STIR (Short TI Inversion Recovery) is an MRI pulse sequence that provides T2-weighted images with fat suppression. It uses an inversion time that nuls the signal from fat. STIR produces uniform fat suppression that is relatively independent of magnetic field inhomogeneities. It is useful for imaging tissues with high water content like edema or lesions. On STIR images, fluid appears bright while fat and tissues with short T1 values appear dark. Pathologies that increase water content also appear brighter. STIR is commonly used for musculoskeletal, spinal, and abdominal imaging to improve lesion conspicuity and tissue contrast.

1. STIR Short TI OR tau
Inversion Recovery

2. STIR IS A T2 weighted images
STIR (Short TI Inversion Recovery) or (Short tau inversion recovery )
suppress the signal from fat.
FLAIR is a similar technique to suppress water
STIR stands for Short-TI Inversion Recovery and is
typically used to null the signal from fat.

3. The fat suppression possible by STIR is generally
uniform and relatively independent of magnetic
field inhomogeneities.
http://mriquestions.com/stir.html

4. STIR may be superior to other fat saturation methods (such as spectral
"fat-sat") especially
1. near metallic foreign bodies,
2. near tissue interfaces with high susceptibility differences (like
the skull base/sinuses),
3. across large body parts (such as the abdomen and pelvis).
.
http://mriquestions.com/stir.html

5. It is even possible to perform whole-body STIR imaging as a
screening technique for bone metastases.
In lower field permanent magnet scanners with relatively
poor homogeneity, STIR is one of the only fat suppression
methods available.
http://mriquestions.com/stir.html

6. MRI image appearance
The easiest way to identify STIR images is to look for fat and
fluid filled space in the body (e.g. CSF, synovial fluid in joints,
oedema or any other pathological fluid collection in the body).
in a STIR image:
• Fluids normally appear bright
• fat appear very dark

7. Tissues and their STIR appearance
• Muscles: - darker than fat signal
• White matter - darker than gray
• Bone marrow: - dark
• Moving blood- dark
• Gray matter - gray
• Fluids – very bright
• Bone - dark
• Fat – dark
• Air - dark

8. Pathological appearance
Pathological processes normally increase the water content in
tissues. Due to the added water component this results in a
signal increase on STIR images.
Consequently
pathological processes are usually bright on STIR images.

9. Use:
• Very useful for brachial and lumbar plexus imaging
• Very useful for any musculoskeletal imaging
• Very useful for extremity imaging
• Very useful for spine imaging

10. limitations:
 STIR cannot be used as a fat suppression technique post-
gadolinium. STIR does not specifically suppress fat; it only
suppresses tissues with T1 values in the range of fat (200-300 ms).
Thus gadolinium-containing tissues with similar relaxation times
will also be suppressed. Likewise, suppression proteinaceous
materials and other short T1 tissues may occur.
 Although contrast-to-noise for certain lesions may be improved,
overall signal-to-noise may be poor.
 The multiple 180°-pulses cause deposit extra energy and may result
in tissue heating.
http://mriquestions.com/stir.html

12. A STIR image, revealing cancer
lesions within spinal vertebrae at
1.0 T.
http://www.revisemri.com/que
stions/pulse_sequences/stir

17. STIR coronal
sequence used in
elbow imaging

19. STIR
coronal
sequence
used in hips
imaging

20. STIR coronal
sequence used in
thigh imaging

22. STIR coronal sequence used
in lower legs imaging

25. Short tau inversion recovery (STIR ) also called short T1 inversion recovery is
a fat suppression technique with an inversion time TI = T1 ln2 where the signal
of fat is zero. This equates to approximately 140 ms at 1.5 T.
To distinguish two tissue components with this technique, the T1 values must
be different. FLAIR is a similar technique to suppress water.
Inversion-recovery imaging allows homogeneous and global fat suppression
and can be used with low-field-strength magnets. However, this technique is
not specific for fat, and the signal intensity of tissue with a long T1 and
tissue with a short T1 may be ambiguous.
http://radiopaedia.org/articles/short-tau-inversion-recovery

26. http://mriquestions.com/stir.html

27. STIR image with excellent fat
suppression, allowing optic
neuritis to be well seen.
http://mriquestions.com/stir.html

