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Searchterm 'MRI' was also found in the following services: 
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News  (1300)  Resources  (333)  Forum  (379)  
 
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
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.
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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:
    • MRI Scan
    • MRI Safety
    • Magnetic Forces
    • Brain MRI
    • Cardiovascular Imaging
 
Further Reading:
  Basics:
MRI in Patients with Implanted Devices: Current Controversies
Monday, 1 August 2016   by www.acc.org    
Magnetic resonance imaging in patients with cardiac pacemakers: era of MR Conditional designs
Thursday, 27 October 2011   by 7thspace.com    
  News & More:
Newer Heart Devices Safe During MRI
Monday, 23 August 2004   by www.hospimedica.com    
BIOTRONIK debuts pacemaker with continuous MRI sensor
Wednesday, 30 August 2023   by www.medicaldevice-network.com    
Patients with standard pacemakers, ICDs may safely undergo MRIs
Friday, 24 February 2017   by www.cardiovascularbusiness.com    
ITOCHU Named the Exclusive Distributor for ViewRay's MRI-Guided Radiation Therapy System in Japan
Thursday, 22 January 2015   by www.prnewswire.com    
Modern Implantable Heart Devices Safe For Use In MRI Scans
Wednesday, 16 March 2005   by www.sciencedaily.com    
Searchterm 'MRI' was also found in the following services: 
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Radiology  (20) Open this link in a new windowUltrasound  (24) Open this link in a new window
ClaustrophobiaForum -
related threads
 
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.
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• View the DATABASE results for 'Claustrophobia' (16).Open this link in a new window

 
Further Reading:
  Basics:
Claustrophobia in Magnetic Resonance Imaging: An Analysis of Causes, Impacts and Solutions
Friday, 19 January 2024   by www.diagnosticimaging.com    
Open MRI scanners reduce anxiety in patients
Thursday, 8 September 2011   by www.mtbeurope.info    
  News & More:
CSU study explores MRI distress and patient experience
Thursday, 7 May 2020   by www.portnews.com.au    
Lego Open MRI aims to reduce anxiety
Thursday, 21 February 2019   by www.inhealthgroup.com    
VR application helps patients overcome MRI anxiety, claustrophobia
Tuesday, 4 December 2018   by www.radiologybusiness.com    
Women Suffer from Claustrophobia More Often Than Men
Saturday, 25 July 2015   by www.youthhealthmag.com    
MRI Safety Resources 
Safety pool - Claustrophobia - Safety Products - Shielding - Nerve Stimulator
 
Contrast AgentsForum -
related threadsInfoSheet: - Contrast Agents - 
Intro, Overview, 
Characteristics, 
Types of, 
etc.MRI Resource Directory:
 - Contrast Agents -
 
Contrast agents are chemical substances introduced to the anatomical or functional region being imaged, to increase the differences between different tissues or between normal and abnormal tissue, by altering the relaxation times. MRI contrast agents are classified by the different changes in relaxation times after their injection.
•
Positive contrast agents cause a reduction in the T1 relaxation time (increased signal intensity on T1 weighted images). They (appearing bright on MRI) are typically small molecular weight compounds containing as their active element Gadolinium, Manganese, or Iron. All of these elements have unpaired electron spins in their outer shells and long relaxivities.
Some typical contrast agents as gadopentetate dimeglumine, gadoteridol, and gadoterate meglumine are utilized for the central nervous system and the complete body; mangafodipir trisodium is specially used for lesions of the liver and gadodiamide for the central nervous system.
•
Negative contrast agents (appearing predominantly dark on MRI) are small particulate aggregates often termed superparamagnetic iron oxide (SPIO). These agents produce predominantly spin spin relaxation effects (local field inhomogeneities), which results in shorter T1 and T2 relaxation times.
SPIO's and ultrasmall superparamagnetic iron oxides (USPIO) usually consist of a crystalline iron oxide core containing thousands of iron atoms and a shell of polymer, dextran, polyethyleneglycol, and produce very high T2 relaxivities. USPIOs smaller than 300 nm cause a substantial T1 relaxation. T2 weighted effects are predominant.
•
A special group of negative contrast agents (appearing dark on MRI) are perfluorocarbons (perfluorochemicals), because their presence excludes the hydrogen atoms responsible for the signal in MR imaging.

The design objectives for the next generation of MR contrast agents will likely focus on prolonging intravascular retention, improving tissue targeting, and accessing new contrast mechanisms. Macromolecular paramagnetic contrast agents are being tested worldwide. Preclinical data shows that these agents demonstrate great promise for improving the quality of MR angiography, and in quantificating capillary permeability and myocardial perfusion.
Ultrasmall superparamagnetic iron oxide (USPIO) particles have been evaluated in multicenter clinical trials for lymph node MR imaging and MR angiography, with the clinical impact under discussion. In addition, a wide variety of vector and carrier molecules, including antibodies, peptides, proteins, polysaccharides, liposomes, and cells have been developed to deliver magnetic labels to specific sites. Technical advances in MR imaging will further increase the efficacy and necessity of tissue-specific MRI contrast agents.

