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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

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:
Magnetite albumin microsphere

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:
Negative GI Contrast Agents
   by www.mritutor.org    
MRI Resources 
Education pool - Non-English - Absorption and Emission - MRI Technician and Technologist Schools - Pathology - Musculoskeletal and Joint MRI
 
GastroMARK®InfoSheet: - Contrast Agents - 
Intro, Overview, 
Characteristics, 
Types of, 
etc.MRI Resource Directory:
 - Contrast Agents -
 
GastroMARK® belongs to the negative oral contrast agents (same as Lumirem®, another brand name for ferumoxsil). GastroMARK® is used to distinguish the loops of the bowel from other abdominal structures and physiology. When GastroMARK® is ingested, it flows through and darkens the stomach and the small intestine in 30 to 45 minutes. By more clearly identifying the intestinal loops, GastroMARK® improves visualization of adjacent abdominal tissues such as the pancreas.
Drug Information and Specification
NAME OF COMPOUND
Ferumoxsil, silicone-coated superparamagnetic iron oxide, USAN, AMI-121
CENTRAL MOIETY
Fe3+/Fe2+
CONTRAST EFFECT
T2*enhanced
r1=3.4, r2=3.8, B0=1.0T
PHARMACOKINETIC
Gastrointestinal
OSMOLALITY
250 mosm/kgH2O
CONCENTRATION
52.5mg Fe/300mL
DOSAGE
300 mL oral
PREPARATION
Finished product
INDICATION
Bowel marking
DEVELOPMENT STAGE
For sale
DISTRIBUTOR
See below
PRESENTATION
Bottles containing 300 mL
DO NOT RELY ON THE INFORMATION PROVIDED HERE, THEY ARE
NOT A SUBSTITUTE FOR THE ACCOMPANYING PACKAGE INSERT!
Distribution Information
TERRITORY
TRADE NAME
DEVELOPMENT
STAGE
DISTRIBUTOR
USA
GastroMARK®
For sale
EU
For sale
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• View the DATABASE results for 'GastroMARK®' (6).Open this link in a new window

 
Further Reading:
  Basics:
ferumoxsil, oral suspension GastroMARK GastroMARK ®
MATERIAL SAFETY DATA SHEET
   by dailymed.nlm.nih.gov    
Gating
 
Synchronization of imaging with a phase of the cardiac or respiratory cycles.
A variety of means for detecting these cycles can be used, such as the ECG, peripheral pulse, chest motion, etc. The synchronization can be prospective or retrospective.
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• View the DATABASE results for 'Gating' (67).Open this link in a new window

 
Further Reading:
  Basics:
Electrocardiogram in an MRI Environment: Clinical Needs, Practical Considerations, Safety Implications, Technical Solutions and Future Directions
Wednesday, 25 January 2012   by cdn.intechopen.com    
GaussForum -
there are related threads
 
(G) An older unit of flux density. The currently preferred SI unit is the tesla (T).
Definition: 1 gauss is defined as 1 line of flux per cm2. The Earth's magnetic field is approximately one half gauss to one gauss, depending on location. For the large magnetic fields used by MRI, the unit gauss (G) has been replaced by the more practical unit tesla (T), where 1 T = 10 000 G.
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• View the DATABASE results for 'Gauss' (66).Open this link in a new window

 
Further Reading:
  Basics:
A Short History of the Magnetic Resonance Imaging (MRI)
   by www.teslasociety.com    
Magnetic Field
   by hyperphysics.phy-astr.gsu.edu    
  News & More:
Self-assembling gauss gun idea would heal patients from the inside
Saturday, 27 June 2015   by www.engadget.com    
Hamilton Medical's MRI Compatible Ventilator Cleared in U.S.
Monday, 10 February 2014   by www.medgadget.com    
MRI Resources 
Corporations - Liver Imaging - MR Guided Interventions - Spectroscopy pool - Mobile MRI Rental - MRI Physics
 
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