MRI in the optimal imaging study in the diagnosis of subdural empyema. Findings on MRI suggestive of subdural empyema are similar to those on CT scan, and include a crescent or bi-convex shaped collection. A surrounding membrane that enhances intensely and uniformly following gadolinium enhancement is typically identified and may also demonstrate restricted diffusion.^[1]

MRI with gadolinium enhancement is considered the optimal imaging study for intracranial and spinal subdural empyema. MRI clearly reveals pus collections, and potentially meningitis. The characteristic image suggestive of a subdural empyema on an MRI is a fluid collection in a crescent shape surrounded by a contrast-enhancing rim. On MRI, subdural empyema appears with a low signal on T1 and a high signal on T2 weighted images.^[2] MRI may be used in emergency situations, with high level of suspicion, for the potential diagnosis of subdural empyema at a time when symptoms include headache and fever, and there is absence of focal neurologic signs.^[3] The diffusion-weighted imaging method increases the precision of diagnosis and offers the ability to monitor antibiotic therapy.^[4] Additionally, the MRI should be evaluated for the presence of epidural abscess, meningitis, brain abscess, cerebral edema, sinusitis, otitis, and mastoiditis.^[3]