title: Yield of diffusion-weighted MRI for detection of potentially relevant findings in stroke patients.
abstract: OBJECTIVE
  To determine whether diffusion-weighted imaging (DWI) could identify potentially clinically relevant findings in patients presenting more than 6 hours after stroke onset when compared with conventional MRI.
  
  
  METHODS
  MRI with both conventional (T2 and proton density images) and echoplanar imaging (DWI and apparent diffusion coefficient maps) was performed 6 to 48 hours after symptom onset (mean, 27 hours) in 40 consecutive patients with acute stroke. All acute lesions were identified first on conventional images, then on DWI, by a neuroradiologist who was provided with the suspected lesion location, based on a neurologist's examination before imaging. Abnormalities were rated as potentially clinically relevant if they were detected only on DWI and 1) confirmed the acute symptomatic lesion to be in a different vascular territory than suspected clinically, 2) revealed multiple lesions in different vascular territories suggestive of a proximal source of embolism, or 3) clarified that a lesion, thought to be acute on conventional imaging, was not acute.
  
  
  RESULTS
  The initial clinical impression of lesion localization was incorrect in 12 patients (30%). Clinically significant findings were detected by DWI alone in 19 patients (48%). DWI demonstrated the symptomatic lesion in a different vascular territory than suspected clinically or by conventional MRI in 7 patients (18%) and showed acute lesions in multiple vascular distributions in 5 patients (13%). In 8 patients (20%), DWI clarified that lesions thought to be acute on conventional MRI were actually old.
  
  
  CONCLUSIONS
  In patients imaged 6 to 48 hours after stroke onset, DWI frequently provided potentially clinically relevant findings that were not apparent on conventional MRI.
authors.affiliation: Stanford Stroke Center, Palo Alto, CA 94304, USA. albers@leland.stanford.edu
authors.forename: G W
authors.initials: GW
authors.lastname: Albers
authors.forename: M G
authors.initials: MG
authors.lastname: Lansberg
authors.forename: A M
authors.initials: AM
authors.lastname: Norbash
authors.forename: D C
authors.initials: DC
authors.lastname: Tong
authors.forename: M W
authors.initials: MW
authors.lastname: O'Brien
authors.forename: A R
authors.initials: AR
authors.lastname: Woolfenden
authors.forename: M P
authors.initials: MP
authors.lastname: Marks
authors.forename: M E
authors.initials: ME
authors.lastname: Moseley
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001921:Brain / Q000473:pathology; D002545:Brain Ischemia / Q000175:diagnosis* / Q000209:etiology; D004058:Diffusion; D005260:Female; D006801:Humans; D007089:Image Enhancement / Q000379:methods; D020766:Intracranial Embolism / Q000150:complications / Q000175:diagnosis*; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008297:Male; D008875:Middle Aged; D011237:Predictive Value of Tests; D015203:Reproducibility of Results; D020521:Stroke / Q000175:diagnosis* / Q000209:etiology