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Result : Searchterm 'Ferumoxide' found in 1 term [ ] and 4 definitions [ ]
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MRI Resources |
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| Ferumoxide |  |
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Short name: AMI-25, generic name: Ferumoxide (SPIO)
Ferumoxides are superparamagnetic (T2*) MRI contrast agents, so the largest signal change is on T2 and T2* weighted images.
The agent distributes relatively rapidly to organs with reticuloendothelial cells primarily the liver, spleen and bone marrow.
The liver shows decreased signal intensity, as does the spleen and marrow. The agent is taken up by the normal liver, resulting in increased CNR between tumor and normal liver. Hepatocellular lesions, such as adenoma or focal nodular hyperplasia, contain reticuloendothelial cells, so they will behave similar to the liver, with decreased signal on T2 weighted images. On T1 images, there is typically some circulating contrast agent, and blood vessels show increased signal intensity.
Current MRI protocols involve T1 weighted breath-hold gradient echo images of the liver, and fast spin echo T2 weighted pictures. This requires about 15 minutes. The patient is then removed from the scanner, and the contrast agent administered. After contrast administration, the same pulse sequences are again repeated.
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| Endorem™ |  |
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A brand name for ferumoxide (same as Feridex®)
Endorem™ is a black to reddish-brown aqueous colloid of superparamagnetic iron oxide associated with dextran for intravenous administration as a MRI contrast medium for the detection of liver lesions that are associated with an alteration in the RES.
Endorem™ is taken up by macrophages, found only in healthy liver cells but not in most tumors. Tissues such as metastases, primary liver cancer, cysts and various benign tumors, adenomas and hyperplasia retain their native signal intensity, so the contrast between normal and abnormal tissue is increased.
See also Ferumoxide.
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Drug Information and Specification |
| NAME OF COMPOUND |
Dextran-coated ferumoxide, Ami-25
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| DEVELOPER |
AMAG Pharmaceuticals, Inc., Guerbet S.A.
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| CENTRAL MOIETY |
Fe2+/Fe3+ |
| CONTRAST EFFECT |
T2, predominantly negative enhancement |
| RELAXIVITY |
r1=40.0, r2=160, B0=0.47T |
| PHARMACOKINETIC |
RES-directed |
| OSMOLALITY |
340 mosm/kgH2O |
| CONCENTRATION |
11.2mg Fe/ml |
| DOSAGE |
15 µmol Fe/kg |
| PREPARATION |
Suspend in an isotonic glucose solution |
| INDICATION |
Liver |
| DEVELOPMENT STAGE |
For sale |
| DISTRIBUTOR |
See below |
| PRESENTATION |
Ampoule of 8 mL |
| DO NOT RELY ON THE INFORMATION PROVIDED HERE, THEY ARE NOT A SUBSTITUTE FOR THE ACCOMPANYING
PACKAGE INSERT! |
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Basics:
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MRI Resources |
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| Feridex® | |
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A brand name for ferumoxide (same as Endorem™)
Feridex® is a sterile aqueous colloid of superparamagnetic iron oxide associated with dextran for intravenous administration as a MRI contrast medium for the detection of liver lesions that are associated with an alteration in the RES.
Feridex® is taken up by macrophages, found only in healthy liver cells but not in most tumors. Tissues such as metastases, primary liver cancer, cysts and various benign tumors, adenomas and hyperplasia retain their native signal intensity, so the contrast between normal and abnormal tissue is increased.
Feridex® is a black to reddish-brown aqueous colloid.
See also Ferumoxide.
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Drug Information and Specification |
| NAME OF COMPOUND |
Dextran-coated ferumoxide, Ami-25
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| DEVELOPER |
AMAG Pharmaceuticals, Inc.
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| CENTRAL MOIETY |
Fe2+/Fe3+ |
| CONTRAST EFFECT |
T2, predominantly negative enhancement |
| RELAXIVITY |
r1=40.0, r2=160, B0=0.47T |
| PHARMACOKINETIC |
RES-directed |
| OSMOLALITY |
340 mosm/kgH2O |
| CONCENTRATION |
11.2mg Fe/ml |
| DOSAGE |
15 µmol Fe/kg |
| PREPARATION |
Suspend in an isotonic glucose solution |
| INDICATION |
Liver |
| DEVELOPMENT STAGE |
For sale |
| DISTRIBUTOR |
See below |
| PRESENTATION |
Ampoule of 8 mL |
| DO NOT RELY ON THE INFORMATION PROVIDED HERE, THEY ARE NOT A SUBSTITUTE FOR THE ACCOMPANYING
PACKAGE INSERT! |
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| Further Reading: |
Basics:
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News & More:
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| Liver Imaging |  |
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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 allow only for a small temporal window (seconds) for liver MRI after which they begin to diffuse to the interstitial space not only of healthy liver 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). 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, which are called superparamagnetic
iron oxides. The smaller ones, possessing a total particle size in the order of 30 nm, are called ultrasmall
iron oxide particles and they suffer a slower uptake by RES cells.
Primarily targeted the normal liver parenchyma and not to pathological cells.
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. |
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| | | | | •• There are 10 news about 'Liver Imaging'. | |
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| Superparamagnetic Iron Oxide | |
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(SPIO) Relatively new types of MRI contrast agents are superparamagnetic iron oxide-based colloids (median diameter greater than 50nm). These compounds consist of nonstoichiometric microcrystalline magnetite cores, which are coated with dextrans (in ferumoxide) or siloxanes (in ferumoxsil). After injection they accumulate in the reticuloendothelial system (RES) of the liver (Kupffer cells) and the spleen. At low doses circulating iron decreases the T1 time of blood, at higher doses predominates the T2* effect.
SPIO agents are much more effective in MR relaxation than paramagnetic agents. Since hepatic tumors either do not contain RES
cells or their activity is reduced, the contrast between liver and lesion is improved. Superparamagnetic iron oxides cause noticeable shorter T2 relaxation times with signal loss in the targeted tissue (e.g., liver and spleen) with all standard pulse sequences.
Magnetite, a mixture of FeO and Fe2O3, is one of the used iron oxides. FeO can be replaced by Fe3O4.
Use of these colloids as tissue specific contrast agents is now a well-established area of pharmaceutical development. Feridex®, Endorem™, GastroMARK®, Lumirem®, Sinerem®, Resovist® and more patents pending tell us that the last word in this area is not said.
Some remarkable points using SPIO:
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A minimum delay of about 10 min. between injection (or infusion) and MR imaging, extends the examination time.
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Cross-section flow void in narrow blood vessels may impede the differentiation from small liver lesions. |
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Aortic pulsation artifacts become more pronounced. |
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See also Superparamagnetism, Superparamagnetic Contrast Agents and Classifications, Characteristics, etc.. |
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News & More:
| | | | | •• There are 3 news about 'Superparamagnetic Iron Oxide'. | |
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