2. Most of the
1. extremity,
2. spine
3. pelvis
examinations use STIR sequences.
3. Fat saturation is an MRI technique used to suppress the signal from
normal adipose tissue to reduce chemical shift artefact, improve
visualization of uptake of contrast material and tissue characterization.
https://mrimaster.com/characterise%20image%20t2%20fat%20sat.html
4. The Fat-Sat technique is the most widely used method for
fat suppression. The popularity of this method derives from
the fact that it is easy to implement, generally effective, and
can be used in conjunction with virtually any imaging
sequence
http://mriquestions.com/fat-sat-pulses.html
5. To suppress the fat signal from an MRI sequence, a special fat suppression module is
inserted at the beginning of a normal MRI sequence.
Fat suppression in an MRI sequence can be achieved with five techniques:
1. spectral fat saturation,
2. short tau inversion recovery (STIR),
3. spectral presaturation with inversion recovery (SPAIR),
4. dixon method and
5. water excitation method.
https://mrimaster.com/characterise%20image%20t2%20fat%20sat.html
6. MRI T1 weighted fat saturated image appearance
The easiest way is to look for adipose tissues in the body (e.g.
marrow).
Areas contain adipose tissues appear dark on T1 weighted fat saturated
All the other characteristics of the T1 weighted fat saturated images
weighted images
https://mrimaster.com/characterise%20image%20t2%20fat%20sat.html
7. Tissues and their T1 fat saturated appearance
Bone marrow : - dark
Muscles- gray
Moving blood : - dark
White matter : - whiter
Gray matter : - gray
Fluids : - dark gray
Bone : - dark
Fat : - dark
Air : - dark
https://mrimaster.com/characterise%20image%20t2%20fat%20sat.html
8. Pathological appearance
Pathologies with adipose tissues content will appear as dark on T1
weighted fat saturated images (e.g. lipoma).
Use
Very useful for pituitary imaging
Very useful for spine imaging
Very useful for pelvic imaging
Very useful for anterior neck, orbits and face imaging
Very useful for any musculoskeletal imaging
Very useful for extremity imaging
https://mrimaster.com/characterise%20image%20t2%20fat%20sat.html
9. MRI T2 weighted fat saturated image appearance
Areas contain adipose tissues appear dark on T2 weighted fat
All the other characteristics of the T2 weighted fat saturated
as the T2 weighted images
https://mrimaster.com/characterise%20image%20t2%20fat%20sat.html
10. Tissues and their T2 fat saturated image appearance
Bone marrow: - dark
Muscles- dark gray
Fat – dark
White matter - dark gray
Moving blood- dark
Gray matter - gray
Fluids – bright
Bone - dark
Air – dark
https://mrimaster.com/characterise%20image%20t2%20fat%20sat.html
11. Pathological appearance
Pathologies with adipose tissues content will appear dark on T2 weighted fat saturated
images (e.g. lipoma). Due to the added fat suppression, pathological processes are usually
very bright on T2 weighted fat saturated images.
Use
Useful for chest imaging
Useful for pancreas imaging
Useful for kidney imaging
Useful for abdominal imaging
Useful for spine imaging
Useful for pelvic imaging
Useful for anterior neck, orbits and face imaging
Useful for any musculoskeletal imaging
Useful for extremity imaging
https://mrimaster.com/characterise%20image%20t2%20fat%20sat.html
12. T2 fat sat axial sequence
used in knee imaging
13. Figure 2. MR
arthrography of the
Coronal fat saturation
weighted MR image
[repetition time
time msec]) shows
material within a
tear of the medial
(arrow).
https://pubs.rsna.org/doi/10.1148/
radiographics.19.2.g99mr03373
14.
15.
16. Illustration of the susceptibility for field inhomogeneities of spectral fat suppression
sequences (e.g. SPIR, SPAIR, fatsat) as compared to inversion recovery sequences (e.g.
STIR). Note both subcutaenous fat and the fat-containing bone marrow of the osseous
structures.
SPAIR is much more affected by magnetic field inhomogeneities, such as caused by metal
in this case. For this reason inversion recovery sequences may be preferred when
orthopaedic hardware is present to achieve better fat suppression.
