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Contrast AgentsForum -
there are 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 NEWS results for 'Contrast Agents' (25).Open this link in a new window.

• View the DATABASE results for 'Contrast Agents' (122).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    
Contrast Enhanced FASTInfoSheet: - Sequences -
Intro, Overview, 
Types of, 
etc.MRI Resource Directory:
 - Sequences -
 
(CE-FAST) In this technique, the MR signal is sampled immediately prior to each RF pulse. Because the signal is formed by a true spin echo, its contrast is predominantly T2-, rather than T2*-based and is less sensitive to artifacts and signal losses related to field non-uniformity and susceptibility variation. While the signal to noise ratio is limited, the CE-FAST method has the advantage of good contrast.

See Contrast Enhanced Gradient Echo Sequence and Gradient Echo Sequence.
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• View the DATABASE results for 'Contrast Enhanced FAST' (5).Open this link in a new window

MRI Resources 
MRI Reimbursement - Equipment - Education - Guidance - Cochlear Implant - Implant and Prosthesis
 
Contrast Enhanced Fast Field Echo with T1 WeightingInfoSheet: - Sequences -
Intro, Overview, 
Types of, 
etc.
 
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• View the DATABASE results for 'Contrast Enhanced Fast Field Echo with T1 Weighting' (2).Open this link in a new window

Contrast Enhanced Fast Field Echo with T2 Star WeightingMRI Resource Directory:
 - Sequences -
 
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Contrast Enhanced FLASHInfoSheet: - Sequences -
Intro, Overview, 
Types of, 
etc.
 
(CE FLASH) A fast T2 weighted imaging sequence utilizing refocused transverse coherence.

See Contrast Enhanced Echo Sequence.
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MRI Resources 
Mass Spectrometry - Movies - Mobile MRI - Jobs pool - Societies - MRI Training Courses
 
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