MRI features of Cerebral Abscess

MRI is more sensitive and especially with the addition MRS and DWI far more specific for the diagnosis of cerebral abscesses. 

T1 "MRI features of Cerebral Abscess"

• central low intensity (hyperintense to CSF)
• peripheral low intensity (vasogenic oedema) 
• ring enhancement 
• ventriculitis may be present, in which case hydrocephalus will commonly also be seen

T2 / FLAIR "MRI features of Cerebral Abscess"

• central high intensity (hypointense to CSF, does not attenuate on FLAIR)
• peripheral high intensity (vasogenic oedema)
• the abscess capsule may be visible as a intermediate to slightly low signal thin rim 1.

DWI / ADC "MRI features of Cerebral Abscess"

• high DWI signal is usually present centrally
• often this represents true restricted diffusion (low signal on ADC)
• peripheral or patchy restricted diffusion may also be seen; this finding is however not as constant as one may think, with up to half of rim enhancing lesions demonstrating some restriction not proving to be abscesses 2.  
• in many instances high DWI are associated with high ADC signal, consistent with T2 shine through of the central necrotic portion

MR perfusion : rCBV is reduced in the surrounding oedema c.f. to both normal white matter and tumour oedema seen in high grade gliomas 2.
MR spectroscopy : elevation of a succinate peak is relatively specific but not present in all abscesses ; high lactate, acetate, alanine, valine, leucine, and isoleucine levels peak may be present ; Cho / Crn and NAA peaks are reduced.