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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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Rapid Excitation Magnetic Resonance ImagingInfoSheet: - Sequences - 
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(RE MRI) There are several approaches to speeding up the MRI data acquisition process by repeating the excitation by RF pulses in times short compared to T1, typically using small flip angles and gradient echo refocusing. When TR is also on the order of or shorter than T2, the repeated RF pulses will tend to refocus transverse magnetization remaining from prior excitations, setting up a condition of steady state free precession, and a dependence of signal strength (and image contrast) on both T1 and T2.
This can be modified in various ways, particularly:
1) to spoil the tendency to build up a steady state by reducing coherence between excitations, e.g. by variation of the phase or timing of consecutive RF pulses or of the strength of spoiler gradient pulses, thus increasing the relative dependence of signal strength on T1 or
2) acquire the signal when it is refocusing immediately prior to the next RF pulse, thus increasing the relative dependence of signal strength on T2.
See also Ultrafast Gradient Echo Sequence.
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Refocusing
 
A rephasing or refocusing occurs when spins return to the same starting phase they had directly after the initial exciting RF pulse. E.g. spin echo sequences use 180° pulses to refocus the spins to generate signal echoes and gradient echo sequences use a refocusing gradient to maximize remaining transverse magnetization.
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Further Reading:
  Basics:
Clinical evaluation of a speed optimized T2 weighted fast spin echo sequence at 3.0 T using variable flip angle refocusing, half-Fourier acquisition and parallel imaging
Wednesday, 25 October 2006
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Rephasing
 
The process of returning out of phase magnetic moments back into phase coherence. Caused either by rapidly reversing a magnetic gradient (Field Echo) or by applying a 180° RF pulse (Spin Echo). In the spin echo pulse sequence this action effectively cancels out the spurious T2* information from the signal.
See also Spin Echo Sequence and Gradient Echo Sequence.
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Searchterm 'Gradient Echo Sequence' was also found in the following services: 
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Scan TimeForum -
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(SCT) The total scan time is the time required to collect all data needed to generate the programmed images. The scan time is related to the used pulse sequence and dependent on the assemble of parameters like e.g., repetition time (TR), Matrix, number of signal averages (NSA), TSE- or EPI factor and flip angle.
For example, the total scan time for a standard spin echo or gradient echo sequence is number of repetitions x the scan time per repetition (means the product of repetition time (TR), number of phase encoding steps, and NSA).
See also Number of Excitations, Turbo Spin Echo Turbo Factor, Echo Planar Imaging Factor, Flip Angle and Image Acquisition Time.
See also acronyms for 'scan time parameters' from different manufacturers.
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• View the NEWS results for 'Scan Time' (10).Open this link in a new window.
 
Further Reading:
  Basics:
Musculoskeletal MRI at 3.0 T: Relaxation Times and Image Contrast
Sunday, 1 August 2004   by www.ajronline.org    
  News & More:
Clinical examination or whole-body magnetic resonance imaging: the Holy Grail of spondyloarthritis imaging
Tuesday, 28 February 2012   by 7thspace.com    
Real-time MRI: recent advances using radial FLASH
Wednesday, 4 April 2012   by www.futuremedicine.com    
For MRI, time is of the essence A new generation of contrast agents could make for faster and more accurate imaging
Tuesday, 28 June 2011   by scienceline.org    
Clinical evaluation of a speed optimized T2 weighted fast spin echo sequence at 3.0 T using variable flip angle refocusing, half-Fourier acquisition and parallel imaging
Wednesday, 25 October 2006
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Short Repetition TechniquesInfoSheet: - Sequences - 
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(SHORT) Gradient echo sequences.
See Incoherent Gradient Echo (gradient spoiled.
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Stent - Calculation - MRA - Portals - MRI Physics - Distributors
 
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