Spin echo sequences

Last revised by Raymond Chieng on 11 Apr 2022

Spin-echo pulse sequences are one of the earliest developed and still widely used (in the form of fast spin echo) of all MRI pulse sequences. The pulse sequence timing can be adjusted to give T1-weighted, proton density, and T2-weighted images. Dual echo and multiecho sequences can be used to obtain both proton density and T2-weighted images simultaneously.

The two variables of interest in spin echo sequences are the repetition time (TR) and the echo time (TE). All spin echo sequences include a slice selective 90-degree pulse followed by one or more 180 degree refocusing pulses as shown in the diagrams.

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Cases and figures

  • Figure 1: spin echo (SE)
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  • Figure 2: fast spin echo (FSE)
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  • Figure 1: SE vs FSE
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  • Figure 4: spin echo sequence
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