CASE 46: MRI

35 Male, Mitral Valve Disease with fever

MR Findings reveal a well defined cystic lesion in the left occipito-parietal region, with rim enhancement and surrounding edema. Mass effect is seen, with midline shift. Restricted diffusion is noted on gradient imaging

IMPRESSION

BRAIN ABSCESS

DISCUSSION

Brain abscesses start at cerebritis, and then progress to abscess formation.

Spread is usually hematogenous, and predisposing conditions include right to left shunts, bacterial endocarditis in preexisting cardiac conditions, IV drug abuse, lung infections, or systemic sepsis.

Streptococcus is the most common organism followed by Staph aureus (following brain surgeries), and anerobic infections in infants.

MRI is most sensitive for a specific diagnosis with hypointense signal on T1 and hyperintense on T2WI and FLAIR, with retricted diffusion on DWI and rim enhancement on contrast. Dual rim sign may be seen on SWI.

Treatment involves surgical drainage.