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Result : Searchterm 'MRI Scan' found in 1 term [] and 72 definitions []
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Searchterm 'MRI Scan' was also found in the following services: 
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News  (319)  Resources  (55)  Forum  (21)  
 
MRI RisksMRI Resource Directory:
 - Safety -
 
The subacute risks and side effects of magnetic and RF fields (for patients and staff) have been intensively examined for a long time, but there have been no long-term studies following persons who have been exposed to the static magnetic fields used in MRI. However, no permanent hazardous effects of a static magnetic field exposure upon human beings have yet been demonstrated.
Temporary possible side effects of high magnetic and RF fields:
•
Varying magnetic fields can induce so-called magnetic phosphenes that occur when an individual is subject to rapid changes of 2-5 T/s, which can produce a flashing sensation in the eyes. This temporary side effect does not seem to damage the eyes. Static field strengths used for clinical MRI examinations vary between 0.2 and 3.0 tesla;; field changes during the MRI scan vary in the dimension of mT/s. Experimental imaging units can use higher field strengths of up to 14.0 T, which are not approved for human use.
•
The Radio frequency pulses mainly produce heat, which is absorbed by the body tissue. If the power of the RF radiation is very high, the patient may be heated too much. To avoid this heating, the limit of RF exposure in MRI is up to the maximum specific absorption rate (SAR) of 4 W/kg whole body weight (can be different from country to country). For MRI safety reasons, the MRI machine starts no sequence, if the SAR limit is exceeded.
•
Very high static magnetic fields are needed to reduce the conductivity of nerves perceptibly. Augmentation of T waves is observed at fields used in standard imaging but this side effect in MRI is completely reversible upon removal from the magnet. Cardiac arrhythmia threshold is typically set to 7-10 tesla. The magnetohydrodynamic effect, which results from a voltage occurring across a vessel in a magnetic field and percolated by a saline solution such as blood, is irrelevant at the field strengths used.

The results of some animal and cellular studies suggest the possibility that electromagnetic fields may act as co-carcinogens or tumor promoters, but the data are inconclusive. Up to 45 tesla, no important effects on enzyme systems have been observed. Neither changes in enzyme kinetics, nor orientation changes in macromolecules have been conclusively demonstrated.
There are some publications associating an increase in the incidence of leukemia with the location of buildings close to high-current power lines with extremely low-frequency (ELF) electromagnetic radiation of 50-60 Hz, and industrial exposure to electric and magnetic fields but a transposition of such effects to MRI or MRS seems unlikely.
Under consideration of the MRI safety guidelines, real dangers or risks of an exposure with common MRI field strengths up to 3 tesla as well as the RF exposure during the MRI scan, are not to be expected.

For more MRI safety information see also Nerve Conductivity, Contraindications, Pregnancy and Specific Absorption Rate.

See also the related poll result: 'In 2010 your scanner will probably work with a field strength of'
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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:
    • Active Device
    • Cardiovascular Imaging
    • Absorbed Dose
    • Nerve Conductivity
    • Implants
 
Further Reading:
  Basics:
MRI in Patients with Implanted Devices: Current Controversies
Monday, 1 August 2016   by www.acc.org    
Working with MRI machines may cause vertigo: Study
Wednesday, 25 June 2014   by www.cos-mag.com    
Physics of MRI Safety
   by www.aapm.org    
When Your Kid Needs an MRI: Optimizing the Experience
Tuesday, 29 March 2016   by health.usnews.com    
  News & More:
How safe is 7T MRI for patients with neurosurgical implants?
Thursday, 17 November 2022   by healthimaging.com    
CT contrast reaction raises MRI contrast risk
Tuesday, 22 February 2022   by www.sciencedaily.com    
CSU study explores MRI distress and patient experience
Thursday, 7 May 2020   by www.portnews.com.au    
Noise from Magnetic Resonance Imaging Can Have Short-Term Impact on Hearing
Thursday, 22 February 2018   by www.diagnosticimaging.com    
Women with permanent make-up tattoos suffer horrific facial burns after going in for MRI scans - which create an electric current in the ink
Monday, 4 July 2016   by www.dailymail.co.uk    
FDA Dials in on MRI Safety of Passive Implantable Medical Devices
Wednesday, 24 June 2015   by www.raps.org    
Searchterm 'MRI Scan' was also found in the following services: 
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Ultrasound  (1) Open this link in a new window
Nerve Conductivity
 
Rapid echo planar imaging and high-performance MRI gradient systems create fast-switching magnetic fields that can stimulate muscle and nerve tissues produced by either changing the electrical resistance or the potential of the excitation. There are apparently no effects on the conduction of impulses in the nerve fiber up to field strength of 0.1 T. A preliminary study has indicated neurological effects by exposition to a whole body imager at 4.0 T. Theoretical examinations argue that field strengths of 24 T are required to produce a 10% reduction of nerve impulse conduction velocity.
Nerve stimulations during MRI scans can be induced by very rapid changes of the magnetic field. This stimulation may occur for example during diffusion weighted sequences or diffusion tensor imaging and can result in muscle contractions caused by effecting motor nerves. The so-called magnetic phosphenes are attributed to magnetic field variations and may occur in a threshold field change of between 2 and 5 T/s. Phosphenes are stimulations of the optic nerve or the retina, producing a flashing light sensation in the eyes. They seem not to cause any damage in the eye or the nerve.
Varying magnetic fields are also used to stimulate bone-healing in non-unions and pseudarthroses. The reasons why pulsed magnetic fields support bone-healing are not completely understood. The mean threshold levels for various stimulations are 3600 T/s for the heart, 900 T/s for the respiratory system, and 60 T/s for the peripheral nerves.
Guidelines in the United States limit switching rates at a factor of three below the mean threshold for peripheral nerve stimulation. In the event that changes in nerve conductivity happens, the MRI scan parameters should be adjusted to reduce dB/dt for nerve stimulation.
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• View the DATABASE results for 'Nerve Conductivity' (2).Open this link in a new window

