Imaging Aspects of Pyogenic Infections of the Central Nervous System

Abstract

Although pyogenic infections of the central nervous system are not a frequent group of diseases, their morbidity and mortally are very high. For this reason they require prompt diagnosis and treatment to avoid several complications that can lead to an undesired outcome. In this article, we review the imaging findings of these infections according to the anatomic site, their complications, and their differential diagnosis. Special attention is given to the different techniques of magnetic resonance imaging like perfusion, spectroscopy, and diffusion, for each specific situation such as meningitis, abscess, ventriculitis, purulent extra axial collections, and vascular complications.

Susceptibility-Weighted Imaging in Patients with Pyogenic Brain Abscesses at 1.5T: Characteristics of the Abscess Capsule

“…In the experimental setting, brain abscesses have been shown to have relatively high amounts of mature collagen and decreased neovascularity. 22,23 During early capsule formation (day 10 -13), increase of the layer of the fibroblasts with a rim of neovascularization at the periphery of the necrotic zone forms the abscess capsule. These newly formed capillaries lack tight junctions and leak proteinaceous fluid, suggesting that the postcontrast enhancement of the abscess capsules on T1-weighted images is probably due to increased permeability of the capillary wall rather than an increase in blood volume.…”

“…[19][20][21][22] On nonenhanced T1-weighted images, the capsule may be isointense or slightly hyperintense, on T2-weighted images, hypointense compared with the necrotic core and the surrounding edema. The signal intensity properties of the abscess periphery on these conventional MR images were believed to be due to collagen, products of hemorrhages, or presence of free paramagnetic radicals in macrophages participating in phagocytosis, heterogeneously distributed on the abscess periphery.…”

“…The signal intensity properties of the abscess periphery on these conventional MR images were believed to be due to collagen, products of hemorrhages, or presence of free paramagnetic radicals in macrophages participating in phagocytosis, heterogeneously distributed on the abscess periphery. [19][20][21][22] Successful surgical or therapeutic treatment of abscess leads to decrease of activity of macrophages and disappearance of the hypointense rim on T2-weighted images.…”

In Vivo Differentiation of Aerobic Brain Abscesses and Necrotic Glioblastomas Multiforme Using Proton MR Spectroscopic Imaging

“…In the experimental setting, brain abscesses have been shown to have relatively high amounts of mature collagen and decreased neovascularity. 27,28 The Cho/Cr ratio of rim-enhancing lesion of abscesses would be presumed to be less than that of GBMs.…”

Pyogenic and non-pyogenic spinal infections: emphasis on diffusion-weighted imaging for the detection of abscesses and pus collections

“…[5][6][7][8] Therefore, DWI is considered to be useful in the evaluation of the extension of abscesses and pus collections in spinal and paraspinal infections. 9,10 It is often a key image in the differential diagnosis.…”