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Active Device
 
The term 'active' refers to any medical device that can only serve its intended use with the supply of power by any means including, but not limited to line, battery, or gas power. Examples of active devices include ventilators, pacemakers, and patient monitoring devices.
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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.

 
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Further Reading:
  News & More:
Modern Implantable Heart Devices Safe For Use In MRI Scans
Wednesday, 16 March 2005   by www.sciencedaily.com    
Newer Heart Devices Safe During MRI
Monday, 23 August 2004   by www.hospimedica.com    
MRI Safety Resources 
Nerve Stimulator - Pregnancy - Shielding - Breast Implant - Safety Training
 
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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• View the DATABASE results for 'Contraindications' (11).Open this link in a new window

 
Further Reading:
  Basics:
MRI in Patients with Implanted Devices: Current Controversies
Monday, 1 August 2016   by www.acc.org    
Newer Heart Devices Safe During MRI
Monday, 23 August 2004   by www.hospimedica.com    
Physics of MRI Safety
   by www.aapm.org    
FDA Releases New Guidance On Establishing Safety, Compatibility Of Passive Implants In MR Environments
Tuesday, 16 December 2014   by www.meddeviceonline.com    
  News & More:
Making Pacemakers and ICDs MRI-Safe
Wednesday, 8 March 2017   by www.mddionline.com    
Implantable Infusion Pumps in the Magnetic Resonance (MR) Environment: FDA Safety Communication - Important Safety Precautions
Wednesday, 11 January 2017   by www.fda.gov    
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    
Positive diagnosis for neural therapeutic implants
Tuesday, 19 April 2016   by medicalxpress.com    
Codman Neuro develops new MRI-resistant programmable valve for treatment of hydrocephalus
Tuesday, 22 September 2015   by www.news-medical.net    
MRI Resources 
Lung Imaging - DICOM - MR Guided Interventions - Societies - Portals - Safety Training
 
MRI Procedure
 
The MRI device is located within a specially shielded room (Faraday cage) to avoid outside interference, caused by the use of radio waves very close in frequency to those of ordinary FM radio stations.
The MRI procedure can easily be performed through clothing and bones, but attention must be paid to ferromagnetic items, because they will be attracted from the magnetic field. A hospital gown is appropriate, or the patient should wear clothing without metal fasteners and remove any metallic objects like hairpins, jewelry, eyeglasses, clocks, hearing aids, any removable dental work, lighters, coins etc., not only for MRI safety reasons. Metal in or around the scanned area can also cause errors in the reconstructed images (artifacts). Because the strong magnetic field can displace, or disrupt metallic objects, people with an implanted active device like a cardiac pacemaker cannot be scanned under normal circumstances and should not enter the MRI area.
The MRI machine can look like a short tunnel or has an open MRI design and the magnet does not completely surround the patient. Usually the patient lies on a comfortable motorized table, which slides into the scanner, depending on the MRI device, patients may be also able to sit up. If a contrast agent is to be administered, intravenous access will be placed. A technologist will operate the MRI machine and observe the patient during the examination from an adjacent room. Several sets of images are usually required, each taking some minutes. A typical MRI scan includes three to nine imaging sequences and may take up to one hour. Improved MRI devices with powerful magnets, newer software, and advanced sequences may complete the process in less time and better image quality.
Before and after the most MRI procedures no special preparation, diet, reduced activity, and extra medication is necessary. The magnetic field and radio waves are not felt and no pain is to expect.
Movement can blur MRI images and cause certain artifacts. A possible problem is the claustrophobia that some patients experience from being inside a tunnel-like scanner. If someone is very anxious or has difficulty to lie still, a sedative agent may be given. Earplugs and/or headphones are usually given to the patient to reduce the loud acoustic noise, which the machine produces during normal operation. A technologist observes the patient during the test. Some MRI scanners are equipped with televisions and music to help the examination time pass.
MRI is not a cheap examination, however cost effective by eliminating the need for invasive radiographic procedures, biopsies, and exploratory surgery. MRI scans can also save money while minimizing patient risk and discomfort. For example, MRI can reduce the need for X-ray angiography and myelography, and can eliminate unnecessary diagnostic procedures that miss occult disease.
See also Magnetic Resonance Imaging MRI, Medical Imaging, Cervical Spine MRI, Claustrophobia, MRI Risks and Pregnancy.
For Ultrasound Imaging (USI) see Ultrasound Imaging Procedures at US-TIP.com.

