title: Magnetic resonance imaging in minor head injury.
abstract: OBJECTIVE
  To investigate the role of cranial magnetic resonance (MR) imaging in evaluating patients discharged from the emergency department after minor head injury.
  
  
  METHODS
  A prospective blinded cohort study.
  
  
  METHODS
  University hospital ED.
  
  
  METHODS
  Fifty-eight patients with minor head injury who were discharged from the ED with written head injury instructions. Patients admitted to the hospital were excluded.
  
  
  METHODS
  Ultra-low-field cranial MR scans were performed on patients within 24 hours of discharge. Scans were read blindly by two radiologists.
  
  
  RESULTS
  Fisher's exact test was used to compare symptoms in patients with abnormal and normal MR scans. There was no significant difference in symptoms between patients with abnormal and those with normal scans (P greater than .10). The proportion of abnormal MR scans was analyzed using the binomial distribution. Six of the 58 patients (10.3%) had traumatic intracranial abnormalities (proportion, 0.103; SD, 0.04; 95% CI, 0.04-0.21). Three had cortical contusions, and three had small subdural hematomas. Two of the six patients with abnormal MR scans, both with small subdural hematomas, had normal computed tomography scans.
  
  
  CONCLUSIONS
  Ten percent of patients discharged from the ED after minor head injury had abnormal ultra-low-field cranial MR scans. Additional research is needed to establish the clinical importance of this unexpected observation.
authors.affiliation: Division of Emergency Medicine, University of New Mexico School of Medicine, Albuquerque 87131.
authors.forename: D
authors.initials: D
authors.lastname: Doezema
authors.forename: J N
authors.initials: JN
authors.lastname: King
authors.forename: D
authors.initials: D
authors.lastname: Tandberg
authors.forename: M C
authors.initials: MC
authors.lastname: Espinosa
authors.forename: W W
authors.initials: WW
authors.lastname: Orrison
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D016010:Binomial Distribution; D001924:Brain Concussion / Q000175:diagnosis; D002648:Child; D002675:Child, Preschool; D015331:Cohort Studies; D006259:Craniocerebral Trauma / Q000175:diagnosis*; D006408:Hematoma, Subdural / Q000175:diagnosis; D006801:Humans; D008279:Magnetic Resonance Imaging; D008875:Middle Aged; D010351:Patient Discharge; D011446:Prospective Studies; D014057:Tomography, X-Ray Computed