Approach to Basic MRI Head

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Part 4

Approach to Basic MRI Head Case 2 Part 4

On DWI we can see that there is restricted diffusion in the central, fluid portion, of the lesion. We know it’s true restricted diffusion because the signal on DWI is high and on ADC is low. There is some surrounding FLAIR hyperintensity that could be due to oedema. Therefore, this is an abscess within the left thalamus filled with pus.

Abscess

For comparison, the image below shows the imaging features of a necrotic tumour.

Tumour

mod1_case2_tumour_all

Similar to abscess

  • necrotic centre (low on T1WI, high on T2WI, doesn’t completely saturate on FLAIR)
  • rim enhancement
  • surrounding oedema

Different to abscess

  •  no central restricted diffusion of the fluid component
  • may have restricted diffusion of the peripheral solid component i.e. the hypercellular region.
In the provided image there is restricted diffusion along the medial aspect of the lesion which correlates to the solid enhancing portion of the tumour)
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