28. STIR (as well as other short and medium-TI sequences) has an additional useful
feature — additive T1+T2 contrast.
In routine SE imaging lesions with prolonged T1 and T2 have competitive
effects on signal intensity (↑T1 reduces signal while ↑T2 increases signal).
In STIR imaging the effects of ↑T1 and ↑T2 are additive. This results from the
fact that the longitudinal magnetization of long T1 lesions on STIR remain
inverted and produce a high signal as shown below.
http://mriquestions.com/stir.html

29. At short to medium
TI’s, long T1
substances (such as
CSF) are bright on
magnitude IR. This is
opposite to SE where
long T1 values cause
reduced signal
intensity.
http://mriquestions.com/stir.html

30. Additive T1
and T2 effects.
MS plaque seen
better on STIR
image (right)
than SE image
(left)
http://mriquestions.com/stir.html

31. References
Bydder GM, Young IR. MR imaging: clinical use of the
inversion recovery sequence. J Comput Assist Tomogr 1985;
9:659-675.
Krinsky G, Rofsky NM, Weinreb JC. Nonspecificity of short
inversion time inversion recovery (STIR) as a technique of fat
suppression: pitfalls in image interpretation. Am J Roentgenol
1996; 166:523-526.
Smith RC, Constable RT, Reinhold C, et al. Fast spin echo
STIR imaging. J Comput Assist Tomogr 1994;18:209–213
Sugimoto H, Sakai O, Shinozaki T et al. Effect of water
fraction in selection of optimal TI value for STIR sequences. J
Comput Assist Tomogr 1994; 18:119-125.
http://mriquestions.com/stir.html

32. MRI image appearance
The easiest way to identify STIR images is to look for fat and
fluid filled space in the body (e.g. Cerebrospinal fluid in the
brain ventricles and spinal canal, free fluid in the abdomen,
fluid in the gall bladder and common bile duct, synovial fluid in
joints, fluid in the urinary tract and urinary bladder, oedema or
any other pathological fluid collection in the body).
Fluids normally appear bright and fat appear very dark in a
STIR image.
https://mrimaster.com/characterise%20image%20stir.html

33. Tissues and their STIR appearance
Muscles: - darker than fat signal
White matter - darker than gray
Bone marrow: - dark
Moving blood- dark
Gray matter - gray
Fluids – very bright
Bone - dark
Fat – dark
Air - dark
https://mrimaster.com/characterise%20image%20stir.html

34. Pathological appearance
Pathological processes normally increase the water content in
tissues. Due to the added water component this results in a
signal increase on STIR images. Consequently pathological
processes are usually bright on STIR images.
https://mrimaster.com/characterise%20image%20stir.html

35. Use
Very useful for brachial and lumbar plexus imaging
Very useful for anterior neck orbits and face imaging
Very useful for any musculoskeletal imaging
Very useful for extremity imaging
Very useful for spine imaging
Useful for abdominal imaging (respiratory gated STIR)
Useful for chest imaging (respiratory gated STIR)
https://mrimaster.com/characterise%20image%20stir.html

36. https://www.startradiology.com/the-basics/mri-technique/
Fat suppression STIR short tau inversion recovery
Suppression of fat tissue is one of the many options that can be used in an MRI sequence.
In virtually all abdominal MRI examinations, suppressing the fat tissue signal is advisable. The created low signal
intensity of fat then contrasts more strongly with the vessels & pathology (high signal intensity!).
Also in skeletal imaging, it may be useful to make a sequence with fat suppression. Bone marrow contains fat and
may mask bone marrow edema on a T2 weighted image.
There are several technical options to suppress fat tissue. Frequently used sequences are the STIR (short-tau
inversion recovery) and the SPIR (spectral pre-saturation inversion recovery) sequences. Both are T2 weighted
images.
You can also recognize fat suppression by the abbreviation FatSat, meaning Fat Saturation (e.g. T2wFatSat).
Tip: you can easily recognize fat suppression by looking at the subcutaneous fat (fig. 19). When it has a low
signal, you are looking at a fat suppression sequence. The technique may be used 'as extra’ in T1, T2 and PD
weighted images.

37. https://www.startradiology.com/the-basics/mri-technique/
Figure 19. STIR sequence in transversal direction of the upper legs. Note also the good contrast with the
vessels (fluid!).

38. https://www.startradiology.com/the-basics/mri-technique/

39. A FLAIR image, revealing periventricular lesions more clearly
because the adjacent fluid signal is suppressed.
http://www.revisemri.com/questions/pulse_sequences/stir