 | Info
Sheets |
| | | | | | | | | | | | | | | | | | | | | | | | |
 | Out-
side |
| | | | |
|
| | | | |
Result : Searchterm 'Contrast Agents' found in 17 terms [ ] and 105 definitions [ ]
| | 1 - 5 (of 122) nextResult Pages : [1 2 3 4] [5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 ... ] |  | |  | Searchterm 'Contrast Agents' was also found in the following services: | | | | |
| |  |
| |
|
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.
| |
|
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' |
| | | | | | | | | | | | | • Share the entry 'Contrast Agents':    | | | | | | | | | |  Further Reading: | | Basics:
|
|
News & More:
| |
| |
| | | Searchterm 'Contrast Agents' was also found in the following services: | | | | |
| | |
| |
|
| | | |
• View the DATABASE results for 'Oral Contrast Agents' (17).
| | | | | | Further Reading: | News & More:
|
|
| |
| | | | | |
| |
|
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' |
| | | | | |
• View the DATABASE results for 'Paramagnetic Contrast Agents' (22).
| | |
• View the NEWS results for 'Paramagnetic Contrast Agents' (1).
| | | | | | Further Reading: | Basics:
|
|
News & More:
| |
| |
| | | Searchterm 'Contrast Agents' was also found in the following services: | | | | |
| | | | | Searchterm 'Contrast Agents' was also found in the following services: | | | | |
| | |
| |
|
The characteristics of a hepatobiliary contrast agent are specific liver uptake and excretion via the biliary system. The paramagnetic substance (e.g. manganese, gadolinium) is taken up by normal hepatocytes. Diseased liver tissue did not include hepatocytes or their function is disturbed. Therefore, the signal of healthy liver tissue increases on T1 weighted sequences, but not in the liver lesions.
Another type of liver imaging contrast agent is superparamagnetic iron oxide. These particles accumulate in the reticuloendothelial system (RES) of the liver, and darken the healthy liver tissue in T2 weighted images. RES cells (including Kupffer cells) are existing in healthy liver tissue, in altered tissue with reduced RES activity or without RES cells the contrast agent concentration is also low or not existing, which improves the liver to lesion contrast.
Benefits of hepatobiliary contrast agents:
|
 |
Liver lesions (e.g., tumor, metastases, haemangioma etc.) are better detectable and to characterize. |
|
|
These contrast agents are useful to analyze and evaluate the liver function (in cases of diffuse liver diseases e.g., cirrhosis). |
|
|
Imaging of the gallbladder and biliary system is improved. |
| |
Differences of a hepatobiliary contrast agent compared with a targeted contrast agent for Kupffer cells:
|
|
|
The higher number of hepatocytes than Kupffer cells improves the uptake effectiveness of the contrast agent. |
|
Hepatobiliary contrast agents enable a better opacification of the biliary ducts and the gallbladder caused by the biliary excretion. |
|
Hepatobiliary contrast media are fast excreted agents. RES targeted contrast agents remain longer in the body, a fact that can increase possible side effects. |
|
See also Superparamagnetic Contrast Agents, Hepatobiliary Chelates, Liver Imaging, Endorem™, Primovist™, and Classifications, Characteristics, etc.
See also the related poll result: 'The development of contrast agents in MRI is' |
| | | |
• View the DATABASE results for 'Hepatobiliary Contrast Agents' (11).
| | | | | | Further Reading: | News & More:
|
|
| |
| | | | |
| | | |
|
| |
 | Look
Ups |
| |
(.pdf)
Random Page
top
