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 'Paramagnetic Contrast Agents' 
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Result : Searchterm 'Paramagnetic Contrast Agents' found in 4 terms [] and 19 definitions []
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Paramagnetic Contrast AgentsInfoSheet: - Contrast Agents - 
Intro, Overview, 
Characteristics, 
Types of, 
etc.MRI Resource Directory:
 - Contrast Agents -
 
Magnetic relaxation in tissues can be enhanced using contrast agents. The most commonly used for MRI are the paramagnetic contrast agents, which have their strongest effect on the T1, by increasing T1 signal intensity in tissues where they have accumulated.
MRI collects signal from the water protons, but the presence of these contrast agents enhances the relaxation of water protons in their vicinity. Paramagnetic contrast agents contain magnetic centers that create magnetic fields approximately one thousand times stronger than those corresponding to water protons. These magnetic centers interact with water protons in exactly the same way as the neighboring protons, but with much stronger magnetic fields, and therefore, have a much greater impact on relaxation rates, particularly on T1. In MRI, contrast agents are routinely injected intravenously to help identify areas of hypervascularity, as in malignant tumors.
See also Contrast Agents, Gadovist®, MultiHance®, Omniscan®, OptiMARK®.

See also the related poll result: 'The development of contrast agents in MRI is'
 
Images, Movies, Sliders:
 MRI Upper Abdomen T1 with Contrast  Open this link in a new window
    
 MRI Orbita T1  Open this link in a new window
 MRI Orbita T1 with Contrast  Open this link in a new window
    
 
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• Related Searches:
    • Chelate
    • T1 Relaxation
    • Oral Contrast Agents
    • Hepatobiliary Contrast Agents
    • Nephrogenic Systemic Fibrosis
 
Further Reading:
  Basics:
LEARNING CENTER FOR PARAMAGNETISM
2003   by www.naturesalternatives.com    
Contrast Agents: Safety Profile
   by www.clinical-mri.com    
Contrast Agents in Magnetic Resonance Imaging
1997
  News & More:
Gadolinium-containing contrast agents: removal of Omniscan and iv Magnevist, restrictions to the use of other linear agents
Friday, 5 January 2018   by www.gov.uk    
EMA's final opinion confirms restrictions on use of linear gadolinium agents in body scans
Friday, 21 July 2017   by www.ema.europa.eu    
FDA Drug Safety Communication: FDA warns that gadolinium-based contrast agents (GBCAs) are retained in the body; requires new class warnings
Tuesday, 19 December 2017   by www.fda.gov    
RSNA Statement on Gadolinium-Based MR Contrast Agents
Thursday, 1 February 2018   by www.rsna.org    
Contrast MRIs cause claims, concern, over residual metal in brain
Tuesday, 8 December 2015   by www.afr.com    
MRI Resources 
Raman Spectroscopy - Colonography - Bioinformatics - Breast Implant - Contrast Enhanced MRI - MRI Physics
 
Superparamagnetic Contrast AgentsInfoSheet: - Contrast Agents - 
Intro, Overview, 
Characteristics, 
Types of, 
etc.MRI Resource Directory:
 - Contrast Agents -
 
Small particles of ferrite are used as superparamagnetic contrast medium in MR imaging (appearing predominantly dark on MRI). These agents exhibit strong T1 relaxation properties, and due to susceptibility differences to their surroundings also produce a strongly varying local magnetic field, which enhances T2 relaxation to darken the contrast media containing structures.
Superparamagnetic contrast agents are also known by the abbreviation SPIO's (small particle iron oxide or superparamagnetic iron oxide) and USPIO's (ultrasmall particle iron oxide or ultrasmall superparamagnetic iron oxide).
Two types of USPIO will be available on the market as blood pool agents, while SPIO's have been used as darkening contrast agents for liver imaging. As particulate matter they are taken up by the RES. Very small particles of less than 300 nanometers also remain intravascular for a prolonged period of time and thus can serve as blood pool agents.

See also the related poll result: 'The development of contrast agents in MRI is'
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• View the DATABASE results for 'Superparamagnetic Contrast Agents' (12).Open this link in a new window

 
Further Reading:
  News & More:
Optimized Labelling of Human Monocytes with Iron Oxide MR Contrast Agents
Sunday, 30 November 2003   by rsna2003.rsna.org    
Poly (dopamine) coated superparamagnetic iron oxide nanocluster for noninvasive labeling, tracking, and targeted delivery of adipose tissue-derived stem cells
Tuesday, 5 January 2016   by www.nature.com    
MRI Resources 
Claustrophobia - DICOM - Education - MR Myelography - Sequences - Used and Refurbished MRI Equipment
 
Gastrointestinal Paramagnetic Contrast AgentsInfoSheet: - Contrast Agents - 
Intro, Overview, 
Characteristics, 
Types of, 
etc.MRI Resource Directory:
 - Contrast Agents -
 
