Free induction decay

Last revised by Sonam Vadera on 14 Oct 2020

Citation, DOI, disclosures and article data

Citation:

Bashir U, Vadera S, Foster T, et al. Free induction decay. Reference article, Radiopaedia.org (Accessed on 16 Apr 2024) https://doi.org/10.53347/rID-16493

DOI:

https://doi.org/10.53347/rID-16493

Permalink:

https://radiopaedia.org/articles/16493

rID:

16493

Article created:

22 Jan 2012, Usman Bashir

Disclosures:

At the time the article was created Usman Bashir had no recorded disclosures.

View Usman Bashir's current disclosures

Last revised:

14 Oct 2020, Sonam Vadera ◉

Disclosures:

At the time the article was last revised Sonam Vadera had no recorded disclosures.

View Sonam Vadera's current disclosures

Revisions:

5 times, by 4 contributors - see full revision history and disclosures

Sections:

Imaging Technology

Tags:

stub, refs

Synonyms:

Free induction decay (FID)
FID

Free induction decay (FID) refers to a short-lived sinusoidal electromagnetic signal which appears immediately following the 90° pulse. It is induced in the receiver coil by the rotating component of the magnetization vector in the x-y plane which crosses the coil loops perpendicularly. It does not contribute to MR image but is used for single voxel MR spectroscopy.This sinusoidal signal decays exponentially with a time constant of T2*.

A spin echo produced by a 180° pulse following a 90° pulse appears as a back-to-back FID where the signal increases exponentially to the middle of the signal then decreases exponentially like the FID.