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 'Ghosting Artifact' 
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Result : Searchterm 'Ghosting Artifact' found in 1 term [] and 4 definitions [], (+ 11 Boolean[] results
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Ghosting ArtifactInfoSheet: - Artifacts - 
Case Studies, 
Reduction Index, 
etc.MRI Resource Directory:
 - Artifacts -
 
Quick Overview
Artifact Information
NAME
Ghosting, ghost
DESCRIPTION
Displaced reduplications of image in phase encoding direction
REASON
Motion, heartbeat, respiration
HELP
Triggering, breath hold, pharmaceuticals to reduce bowel motion
Ghosting artifacts are in the most cases caused by movements (e.g., respiratory motion, bowel motion, arterial pulsations, swallowing, and heartbeat) and appear in the phase encoding direction.
mri safety guidance
Image Guidance
Ghosting artifacts can be reduced by respiratory and cardiac triggering, the use of breath holding pulse sequences, flow compensation or presaturation pulses, depending on their origin. To reduce bowel motion also pharmaceuticals, such as glucagon or scopolamine are useful. This will decrease artifacts from both peristalsis and breathing.

See also Motion Artifact, Phase Encoded Motion Artifact, Cardiac Motion Artifact, and Artifact Reduction - Motion.
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Further Reading:
  Basics:
MRI Artifact Gallery
   by chickscope.beckman.uiuc.edu    
MRI Resources 
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Flow 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
DESCRIPTION
Vascular ghosts (ghosting artifact), anomalous intensities in images
REASON
Movement of body fluids
HELP
Flow compensation, presaturation, triggering
Flow effects in MRI produce a range of artifacts, e.g. intravascular signal void by time of flight effects; turbulent dephasing and first echo dephasing, caused by flowing blood.
Through movement of the hydrogen nuclei (e.g. blood flow), there is a location change between the time these nuclei experience a radio frequency pulse and the time the emitted signal is received (because the repetition time is asynchronous with the pulsatile flow).
The blood flow occasionally produces intravascular high signal intensities due to flow related enhancement, even echo rephasing and diastolic pseudogating. The pulsatile laminar flow within vessels often produces a complex multilayered band that usually propagates outside the head in the phase encoded direction. Blood flow artifacts should be considered as a special subgroup of motion artifacts.
mri safety guidance
Image Guidance
Artifacts can be reduced by reduction of phase shifts with flow compensation (gradient moment nulling), suppression of the blood signal with saturation pulses parallel to the slices, synchronization of the imaging sequence with the heart cycle (cardiac triggering) or can be flipped 90° by swapping the phase//frequency encoding directions.

See also Flow Related Enhancement and Flow Effects.
 
Images, Movies, Sliders:
 Knee MRI Sagittal T1 003  Open this link in a new window
 
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• View the DATABASE results for 'Flow Artifact' (6).Open this link in a new window

 
Further Reading:
  News & More:
MRI measure of blood flow over atherosclerotic plaque may detect dangerous plaque
Friday, 5 April 2013   by www.sciencecodex.com    
Advanced Visualization Techniques Could Change the Paradigm for Diagnosis and Treatment of Heart Disease
Thursday, 31 May 2012   by www.sciencedaily.com    
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Negative Oral Contrast AgentsForum -
related threadsInfoSheet: - Contrast Agents - 
Intro, Overview, 
Characteristics, 
Types of, 
etc.MRI Resource Directory:
 - Contrast Agents -
 
Categories of negative oral contrast agents:
Negative oral contrast media are usually based on superparamagnetic particles and act by inducing local field inhomogeneities, which results in shortening of both T1 and T2 relaxation times. Superparamagnetic contrast agents have predominant T2 weighted effects. Biphasic contrast media are agents that have different signal intensities on different sequences, depending on the concentration at which they are used.
Suitable materials for oral contrast agents should have little or no absorption by the stomach or intestines, complete excretion, no motion or susceptibility artifacts, affordability, and uniform marking of the gastrointestinal tract. Benefits of negative oral contrast agents are the reduction of ghosting artifacts caused by the lack of signal. Superparamagnetic iron oxides produce also in low concentrations a noticeable signal loss; but can generate susceptibility artifacts especially in gradient echo sequences. Perfluorochemicals do not dilute in the bowel because they are not miscible with water.
High cost, poor availability, and limited evaluations of side effects are possible disadvantages.
Negative oral contrast agents are used e.g., in MRCP, where the ingestion of 600-900 ml of SPIO cancels out the signal intensity of the lumen (in addition after the injection of a gadolinium-based contrast medium, the enhancement of the inflammatory tissues is clearer seen), and in MR abdominal imaging of Crohn's disease in combination with mannitol.
mri safety guidance
Contrast Guidance
Blueberry or pineapple juices are useable for examinations of the pancreas (MRCP, upper abdominal imaging) as cheep contrast agents, because of the content of magnetic substances (e.g. manganese).

See also Ferristene, Ferumoxsil, Oral Magnetic Particles, Gastrointestinal Imaging.
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• View the DATABASE results for 'Negative Oral Contrast Agents' (7).Open this link in a new window

 
Further Reading:
  Basics:
Components of Oral Contrast Agent for Magnetic Resonance Imaging(.pdf)
   by www.ffcr.or.jp    
MRI Resources 
IR - Crystallography - Journals - NMR - Cardiovascular Imaging - Image Quality
 
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.
mri safety guidance
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

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Respiratory Ordered Phase Encoding
 
Respiratory synchronization that acquires image data at regular times independent of the respiratory cycle, but chooses the sequence of phase encoding data acquisition so as to minimize the respiratory motion-induced artifacts in the resulting image. For example, choosing the sequence of phase encoding such that adjacent samples in the final full data set have minimal differences in respiratory phase will minimize the spacing of ghosting artifacts in the final image.
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• View the DATABASE results for 'Respiratory Ordered Phase Encoding' (5).Open this link in a new window

MRI Resources 
Blood Flow Imaging - Mobile MRI Rental - - Claustrophobia - Process Analysis - MRA
 
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