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MRI is trending to low field magnets :
reduced costs will lead to this change 
AI will close the gap to high field 
only in remote areas 
is only temporary 
never 




 
MRI Sequences
 
 
 
ball_redIncoherent Gradient Echo (RF Spoiled) 
A gradient echo is generated by using a pair of bipolar gradient pulses. The gradient field is negatively pulsed, causing the spins of the xy-magnetization to dephase. A second gradient pulse is applied with the opposite polarity. During the pulsing, the spins that dephased begin to rephase and generate a gradient echo.
Spoiling can be accomplished by RF or a gradient. The incoherent RF spoiled type of a gradient echo sequence use a continuous shifting of the RF pulse to spoil the residual transverse magnetization. The phase of the RF excitation and receiver channel are varied pseudo randomly with each excitation cycle to prevent the xy magnetization from achieving steady state. T2* does not dominate image contrast, so T1 and PD weighting is practical. This method is effective and can be used to achieve a shorter TR, due to a lack of additional gradients. Spoiling eliminates the effect of the remaining xy-magnetization and leads to steady state longitudinal magnetization. These sequences can be used for breath hold, dynamic imaging and in cine and volume acquisitions.
Gradient Field Echo 

• View the DATABASE results for 'Gradient Field Echo' (4).Open this link in a new window

 
Further Reading:
  News & More:
Principles, Techniques, and Applications of T2*- based MR Imaging and Its Special Applications1
September 2009   by pubs.rsna.org    
Radio Frequency Spoiled Steady State Acquisition Rewound Gradient Echo 
(RSSARGE) A sequence with spoiled gradient echoes.
See Spoiled Gradient Echo Sequence.

• View the DATABASE results for 'Radio Frequency Spoiled Steady State Acquisition Rewound Gradient Echo' (2).Open this link in a new window

RF Spoiled Fourier Acquired Steady State Technique 
(RF-FAST / RF spoiled FAST) A gradient echo sequence.
See Spoiled Gradient Echo Sequence.

• View the DATABASE results for 'RF Spoiled Fourier Acquired Steady State Technique' (2).Open this link in a new window

Small Tip Angle Gradient Echo T1 Weighted 
Spoiled Gradient Recalled 
(SPGR) The SPGR pulse sequence is similar to the spoiled GRASS sequence. The spoiled gradient recalled (SPGR) acquisition in steady state uses semi-random changes in the phase of the radio frequency (RF) pulses to produce a spatially independent phase shift.

See also Spoiled Gradient Echo Sequence and Gradient Recalled Acquisition in Steady State (GRASS).

• View the DATABASE results for 'Spoiled Gradient Recalled' (2).Open this link in a new window

 
Further Reading:
  News & More:
Comparison of New Methods for Magnetic Resonance Imaging of Articular Cartilage(.pdf)
2002
  Steady State Free Precession top
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- Woody Allen
 
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