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Result : Searchterm 'Signal Intensity' found in 1 term [] and 55 definitions []
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Searchterm 'Signal Intensity' was also found in the following services: 
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News  (5)  Resources  (1)  Forum  (4)  
 
FerumoxideInfoSheet: - Contrast Agents - 
Intro, Overview, 
Characteristics, 
Types of, 
etc.
 
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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• Related Searches:
    • Very Small Superparamagnetic Iron Oxide Particles
    • Superparamagnetic Contrast Agents
    • Ultrasmall Superparamagnetic Iron Oxide
    • Superparamagnetic Iron Oxide
    • Crosslinked Iron Oxide
 
Further Reading:
  Basics:
Comparison of Two Superparamagnetic Viral-Sized Iron Oxide Particles Ferumoxides and Ferumoxtran-10 with a Gadolinium Chelate in Imaging Intracranial Tumors
2002   by www.ajnr.org    
Optimized Labelling of Human Monocytes with Iron Oxide MR Contrast Agents
Sunday, 30 November 2003   by rsna2003.rsna.org    
Searchterm 'Signal Intensity' was also found in the following service: 
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Radiology  (1) Open this link in a new window
Inflow Magnetic Resonance AngiographyMRI Resource Directory:
 - MRA -
 
(I MRA) In MR imaging, inflowing non-saturated fluid gives a higher signal intensity than stationary tissue. This effect makes it especially useful for imaging of flowing blood. Other factors such as susceptibility and spin saturation, can affect the signal of the blood within the vessels. Furthermore turbulence is part of normal blood flow and can decrease signal intensity.
See also Time of Flight Angiography.
 
Images, Movies, Sliders:
 TOF-MRA Circle of Willis Inverted MIP  Open this link in a new window
    

 Circle of Willis, Time of Flight, MIP  Open this link in a new window
    
SlidersSliders Overview

 
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MRI Resources 
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Magnetic Resonance CholangiopancreaticographyMRI Resource Directory:
 - MRCP -
 
(MRCP) This MR imaging technique takes advantage of the high signal intensity of body fluids and acquires heavy T2 weighted images of the gall bladder, the pancreas and parts of the liver. Due to the T2 weighting, the liver and other solid parenchyma are signal suppressed and only fluid-filled structures in addition to the gall bladder, the bile and pancreatic ducts retain important signal intensity. Hepatobiliary contrast agents (e.g. Gadoxetic Acid, CMC 001) can be useful for enhancement of the bile ducts and better imaging of the biliary tract.
A 2D cholangiogram, often only one thick slice (a volume with a thickness of 4 - 8 cm, mostly coronal planned) or 5 - 6 radial placed slices, shows a view like single slices. If a 3D acquisition is used, the postprocessing function maximum intensity projection (MIP) can show reconstructions from multiple sides.
Radiology-tip.comBiliary Contrast Agents
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Radiology-tip.comGallbladder Ultrasound
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• View the DATABASE results for 'Magnetic Resonance Cholangiopancreaticography' (3).Open this link in a new window

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Opposed Phase ImageInfoSheet: - Sequences - 
Intro, 
Overview, 
Types of, 
etc.
 
An image in which the signal from two spectral components (such as fat and water) is 180° out of phase and leads to destructive interference in a voxel.
Since fat precesses slower than water, based on their chemical shift, their signals will decay and precess in the transverse plane at different frequencies. When the phase of the TE becomes opposed (180°), their combined signal intensities subtract with each other in the same voxel, producing a signal void or dark band at the fat/water interface of the tissues being examined.
Opposed phase gradient echo imaging for the abdomen is a lipid-type tissue sensitive sequence particularly for the liver and adrenal glands, which puts a signal intensity around abnormal water-based tissues or lesions that are fatty. Due to the increased sensitivity of opposed phase, the tissue visualization increases the lesion-to-liver contrast and exhibits more signal intensity loss in tissues containing small amounts of lipids compared to a spin echo T1 with fat suppression. Using an opposed phase gradient echo also provides the ability to differentiate various pathologies in the brain, including lipids, methaemoglobin, protein, calcifications and melanin.
See also Out of Phase, and Dixon.
 
Images, Movies, Sliders:
 MRI Liver Out Of Phase  Open this link in a new window
    
 
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• View the DATABASE results for 'Opposed Phase Image' (5).Open this link in a new window

 
Further Reading:
  Basics:
Scanning the Abdomen
   by www.mrprotocols.com    
  News & More:
Adrenal Myelolipoma
Tuesday, 19 June 2001   by www.emedicine.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    
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Radiology  (1) Open this link in a new window
Partial Flip Angle
 
(PFI) A flip angle of less than 90° only partially converts the z-magnetization, leaving a fraction cos a along the longitudinal direction. A flip angle of 90° converts all the z-magnetization into xy-magnetization.
When the repetition time is shorter than T1, the use of a partial flip angle can lead to higher signal intensity. The maximum signal intensity is given by the Ernst angle. For spin echo pulse sequences using an odd number of 180° pulses, an effect similar to the use of a partial flip angle is obtained by using a flip angle greater than 90° to offset the inversion of the remaining longitudinal magnetization by the 180° pulse.
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