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Result : Searchterm 'Chelate' found in 2 terms [] and 33 definitions []
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ChelateInfoSheet: - Contrast Agents - 
Intro, Overview, 
Characteristics, 
Types of, 
etc.
 
A chelate is a heterocyclic chemical compound whose molecules consist of a metal ion attached by coordinate bonds to at least two nonmetal ions. The parent organic compound is known as a chelating agent - for example, DTPA (diethylenetriaminepentaacetic acid) used in contrast agents. Chelates are used in analytical chemistry, in agriculture as carriers of essential trace metals, in water softening, and to remove an excess of iron, which may build up to toxic levels in the body. Metalloproteins may influence the performance of enzymes or provide a mechanism for the storage of iron in the spleen and plasma of the human body.
Paramagnetic metal ions such as gadolinium improve the MRI signal, but the toxicity of these uncomplexed metal ions makes the use of a chelate to bind the metal ion essential. The chelated metal ion could be safely excreted.

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Further Reading:
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Definition of chelate - WordReference.com Dictionary
   by www.wordreference.com    
  News & More:
Tumor-targeted MR Contrast Agents: Hype or Future Hope?
November 2004   by radiology.rsnajnls.org    
Spurious Hypocalcemia After Omniscan- or OptiMARK-Enhanced Magnetic Resonance Imaging: An Algorithm for Minimizing a False-Positive Laboratory Value
October 2004   by www.findarticles.com    
Multimodal Nanoparticles for Quantitative Imaging(.pdf)
Tuesday, 13 December 2011   by alexandria.tue.nl    
Searchterm 'Chelate' was also found in the following service: 
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Ultrasound  (1) Open this link in a new window
Hepatobiliary ChelatesInfoSheet: - Contrast Agents - 
Intro, Overview, 
Characteristics, 
Types of, 
etc.
 
Hepatobiliary chelates used in MRI are paramagnetic contrast agents consisting of a metal ion bound to an organic ligand. Paramagnetic metal ions such as gadolinium improve the MRI signal, but the toxicity of these uncomplexed metal ions makes the use of a chelate to bind the metal ion essential. Due to the hepatocyte uptake of this chelate complex, the different contrast between normal parenchyma and liver lesions improves the detection and characterization of specific diseases. In addition, the hepatobiliary excretion allows the assessment of the hepatobiliary system.
Chelates for hepatobiliary imaging: MultiHance® (Gadobenate Dimeglumine), Teslascan® (Mangafodipir Trisodium), Gd-HIDA, Cr-HIDA, and Fe-EHPG IronIII or other derivatives. See also Hepatobiliary Contrast Agents, Liver Imaging.
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Further Reading:
  Basics:
MR contrast agents: Applications in hepatobiliary imaging
Thursday, 11 November 2010   by www.appliedradiology.com    
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Liver ImagingForum -
related threadsMRI Resource Directory:
 - Liver Imaging -
 
Liver imaging can be performed with sonography, computed tomography (CT) and magnetic resonance imaging (MRI). Ultrasound is, caused by the easy access, still the first-line imaging method of choice; CT and MRI are applied whenever ultrasound imaging yields vague results. Indications are the characterization of metastases and primary liver tumors e.g., benign lesions such as focal nodular hyperplasia (FNH), adenoma, hemangioma and malignant lesions (cancer) such as hepatocellular carcinomas (HCC). The decision, which medical imaging modality is more suitable, MRI or CT, is dependent on the different factors. CT is less costly and more widely available; modern multislice scanners provide high spatial resolution and short scan times but has the disadvantage of radiation exposure.
With the introduction of high performance MR systems and advanced sequences the image quality of MRI for the liver has gained substantially. Fast spin echo or single shot techniques, often combined with fat suppression, are the most common T2 weighted sequences used in liver MRI procedures. Spoiled gradient echo sequences are used as ideal T1 weighted sequences for evaluating of the liver. The repetition time (TR) can be sufficiently long to acquire enough sections covering the entire liver in one pass, and to provide good signal to noise. The TE should be the shortest in phase echo time (TE), which provides strong T1 weighting, minimizes magnetic susceptibility effects, and permits acquisition within one breath hold to cover the whole liver. A flip angle of 80° provides good T1 weighting and less of power deposition and tissue saturation than a larger flip angle that would provide comparable T1 weighting.
Liver MRI is very dependent on the administration of contrast agents, especially when detection and characterization of focal lesions are the issues. Liver MRI combined with MRCP is useful to evaluate patients with hepatic and biliary disease.
Gadolinium chelates are typical non-specific extracellular agents diffusing rapidly to the extravascular space of tissues being cleared by glomerular filtration at the kidney. These characteristics are somewhat problematic when a large organ with a huge interstitial space like the liver is imaged. These agents provide a small temporal imaging window (seconds), after which they begin to diffuse to the interstitial space not only of healthy liver cells but also of lesions, reducing the contrast gradient necessary for easy lesion detection. Dynamic MRI with multiple phases after i.v. contrast media (Gd chelates), with arterial, portal and late phase images (similar to CT) provides additional information.
An additional advantage of MRI is the availability of liver-specific contrast agents (see also Hepatobiliary Contrast Agents). Gd-EOB-DTPA (gadoxetate disodium, Gadolinium ethoxybenzyl dimeglumine, EOVIST Injection, brand name in other countries is Primovist) is a gadolinium-based MRI contrast agent approved by the FDA for the detection and characterization of known or suspected focal liver lesions.
Gd-EOB-DTPA provides dynamic phases after intravenous injection, similarly to non-specific gadolinium chelates, and distributes into the hepatocytes and bile ducts during the hepatobiliary phase. It has up to 50% hepatobiliary excretion in the normal liver.
Since ferumoxides are not eliminated by the kidney, they possess long plasmatic half-lives, allowing circulation for several minutes in the vascular space. The uptake process is dependent on the total size of the particle being quicker for larger particles with a size of the range of 150 nm (called superparamagnetic iron oxide). The smaller ones, possessing a total particle size in the order of 30 nm, are called ultrasmall superparamagnetic iron oxide particles and they suffer a slower uptake by RES cells. Intracellular contrast agents used in liver MRI are primarily targeted to the normal liver parenchyma and not to pathological cells. Currently, iron oxide based MRI contrast agents are not marketed.
Beyond contrast enhanced MRI, the detection of fatty liver disease and iron overload has clinical significance due to the potential for evolution into cirrhosis and hepatocellular carcinoma. Imaging-based liver fat quantification (see also Dixon) provides noninvasively information about fat metabolism; chemical shift imaging or T2*-weighted imaging allow the quantification of hepatic iron concentration. See also Abdominal Imaging, Primovist™, Liver Acquisition with Volume Acquisition (LAVA), T1W High Resolution Isotropic Volume Examination (THRIVE) and Bolus Injection.

