T1 and T2 weighted
On T2, H2O (including CSF) = bright
Includes oedema which signifies disease
- Bright on both = fat
- Grey on both = soft tissues
- Black on both = bone, air, flowing blood
Gadolinium-enhanced
Same as T1 but…
- Gadolinium, a contrast agent, is given
- Enhances areas of leaky blood vessels (pathological tissues e.g. tumours, areas of inflammation/infection)
Fluid-attenuated (FLAIR)
Same as T2 but…
- Flowing water (like CSF) is supressed, so appears black
- Only non-flowing water appears bright
- Helps differentiate pathologic oedematous lesions from normal flowing water (like CSF)
A patient presents to ED with chest pain and this trace. What would you do?
Interpretation management
Fat-supressed
- Fat supressed T1 or T2
- Used to make fat appear dark
- Often used when giving gadolinium contrast on T1, or on T2 to allow fluid to stand out
Diffusion-weighted image (DWI)
- Shows passive diffusion of water
- Consists of two main images:
- DWI – combination of actual diffusion and T2 (restricted diffusion = bright)
- ADC – represents actual diffusion without T2 effects (restricted diffusion = dark)
- Cytotoxic oedema = bright on DWI and dark on ADC
- Most useful when looking for ischaemic brain tissue in stroke
- Note, DWI is derived from T2; therefore, some tissues that are bright on T2 also appear bright on DWI (T2 shine through effect)
