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 'Motion Artifact' 
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Result : Searchterm 'Motion Artifact' found in 5 terms [] and 19 definitions []
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Resources  (1)  
 
Motion ArtifactInfoSheet: - Artifacts - 
Case Studies, 
Reduction Index, 
etc.MRI Resource Directory:
 - Artifacts -
 
Quick Overview
Please note that there are different common names for this artifact.

Artifact Information
NAME Motion, phase encoded motion, instability, smearing
DESCRIPTION Blurring and ghosting
REASON Movement of the imaged object
HELP Compensation techniques, more averages, anti spasmodic

Patient motion is the largest physiological effect that causes artifacts, often resulting from involuntary movements (e.g. respiration, cardiac motion and blood flow, eye movements and swallowing) and minor subject movements.
Movement of the object being imaged during the sequence results in inconsistencies in phase and amplitude, which lead to blurring and ghosting. The nature of the artifact depends on the timing of the motion with respect to the acquisition. Causes of motion artifacts can also be mechanical vibrations, cryogen boiling, large iron objects moving in the fringe field (e.g. an elevator), loose connections anywhere, pulse timing variations, as well as sample motion. These artifacts appear in the phase encoding direction, independent of the direction of the motion.


Image Guidance
Motion artifacts can be flipped 90 by swapping the phase//frequency encoding directions.
The artifacts can be reduced by using breath holding, cardiac synchronization or respiratory compensation techniques: triggering, gating, retrospective triggering or phase encoding artifact reduction. Flow effects can be reduced by using gradient moment nulling of the first order of flow, gradient moment rephasing or flow compensation, depending of the MRI system.
Peristaltic motion can be reduced with the intravenous injection of an anti-spasmodic (e.g. Buscopan).
By using multiple averages, respiratory motion can be reduced in the same way that multiple averages increase the signal to noise ratio. Noticeable motion averaging is seen when four averages are obtained, six averages are often as good as respiratory compensation techniques and higher averages will continue to improve image quality.
In some cases will help a presaturation of the anatomy that was generating the motion.
See also Phase Encoded Motion Artifact.
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• Related Searches:
    • Motion Compensation Pulse Sequences
    • Phase Encoded Motion Artifact
    • Claustrophobia
    • Blurring
    • MRI Procedure
 
Further Reading:
  News & More:
Motion-compensation of Cardiac Perfusion MRI using a Statistical Texture Ensemble(.pdf)
June 2003   by www.imm.dtu.dk    
Searchterm 'Motion Artifact' was also found in the following service: 
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Radiology  (2) Open this link in a new window
Cardiac Motion ArtifactInfoSheet: - Artifacts - 
Case Studies, 
Reduction Index, 
etc.MRI Resource Directory:
 - Artifacts -
 
Quick Overview
Artifact Information
NAME Cardiac motion
DESCRIPTION Blurring, ghosting
REASON Cardiac motion
HELP cardiac and respiratory synchronization

Movement of the heart causes blurring and ghosting in the images. The artifacts appear in the phase encoding direction, independent of the direction of the motion.


Image Guidance
These artifacts can be reduced by using cardiac synchronization: triggering, gating or retrospective triggering. Maximum reduction can be achieved by using triggering in combination with flow compensation, respiratory triggering or breath hold and regional saturation techniques.
See also Motion Artifact.

 
Images, Movies, Sliders:
 Cardiac Infarct Short Axis Cine bFFE 1  Open this link in a new window
    
 Normal Dual Inversion Fast Spin-echo  Open this link in a new window
 
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• View the DATABASE results for 'Cardiac Motion Artifact' (2).Open this link in a new window

 
Further Reading:
  Basics:
Motion-compensation of Cardiac Perfusion MRI using a Statistical Texture Ensemble(.pdf)
June 2003   by www.imm.dtu.dk    
MRI Resources 
Crystallography - Stent - Open Directory Project - Mobile MRI Rental - Resources - Cardiovascular Imaging
 
Phase Encoded Motion ArtifactInfoSheet: - Artifacts - 
Case Studies, 
Reduction Index, 
etc.MRI Resource Directory:
 - Artifacts -
 
Quick Overview
Please note that there are different common names for this artifact.

Artifact Information
NAME Phase encoded motion, motion, phase effect
DESCRIPTION Blurring and ghosting
REASON Movement of the imaged object
HELP Compensation techniques, more averages, anti spasmodic, presaturation

This artifact is caused by movements of the patient or organic processes taking place in the body of the patient. The artifact appears as bright noise, repeating densities or ghosting in the phase encoding direction.


Image Guidance
There are different solutions for reduction of phase encoded motion artifacts.
Cardiac and respiratory gating, breath holding, sedation of the patient, presaturation pulses for flow artifacts (e.g. arterial pulsation, breathing), fast imaging sequences, etc.
See also Motion Artifact, Ghosting Artifact, Motion Compensation Pulse Sequences and Artifact Reduction - Motion.
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• View the DATABASE results for 'Phase Encoded Motion Artifact' (5).Open this link in a new window

 
Further Reading:
  Basics:
Artifacts in MRI
Saturday, 1 October 2011   by www.huc.min-saude.pt    
Searchterm 'Motion Artifact' was also found in the following services: 
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Resources  (1)  
 
Motion Artifact Suppression TechniqueMRI Resource Directory:
 - Artifacts -
 
(MAST) See Gradient Motion Rephasing and Motion Artifact.
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• View the DATABASE results for 'Motion Artifact Suppression Technique' (3).Open this link in a new window

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Radiology  (2) Open this link in a new window
Shimadzu Motion Artifact Reduction Technique
 
(SMART) Movement of the chest and abdominal wall also causes blurring and ghosting in the images due to variation of signal during data collection. Using SMART averaging is one way of reducing these artifacts but is not always possible or effective enough.
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• View the DATABASE results for 'Shimadzu Motion Artifact Reduction Technique' (2).Open this link in a new window

MRI Resources 
Cardiovascular Imaging - Sequences - Corporations - - Education - Cochlear Implant
 
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