Steady gradient spin echo

SGSE steady-gradient spin-echo method of measuring self-diffusion. 

Figure Bl.14.9. Imaging pulse sequence including flow and/or diflfiision encoding. Gradient pulses before and after the inversion pulse are supplemented in any of the spatial dimensions of the standard spin-echo imaging sequence. Motion weighting is achieved by switching a strong gradient pulse pair G, (see solid black line). The steady-state distribution of flow (coherent motion) as well as diffusion (spatially...

The parameter to be measured in spin-echo diffusion experiments is the amplitude A of the echo. Its magnitude depends 3) on the spin-spin relaxation time T2 and on the diffusion coefficient D. For an SGSE experiment employing a 90°-t-180° rf pulse sequence in the presence of a steady field gradient of magnitude G0 4),... 

To amplify the effects of diffusion, a pair of magnetic field gradient pulses of magnitude G is applied in addition to the small value Gq of steady gradient. According to Stejskal and Tanner, the amplitude of the attenuated spin echo is given by °... 

TSE, turbo spin echo also known as FSE, fast spin echo TR, repetition time TE, time to echo TI, time for inversion coronal oblique, parallel to the long axis of the uterus axial oblique, parallel to the short axis of the uterus TRUFISP, fast induction steady state potential gradient sequence (Siemens Medical, Germany). 

Gradient echo-based sequences, such as constructive interference in steady state sequences, also are used for the imaging of the inner ear region (Casselman et al. 1996 Held et al. 1997). However, the specific absorption rate of these sequences may be higher than that of 3D fast spin echo-based sequences, and susceptibility artifacts may be more pronounced, especially at 3 T scanners. 

T2-weighted gradient-echo sequences with the steady-state free precession (SSFP) technique were initially usedby Wallner et al. (1991), Morimoto et al. (1992),HALL-CRAGGsetal. (1993), and IsmzAKiet al. (1993). Subsequently, other investigators have utilized two-dimensional (2D) and three-dimensional (3D) heavily T2-weighted fast spin-echo sequences... 

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