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MRI SafetyMRI Resource Directory:
 - Safety -
 
There are different types of contraindications that would prevent a person from being examined with an MRI scanner. MRI systems use strong magnetic fields that attract any ferromagnetic objects with enormous force. Caused by the potential risk of heating, produced from the radio frequency pulses during the MRI procedure, metallic objects like wires, foreign bodies and other implants needs to be checked for compatibility. High field MRI requires particular safety precautions. In addition, any device or MRI equipment that enters the magnet room has to be MR compatible. MRI examinations are safe and harmless, if these MRI risks are observed and regulations are followed.

Safety concerns in magnetic resonance imaging include:
the magnetic field strength;
possible 'missile effects' caused by magnetic forces;
the potential for heating of body tissue due to the application of the radio frequency energy;
the effects on implanted active devices such as cardiac pacemakers or insulin pumps;
magnetic torque effects on indwelling metal (clips, etc.);
the audible acoustic noise;
danger due to cryogenic liquids;
the application of contrast medium;


MRI Safety Guidance
It is important to remember when working around a superconducting magnet that the magnetic field is always on. Under usual working conditions the field is never turned off. Attention must be paid to keep all ferromagnetic items at an adequate distance from the magnet. Ferromagnetic objects which came accidentally under the influence of these strong magnets can injure or kill individuals in or nearby the magnet, or can seriously damage every hardware, the magnet itself, the cooling system, etc.. See MRI resources Accidents.
The doors leading to a magnet room should be closed at all times except when entering or exiting the room. Every person working in or entering the magnet room or adjacent rooms with a magnetic field has to be instructed about the dangers. This should include the patient, intensive-care staff, and maintenance-, service- and cleaning personnel, etc..
The 5 Gauss limit defines the 'safe' level of static magnetic field exposure. The value of the absorbed dose is fixed by the authorities to avoid heating of the patient's tissue and is defined by the specific absorption rate. Leads or wires that are used in the magnet bore during imaging procedures, should not form large-radius wire loops. Leg-to-leg and leg-to-arm skin contact should be prevented in order to avoid the risk of burning due to the generation of high current loops if the legs or arms are allowed to touch. The patient's skin should not be in contact with the inner bore of the magnet.
The outflow from cryogens like liquid helium is improbable during normal operation and not a real danger for patients.
The safety of MRI contrast agents is tested in drug trials and they have a high compatibility with very few side effects. The variations of the side effects and possible contraindications are similar to X-ray contrast medium, but very rare. In general, an adverse reaction increases with the quantity of the MRI contrast medium and also with the osmolarity of the compound.
See also 5 Gauss Fringe Field, 5 Gauss Line, Cardiac Risks, Cardiac Stent, dB/dt, Legal Requirements, Low Field MRI, Magnetohydrodynamic Effect, MR Compatibility, MR Guided Interventions, Claustrophobia, MRI Risks and Shielding.
Radiology-tip.comRadiation Safety,  Ionizing Radiation
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Radiology-tip.comUltrasound Safety,  Absorbed Dose
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• For this and other aspects of MRI safety see our InfoSheet about MRI Safety.
• Patient-related information is collected in our MRI Patient Information.

 
• Related Searches:
    • Specific Absorption Rate
    • Nephrogenic Systemic Fibrosis
    • Magnetic Field
    • Cardiac Risks
    • 5 Gauss Limit
 
Further Reading:
  Basics:
MRI Safety
2001   by www.fda.gov    
What MRI Sequences Produce the Highest Specific Absorption Rate (SAR), and Is There Something We Should Be Doing to Reduce the SAR During Standard Examinations?
Thursday, 16 April 2015   by www.ajronline.org    
Contrast Agents: Safety Profile
   by www.clinical-mri.com    
  News & More:
Implantable Infusion Pumps in the Magnetic Resonance (MR) Environment: FDA Safety Communication - Important Safety Precautions
Wednesday, 11 January 2017   by www.fda.gov    
Newer Heart Devices Safe During MRI
Monday, 23 August 2004   by www.hospimedica.com    
FDA Releases New Guidance On Establishing Safety, Compatibility Of Passive Implants In MR Environments
Tuesday, 16 December 2014   by www.meddeviceonline.com    
Modern Implantable Heart Devices Safe For Use In MRI Scans
Wednesday, 16 March 2005   by www.sciencedaily.com    
MRI Safety Resources 
Stimulator pool - Guidance - Implant and Prosthesis pool - Safety pool - Pregnancy
 
Magnetic FieldForum -
related threads
 
(H) The region surrounding a magnet (or current carrying conductor) is equipped with certain properties like that a small magnet in such a region experiences a torque that tends to align it in a given direction. Magnetic field is a vector quantity; the direction of the field is defined as the direction that the north pole of the small magnet points when in equilibrium.


