Many infectious and inflammatory processes can present clinically as space-occupying pathologies, suggesting the need for resection or surgical sampling. The primary purpose of this review is the identification of imaging features that may suggest these pathologies and thus possibly avoid unnecessary surgical interventions; to accomplish this, we also describe some of the non-neoplastic pathologies that present this clinical challenge.
A ring-enhancing lesion in the brain parenchyma with central restricted diffusion is the typical magnetic resonance imaging (MRI) appearance of a pyogenic brain abscess (Figure 1). This central decrease of water diffusion is characteristically helpful in their differentiation from tumors (wherein the restricted diffusion is characteristically within the enhancing mural component).1,2 However, inflammatory processes (such as tumefactive demyelinating lesions) can also present as ring-enhancing lesions but typically with peripheral restricted diffusion.3 Some abscess are more heterogeneous and do not demonstrate central restricted diffusion, particularly due to atypical microorganisms4 (see discussion about fungal and mycobacterial infections later on).
To view the rest of the article, click here.