- Manipulating TR and TE helps us to weight the contrast of the image to a certain parameter while diminishing the impact of other parameters
- In T1 weighting, the T1 relaxation time of tissues is accentuated and the T2 effects decreased
- How we achieve this is by using a short TR – which prevents fat or water to fully relax, then we immediately apply another RF pulse, which saturates both fat and water. At the same time, in order to diminish the T2 effects, we use a short TE
- It’s classically described to demonstrate anatomy and in post-contrast imaging
Why does fat appear bright in T1 weighted imaging?
- The short TR used is sufficient for fat to recover most of its longitudinal magnetization and as a result more magnetization is available to be flipped into transverse plane
Why is water dark in T1 weighted imaging?
- When TR is short, water does not recover enough longitudinal magnetization and as a result, there is not enough magnetization to be flipped into transverse plane when the next RF pulse is applied.
What values do you enter to get a T1 weighted image?
- TR: 400 – 700 ms
- TE: 10 – 30 ms
What are the common sequences used to produce T1 weighted imaging?
- Spin echo
- Turbo spin echo
- Inversion recovery
- Incoherent gradient echo