Intracranial infections – 3 – Focal Infections
Focal infections are those infections of the brain which are walled off either within the brain parenchyma or in the extra-axial space, such as subdural or epidural abscess.
This lecture is the third in a series of 5 about imaging intracranial infection and covers focal brain infections. The series of videos will cover:
1) General considerations
2) Diffuse infections
3) Focal infection
4) Immunocompromised patients
5) Other considerations
Abscess in the brain, regardless of location, is characterized by hyperintensity on diffusion weighted imaging. There is often mass effect, surrounding edema, and a peripherally enhancing fluid collection. Abscess can arise from local infection, such as a surgery or sinusitis, or can occur from hematogenous spread.
Ventriculitis is a highly morbid complication of intracranial abscess, as can be found when pus spills into the ventricle. Sinus thrombosis is also a potential complication of intracranial abscess.
One key feature which separates the diffusion restriction of abscess from lymphoma is that the abnormal DWI is in the center of a peripherally enhancing collection, whereas in lymphoma it is the enhancing portion itself which is restricted.
The level of this lecture is appropriate for radiology residents, radiology fellows, and trainees in other specialties who have an interest in neuroradiology or may see patients with CNS infections.