase unwrapping process is incomplete or inaccurate, it can lead to artifacts at the borders of the phase wrap.
Inaccurate phase information: If the phase information from multiple images is not accurate or consistent, it can lead to phase combine artifact.
Image registration issues: If the images are not properly registered, it can lead to phase combine artifact.

Potential Solutions

To address phase combine artifact, several potential solutions can be explored:

Using a different phase unwrapping algorithm: Instead of using the Romeo algorithm, other phase unwrapping algorithms such as Laplacian unwrapping can be used.
Adjusting the phase unwrapping parameters: Adjusting the phase unwrapping parameters, such as the threshold or the number of seeds, can help to improve the accuracy of the phase unwrapping process.
Using a different image registration method: Instead of using the default image registration method, other methods such as mutual information or feature-based registration can be used.
Using a different QSM or SWI reconstruction algorithm: Instead of using the ClearSWI algorithm, other QSM or SWI reconstruction algorithms such as MEDI or SWI can be used.

Case Study: ClearSWI and Romeo

In the case study presented, the ClearSWI algorithm was used with the Romeo phase unwrapping algorithm to produce a QSM image. However, the phase combine artifact was observed in the resulting image. The settings for ClearSWI and Romeo are presented below:

ClearSWI Settings

phase-scaling-strength: 4
output: clearSWI
phase-scaling-type: tanh
no-phase-rescale: false
mag-softplus-scaling: on
fix-ge-phase: false
mip-slices: 7
writesteps: nothing
magnitude: mag4D.nii.gz
no-mmap: true
verbose: true
qsm: false
unwrapping-algorithm: romeo
phase:  phase4D.nii.gz
mag-sensitivity-correction: on
Arguments: -m mag4D.nii.gz -p phase4D.nii.gz -o clearSWI -t [5.25, 11.08, 16.91, 22.74, 28.57] --unwrapping-algorithm romeo -v
ClearswiApp version: 1.3.3

Romeo Settings

compute-B0: true
output: romeo/Unwrapped.nii
mask-unwrapped: false
weights: romeo3
max-seeds: 1
individual-unwrapping: false
write-quality-all: false
correct-global: false
write-quality: true
temporal-uncertain-unwrapping: false
no-rescale: false
magnitude: mag4D.nii.gz
phase-offset-correction: on
no-mmap: false
wrap-addition: 0.0
write-phase-offsets: false
verbose: false
correct-regions: false
merge-regions: false
template: 2
threshold: Inf
phase: phase4D.nii.gz
Arguments: -p phase4D.nii.gz -o romeo/Unwrapped.nii -B -m  mag4D.nii.gz -t [5.25 11.08 16.91 22.74 28.57] -k Mask.nii --phase-offset-correction on -q
RomeoApp version: 3.2.8

Conclusion

Phase combine artifact is a common issue in QSM and SWI, which can lead to incomplete phase unwrapping and artifacts at the borders of the phase wrap. By understanding the causes of this problem and exploring potential solutions, researchers and clinicians can improve the accuracy and reliability of QSM and SWI images. In this article, we presented a case study of ClearSWI and Romeo, highlighting the settings and potential solutions for addressing phase combine artifact.

Future Directions

Future research should focus on developing more accurate and robust phase unwrapping algorithms, as well as improving image registration methods. Additionally, exploring different QSM and SWI reconstruction algorithms can help to improve the accuracy and reliability of QSM and SWI images.

Recommendations

Based on the case study presented, the following recommendations can be made:

Use a different phase unwrapping algorithm: Instead of using the Romeo algorithm, other phase unwrapping algorithms such as Laplacian unwrapping can be used.
Adjust the phase unwrapping parameters: Adjusting the phase unwrapping parameters, such as the threshold or the number of seeds, can help to improve the accuracy of the phase unwrapping process.
Use a different image registration method: Instead of using the default image registration method, other methods such as mutual information or feature-based registration can be used.
Use a different QSM or SWI reconstruction algorithm: Instead of using the ClearSWI algorithm, other QSM or SWI reconstruction algorithms such as MEDI or SWI can be used.

By following these recommendations, researchers and clinicians can improve the accuracy and reliability of QSM and SWI images, leading to better diagnosis and treatment of neurological disorders.

Introduction

Phase combine artifact is a common issue in quantitative susceptibility mapping (QSM) and susceptibility-weighted imaging (SWI), which can lead to incomplete phase unwrapping and artifacts at the borders of the phase wrap. In this article, we will address some of the frequently asked questions (FAQs) related to phase combine artifact in QSM and SWI.

Q: What is phase combine artifact?

