title: A rule to identify patients who require magnetic resonance imaging after intracerebral hemorrhage.
abstract: BACKGROUND
  A study performed in Hong Kong of catheter angiography after ICH found a high rate of structural lesions in patients 45 years of age or younger, without a history of hypertension, or with lobar hemorrhage. We hypothesized that a clinical decision rule based on these Hong Kong criteria would reliably identify patients who require MRI after ICH.
  
  
  METHODS
  We identified all patients admitted with ICH to our medical center during a 5-year period who underwent brain MRI. Patients were excluded if the history revealed an obvious cause of ICH. Two study neurologists independently adjudicated whether MRI revealed the cause of ICH. We devised a rule recommending MRI if patients met one or more Hong Kong criteria, and calculated the proportion of patients with diagnostic MRI studies who would have been identified by this rule. We also examined the performance of a modified rule using age ≤ 55 years.
  
  
  RESULTS
  The original Hong Kong rule applied to 102 of the 148 patients in our cohort (69%), and would have recommended MRI in 25 of 27 patients with diagnostic MRI studies (93%, 95% CI 76-99%). The modified rule applied to 110 patients (74%), and would have recommended MRI in all 27 patients with diagnostic MRI studies (100%, 95% CI 91-100%).
  
  
  CONCLUSIONS
  A rule based on simple clinical criteria may be useful for stratifying the yield of MRI after ICH. If validated in further studies, such a rule could reduce the number of unnecessary MRI studies after ICH, leading to more cost-effective care.
authors.affiliation: Department of Neurology and Neuroscience, Weill Cornell Medical College, New York, NY 10065, USA. hok9010@med.cornell.edu
authors.forename: Hooman
authors.initials: H
authors.lastname: Kamel
authors.forename: Babak B
authors.initials: BB
authors.lastname: Navi
authors.forename: J Claude
authors.initials: JC
authors.lastname: Hemphill
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D002543:Cerebral Hemorrhage / Q000175:diagnosis* / Q000209:etiology; D015331:Cohort Studies; D003661:Decision Support Techniques; D005260:Female; D006801:Humans; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D018579:Patient Selection; D012189:Retrospective Studies; D012307:Risk Factors