title: Magnetic resonance imaging and computed tomography in emergency assessment of patients with suspected acute stroke: a prospective comparison.
abstract: BACKGROUND
  Although the use of magnetic resonance imaging (MRI) for the diagnosis of acute stroke is increasing, this method has not proved more effective than computed tomography (CT) in the emergency setting. We aimed to prospectively compare CT and MRI for emergency diagnosis of acute stroke.
  
  
  METHODS
  We did a single-centre, prospective, blind comparison of non-contrast CT and MRI (with diffusion-weighted and susceptibility weighted images) in a consecutive series of patients referred for emergency assessment of suspected acute stroke. Scans were independently interpreted by four experts, who were unaware of clinical information, MRI-CT pairings, and follow-up imaging.
  
  
  RESULTS
  356 patients, 217 of whom had a final clinical diagnosis of acute stroke, were assessed. MRI detected acute stroke (ischaemic or haemorrhagic), acute ischaemic stroke, and chronic haemorrhage more frequently than did CT (p<0.0001, for all comparisons). MRI was similar to CT for the detection of acute intracranial haemorrhage. MRI detected acute ischaemic stroke in 164 of 356 patients (46%; 95% CI 41-51%), compared with CT in 35 of 356 patients (10%; 7-14%). In the subset of patients scanned within 3 h of symptom onset, MRI detected acute ischaemic stroke in 41 of 90 patients (46%; 35-56%); CT in 6 of 90 (7%; 3-14%). Relative to the final clinical diagnosis, MRI had a sensitivity of 83% (181 of 217; 78-88%) and CT of 26% (56 of 217; 20-32%) for the diagnosis of any acute stroke.
  
  
  CONCLUSIONS
  MRI is better than CT for detection of acute ischaemia, and can detect acute and chronic haemorrhage; therefore it should be the preferred test for accurate diagnosis of patients with suspected acute stroke. Because our patient sample encompassed the range of disease that is likely to be encountered in emergency cases of suspected stroke, our results are directly applicable to clinical practice.
authors.affiliation: Medical University of South Carolina, Charleston, SC, USA.
authors.forename: Julio A
authors.initials: JA
authors.lastname: Chalela
authors.forename: Chelsea S
authors.initials: CS
authors.lastname: Kidwell
authors.forename: Lauren M
authors.initials: LM
authors.lastname: Nentwich
authors.forename: Marie
authors.initials: M
authors.lastname: Luby
authors.forename: John A
authors.initials: JA
authors.lastname: Butman
authors.forename: Andrew M
authors.initials: AM
authors.lastname: Demchuk
authors.forename: Michael D
authors.initials: MD
authors.lastname: Hill
authors.forename: Nicholas
authors.initials: N
authors.lastname: Patronas
authors.forename: Lawrence
authors.initials: L
authors.lastname: Latour
authors.forename: Steven
authors.initials: S
authors.lastname: Warach
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D004636:Emergency Service, Hospital; D006801:Humans; D020300:Intracranial Hemorrhages / Q000175:diagnosis*; D008279:Magnetic Resonance Imaging; D008875:Middle Aged; D017202:Myocardial Ischemia / Q000175:diagnosis*; D011446:Prospective Studies; D020521:Stroke / Q000175:diagnosis*; D013997:Time Factors; D014057:Tomography, X-Ray Computed