Magnetic Resonance - Technology Information Portal Welcome to MRI Technology
Info
  Sheets


Out-
      side
 



 
 'Metal Artifact' 
SEARCH FOR    
 
  2 3 5 A B C D E F G H I J K L M N O P Q R S T U V W X Y Z
Result : Searchterm 'Metal Artifact' found in 1 term [] and 1 definition [], (+ 4 Boolean[] results
1 - 5 (of 6)     next
Result Pages : [1]  [2]
Searchterm 'Metal Artifact' was also found in the following service: 
spacer
Resources  (1)  
 
Metal ArtifactInfoSheet: - Artifacts - 
Case Studies, 
Reduction Index, 
etc.MRI Resource Directory:
 - Artifacts -
 
Quick Overview

Artifact Information
NAME Metal, susceptibility
DESCRIPTION Signal dropout, bright spots
REASON Field inhomogeneity
HELP Remove the metal

Ferromagnetic metal will cause a magnetic field inhomogeneity, which in turn causes a local signal void, often accompanied by an area of high signal intensity, as well as a distortion of the image. They create their own magnetic field and dramatically alter precession frequencies of protons in the adjacent tissues. Tissues adjacent to ferromagnetic components become influenced by the induced magnetic field of the metal hardware rather than the parent field and, therefore, either fail to precess or do so at a different frequency and hence do not generate useful signal. Two components contribute to susceptibility artifact, induced magnetism in the ferromagnetic component itself and induced magnetism in protons adjacent to the component.
Artifacts from metal may have varied appearances on MRI scans due to different type of metal or configuration of the piece of metal. The biocompatibility of metallic alloys, stainless steel, cobalt chrome and titanium alloy is based on the presence of a constituent element within the alloy that has the ability to form an adherent oxide coating that is stable, chemically inert and hence biocompatible. In relation to imaging titanium alloys are less ferromagnetic than both cobalt and stainless steel, induce less susceptibility artifact and result in less marked image degradation.


Image Guidance
Remove the metal when possible or take a not so sensitive sequence (a SE or another sequence with a rephasing 180 pulse). See also Susceptibility Artifact.
spacer
 
• Share the entry 'Metal Artifact':  Facebook  Twitter  LinkedIn  
 
• Related Searches:
    • Magnetism
    • MRI Risks
    • Magnetization
    • Metallofullerenes
    • Susceptibility Artifact
 
Further Reading:
  Basics:
Metal-Induced Artifacts in MRI
   by www.ajronline.org    
Metal Artefact Reduction
Thursday, 9 June 2011   by www.revisemri.com    
MRI Resources 
NMR - IR - Open Directory Project - Mobile MRI - Equipment - MRI Physics
 
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.
spacer

• 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 
Open Directory Project - Musculoskeletal and Joint MRI - Hospitals - Most Wanted - Libraries - Movies
 
ArtifactForum -
related threadsInfoSheet: - Artifacts - 
Case Studies, 
Reduction Index, 
etc.MRI Resource Directory:
 - Artifacts -
 
An image artifact is a structure not normally present but visible as a result of a limitation or malfunction in the hardware or software of the MRI device, or in other cases a consequence of environmental influences as heat or humidity or it can be caused by the human body (blood flow, implants etc.). The knowledge of MRI artifacts (brit. artefacts) and noise producing factors is important for continuing maintenance of high image quality. Artifacts may be very noticeable or just a few pixels out of balance but can give confusing artifactual appearances with pathology that may be misdiagnosed.
Changes in patient position, different pulse sequences, metallic artifacts, or other imaging variables can cause image distortions, which can be reduced by the operator; artifacts due to the MR system may require a service engineer.
Many types of artifacts may occur in magnetic resonance imaging. Artifacts in magnetic resonance imaging are typically classified as to their basic principles, e.g.:
Physiologic (motion, flow)
Hardware (electromagnetic spikes, ringing)
Inherent physics (chemical shift, susceptibility, metal)

Several techniques are developed to reduce these artifacts (e.g. respiratory compensation, cardiac gating, eddy current compensation) but sometimes these effects can also be exploited, e.g. for flow measurements.

