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Diffusion-weighted MR imaging of subdural empyemas in children

Alex M Wong1, Robert A Zimmerman, Erin M Simon

  • 1Department of Radiology, the Children Hospital of Philadelphia, PA 19104-4399, USA.

AJNR. American Journal of Neuroradiology
|June 19, 2004
PubMed
Abstract

Insights

Subdural empyema (SDE) appears bright on diffusion-weighted imaging (DWI) and dark on apparent diffusion coefficient (ADC) maps. This MRI technique aids in differentiating SDE from effusions and monitoring infection.

Area of Science:

  • Neuroradiology
  • Infectious Disease Imaging
  • Medical Imaging

Background:

  • Subdural empyema (SDE) is a subdural space infection, often a pediatric complication of meningitis, sinusitis, or otitis media.
  • Diffusion-weighted imaging (DWI) is utilized for investigating intracranial infections.

Purpose of the Study:

  • To characterize the signal intensity of SDE on DWI.
  • To evaluate apparent diffusion coefficient (ADC) values in SDE.

Main Methods:

  • Retrospective review of 10 SDE patients' MRI studies.
  • Inclusion of routine sequences and DWI with b values of 0, 500, and 1000 s/mm(2).
  • Calculation of ADC values in seven patients and follow-up imaging in seven patients.

Main Results:

  • SDE was hyperintense on DWI in 9/10 patients; one showed mixed intensity.
  • ADC values of SDE were lower than normal cortical gray matter and reactive subdural effusions.
  • Persistent SDEs remained hyperintense on follow-up DWI in all seven patients.

Conclusions:

  • SDE exhibits high signal intensity on DWI and low signal intensity on ADC maps.
  • ADC values for SDE are lower than those of normal cortical gray matter.
  • Diffusion MRI is valuable for distinguishing SDE from effusion and for follow-up.

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