See also Adverse Reaction and Nephrogenic Systemic Fibrosis.

See also the related poll result: 'The development of contrast agents in MRI is'
 
Images, Movies, Sliders:
 Delayed Myocardial Contrast Enhancement from Infarct  Open this link in a new window
      

Courtesy of  Robert R. Edelman
 Left Circumflex Ischemia First-pass Contrast Enhancement  Open this link in a new window
 MR Colonography Gadolinium per Rectum  Open this link in a new window
      

Courtesy of  Robert R. Edelman
 CE MRA of the Aorta  Open this link in a new window
    
SlidersSliders Overview

 
Radiology-tip.comradContrast Agents,  Safety of Contrast Agents
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Medical-Ultrasound-Imaging.comUltrasound Contrast Agents,  Ultrasound Contrast Agent Safety
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• View the DATABASE results for 'Contrast Agents' (122).Open this link in a new window


• View the NEWS results for 'Contrast Agents' (25).Open this link in a new window.
 
Further Reading:
  Basics:
Analysis of MRI contrast agents
Thursday, 17 November 2022   by www.sciencedaily.com    
New guidelines urge caution on use of contrast agents during MR scans
Tuesday, 8 August 2017   by www.dotmed.com    
New Study Sheds Light on Safety of Gadolinium-Based Contrast Agents
Wednesday, 29 November 2017   by www.empr.com    
A safer approach for diagnostic medical imaging
Monday, 29 September 2014   by www.eurekalert.org    
Manganese-based MRI contrast agents: past, present and future
Friday, 4 November 2011   by www.ncbi.nlm.nih.gov    
  News & More:
Brain imaging method may aid mild traumatic brain injury diagnosis
Tuesday, 16 January 2024   by parkinsonsnewstoday.com    
A Targeted Multi-Crystalline Manganese Oxide as a Tumor-Selective Nano-Sized MRI Contrast Agent for Early and Accurate Diagnosis of Tumors
Thursday, 18 January 2024   by www.dovepress.com    
FDA Approves Gadopiclenol for Contrast-Enhanced Magnetic Resonance Imaging
Tuesday, 27 September 2022   by www.pharmacytimes.com    
How to stop using gadolinium chelates for magnetic resonance imaging: clinical-translational experiences with ferumoxytol
Saturday, 5 February 2022   by www.ncbi.nlm.nih.gov    
Estimation of Contrast Agent Concentration in DCE-MRI Using 2 Flip Angles
Tuesday, 11 January 2022   by pubmed.ncbi.nlm.nih.gov    
Manganese enhanced MRI provides more accurate details of heart function after a heart attack
Tuesday, 11 May 2021   by www.news-medical.net    
Gadopiclenol: positive results for Phase III clinical trials
Monday, 29 March 2021   by www.pharmiweb.co    
Gadolinium-Based Contrast Agents Hypersensitivity: A Case Series
Friday, 4 December 2020   by www.dovepress.com    
Polysaccharide-Core Contrast Agent as Gadolinium Alternative for Vascular MR
Monday, 8 March 2021   by www.diagnosticimaging.com    
Water-based non-toxic MRI contrast agents
Monday, 11 May 2020   by chemistrycommunity.nature.com    
New method to detect early-stage cancer identified by Georgia State, Emory research team
Friday, 7 February 2020   by www.eurekalert.org    
Researchers Brighten Path for Creating New Type of MRI Contrast Agent
Friday, 7 February 2020   by www.newswise.com    
Manganese-based MRI contrast agent may be safer alternative to gadolinium-based agents
Wednesday, 15 November 2017   by www.eurekalert.org    
Sodium MRI May Show Biomarker for Migraine
Friday, 1 December 2017   by psychcentral.com    
A natural boost for MRI scans
Monday, 21 October 2013   by www.eurekalert.org    
For MRI, time is of the essence A new generation of contrast agents could make for faster and more accurate imaging
Tuesday, 28 June 2011   by scienceline.org    
Searchterm 'MRI' was also found in the following services: 
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News  (1300)  Resources  (333)  Forum  (379)  
 
Lung ImagingMRI Resource Directory:
 - Lung Imaging -
 
Lung imaging is furthermore a challenge in MRI because of the predominance of air within the lungs and associated susceptibility issues as well as low signal to noise of the inflated lung parenchyma. Cardiac and respiratory triggered or breath hold sequences allow diagnostic imaging, however a comparable image quality with computed tomography is still difficult to achieve.
Assumptions for lung MRI:
•
Low signal to noise ratio of the inherently low lung proton density.
•
Cardiac and respiratory motion artifacts.
•
Magnetic susceptibility effects of large magnetic field gradients.
•
Very short transverse relaxation times and significant diffusion yielding short T2 (30-70 msec), short T2* (1-3 msec), and additional long T1 relaxation times (1300-1500 msec).
•
The extreme short T2 values are responsible for a fast signal decay during a single shot readout, resulting in blurring.