MRI Safety Guidance
A magnetic field produces a magnetizing force on a body within it. Although the dangers of large magnetic fields are largely hypothetical, this is an area of potential concern for safety limits. Formally, the forces experienced by moving charged particles, current carrying wires, and small magnets in the vicinity of magnet are due to magnetic induction (B), which includes the effect of magnetization, while the magnetic field (H) is defined so as not to include magnetization. However, both B and H are often loosely used to denote magnetic fields.
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• View the DATABASE results for 'Magnetic Field' (219).Open this link in a new window


• View the NEWS results for 'Magnetic Field' (25).Open this link in a new window.
 
Further Reading:
  Basics:
Magnet basics
   by my.execpc.com    
Magnetic Field
   by hyperphysics.phy-astr.gsu.edu    
Magnetic Field
   by en.wikipedia.org    
How strong are magnets?
   by my.execpc.com    
  News & More:
Two stuck to MRI machine for 4 hrs
Tuesday, 11 November 2014   by www.mumbaimirror.com    
Commission proposes to revamp rules to protect EU workers from harmful electromagnetic fields
Tuesday, 14 June 2011   by finchannel.com    
Magnetic fields drive drug-loaded nanoparticles to reduce blood vessel blockages in an animal study
Monday, 19 April 2010   by www.eurekalert.org    
MRI Resources 
IR - Hospitals - Service and Support - Spectroscopy pool - Case Studies - MRCP
 
Magnetohydrodynamic Effect
 
This effect is an additional electrical charge generated by ions in blood (loaded particles) moving perpendicular to the magnetic field. At 1.5 T, no significant changes are expected; at 6.0 T a 10% blood pressure change is expected. A blood pressure increase is predicted theoretically for a field of 10 T. This is claimed to be caused by interaction of induced electrical potentials and currents within a solution, e.g. blood, and an electrical volume force causing a retardation in the direction opposite to the fluid flow. This decrease in blood flow-velocity must be compensated for by an elevation in pressure.
Static magnetic field gradients of 0.01 T/cm (100 G/cm) make no significant difference in the membrane transport processes. The influence of a static magnetic field upon erythrocytes is not sufficient to provoke sedimentation, as long as there is a normal blood circulation.


MRI Safety Guidance
The magnetohydrodynamic effect which results from a voltage occurring across a vessel in a magnetic field, is irrelevant at the field strengths used.
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Searchterm 'Safety Guidance' was also found in the following service: 
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Nerve StimulatorForum -
related threadsMRI Resource Directory:
 - Safety -
 
An implantable medical device that stimulates nerves.
MRI Safety Guidance
Depending on the used MRI field strength not necessarily a contraindication, but the examination may damage or impair it. In mid to high field MRI machines the reduction of the SAR value during the scan is necessary to avoid the risk of heating.
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• View the DATABASE results for 'Nerve Stimulator' (2).Open this link in a new window

 
Further Reading:
  News & More:
Stimwave Announces First Full Body 3-Tesla MRI Conditional Neuromodulation Medical Implantable Device (AMID) Without Any Limitations for Body Part Imaging
Tuesday, 10 March 2015   by www.businesswire.com    
MRI Resources 
Services and Supplies - Hospitals - Libraries - Developers - Implant and Prosthesis - Societies
 
PregnancyMRI Resource Directory:
 - Safety -
 
MRI can be indicated for use in pregnant women if other forms of diagnostic imaging are inadequate or require exposure to ionizing radiation such as X-ray or CT.
As a safety precaution, MR scanning should be avoided in the first three months of pregnancy.
Similar considerations hold for pregnant staff of a magnetic resonance department. An epidemiological study (by Kanal, et al.) concluded that data collected from MRI technologists were negative with respect to any statistically significant elevations in the rates of spontaneous abortion, infertility and premature delivery.
However, also for psychological reasons, it might be a wise precaution that pregnant staff members do not remain in the scan room during actual scanning.
There have been several reports (results could not be reproduced) that static magnetic fields may provoke genetic mutations, changes in growth rate and leukocyte count and other effects. No reports have been published that persons exposed to magnetic fields, including staff at MR departments, have a higher incidence of genetic damage to their children than found in the average population.
This research needs further investigation and for this purpose pregnancy should be considered a relative contraindication for MR spectroscopy and MRI procedures.
Taking into account that clinical MR imaging devices operate at field strengths of between 0.2 and 2.0 T, higher field strengths need more investigation.


MRI Safety Guidance
Today, there is no sign that MR can harm the fetus or embryo (MRI is used for fetal MRI - fetography). However, if a MRI examination is ordered, there should be a strict indication for this examination.

See also the related poll result: 'MRI will have replaced 50% of x-ray exams by'
 
Images, Movies, Sliders:
 Normal Fetus  Open this link in a new window
    

Courtesy of  Robert R. Edelman
 Pregnancy and Small Bowel Obstruction  Open this link in a new window
 
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• View the NEWS results for 'Pregnancy' (1).Open this link in a new window.
 
Further Reading:
  News & More:
MRI rules out appendicitis during pregnancy
Wednesday, 1 March 2006   by www.medicineonline.com    
MRI helps predict preterm birth
Tuesday, 15 March 2016   by www.eurekalert.org    
MRI Resources 
Pathology - MRI Physics - MRI Technician and Technologist Jobs - Resources - Safety Training - Devices
 
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