T2 TSE / T2 FSE Fat Saturated MRI Sequence
A T2 fat-saturated MRI sequence is a specialized magnetic resonance imaging sequence that combines T2 weighting with fat suppression techniques. In T2 weighting, fluids like cerebrospinal fluid and pathology-associated edema appear bright, while other tissues have varying intensities. The fat-saturation component suppresses the bright signal normally seen from fatty tissues, making them appear dark. By doing so, this sequence enhances the contrast between pathological changes associated with fluid accumulation (like edema, inflammation, cysts) and the surrounding fatty tissues. This is particularly beneficial in musculoskeletal imaging to visualize lesions in joints or soft tissue, and in the brain, abdomen and pelvis to differentiate between certain types of lesions.
MRI Image Appearance of T2 Fat Saturated Sequence
The easiest way to identify T2-weighted fat-saturated images is to observe the presence of adipose tissues in the body, such as subcutaneous fat and fat in the bone marrow. Areas containing adipose tissues appear dark on T2-weighted fat-saturated images. All other characteristics of the T2-weighted fat-saturated images remain the same as those in T2-weighted images.
Tissues and their T2 fat saturated image appearance
Brain:
- CSF: Bright.
- Fat: Dark.
- White Matter: Intermediate to dark.
- Gray Matter: Intermediate to bright.
- Bone (skull): Dark.
- Bone Marrow: Intermediate to dark.
- Blood Vessels: Mostly Dark; Depending on flow characteristics, can be bright or dark
- Pituitary Gland: Intermediate.
- Choroid Plexus: Intermediate.
- Cerebellum: Gray matter Brighter than white matter.
- Brain Stem: Intermediate.
- Sinuses: Dark (air-filled).
- Thalamus, Putamen, Hippocampus, Caudate Nucleus: Intermediate.
- Corpus Callosum: Intermediate.
- Pineal Gland: Intermediate.
Spine:
- Spinal Cord: Intermediate.
- CSF: Bright.
- Bone: Dark.
- Bone Marrow: Intermediate to dark.
- Intervertebral Disc: Intermediate.
- Ligaments: Intermediate to Dark.
- Nerve Roots: Intermediate.
Abdomen and Pelvis:
- Liver: Intermediate to dark.
- Gallbladder and Common Bile Duct: Bright.
- Spleen: Intermediate to dark.
- Kidney: Intermediate.
- Ureters: Intermediate.
- Pancreas: Intermediate to dark.
- Urinary Bladder: Bright.
- Prostate: Intermediate.
- Uterus: Intermediate.
Musculoskeletal:
- Muscle: Intermediate to dark.
- Bone: Dark (low signal).
- Bone Marrow: Intermediate to dark.
- Blood Vessels: Mostly Dark; Depending on flow characteristics, can be bright or dark.
- Fat: Dark.
- Ligaments: Intermediate to dark.
- Nerve Roots: Intermediate.
- Cartilage: Intermediate to dark.
- Synovial Fluid: Bright.
- Tendons: Intermediate to dark.
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
Pathological appearance
n T2 fat-saturated (fat-suppressed) MRI sequences, the primary goal is to suppress the bright signal from fat, which can often obscure the visualization of certain pathologies. The appearance of various pathologies in T2 fat-saturated scans is as follows:
- Edema and Inflammation: Areas of edema or inflammation will appear bright on T2 fat-saturated images. Examples include:
- Muscular strain: Bright signal within muscle due to edema.
- Bone marrow edema: Bright signal in bone marrow, commonly seen in stress fractures or osteoarthritis.
- Synovitis: Enhanced signal in joints due to inflammatory synovial fluid.
Tumors:
- Tumors with high water content: These will typically appear bright on T2 fat-saturated images. Examples include:
- Gliomas: In the brain.
- Myxoid tumors: Soft tissue tumors with high water content.
- Lipomas: Despite being comprised of fat, these will appear dark on T2 fat-saturated images due to the fat suppression.
- Hemangiomas: While these are bright on standard T2 sequences due to their high water content, the fat within some hemangiomas will be suppressed on T2 fat-saturated scans.
- Tumors with high water content: These will typically appear bright on T2 fat-saturated images. Examples include:
Fluid collections:
- Cysts: Simple cysts, such as Baker’s cysts in the knee or ovarian cysts, will appear bright due to their fluid content.
- Abscesses: These will also appear bright.
Cartilage and Meniscal lesions: In joints, especially the knee, T2 fat-saturated sequences can highlight cartilage defects or meniscal tears, appearing as bright signal irregularities within the otherwise intermediate signal of cartilage or dark signal of the meniscus.
Tendons and Ligaments: Tears or inflammation (tendinitis) will show as a bright signal within the usually dark-appearing tendons and ligaments.
T2 fat Saturated axial sequence used in chest imaging.
T2 fat Saturated axial sequence used in pancreas imaging.
T2 fat Saturated axial sequence used in pelvis fistula imaging.
T2 fat Saturated axial sequence used in knee imaging.
