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5 Gauss Line
 
This line specifies the perimeter around a MR scanner within which the static magnetic fields are higher than five gauss. Five gauss and below are considered 'safe' levels of static magnetic field exposure for the general public.
Portable devices requiring a separation distance between the device and the MR magnet, should not be considered 'MR Safe', 'MR Compatible', or intended for use in the MR environment. Typically the 5 gauss line is the only location where the static magnetic field strength is specified around a MR scanner. Therefore, labeling specifying a separation distance between the MR magnet and the device to ensure safe or proper operation of the device should be avoided.

See also the related poll result: 'In 2010 your scanner will probably work with a field strength of'
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Further Reading:
  Basics:
MRI SafetyOpen this link in a new window
   by imaging.ugent.be    
  News & More:
Boston Scientific and Biophan in MRI CollaborationOpen this link in a new window
Friday, 21 November 2003   by www.medinews.com    
ContraindicationsForum -
related threadsMRI Resource Directory:
 - Safety -
 
The principal contraindications of the MRI procedure are mostly related to the presence of metallic implants in a patient. The risks of MRI scans increase with the used field strength. In general, implants are becoming increasingly MR safe and an individual evaluation is carried out for each case.


MRI Safety Guidance
Some patients should not be examined in MRI machines, or come closer than the 5 Gauss line to the system.
Absolute Contraindications for the MRI scan:
electronically, magnetically, and mechanically activated implants
ferromagnetic or electronically operated active devices like automatic cardioverter defibrillators
cardiac pacemakers
metallic splinters in the eye
ferromagnetic haemostatic clips in the central nervous system (CNS)
Patients with absolute contraindications should not be examined or only with special MRI safety precautions. Patients with an implanted cardiac pacemaker have been scanned on rare occasions, but pacemakers are generally considered an absolute contraindication. Relative contraindications may pose a relative hazard, and the type and location of an implant should be assessed prior to the MRI examination.
Relative Contraindications for the MRI scan:
cochlear implants
other pacemakers, e.g. for the carotid sinus
insulin pumps and nerve stimulators
lead wires or similar wires (MRI Safety risk)
prosthetic heart valves (in high fields, if dehiscence is suspected)
haemostatic clips (body)
non-ferromagnetic stapedial implants
Osteosynthesis material is usually anchored so well in the patients that no untoward effect will result. Another effect on metal parts in the patient’s body is the heating of these parts through induction. In addition, image quality may be severely degraded. The presence of other metallic implants such as surgical clips etc. should be made known to the MRI operators. Most of these materials are non-magnetic, but if magnetic, they can pose a hazard.
See also MRI safety, Pregnancy, Claustrophobia and Tattoos.

Radiology-tip.comRadiation Safety,  As Low As Reasonably Achievable
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Radiology-tip.comUltrasound Safety
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Further Reading:
  Basics:
Newer Heart Devices Safe During MRIOpen this link in a new window
Monday, 23 August 2004   by www.medinews.com    
  News & More:
Modern Implantable Heart Devices Safe For Use In MRI ScansOpen this link in a new window
Wednesday, 16 March 2005   by www.sciencedaily.com    
MRI Resources  
Fluorescence - Blood Flow Imaging - Health - Pacemaker - Anatomy - Implant and Prosthesis pool
 
Insulin PumpMRI Resource Directory:
 - Safety -
 

MRI Safety Guidance
Not necessarily a contraindication, but the examination may damage or impair it. An insulin pump can be disconnected easily for a period of time. Remove the pump while inside the 5 Gauss line, because the pump batteries and motor are magnetic.
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Further Reading:
  News & More:
MRI SafetyOpen this link in a new window
   by imaging.ugent.be    
MR Guided InterventionsMRI Resource Directory:
 - MR Guided Interventions -
 
Possible MR guided interventions are breast MRI, liver and bone biopsies. Open MRI is advantageous to guide interventional procedures because this type of MRI scanner provides a better patient access.
Before the MRI guided biopsy is started, all the necessary precautions ensuring normal sterile and safe conditions for an intervention have to be performed. This includes the special safety issues concerning MRI surroundings and special equipment, like non-magnetic biopsy needles, localization tools (e.g. wires to mark lesions prior to surgery with breast MRI guidance) etc.
See also 5 Gauss Line, Contraindications, Low Field MRI, MR Compatibility, Magnetic Resonance Guided Focused Ultrasound and Computer Aided Detection.
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Further Reading:
  Basics:
MR Guided Focused Ultrasound, ExAblate 2000 - Non-invasive MR guided Focused Ultrasound Surgery for Uterine FibroidsOpen this link in a new window
Friday, 11 February 2005   by www.gehealthcare.com    
Non-Invasive, MR-guided Focused Ultrasound Surgery System Already Approved to Treat Uterine Fibroids Since 2004Open this link in a new window
Monday, 17 December 2007   by sev.prnewswire.com:80    
  News & More:
Cell therapy offers repair hopeOpen this link in a new window
Monday, 7 January 2008   by www.channel4.com/    
NeuroArm Robot Promises to Revolutionise MRI-guided NeurosurgeryOpen this link in a new window
Wednesday, 7 November 2007   by www.medgadget.com    
Radiologists Offer Non-surgical Treatment For Early-stage Liver CancerOpen this link in a new window
Saturday, 5 March 2005   by www.sciencedaily.com    
Magnetic resonance imaging guided musculoskeletal interventions
at 0.23TOpen this link in a new window
2002
Intrathecal Gadolinium-Enhanced MR-Cisternography: Depiction of the Subarachnoidal Space and Evaluation of Gadobenat-Dimeglumin-(Gd-BOPTA, “Multihance®”) Toxicity in an Animal Model and a Clinical Case(.pdf)Open this link in a new window
July 2002   by www.academicradiology.com       [Free, but registration is required.]
Fast T2 weighted imaging by PSIF at 0.2T for interventional MRI.(.pdf)Open this link in a new window
   by cds.ismrm.org    
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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Further Reading:
  Basics:
MRI SafetyOpen this link in a new window
2001   by www.fda.gov    
Guidelines for Ethics Approval of Research Protocols Involving Human Exposure to Magnetic Resonance ImagingOpen this link in a new window
   by www.uwo.ca    
Contrast Agents: Safety ProfileOpen this link in a new window
   by www.clinical-mri.com    
  News & More:
Newer Heart Devices Safe During MRIOpen this link in a new window
Monday, 23 August 2004   by www.medinews.com    
Modern Implantable Heart Devices Safe For Use In MRI ScansOpen this link in a new window
Wednesday, 16 March 2005   by www.sciencedaily.com    
Gadolinium-Based Contrast Agents for Magnetic Resonance Imaging Scans (marketed as Omniscan, OptiMARK, Magnevist,ProHance, and MultiHance)Open this link in a new window
Thursday, 21 December 2006   by www.fda.gov    
 •• There are 13 news about 'MRI Safety'.
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