Part 3
Here we confirm that the lesion is actually enhancing. Although we’re seeing some low signal on SWI indicating blood products (yellow arrows), which can cause intrinsic high signal on T1WI, the signal on the pre-contrast T1WI is low.
So, we have a lesion with:
- ring enhancement
- central low signal on T1WI (not as low as CSF so it isn’t pure fluid)
- some haemorrhagic staining at the periphery of the lesion
The main two considerations for a rim-enhancing necrotic lesion are:
- tumour
- infection
Which sequence will help us to decide whether this is an abscess or a neoplasm?
T2WI
This will show us surrounding oedema and a central necrotic core which can be seen in both conditions.
FLAIR
This will show us surrounding oedema and a central necrotic core, which can be seen in both conditions.
DWI and ADC
Correct! Abscesses are filled with pus, which restricts, but tumours are filled with necrotic material, which does not.
MRA
MRA is a tool to image the arteries. This will not help us differentiate between an abscess and a neoplasm.