IR, STIR, FLAIR

Expansion:

Inversion Recovery Imaging

Short Tau Inversion Recovery

Fluid Attenuation Inversion Recovery

Technique:

An initial 180 degree inversion radiofrequency pulse is applied, inverting the net vector of the spins to the -Z plane. After inversion time (TI), an imaging sequence is performed, such as a SE (spin echo), GRE (gradient echo) or EPI (echo planar) sequence.

Typical Parameters:

TI: Should be 0.7 * T1 of the tissue to be supressed.

    400-600 (IR), 150 (STIR), 2000 (FLAIR)

TR: 3-5x the T1 of the desired material

    >3000 msec (IR and STIR), >8000 msec (FLAIR)

TE: as desired

Reference:

 

Contributor:

 

Related Sequences/Terms:

FLAIR, STIR

Comments:

the signal from a specific tissue can be eliminated by setting the TI to the zero crossing time of the T1 recovery curve for a particular tissue (170 for fat, 2000 for CSF at 1.5 T).

STIR (TI=170) inverts fat protons

FLAIR (TI=2000) inverts CSF, with a long TR producing heavy T2-weighting

 

Pulse Sequence Diagrams:

spin-echo inversion recovery sequence