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5 Gauss LimitMRI Resource Directory:
 - Safety -
The national regulatory boards decided to limit the threshold for access to MRI areas to 5 gauss.

MRI Safety Guidance
It is of special interest for the observer of bureaucratic procedures that the 5 gauss safety limit is ten times higher than the average earth magnetic field, but lower than the magnetic field in electric trains such as subways (up to 7 gauss). For example, the fields measured on the surface of the receiver of a telephone are 35 gauss and of an audio headset 100 gauss.
• For this and other aspects of MRI safety see our InfoSheet about MRI Safety.
• Patient-related information is collected in our MRI Patient Information.

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Further Reading:
Magnetic Sensitivity of MRI Systems to External Iron: The Design Process
  News & More:
A Primer on Medical Device Interactions with Magnetic Resonance Imaging Systems
Modern Implantable Heart Devices Safe For Use In MRI Scans
Wednesday, 16 March 2005   by    
MRI Safety Resources 
Safety Products - Safety Training - Safety pool - Stimulator pool - Shielding
Cardiac PacemakerMRI Resource Directory:
 - Safety -
A pacemaker is a device for internal or external battery-operated cardiac pacing to overcome cardiac arrhythmias or heart block. All implanted electronic devices are susceptible to the electromagnetic fields used in magnetic resonance imaging. Therefore, the main magnetic field, the gradient field, and the radio frequency (RF) field are potential hazards for cardiac pacemaker patients.
The pacemaker’s susceptibility to static field and its critical role in life support have warranted special consideration. The static magnetic field applies force to magnetic materials. This force and torque effects rise linearly with the field strength of the MRI machines. Both, RF fields and pulsed gradients can induce voltages in circuits or on the pacing lead, which will heat up the tissue around e.g. the lead tip, with a potential risk of thermal injury.
Regulations for pacemakers provide that they have to switch to the magnet mode in static magnetic fields above 1.0 mT. In MR imaging, the gradient and RF fields may mimic signals from the heart with inhibition or fast pacing of the heart. In the magnet mode, most of the current pacemakers will pace with a fix pulse rate because they do not accept the heartsignals. However, the state of an implanted pacemaker will be unpredictable inside a strong magnetic field. Transcutaneous controller adjustment of pacing rate is a feature of many units. Some achieve this control using switches activated by the external application of a magnet to open/close the switch. Others use rotation of an external magnet to turn internal controls. The fringe field around the MRI magnet can activate such switches or controls. Such activations are a safety risk.
Areas with fields higher than 0.5 mT (5 Gauss Limit) commonly have restricted access and/or are posted as a safety risk to persons with pacemakers.

MRI Safety Guidance
A Cardiac pacemaker is because the risks, under normal circumstances an absolute contraindication for MRI procedures.
Nevertheless, with special precaution the risks can be lowered. Reprogramming the pacemaker to an asynchronous mode with fix pacing rate or turning off will reduce the risk of fast pacing or inhibition. Reducing the SAR value reduces the potential MRI risks of heating. For MRI scans of the head and the lower extremities, tissue heating also seems to be a smaller problem. If a transmit receive coil is used to scan the head or the feet, the cardiac pacemaker is outside the sending coil and possible heating is very limited.


• View the DATABASE results for 'Cardiac Pacemaker' (6).Open this link in a new window

Further Reading:
A Primer on Medical Device Interactions with Magnetic Resonance Imaging Systems
Magnetic Resonance Imaging and Cardiac Pacemaker Safety at 1.5-Tesla(.pdf)
Magnetic Resonance Imaging in patients with ICDs and Pacemakers (.pdf)
2005   by    
  News & More:
Newer Heart Devices Safe During MRI
Monday, 23 August 2004   by    
Patients with standard pacemakers, ICDs may safely undergo MRIs
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Biotronik's new Ilivia ICDs and CRT-Ds with MRI AutoDetect receives CE approval
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MRI Resources 
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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
Radiology-tip.comUltrasound Safety,  Absorbed Dose

