Brain Abscess

Findings:

Coronal T1 postcontrast MR and axial DWI/ADC/EXP maps demonstrate an irregular ring enhancing lesion in the right frontal lobe associated with vasogenic edema and mass effect. The core of the lesion has complex diffusion characteristics, but predominantly reduced ADC values.

Differential diagnosis:

Brain abscess, glioblastoma, metastasis, tumefactive demyelination (less likely w edema and mass effect)

Discussion:

-early cerebritis (3-5d), late cerebritis (2 wks), early capsule (>2 wks), late capsule (wks-mos)

-only 50% have fever or WBC count, 90% have headache, most have high ESR

-less than 2.5 cm may be treated with Abx alone,  greater need drainage

-internal DWI hyperintensity characteristic, some help in dist GBM/mets from abscess, not absolute

-DWI may be helpful in f/u, development of hyper DWI may indicate recurrence

-T2 hypointense rim with late cerebritis and early capsule, also not absolute

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