For Ultrasound Imaging (USI) see Liver Sonography at US-TIP.com.
 
Images, Movies, Sliders:
 Anatomic Imaging of the Liver  Open this link in a new window
      

 MRI Liver T2 TSE  Open this link in a new window
    
 
Radiology-tip.comAbdomen CT,  Biliary Contrast Agents
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Radiology-tip.comLiver Sonography,  Vascular Ultrasound Contrast Agents
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• View the DATABASE results for 'Liver Imaging' (13).Open this link in a new window


• View the NEWS results for 'Liver Imaging' (10).Open this link in a new window.
 
Further Reading:
  Basics:
Contrast MRI Best at Finding Liver Trouble - But Timing Matters
Sunday, 6 March 2011   by www.searchmedica.com    
MR contrast agents: Applications in hepatobiliary imaging
Thursday, 11 November 2010   by www.appliedradiology.com    
Elastography: A Useful Method in Depicting Liver Hardness
Thursday, 15 April 2010   by www.sciencedaily.com    
Iron overload: accuracy of in-phase and out-of-phase MRI as a quick method to evaluate liver iron load in haematological malignancies and chronic liver disease
Friday, 1 June 2012   by www.ncbi.nlm.nih.gov    
MAGNETIC RESONANCE IMAGING OF FOCAL LIVER LESIONS(.pdf)
2002
  News & More:
MRI-PDFF images successfully measure liver fat content
Tuesday, 28 February 2017   by www.healio.com    
EORTC study aims to qualify ADC as predictive imaging biomarker in preoperative regimens
Monday, 4 January 2016   by www.eurekalert.org    
MRI effectively measures hemochromatosis iron burden
Saturday, 3 October 2015   by medicalxpress.com    
Total body iron balance: Liver MRI better than biopsy
Sunday, 15 March 2015   by www.eurekalert.org    
Perspectum Diagnostics Announces FDA Clearance for LiverMultiscan MR Imaging Device
Thursday, 12 November 2015   by www.fiercemedicaldevices.com    
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DTPAInfoSheet: - Contrast Agents - 
Intro, Overview, 
Characteristics, 
Types of, 
etc.
 
The diethylenetriaminepentaacetic acid-chelate contains five acetate moieties linked by a molecular backbone, which bind a metallic ion complex. This chemical bonding solves the problem of toxicity of, e.g. Gadolinium, because DTPA complexes are very stable.
DTPA is used together with technetium-99m as a nuclear imaging radiopharmaceutical and with gadolinium as a MR contrast medium. DTPA chelates undergo renal glomerular filtration and can be used to quantify it. DTPA is also used as a decontamination agent in individuals who have ingested radioactive materials.

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• View the DATABASE results for 'DTPA' (42).Open this link in a new window


• View the NEWS results for 'DTPA' (5).Open this link in a new window.
 
Further Reading:
  Basics:
Evaluation of Gd-DTPA-labeled dextran as an intravascular MR contrast agent: imaging characteristics in normal rat tissues
   by radiology.rsnajnls.org    
  News & More:
MRI Contrast Agent Analysis from Bruker
Sunday, 11 August 2013   by www.azom.com    
Searchterm 'Chelate' was also found in the following service: 
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Ultrasound  (1) Open this link in a new window
DysprosiumInfoSheet: - Contrast Agents - 
Intro, Overview, 
Characteristics, 
Types of, 
etc.
 
(Dy) The Dysprosium chelates are analogs of the extracellular gadolinium chelates, with substitution of the dysprosium ion for the gadolinium ion and offers advantages in application on first pass studies. The use of a dysprosium-based contrast agent (Dy-type) instead of a gadolinium-type (Gd-type) is an alternative in cases of a disrupted blood brain barrier. Because of its much smaller T1 enhancement, this contrast agent should give more accurate perfusion calculations in brain MRI.

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• View the NEWS results for 'Dysprosium' (1).Open this link in a new window.
 
Further Reading:
  Basics:
A LANTHANIDE LANTHOLOGY(.pdf)
   by www.phy.davidson.edu    
Dysprosium
   by www.scescape.net    
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