Saturday, 14 January 2012

Leptomeningeal Enhancement

A young male, known case of tubercular meningitis came for follow up imaging.
Contrast Enhanced CT study of brain show abnormal lepto meningeal entrancement along inter hemispheric fissure.

Contrast enhancement on cross-sectional imaging divided into Extra axial and Intra axial (Parenchymal) Enhancement. Extra axial enhancement can be further classified into Pachy meningeal (Dura-Arachnoid Enhancement) or Lepto meningeal (Pia-Arachnoid Enhancement).

Leptomeningeal enhancement is the enhancement pattern, which follows the pial surface of brain and fills the subarachnoid spaces of the sulci and cisterns.
Usually associated with meningitis; bacterial, viral, or fungal.
Mechanism of this enhancement is breakdown of the blood-brain barrier. Pathogens release Glycoproteins which cause breakdown of the blood-brain barrier and allow contrast material to leak from vessels into the cerebrospinal fluid. The subarachnoid space is infiltrated with inflammatory cells which also retain contrast. The permeability in the meninges itself increase in response to inflammation.

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