See also the related poll result: 'MRI will have replaced 50% of x-ray exams by'
 
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 Sagittal Knee MRI Images T1 Weighted  Open this link in a new window
      

 
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• View the DATABASE results for 'MRI Procedure' (11).Open this link in a new window


• View the NEWS results for 'MRI Procedure' (6).Open this link in a new window.
 
Further Reading:
  News & More:
Metamaterials boost sensitivity of MRI machines
Thursday, 14 January 2016   by www.eurekalert.org    
Casting patterns make MRI safer
Tuesday, 13 January 2015   by www.engineeringcapacity.com    
Working with MRI machines may cause vertigo: Study
Wednesday, 25 June 2014   by www.cos-mag.com    
Novel Imaging Technique Improves Prostate Cancer Detection
Tuesday, 6 January 2015   by health.ucsd.edu    
MRI Improves Breast Cancer Screening in Older BRCA Carriers
Monday, 5 January 2015   by www.cancernetwork.com    
Searchterm 'Active Device' was also found in the following services: 
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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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• View the DATABASE results for 'MRI Safety' (42).Open this link in a new window


• View the NEWS results for 'MRI Safety' (13).Open this link in a new window.
 
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 Resources 
Nerve Stimulator - Artifacts - Mobile MRI Rental - Education pool - Image Quality - Cardiovascular Imaging
 
MAGNETOM Prisma
 
From Siemens Medical Systems;
www.healthcare.siemens.com/magnetic-resonance-imaging/3t-mri-scanner/magnetom-prisma Received FDA clearance in 2013.
The MAGNETOM Prisma is the 3T PowerPack for exploration that offers most demanding clinical and research challenges of today and the future. The latest parallel transmit technology, TimTX TrueShape, enables zooming into specific body regions for enhanced image quality. Furthermore, the Tim 4G integrated coil technology offers remarkable imaging flexibility and supports complex examinations across the whole body.
Onsite upgrades to the MAGNETOM Prisma for customers who have already installed the 3 Tesla MAGNETOM Trio are possible.


Device Information and Specification
CLINICAL APPLICATION Whole Body
CONFIGURATION Ultra-short bore
FIELD STRENGTH 3 Tesla
SURFACE COILS Head, spine, torso/ body coil, neurovascular, cardiac, neck, shoulder, knee, wrist, foot//ankle and multi-purpose flex coils. Peripheral vascular, breast, shoulder.
CHANNELS (min. / max. configuration) 64, 128
SPECTROSCOPY Yes
IMAGING TECHNIQUES iPAT, mSENSE and GRAPPA (image, k-space), noncontrast angiography, radial motion compensation, Dixon
FOV 0.5 - 50 cm
BORE DIAMETER
or W x H
At isocenter: L-R 60 cm
TABLE CAPACITY 250 kg
MAGNET WEIGHT (gantry included) 13000 kg
DIMENSION H*W*D (gantry included) 173 x 230 x 222 cm
5-GAUSS FRINGE FIELD 2.6 m / 4.6 m
MAGNET TYPE Superconducting
CRYOGEN USE Zero boil off rate, refill approx. 10 years
COOLING SYSTEM Water
SLEW RATE up to 200 T/m/s
MAX. AMPLITUDE 80 mT/m
SHIMMING Passive, active; first order, second order
POWER REQUIREMENTS 380 / 400 / 420 / 440 / 460 / 480 V, 3-phase + ground;
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MRI Resources 
Nerve Stimulator - Developers - Examinations - Colonography - Services and Supplies - Health
 
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