Encephalitis, cerebritis, and brain abscess: pathophysiology and imaging findings.

This article discusses the imaging findings of encephalitis, cerebritis, and brain abscess in immunocompetent patients. MR imaging is the procedure of choice in evaluating suspected intracranial infections because of its inherent contrast resolution, multiplanar capability, improved sensitivity in the posterior fossa, sensitivity to the presence of subacute, and chronic hemorrhage, and its sensitivity to the detection of meningeal disease on postcontrast images. Discussion of pathologic conditions and imaging features of encephalitis are based on the most common causative agents of each type of disease. Imaging features and pathologic conditions of cerebritis and brain abscesses also are reviewed with emphasis on pyogenic bacteria.