The current trends in MRI are the use of new imaging technologies and increasingly powerful magnetic fields. Among these technologies are parallel imaging techniques as well as ventilation agents like hyperpolarized helium for the use as an inert inhalational contrast agent to study lung ventilation properties. With hyperpolarized gases clear images of the lungs can be obtained without using a large magnetic field (see also back projection imaging). Single shot sequences (e.g. TSE or Half Fourier Acquisition Single Shot Turbo Spin Echo HASTE) used in lung MR imaging benefits from parallel imaging techniques due to reduced relaxation time effects during the echo train and therefore reduced image blurring as well as reduced motion artifacts.
In the future, more effective contrast agents may provide an alternative solution to the need for high field MRI. Dynamic contrast enhanced MRI perfusion has demonstrated a potential in the diagnosis of pulmonary embolism or to characterize lung cancer and mediastinal tumors. 3D contrast enhanced magnetic resonance angiography of the thoracic vessel.

See also the related poll result: 'MRI will have replaced 50% of x-ray exams by'
 
Images, Movies, Sliders:
 Anatomic Imaging of the Lungs  Open this link in a new window
      

Courtesy of  Robert R. Edelman
 Normal Lung Gd Perfusion MRI  Open this link in a new window
      

Courtesy of  Robert R. Edelman

 MRI Thorax Basal Plane  Open this link in a new window
 
Radiology-tip.comradLung Scintigraphy
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• View the DATABASE results for 'Lung Imaging' (7).Open this link in a new window


• View the NEWS results for 'Lung Imaging' (3).Open this link in a new window.
 
Further Reading:
  Basics:
A safer approach for diagnostic medical imaging
Monday, 29 September 2014   by www.eurekalert.org    
Parallel Lung Imaging(.pdf)
  News & More:
Chest MRI a viable alternative to chest CT in COVID-19 pneumonia follow-up
Monday, 21 September 2020   by www.healthimaging.com    
CT Imaging Features of 2019 Novel Corona virus (2019-nCoV)
Tuesday, 4 February 2020   by pubs.rsna.org    
Polarean Imaging Phase III Trial Results Point to Potential Improvements in Lung Imaging
Wednesday, 29 January 2020   by www.diagnosticimaging.com    
Low Power MRI Helps Image Lungs, Brings Costs Down
Thursday, 10 October 2019   by www.medgadget.com    
Chest MRI Using Multivane-XD, a Novel T2-Weighted Free Breathing MR Sequence
Thursday, 11 July 2019   by www.sciencedirect.co    
Researchers Review Importance of Non-Invasive Imaging in Diagnosis and Management of PAH
Wednesday, 11 March 2015   by lungdiseasenews.com    
New MRI Approach Reveals Bronchiectasis' Key Features Within the Lung
Thursday, 13 November 2014   by lungdiseasenews.com    
MRI techniques improve pulmonary embolism detection
Monday, 19 March 2012   by medicalxpress.com    
  News & More:
Partnership with VIDA to streamline adoption of advanced MRI of the lungs
Monday, 11 September 2023   by www.itnonline.com    
Searchterm 'MRI' was also found in the following services: 
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Radiology  (20) Open this link in a new windowUltrasound  (24) Open this link in a new window
MagneVu 1000InfoSheet: - Devices -
Intro, 
Types of Magnets, 
Overview, 
etc.MRI Resource Directory:
 - Devices -
 
www.mri4ra.com/isis.html From MagneVu;
The MagneVu 1000 is a compact, robust, and portable, permanent magnet MRI system and operates without special shielding or costly site preparation.
This MRI device utilizes a patented non-homogeneous magnetic field image acquisition method to achieve high performance imaging. The MagneVu 1000 MRI scanner is designed for MRI of the extremities with the current specialty areas in diabetes and rheumatoid arthritis. Easy access is afforded for claustrophobic, pediatric, or limited mobility patients.
In August 1998 FDA marketing clearance and other regulatory approvals have been received.
Until 2008, over 130 devices in the US are in use. Some further developments of MagneVu's extremity scanner are: 'truly Plug n' Play MRI™' and iSiS ( which adds wireless capability to the second generation MV1000-XL).
Device Information and Specification
CLINICAL APPLICATION
Dedicated extremity
CONFIGURATION
Portable open MRI
IMAGING MODES
3-dimensional multi-echo data acquisition
3D: 0.6-1 mm
MAGNET TYPE
Permanent
MAGNET WEIGHT
about 50 kg
POWER REQUIREMENTS
110 V
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• View the DATABASE results for 'MagneVu 1000' (3).Open this link in a new window

 
Further Reading:
  News & More:
VALUE OF 3D T1W & STIR MRI SEQUENCES IN DIAGNOSING EROSIONS IN RHEUMATOID ARTHRITIS
   by www.bocaradiology.com    
MRI Resources 
MRI Physics - Collections - Implant and Prosthesis pool - Colonography - Functional MRI - Pediatric and Fetal MRI
 
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