Spin Echo
1. T1 weighted
Measuring spin–lattice relaxation by using a
short repetition time (TR) and echo time (TE).
- Lower signal for more water content,[4] as in edema, tumor, infarction, inflammation, infection, hyperacute or chronic hemorrhage.[5]
- High signal for fat[4][5]
- High signal for paramagnetic substances, such as MRI contrast agents[5]
Standard foundation and comparison for other sequences
MRI image appearance
The easiest way to identify T1 weighted images is to look for fluid filled spaces in the Cerebro-spinal fluid in the brain ventricles and spinal canal, free fluid in the abdomen, fluid in bladder and common bile duct, synovial fluid in joints, fluid in the urinary tract and urinary oedema or any other pathological fluid collection in the body). Fluids normally appear dark weighted image.
Tissues and their T1 appearance
Bone marrow : - equal to or higher than that of muscle (fatty marrow is usually bright)
- Muscles- gray
- Moving blood : - dark
- White matter : - whiter
- Gray matter : - gray
- Fluids : - dark
- Bone : - dark
- Fat : - bright
- Air : - dark
Pathological appearance
Pathological processes normally increase the water content in tissues. Due to the added water component this results in a signal loss on T1 weighted images and signal increase on T2 weight images. Consequently pathological processes are usually bright on T2 weighted images and dark weighted images.
Use
Useful for pelvic imaging (only used for pelvic infections pre contrast pelvis T1 imaging)
Useful for abdominal imaging (T1 tse respiratory gated scans)
Useful for chest imaging (T1 tse respiratory gated scans)
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 brain imaging
Very useful for spine imaging
2. T2 weighted
Measuring spin–spin relaxation by using long TR and
TE times
- Higher signal for more water content[4]
- Low signal for fat[4] − Note that this only applies to standard Spin Echo (SE) sequences and not the more modern Fast Spin Echo (FSE) sequence (also referred to as Turbo Spin Echo, TSE), which is the most commonly used technique today. In FSE/TSE, fat will have a high signal.[6]
- Low signal for paramagnetic substances[5]
Standard foundation and comparison for other sequences
MRI image appearance
The easiest way to identify T2 weighted images is to look for fluid filled spaces in the boCerebrospinal fluid in the brain ventricles and spinal canal, free fluid in the abdomen, fluid inbladder and common bile duct, synovial fluid in joints, fluid in the urinary tract and urinary oedema or any other pathological fluid collection in the body). Fluids normally appear brighweighted images.
Tissues and their T2 appearance
- Bone marrow: - equal to or higher than that of muscle (fatty marrow is usually bright)
- Muscles- gray (darker than the muscle signal on T1 images)
- Fat – bright (darker than the fat signal on T1 images)
- White matter - darker than gray
- Moving blood- dark
- Gray matter - gray
- Fluids – bright
- Bone - dark
- Air - dark
Pathological appearance
Pathological processes normally increase the water content in tissues. The added water componresults in a signal loss on T1 weighted images and a signal increase on T2 weighted images.Consequently, pathological processes are usually bright on T2 weighted images and dark on t1weighted images.
Use
Very useful for abdominal imaging (breath hold and respiratory gated T2 tse scans)
Very useful for pelvic imaging ( gyne pelvis , prostate, urinary bladder and rectum)
Very useful for chest imaging (breath hold T2 tse scans)
Can be useful for brachial and lumbar plexus imaging
Useful for anterior neck, orbits and face imaging
Very useful for any musculoskeletal imaging
Very useful for extremity imaging
Very useful for brain imaging
Very useful for spine imaging
Long TR (to reduce T1) and short TE (to minimize T2).
Joint disease and injury. High signal from meniscus tears.
MRI image appearance
The easiest way to identify PD weighted images is to compare the fluid against the fat signa
normally appear as grayish white, almost similar appearance as the fat in the body.
Tissues and their PD appearance
- Bone marrow: - equal to or higher than that of muscle (fatty marrow is usually bright)
- Fat – bright (slightly darker than the fat signal in T1 images)
- Fluids – bright (darker than the fluid signal in T2 images)
- White matter - darker than bright gray
- Gray matter - bright gray
- Moving blood- dark
- Muscles-gray
- Bone - dark
- Air - dark
Use
Very useful for
brain imaging
(because of great White matter Gray matter contrast)
Useful for extremity imaging (e.g. ankle, knee, elbow shoulder and hips)
Can be useful in thighs, lower legs, upper arms and forearms imaging
Very useful for
temporomandibular joint imaging