Paramagnetic substances, for example Gd-DTPA solutions, are used as MRI oral contrast agents in gastrointestinal imaging to depict the lumen of the digestive organs. Different Gd-DTPA solutions or zeolites containing gadolinium can be used e.g., for diagnosis of delayed gastric emptying, diagnosis of Crohn's disease etc.
Low concentrations of gastrointestinal paramagnetic contrast agents cause a reduction in T1 relaxation time; consequently, these agents act on T1 weighted images by increasing the signal intensity of the bowel lumen. High concentrations cause T2 shortening by decreasing the signal, similar to superparamagnetic iron oxide. Gd-DTPA chelates are unstable at the low pH in the stomach, therefore buffering is necessary for oral use.
See also Gadopentetate Gastrointestinal, Gadolinium Zeolite, Negative Oral Contrast Agents, Gastrointestinal Superparamagnetic Contrast Agents, and Ferric ammonium citrate.
 
Images, Movies, Sliders:
 MR Colonography Gadolinium per Rectum  Open this link in a new window
      

Courtesy of  Robert R. Edelman
 
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• View the DATABASE results for 'Gastrointestinal Paramagnetic Contrast Agents' (5).Open this link in a new window

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Gastrointestinal Superparamagnetic Contrast AgentsInfoSheet: - Contrast Agents - 
Intro, Overview, 
Characteristics, 
Types of, 
etc.MRI Resource Directory:
 - Contrast Agents -
 
Gastrointestinal (GI) superparamagnetic contrast agents are used in MRI to improve the visualization of e.g., the intestinal tract, the pancreas (see MRCP), etc. Disadvantages are susceptibility artifacts e.g., dependent on delayed imaging or large volumes resulting in artifacts in the colon and distal small bowel loops related to higher concentration of the particles and absorption of the fluid.
Different types of MRI gastrointestinal superparamagnetic contrast agents:
Superparamagnetic iron oxide
Magnetite albumin microsphere
Oral magnetic particles
Usually gastrointestinal superparamagnetic contrast media consist of small iron oxide crystals (ferrites), which produce a signal reduction in the stomach and bowel after oral administration. The T2 shortening caused by these particles is produced from the local magnetic field inhomogeneities associated with the large magnetic moments of superparamagnetic particles. Ferrites are iron oxides of the general formula Fe203.MO, where M is a divalent metal ion and may be mixed with Fe3O4 in different preparations. Ferrites can produce symptoms of nausea after oral administration, as well as flatulence and a transient rise in serum iron. Embedding in inert substances reduce side effects by decreasing the absorption and interaction with body tissues. Combining these contrast materials with polymers such as polyethylene glycol or cellulose, or with sugars such as dextrose, results in improved T1 and/or T2 relaxivity compared with that of the contrast agent alone.
See also Negative Oral Contrast Agents, Gastrointestinal Diamagnetic Contrast Agents, Relaxivity, and Combination Oral Contrast Agents.
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• View the DATABASE results for 'Gastrointestinal Superparamagnetic Contrast Agents' (6).Open this link in a new window

 
Further Reading:
  Basics:
PRODUCTION OF MAGNETICALLY AND PH RESPONSIVE BIODEVICES BY DENSE GAS TECHNOLOGY
2008   by www.isasf.net    
Negative GI Contrast Agents
   by www.mritutor.org    
MRI Resources 
Spectroscopy - Colonography - Homepages - Breast Implant - Shoulder MRI - MRI Physics
 
Combination Oral Contrast AgentsInfoSheet: - Contrast Agents - 
Intro, Overview, 
Characteristics, 
Types of, 
etc.MRI Resource Directory:
 - Contrast Agents -
 
Biphasic oral contrast agents may produce either high or low signal intensities depending on the pulse sequence used, for example low signal intensity on T1 weighted MR images and high signal intensity on T2 weighted images. The combination of different oral contrast agents can generate a macroscopic cancellation of negative and positive magnetic susceptibility, thereby eliminating susceptibility artifacts.
Possible combinations are e.g., ferric ammonium citrate and corn oil, or ferrous sulfate emulsified with baby formula. Paramagnetic agents combined with oil emulsion may be used in MRI as positive abdominal contrast agents. The combination of diamagnetic barium sulfate and superparamagnetic iron oxide (SPIO) in one suspension may be a useful negative contrast agent.
See also Gastrointestinal Paramagnetic Contrast Agents, Gastrointestinal Superparamagnetic Contrast Agents, Gastrointestinal Diamagnetic Contrast Agents, Gastrointestinal Imaging.

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• View the DATABASE results for 'Combination Oral Contrast Agents' (3).Open this link in a new window

 
Further Reading:
  Basics:
Usefulness of MR Imaging for Diseases of the Small Intestine: Comparison with CT
2000   by www.ncbi.nlm.nih.gov    
MRI Resources 
Implant and Prosthesis - MRI Centers - Nerve Stimulator - Mobile MRI - Service and Support - Blood Flow Imaging
 
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