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Result : Searchterm 'Magnetic Susceptibility' found in 1 term [] and 15 definitions [], (+ 11 Boolean[] results
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Magnetic SusceptibilityForum -
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(c) Magnetic susceptibility is the degree of magnetization of a material in response to a magnetic field. Paramagnetic materials strengthen the magnetic field, diamagnetic materials weaken it. The magnetic susceptibility of ferromagnetic substances is not linear; this is called differential susceptibility.
Differences in magnetic susceptibilities are a frequent cause of MRI artifacts.
See also Susceptibility Artifact, Magnetism, Diamagnetism, Paramagnetism, Ferromagnetism.
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    • Balanced Sequence
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    • Diamagnetism
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    • Superparamagnetism
 
Further Reading:
  Basics:
Metal-Induced Artifacts in MRI
   by www.ajronline.org    
Magnetic susceptibility
   by en.wikipedia.org    
MRI Resources 
MRI Technician and Technologist Career - Collections - Spectroscopy - Implant and Prosthesis pool - Breast MRI - Pathology
 
Susceptibility ArtifactInfoSheet: - Artifacts - 
Case Studies, 
Reduction Index, 
etc.MRI Resource Directory:
 - Artifacts -
 
Quick Overview
Artifact Information
NAME Metal artifact, clip artifact, magnetic susceptibility artifact
DESCRIPTION Signal dropout, bright spots, spatial distortion
REASON Field inhomogeneity
HELP Remove the metal, do not take a gradient echo sequence, take a short echo time

Materials with magnetic susceptibility cause this artifact. There are in general three kinds of materials with magnetic susceptibility: ferromagnetic materials (iron, nickel etc.) with a strong influence and paramagnetic/diamagnetic (aluminium, platinum etc./gold, water, most organic compounds etc.) materials with a minimal/non influence on magnetic fields. In MRI, susceptibility artifacts are caused for example by medical devices in or near the magnetic field or by implants of the patient. These materials with magnetic susceptibility distort the linear magnetic field gradients, which results in bright areas (misregistered signals) and dark areas (no signal) nearby the magnetic material.


Image Guidance
Use a spin echo or a fast spin echo sequence, because gradient echo sequences are more sensitive to susceptibility artifacts. A high bandwidth (small water fat shift) and a short echo time help also to reduce this artifact.
In some cases it is even beneficial to use a gradient echo sequence, e.g. a cavernom contains some iron-rich haemosiderin, which also causes a signal void on gradient echo sequences and for this purpose increases the diagnostic image quality.
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• View the DATABASE results for 'Susceptibility Artifact' (8).Open this link in a new window

 
Further Reading:
  Basics:
MRI Artifact Gallery
   by chickscope.beckman.uiuc.edu    
Susceptibility Artifacts
   by www.mritutor.org    
  News & More:
Metal Artefact Reduction
Thursday, 9 June 2011   by www.revisemri.com    
Ultrashort echo time (UTE) MRI of the spine in thalassaemia
February 2004   by bjr.birjournals.org    
MRI Resources 
Mobile MRI - Blood Flow Imaging - Case Studies - Bioinformatics - Cochlear Implant - Shoulder MRI
 
Chemical Shift Reference
 
A compound with respect to whose frequency the chemical shifts of other compounds can be compared. The standard can be either internal or external to the sample. Because of the need for possible corrections due to differential magnetic susceptibility between an external standard and the sample being measured, the use of an internal standard is generally preferred.
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Combination Oral Contrast AgentsInfoSheet: - Contrast Agents - 
Intro, Overview, 
Characteristics, 
Types of, 
etc.MRI Resource Directory:
 - Contrast Agents -
 
Biphasic oral contrast agents may produce either high or low signal intensities depending on the pulse sequence used, for example low signal intensity on T1 weighted MR images and high signal intensity on T2 weighted images. The combination of different oral contrast agents can generate a macroscopic cancellation of negative and positive magnetic susceptibility, thereby eliminating susceptibility artifacts.
Possible combinations are e.g., ferric ammonium citrate and corn oil, or ferrous sulfate emulsified with baby formula. Paramagnetic agents combined with oil emulsion may be used in MRI as positive abdominal contrast agents. The combination of diamagnetic barium sulfate and superparamagnetic iron oxide (SPIO) in one suspension may be a useful negative contrast agent.
See also Gastrointestinal Paramagnetic Contrast Agents, Gastrointestinal Superparamagnetic Contrast Agents, Gastrointestinal Diamagnetic Contrast Agents, Gastrointestinal Imaging.

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Further Reading:
  Basics:
Usefulness of MR Imaging for Diseases of the Small Intestine: Comparison with CT
2000   by www.ncbi.nlm.nih.gov    
MRI Resources 
Most Wanted - Veterinary MRI - Contrast Agents - Artifacts - Spectroscopy pool - MRI Reimbursement
 
Diamagnetism
 
Diamagnetism is a form of magnetism that is only exhibited by a substance in the presence of an externally applied magnetic field. It is the result of changes in the orbital motion of electrons due to the application of an externally applied magnetic field. Applying a magnetic field causes a momentary electromotive force (a consequence of Faraday's law), which modifies the electronic orbitals of atoms/molecules in a substance in such a way, that the orbitals produce an induced magnetic field, which opposes the applied field (a consequence of Lenz's law). However, the induced magnetic moment is very small in most everyday materials.
Diamagnets are repelled by magnetic fields. However, since diamagnetism is such a weak property its effects are not observable in every-day life.
However, in Magnetic Resonance Imaging for example barium sulfate suspensions lead with its weak negative magnetic susceptibility to a decrease in signal. See also magnetism, ferromagnetism, paramagnetism, and superparamagnetism.

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Further Reading:
  Basics:
Magnet basics
   by my.execpc.com    
Diamagnetism
   by en.wikipedia.org    
MRI Resources 
RIS - Knee MRI - Implant and Prosthesis - Education - Societies - Diffusion Weighted Imaging
 
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