A: Phase combine artifact is a common issue in QSM and SWI, where the phase information from multiple images is combined to produce a final image. However, when the phase unwrapping process is incomplete or inaccurate, it can lead to artifacts at the borders of the phase wrap.

Q: What are the causes of phase combine artifact?

A: There are several possible causes of phase combine artifact, including:

Incomplete phase unwrapping: When the phase unwrapping process is incomplete or inaccurate, it can lead to artifacts at the borders of the phase wrap.
Inaccurate phase information: If the phase information from multiple images is not accurate or consistent, it can lead to phase combine artifact.
Image registration issues: If the images are not properly registered, it can lead to phase combine artifact.

Q: How can I prevent phase combine artifact?

A: To prevent phase combine artifact, you can try the following:

Use a different phase unwrapping algorithm: Instead of using the Romeo algorithm, other phase unwrapping algorithms such as Laplacian unwrapping can be used.
Adjust the phase unwrapping parameters: Adjusting the phase unwrapping parameters, such as the threshold or the number of seeds, can help to improve the accuracy of the phase unwrapping process.
Use a different image registration method: Instead of using the default image registration method, other methods such as mutual information or feature-based registration can be used.
Use a different QSM or SWI reconstruction algorithm: Instead of using the ClearSWI algorithm, other QSM or SWI reconstruction algorithms such as MEDI or SWI can be used.

Q: What are the settings for ClearSWI and Romeo?

A: The settings for ClearSWI and Romeo are presented below:

ClearSWI Settings

phase-scaling-strength: 4
output: clearSWI
phase-scaling-type: tanh
no-phase-rescale: false
mag-softplus-scaling: on
fix-ge-phase: false
mip-slices: 7
writesteps: nothing
magnitude: mag4D.nii.gz
no-mmap: true
verbose: true
qsm: false
unwrapping-algorithm: romeo
phase:  phase4D.nii.gz
mag-sensitivity-correction: on
Arguments: -m mag4D.nii.gz -p phase4D.nii.gz -o clearSWI -t [5.25, 11.08, 16.91, 22.74, 28.57] --unwrapping-algorithm romeo -v
ClearswiApp version: 1.3.3

Romeo Settings

compute-B0: true
output: romeo/Unwrapped.nii
mask-unwrapped: false
weights: romeo3
max-seeds: 1
individual-unwrapping: false
write-quality-all: false
correct-global: false
write-quality: true
temporal-uncertain-unwrapping: false
no-rescale: false
magnitude: mag4D.nii.gz
phase-offset-correction: on
no-mmap: false
wrap-addition: 0.0
write-phase-offsets: false
verbose: false
correct-regions: false
merge-regions: false
template: 2
threshold: Inf
phase: phase4D.nii.gz
Arguments: -p phase4D.nii.gz -o romeo/Unwrapped.nii -B -m  mag4D.nii.gz -t [5.25 11.08 16.91 22.74 28.57] -k Mask.nii --phase-offset-correction on -q
RomeoApp version: 3.2.8

Q: What are the potential solutions for phase combine artifact?

A: The potential solutions for phase combine artifact include:

Using a different phase unwrapping algorithm: Instead of using the Romeo algorithm, other phase unwrapping algorithms such as Laplacian unwrapping can be used.
Adjusting the phase unwrapping parameters: Adjusting the phase unwrapping parameters, such as the threshold or the number of seeds, can help to improve the accuracy of the phase unwrapping process.
Using a different image registration method: Instead of using the default image registration method, other methods such as mutual information or feature-based registration can be used.
Using a different QSM or SWI reconstruction algorithm: Instead of using the ClearSWI algorithm, other QSM or SWI reconstruction algorithms such as MEDI or SWI can be used.

Q: What are the future directions for research on phase combine artifact?

A: The future directions for research on phase combine artifact include:

Developing more accurate and robust phase unwrapping algorithms: Developing more accurate and robust phase unwrapping algorithms can help to improve the accuracy and reliability of QSM and SWI images.
Improving image registration methods: Improving image registration methods can help to improve the accuracy and reliability of QSM and SWI images.
Exploring different QSM and SWI reconstruction algorithms: Exploring different QSM and SWI reconstruction algorithms can help to improve the accuracy and reliability of QSM and SWI images.

Conclusion

Phase combine artifact is a common issue in QSM and SWI, which can lead to incomplete phase unwrapping and artifacts at the borders of the phase wrap. By understanding the causes of this problem and exploring potential solutions, researchers and clinicians can improve the accuracy and reliability of QSM and SWI images. In this article, we presented a Q&A section on phase combine artifact, highlighting the settings and potential solutions for addressing this issue.