Magnetic Resonance - Technology Information Portal Welcome to MRI Technology••


The impact of TTIP/TPP on the MRI scanner market will bring :
more variety 
better scanners 
more risk 
less regulation 
cheaper scanners 
Lost in Translation 
no change at all 

MRI Patient Information
  • Side Effects
A psychological reaction to being confined in a relatively small area.
This is a very real psychological danger for some individuals during the MRI procedure. A small percentage of patients is claustrophobic and cannot tolerate the confined space within a closed MRI magnet. Claustrophobia, panic attacks and other psychological stress situations have been reported in about 1-4% of cases as a reason to interrupt the MRI examination. Principally short and wide open MRI devices are advantageous because the percentage of claustrophobic incidents drops significantly.
Detailed explanation of the MRI procedure, careful attention and special equipment (mirrors to look outside the machine, emergency bells) help to reduce claustrophobia significantly. The majority of claustrophobic patients will be sufficiently relaxed with orally or intravenous sedatives.
See also Open MRI.

• View the DATABASE results for 'Claustrophobia' (16).Open this link in a new window

Further Reading:
Open MRI scanners reduce anxiety in patients
Thursday, 8 September 2011   by    
  News & More:
The MRI is a source of anxiety — and musical inspiration
Tuesday, 10 December 2013   by    
Acoustic Noise 
Vibrations of the gradient coil support structure create sound waves. These are caused by the interactions of the magnetic field created by pulses of the current through the gradient coil with the main magnetic field in a manner similar to a loudspeaker coil. The sounds made by the scanner vary in volume and tone with the type of procedure being performed.
Sound pressure is reported on a logarithmic scale called sound-pressure level, expressed in decibel (dB) referenced to the weakest audible 1 000 Hz sound pressure of 2*10-5 pascal (20 micropascal). Sound level meters contain filters that simulate the ear's frequency response. The most commonly used filter provides what is called 'A' weighting, with the letter 'A' appended to the dB units, i.e. dBA.
MRI system noise levels increase with field strength. Disposable earplugs and/or headphones for the patient are recommended in high-field systems. Noise-canceling systems and special earphones are available, and active acoustic control systems were developed, e.g. softtone, pianissimo. A sequence with low noise gradient pulses is also called 'whisper sequence'.
See also Phon and Decibel.

• View the DATABASE results for 'Acoustic Noise' (9).Open this link in a new window

Further Reading:
MRI Noise in Utero Not Harmful for Baby's Ears
Tuesday, 28 September 2010   by    
  News & More:
Noise from Magnetic Resonance Imaging Can Have Short-Term Impact on Hearing
Thursday, 22 February 2018   by    
Echo Planar Imaging at 4 Tesla With Minimum Acoustic Noise(.pdf)
GE Healthcare unveils Silent Scan MRI for patient comfort
Friday, 25 October 2013   by    
Sunday, 29 November 2009   by    
Cardiac Pacemaker 
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:
MRI in Patients with Implanted Devices: Current Controversies
Monday, 1 August 2016   by    
Magnetic resonance imaging in patients with cardiac pacemakers: era of MR Conditional designs
Thursday, 27 October 2011   by    
  News & More:
Newer Heart Devices Safe During MRI
Monday, 23 August 2004   by    
Making Pacemakers and ICDs MRI-Safe
Wednesday, 8 March 2017   by    
Patients with standard pacemakers, ICDs may safely undergo MRIs
Friday, 24 February 2017   by    
Biotronik's new Ilivia ICDs and CRT-Ds with MRI AutoDetect receives CE approval
Wednesday, 3 February 2016   by    
ITOCHU Named the Exclusive Distributor for ViewRay's MRI-Guided Radiation Therapy System in Japan
Thursday, 22 January 2015   by    
Medtronic Gets Japanese Approval, Launches Evera MRI
Monday, 10 November 2014   by    
Modern Implantable Heart Devices Safe For Use In MRI Scans
Wednesday, 16 March 2005   by    
Cardiac Stent 
The MRI safety of cardiac stents is dependent of the material, the examined part of the body and the used field strength. A susceptibility artifact is expected also in low magnetic fields, but less.

MRI Safety Guidance
Most of the used materials are non-magnetic, for this case there is no risk for movement caused through the magnetic field. If the cardiac stent is outside the region of the radio frequency pulse, also the risk of e.g. heating is low.

• View the DATABASE results for 'Cardiac Stent' (4).Open this link in a new window

Further Reading:
  News & More:
Medtronic Receives FDA Approval for Endeavor® Zotarolimus-Eluting Coronary Stent System
Friday, 1 February 2008   by    
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