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• View the NEWS results for 'MRI Safety' (13).Open this link in a new window.
Further Reading:
MRI Safety
2001   by    
Contrast Agents: Safety Profile
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Wednesday, 11 January 2017   by    
Newer Heart Devices Safe During MRI
Monday, 23 August 2004   by    
FDA Releases New Guidance On Establishing Safety, Compatibility Of Passive Implants In MR Environments
Tuesday, 16 December 2014   by    
Modern Implantable Heart Devices Safe For Use In MRI Scans
Wednesday, 16 March 2005   by    
MRI Resources 
Implant and Prosthesis - Devices - Cochlear Implant - Process Analysis - MRI Physics - Knee MRI
From Siemens Medical Systems; Received FDA clearance in 2007.
The MAGNETOM Essenza is designed to combine high system performance with simple installation and power requirements to provide optimal operating costs for limited budgets. The standard system has up to 25 integrated coil elements and 8 independent radio frequency channels. Tim allows the combination of up to 4 different coils that reduce patient and coil repositioning.
The 1.5 Tesla system is designated for a complete range of clinical applications, including neurology, orthopedics, body imaging, angiography, cardiology, breast imaging, oncology and pediatric MRI.

Device Information and Specification
CONFIGURATION Ultra-short bore
SURFACE COILS Head, spine, torso/ body coil, neurovascular, cardiac, neck, and multi-purpose flex coils. Peripheral vascular, breast, shoulder, knee, wrist, foot//ankle, TMJ optional.
CHANNELS (min. / max. configuration) 8, 16
SPECTROSCOPY Chemical shift imaging and single volume spectroscopy
IMAGING TECHNIQUES iPAT, mSENSE and GRAPPA (image, k-space), noncontrast angiography, radial motion compensation
MINIMUM TR 3-D GRE: 1.58 (256 matrix)
MINIMUM TE 3-D GRE: 0.5 (256 matrix)
FOV 0.5 - 45 cm
At isocenter: 60 cm
MAGNET WEIGHT (gantry included) 4350 kg in operation
DIMENSION H*W*D (gantry included) 145 x 226 x 216 cm
5-GAUSS FRINGE FIELD 2.5 m / 4.0 m
MAGNET TYPE Superconducting
CRYOGEN USE Zero boil off rate, approx. 10 years
COOLING SYSTEM Water; single cryogen, 2 stage refrigeration
SLEW RATE up to 100 T/m/s
MAX. AMPLITUDE, RISE TIME 30 mT/m, 300 msec to 10 mT/m
SHIMMING Passive, active; first order standard second order optional
POWER REQUIREMENTS 380 / 400 / 420 / 440 / 460 / 480 V, 3-phase + ground; 45 kVA
Further Reading:
Magnetom Essenza - Typical Room Plan
MRI Resources 
Diffusion Weighted Imaging - Anatomy - Service and Support - Shielding - Implant and Prosthesis - Education pool
FORTE 3.0T™InfoSheet: - Devices -
Types of Magnets, 
etc.MRI Resource Directory:
 - Devices - From ISOL Technology
'Ultra high field MR system , it's right close to you. FORTE 3.0T is the new standard for the future ultra high field MR system. If you are pushing the limits of your existing clinical MR scanner, the FORTE will surely take you to the next level of diagnostic imaging. FORTE is the core leader of the medical technology in the 21st century. Proving effects of fMRI that cannot be measured with MRI less than 2.0T.'
Device Information and Specification
CONFIGURATION Short bore compact
SURFACE COILS Head, C-spine, L-spine, TMJ, Knee, Shoulder, General purpose
SYNCHRONIZATION ECG/peripheral: Optional/yes, external trigger, respiratory gating
PULSE SEQUENCES Spin echo, Gradient echo, Fast spin echo, Inversion recovery, 2D/3D Fast gradient echo sequences FLAIR/STIR, 2D/3D TOF
IMAGING MODES 2D/3D, T1, T2 and Diffusion//Perfusion imaging, MR Angiography package, Advanced EPI package, Multi-nuclei MR Spectroscopy package
FOV 40 cm
DISPLAY MATRIX 128 x 128, 256 x 256, 512 x 512, 1024 x 1024
MAGNET TYPE Superconducting
or W x H
61 cm without body coil
H*W*D 260 x 220 x 235 cm
COOLING SYSTEM TYPE Water-cooled coil and air-cooled amplifier
CRYOGEN USE 0.15 L/hr helium
5-GAUSS FRINGE FIELD 3.3 m / 5.2 m
SHIMMING Passive and active

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MRI Resources 
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