See also the related poll result: 'Most outages of your scanning system are caused by failure of'
spacer

• View the DATABASE results for 'Artifact' (166).Open this link in a new window

 
Further Reading:
  Basics:
ARTEFACT VERSUS ARTIFACT
Saturday, 26 January 2002   by www.worldwidewords.org    
Which dental materials conflict with the use of MRI?
Saturday, 29 December 2012   by www.drbicuspid.com    
  News & More:
Clinical examination or whole-body magnetic resonance imaging: the Holy Grail of spondyloarthritis imaging
Tuesday, 28 February 2012   by 7thspace.com    
On the Horizon - Next Generation MRI
Wednesday, 23 October 2013   by thefutureofthings.com    
Technical Assessment of Artifact Production from Neuro Endovascular Coil At 3 Tesla MRI: An In Vitro Study
2012   by www.tmps.or.th    
Searchterm 'Metal Artifact' was also found in the following service: 
spacer
Resources  (1)  
 
Gastrointestinal Superparamagnetic Contrast AgentsInfoSheet: - Contrast Agents - 
Intro, Overview, 
Characteristics, 
Types of, 
etc.MRI Resource Directory:
 - Contrast Agents -
 
Gastrointestinal (GI) superparamagnetic contrast agents are used in MRI to improve the visualization of e.g., the intestinal tract, the pancreas (see MRCP), etc. Disadvantages are susceptibility artifacts e.g., dependent on delayed imaging or large volumes resulting in artifacts in the colon and distal small bowel loops related to higher concentration of the particles and absorption of the fluid.
Different types of MRI gastrointestinal superparamagnetic contrast agents:
Superparamagnetic iron oxide
Magnetite albumin microsphere
Oral magnetic particles
Usually gastrointestinal superparamagnetic contrast media consist of small iron oxide crystals (ferrites), which produce a signal reduction in the stomach and bowel after oral administration. The T2 shortening caused by these particles is produced from the local magnetic field inhomogeneities associated with the large magnetic moments of superparamagnetic particles. Ferrites are iron oxides of the general formula Fe203.MO, where M is a divalent metal ion and may be mixed with Fe3O4 in different preparations. Ferrites can produce symptoms of nausea after oral administration, as well as flatulence and a transient rise in serum iron. Embedding in inert substances reduce side effects by decreasing the absorption and interaction with body tissues. Combining these contrast materials with polymers such as polyethylene glycol or cellulose, or with sugars such as dextrose, results in improved T1 and/or T2 relaxivity compared with that of the contrast agent alone.
See also Negative Oral Contrast Agents, Gastrointestinal Diamagnetic Contrast Agents, Relaxivity, and Combination Oral Contrast Agents.
spacer

• View the DATABASE results for 'Gastrointestinal Superparamagnetic Contrast Agents' (6).Open this link in a new window

 
Further Reading:
  Basics:
PRODUCTION OF MAGNETICALLY AND PH RESPONSIVE BIODEVICES BY DENSE GAS TECHNOLOGY
2008   by www.isasf.net    
Negative GI Contrast Agents
   by www.mritutor.org    
MRI Resources 
Distributors - MRA - Pregnancy - Implant and Prosthesis pool - Movies - Cochlear Implant
 
Dental Work
 
Metal dental work can cause, depending of the material, an associated artifact distant from the source. There is no risk for the patient but for good MRI quality should every removable dental work be removed.
spacer

• View the DATABASE results for 'Dental Work' (2).Open this link in a new window

MRI Resources 
Open Directory Project - Bioinformatics - Blood Flow Imaging - Mobile MRI Rental - Process Analysis - Veterinary MRI
 
     1 - 5 (of 6)     next
Result Pages : [1]  [2]
 Random Page
 
Share This Page
FacebookTwitterLinkedIn

MR-TIP    
Community   
User
Pass
Forgot your UserID/Password ?  



PET-MRI is :
a valuable new tool 
worth to develop more 
unnecessary 
too expensive 
only for research 
the replacement for PET-CT 
for vets only 

Look
      Ups





Magnetic Resonance - Technology Information Portal
Member of SoftWays' Medical Imaging Group - MR-TIP • Radiology-TIP • US-TIP • The-Medical-Market
Copyright © 2003 - 2014 SoftWays. All rights reserved. [ 22 November 2014]
Terms of Use | Privacy Policy | Advertising
 [last update: 2014-11-17 01:43:06]