Spin echo sequences

Last revised by Lachlan McKay on 4 May 2024

Citation, DOI, disclosures and article data

Citation:

Ballinger J, McKay L, Chieng R, et al. Spin echo sequences. Reference article, Radiopaedia.org (Accessed on 11 May 2024) https://doi.org/10.53347/rID-22136

DOI:

https://doi.org/10.53347/rID-22136

Permalink:

https://radiopaedia.org/articles/22136

rID:

22136

Article created:

14 Mar 2013, J. Ray Ballinger

Disclosures:

At the time the article was created J. Ray Ballinger had no recorded disclosures.

View J. Ray Ballinger's current disclosures

Last revised:

4 May 2024, Lachlan McKay ◉

Disclosures:

At the time the article was last revised Lachlan McKay had no financial relationships to ineligible companies to disclose.

View Lachlan McKay's current disclosures

Revisions:

11 times, by 10 contributors - see full revision history and disclosures

Sections:

Imaging Technology

Synonyms:

Spin echo sequences
Spin echo pulse sequences

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.

The MR signal intensity (S) produced using a spin echo sequence is proportional to the proton density (ρ_H), TR, T1, TE and T2, described by the equation S ∝ ρ_H[1-e^TR/T1]e^-TE/T2 ⁴.