T1 weighted imaging
In T1 weighted imaging (T1WI) fluid is dark. There are a few specific things that are bright on T1WI.
Bright on T1WI
Things that are bright on T1WI:
- fat
- blood (depending on age)
- protein
- melanin
- gadolinium
- some calcium
Dark on T1WI
- fluid
- fibrosis / sclerosis
But, hold on ...
If fluid is dark on both T1WI and on FLAIR, how do I tell which sequence I’m looking at? The way that I have found to be the most useful is the relative signal of CSF, white matter and grey matter.
When working in-to-out (CSF > white matter > grey matter) on both T1WI and T2WI the signals alternate (dark > bright > dark and bright > dark > bright respectively). FLAIR, however, does not (dark > dark >bright).
