Within the superior left frontal lobe there is a 4.5 x 3.4 x 3.0 cm ( AP, trans, CC ) rim enhancing lesion. The lesion demonstrates central T1 hypointensity and T2 hyperintensity which does not completely restrict on FLAIR. There is marked diffusion restriction within this central T1 hypointense region. On susceptibility imaging there is a complete hypointense rim identified. The region demonstrates reduced rCBV with mild elevated MTT.
Spectroscopy (not shown) demonstrates elevated lactate peaks within the central T1 hypointense region and no choline elevation in the surrounding T2 hyperintense white matter.
Surrounding the lesion, there is T2 hyperintensity in keeping with vasogenic oedema. This extends inferiorly to the left corona radiata with resultant mass-effect within the left cerebral hemisphere. There is effacement of the frontal and superior parietal sulci. No hydrocephalus. No subfalcine herniation.
No other lesion identified.
No evidence of sinusitis or mastoiditis.
Rim enhancing lesion within the left superior frontal lobe is most in keeping with a pyogenic abscess. The differential of a GBM/metastasis is less likely given marked central diffusion restriction, and findings on MRS.