Multi-Echo EPI

1.2 Image contrast of Multi-Echo EPI

The signal intensity of the single echo images of the Multi-Echo EPI sequence is simply given by:

S = S0 exp(− TE / T 2*)

where S0 is the signal intensity at echo time 0, which corresponds to the proton density for long repetition times TR, and TE is the echo time. Therefore, the echo times of the different echo-images should be on the order or less than the tissue T2*. Parametric images of the proton density and T2* can be obtained by fitting a model function to the signal intensities at the different echo times (3). Please see the processing options described below.

Figure 2 – Head images acquired on Magnetom TRIO with the Multi-Echo EPI sequence with 4 different echo times in a single shot.

1.3 Processing options

Several processing options are given in the method. The different echo images are always saved separately as the original images and optionally parametric maps can be calculated in the reconstruction. In addition, online 3D-motion correction (even prospective – PACE) and t-test can be performed. Please see sequence and protocols for details.

1.4References

1.P. Mansfield, A.A. Maudsley. Planar Spin Imaging. J. Magn. Reson. 27, 101 (1977)

2.O. Speck, J. Hennig. Functional Imaging by I0- and T2*-Parameter Mapping using Multi-Image-EPI. Magn. Reson. Med. 40(2), 243-248 (1998)

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Siemens 4A21 manual Image contrast of Multi-Echo EPI, Processing options, References
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4A21 specifications

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