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 'Gradient Echo Sequence' 
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Result : Searchterm 'Gradient Echo Sequence' found in 5 terms [] and 80 definitions []
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Searchterm 'Gradient Echo Sequence' was also found in the following services: 
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Susceptibility ArtifactInfoSheet: - Artifacts - 
Case Studies, 
Reduction Index, 
etc.MRI Resource Directory:
 - Artifacts -
Quick Overview
Artifact Information
NAME Metal artifact, clip artifact, magnetic susceptibility artifact
DESCRIPTION Signal dropout, bright spots, spatial distortion
REASON Field inhomogeneity
HELP Remove the metal, do not take a gradient echo sequence, take a short echo time

Materials with magnetic susceptibility cause this artifact. There are in general three kinds of materials with magnetic susceptibility: ferromagnetic materials (iron, nickel etc.) with a strong influence and paramagnetic/diamagnetic (aluminium, platinum etc./gold, water, most organic compounds etc.) materials with a minimal/non influence on magnetic fields. In MRI, susceptibility artifacts are caused for example by medical devices in or near the magnetic field or by implants of the patient. These materials with magnetic susceptibility distort the linear magnetic field gradients, which results in bright areas (misregistered signals) and dark areas (no signal) nearby the magnetic material.

Image Guidance
Use a spin echo or a fast spin echo sequence, because gradient echo sequences are more sensitive to susceptibility artifacts. A high bandwidth (small water fat shift) and a short echo time help also to reduce this artifact.
In some cases it is even beneficial to use a gradient echo sequence, e.g. a cavernom contains some iron-rich haemosiderin, which also causes a signal void on gradient echo sequences and for this purpose increases the diagnostic image quality.
• Related Searches:
    • Echo Planar Imaging
    • Field Strength
    • Magnetization
    • Susceptibility
    • Spatial Misregistration Artifact
Further Reading:
MRI Artifact Gallery
Susceptibility Artifacts
  News & More:
Metal Artefact Reduction
Thursday, 9 June 2011   by    
Ultrashort echo time (UTE) MRI of the spine in thalassaemia
February 2004   by    
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Gradient Field Echo with ContrastInfoSheet: - Sequences - 
Types of, 
(GFEC) A contrast enhanced gradient echo sequence.
See Contrast Enhanced Gradient Echo Sequence and Refocused Gradient Echo Sequence.

• View the DATABASE results for 'Gradient Field Echo with Contrast' (2).Open this link in a new window

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Abdominal ImagingMRI Resource Directory:
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General MRI of the abdomen can consist of T1 or T2 weighted spin echo, fast spin echo (FSE, TSE) or gradient echo sequences with fat suppression and contrast enhanced MRI techniques. The examined organs include liver, pancreas, spleen, kidneys, adrenals as well as parts of the stomach and intestine (see also gastrointestinal imaging). Respiratory compensation and breath hold imaging is mandatory for a good image quality.
T1 weighted sequences are more sensitive for lesion detection than T2 weighted sequences at 0.5 T, while higher field strengths (greater than 1.0 T), T2 weighted and spoiled gradient echo sequences are used for focal lesion detection. Gradient echo in phase T1 breath hold can be performed as a dynamic series with the ability to visualize the blood distribution. Phases of contrast enhancement include the capillary or arterial dominant phase for demonstrating hypervascular lesions, in liver imaging the portal venous phase demonstrates the maximum difference between the liver and hypovascular lesions, while the equilibrium phase demonstrates interstitial disbursement for edematous and malignant tissues.
Out of phase gradient echo imaging for the abdomen is a lipid-type tissue sensitive sequence and is useful for the visualization of focal hepatic lesions, fatty liver (see also Dixon), hemochromatosis, adrenal lesions and renal masses. The standards for abdominal MRI vary according to clinical sites based on sequence availability and MRI equipment. Specific abdominal imaging coils and liver-specific contrast agents targeted to the healthy liver tissue improve the detection and localization of lesions.
See also Hepatobiliary Contrast Agents, Reticuloendothelial Contrast Agents, and Oral Contrast Agents.

For Ultrasound Imaging (USI) see Abdominal Ultrasound at
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• View the DATABASE results for 'Abdominal Imaging' (11).Open this link in a new window

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Further Reading:
Abdominal MRI at 3.0 T: The Basics Revisited
Wednesday, 20 July 2005   by    
Usefulness of MR Imaging for Diseases of the Small Intestine: Comparison with CT
2000   by    
  News & More:
RSI-MRI imaging technology can effectively differentiate aggressive prostate cancer
Thursday, 2 June 2016   by    
Computer-aided detection and diagnosis for prostate cancer based on mono and multi-parametric MRI: A review - Abstract
Tuesday, 28 April 2015   by    
MRI for differentiating ovarian endometrioid adenocarcinoma from high-grade serous adenocarcinoma
Wednesday, 29 April 2015   by    
MRI identifies 'hidden' fat that puts adolescents at risk for disease
Tuesday, 27 February 2007   by    
Nottingham scientists exploit MRI technology to assist in the treatment of IBS
Thursday, 9 January 2014   by    
New MR sequence helps radiologists more accurately evaluate abnormalities of the uterus and ovaries
Thursday, 23 April 2009   by    
Searchterm 'Gradient Echo Sequence' was also found in the following services: 
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Balanced SARGEInfoSheet: - Sequences - 
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etc.MRI Resource Directory:
 - Sequences -
(BASG) The spoiled steady state acquisition rewinded gradient echo sequence with balanced waveform.
See Steady State Free Precession, Gradient Echo Sequence and Balanced Sequence.

• View the DATABASE results for 'Balanced SARGE' (3).Open this link in a new window

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Coherent Gradient EchoInfoSheet: - Sequences - 
Types of, 
etc.MRI Resource Directory:
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Coherent gradient echo sequences can measure the free induction decay (FID), generated just after each excitation pulse or the echo formed prior to the next pulse. Coherent gradient echo sequences are very sensitive to magnetic field inhomogeneity. An alternative to spoiling is to incorporate residual transverse magnetization directly into the longitudinal steady state. These GRE sequences use a refocusing gradient in the phase encoding direction during the end module to maximize remaining transverse (xy) magnetization at the time when the next excitation is due, while the other two gradients are, in any case, balanced.
When the next excitation pulse is sent into the system with an opposed phase, it tilts the magnetization in the -a direction. As a result the z-magnetization is again partly tilted into the xy-plane, while the remaining xy-magnetization is tilted partly into the z-direction.
A fully refocused sequence with a properly selected and uniform f would yield higher signal, especially for tissues with long T2 relaxation times (high water content) so it is used in angiographic, myelographic or arthrographic examinations and is used for T2* weighting. The repetition time for this sequence has to be short. With short TR, coherent GE is also useable for breath hold and 3D technique. If the repetition time is about 200 msec there's no difference between spoiled or unspoiled GE. T1 weighting is better with spoiled techniques.
The common types include GRASS, FISP, FAST, and FFE.
The T2* component decreases with long TR and short TE. The T1 time is controlled by flip angle. The common TR is less than 50 ms and the common TE less than 15 ms
Other types have stronger T2 dependence but lower SNR. They include SSFP, CE-FAST, PSIF, and CE-FFE-T2.
Examples of fully refocused FID sequences are TrueFISP, bFFE and bTFE.


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