Magnetic resonance imaging features of brain stem abscessation in two cats.

Premortem magnetic resonance imaging (MRI) was performed in two cats with brain stem abscessation confirmed post mortem by histology and recovery of multiple bacterial species. The MRI features of the abscesses were distinctive and included a thick and marked enhancement of the abscess capsule and extension of the lesion from a tympanic bulla in one cat. A focal area of increased signal intensity was present on T2-weighted images. A circumscribed area of decreased signal intensity was surrounded by a ring of increased signal intensity on precontrast T1-weighted images. A center of decreased signal intensity with a thick, markedly enhanced abscess capsule was observed on post contrast T1-weighted images. These findings are compared to the current experimental and clinical literature of brain abscess. The underlying pathogenesis of MRI features is reviewed.