Part 2
To assess for infection contrast is very useful.
- abscesses will show rim enhancement, whether they’re parenchymal or subdural
- post-contrast FLAIR is very sensitive to leptomeningeal disease
This is what we see on the contrast-enhanced T1WI:
There is a lesion with low signal in the centre and a rim of high signal. We could be tempted to just call this contrast enhancement but we should check first that it is true enhancement and not just intrinsic high T1 signal such as is seen in haemorrhage.
Which sequences should we look at to see if it is true enhancement?
FLAIR
FLAIR will show us any oedema but it will not clarify whether the high signal on the CE-T1WI is enhancement
Pre-contrast T1WI
Correct. If we see high signal on the pre-contrast T1WI then we know that this is due to intrinsically high signal rather than enhancement
SWI
SWI will show us any haemorrhage contributing to the T1 signal but it does not clarify whether there is any enhancement
DWI
DWI is useful for another reason, that we will come to, but not for clarifying whether there is enhancement