title: Serial diffusion-weighted MRI correlates with clinical course and treatment response in children with intracranial pus collections.
abstract: BACKGROUND
  Accurate assessment of treatment response in children with intracranial pus collections is vital to guide appropriate therapy and reduce morbidity and mortality.
  
  
  OBJECTIVE
  To correlate serial MR-measurable changes in diffusion-weighted imaging (DWI) with clinical response to treatment.
  
  
  METHODS
  We retrospectively reviewed clinical notes, conventional MR sequences and DWI in eight children with intracranial pus collections. Trace DWI signal intensity and apparent diffusion coefficient (ADC) values were compared at three time points: at initial diagnosis (eight children, 13 collections), at follow-up during continued clinical infection (three children, sp collections), and at follow-up when clinical infection had resolved (seven children, 12 collections).
  
  
  RESULTS
  At initial diagnosis all patients were septic and collections showed restricted diffusion (mean ADC 0.61+/-0.15 x 10(-3) mm(2)/s). Patients with persistent clinical sepsis at follow-up DWI had collections with persistent low ADC values (0.66+/-0.21 x 10(-3) mm(2)/s), significantly (P<0.001) below normal cortical gray matter values. Successful resolution of the infection was associated with a significant rise in ADC values (1.57+/-0.57 x 10(-3) mm(2)/s, P<0.01) compared both to patients with signs of continued sepsis and to normal gray matter values.
  
  
  CONCLUSIONS
  Persistent restricted diffusion in pus collections correlates with continued sepsis. Treatment response is associated with clinical resolution of sepsis and ADC value elevation significantly above normal gray matter values.
authors.affiliation: Division of Neuroradiology, Department of Diagnostic Imaging, Hospital for Sick Children, Toronto, Canada.
authors.forename: Noel F
authors.initials: NF
authors.lastname: Fanning
authors.forename: Eoghan E
authors.initials: EE
authors.lastname: Laffan
authors.forename: Manohar M
authors.initials: MM
authors.lastname: Shroff
mesh_terms: D001922:Brain Abscess / Q000175:diagnosis* / Q000628:therapy; D002648:Child; D002675:Child, Preschool; D038524:Diffusion Magnetic Resonance Imaging; D013354:Empyema, Subdural / Q000175:diagnosis* / Q000628:therapy; D005260:Female; D006801:Humans; D007223:Infant; D007231:Infant, Newborn; D008297:Male; D012189:Retrospective Studies; D018709:Statistics, Nonparametric