 
Further Reading:
  Basics:
Electrical eddy currents in the human body: MRI scans and medical implants
   by www.phy.olemiss.edu    
  News & More:
NERVE STIMULATORS
Tuesday, 18 January 2005   by www.health.adelaide.edu.au    
Conductivity tensor mapping of the human brain using diffusion tensor MRI
   by www.pnas.org    
MRI Safety Resources 
Breast Implant - Stimulator pool - Pacemaker - Implant and Prosthesis pool - Safety Training
 
Opera (E-SCAN™ XQ)InfoSheet: - Devices -
Intro, 
Types of Magnets, 
Overview, 
etc.MRI Resource Directory:
 - Devices -
 
www.esaote.com/products/MRI/eScanXQ/products1.htm Manufactured by Esaote S.p.A.;
a low field open MRI scanner with permanent magnet for orthopedic use. The outstanding feature of this MRI system is a patient friendly design with 24 cm diameter, which allows the imaging of extremities and small body parts like shoulder MRI. The power consumption is around 1.3 kW and the needed minimum floor space is an area of 16 sq m.
At RSNA 2006 Hologic Inc. introduced a new dedicated extremity MRI scanner, the Opera. Manufactured by Esaote is the Opera a redesign of Esaote's 0.2 Tesla E-Scan XQ platform, which now enables complete imaging of all extremities, including hip and shoulder applications. 'Real-time positioning' reportedly speeds patient setup and reduces exam times.
Esaote North America and Hologic Inc are the U.S. distributors of this MRI device.
Device Information and Specification
CLINICAL APPLICATION
Dedicated extremity
CONFIGURATION
Extremity, shoulder (2), flex coil, knee dual phased array, ankle//foot dual phased array, hand//wrist dual phased array coil
PULSE SEQUENCES
SE, GE, IR, STIR, FSE, 3D CE, GE-STIR, 3D GE, ME, TME, HSE
IMAGING MODES
Single, multislice, volume study, fast scan, multi slab
TR
10 - 5000 msec
TE
6 - 110 msec
SINGLE SLICE
0.6 sec/image
MULTISLICE
0.6 sec/image
17 cm
2D: 2 mm - 10 mm;
3D: 0.6 mm - 10 mm
MEASURING MATRIX
256 x 256 maximum
PIXEL INTENSITY
4096 gray lvls, 256 lvls in 3D
MAGNET TYPE
Permanent
24 cm H, open
MAGNET WEIGHT
2250 kg, 4960 lbs
H*W*D
79 x 65 x 85 cm
POWER REQUIREMENTS
2,0 kW; 110/220 V single phase
STRENGTH
20 mT/m
5-GAUSS FRINGE FIELD, radial/axial
150 cm/130 cm
Passive
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• View the DATABASE results for 'Opera (E-SCAN™ XQ)' (2).Open this link in a new window

 
Further Reading:
  News & More:
E-Scan, 510(k) Summary(.pdf)
Saturday, 15 May 2004   by www.accessdata.fda.gov    
Searchterm 'MRI Scan' was also found in the following services: 
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News  (319)  Resources  (55)  Forum  (21)  
 
Silicon Graphics® OCTANE®
 
Silicon Graphics workstations are used in products from many other industry-leading medical manufacturers including:
The CT and MR products from General Electric Medical Systems uses Silicon Graphics® O2 and OCTANE workstation.
From Siemens Medical Systems, Inc., the postprocessing CT and MR workstations use Silicon Graphics O2 workstations.
Toshiba America MRI Inc. uses Silicon Graphics O2 workstations in its MRI scanners.
Bruker uses Silicon Graphics O2 workstations in its MRI scanners.
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Searchterm 'MRI Scan' was also found in the following services: 
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Ultrasound  (1) Open this link in a new window
Adverse Reaction
 
Any abnormal reaction of a patient to an examination or procedure, like for example claustrophobia or side effects of MRI contrast agents.
A claustrophobic attack is MRI scanner dependent and more rare with an open MRI. An adverse reaction with magnetic resonance imaging contrast medium is very infrequent. In general, adverse reactions increase with the quantity of contrast media (usual dose of paramagnetic contrast agents is 0.1 mmol/kg) and also with the osmolarity of the compound.
Most frequently encountered adverse reactions are heat sensation, dizziness, nausea, hypotension due to vasodilatation, which can progress to hypotensive shock and anaphylactic reactions.
See also MRI Safety, Contrast Enhanced MRI, Breast MRI, and Cardiac MR imaging.
Radiology-tip.comradSafety of Contrast Agents,  Anaphylactoid Reaction
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Medical-Ultrasound-Imaging.comUltrasound Contrast Agent Safety
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• View the DATABASE results for 'Adverse Reaction' (8).Open this link in a new window

 
Further Reading:
  Basics:
Questions and Answers on Gadolinium-Based Contrast Agents
Friday, 9 January 2009   by www.fda.gov    
Contrast Agents: Safety Profile
   by www.clinical-mri.com    
  News & More:
CT contrast reaction raises MRI contrast risk
Tuesday, 22 February 2022   by www.sciencedaily.com    
MRI Resources 
Portals - MRCP - Stimulator pool - MR Myelography - Databases - Calculation
 
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