title: The growth rate of early DWI lesions is highly variable and associated with penumbral salvage and clinical outcomes following endovascular reperfusion.
abstract: BACKGROUND
  The degree of variability in the rate of early diffusion-weighted imaging expansion in acute stroke has not been well characterized.
  
  
  OBJECTIVE
  We hypothesized that patients with slowly expanding diffusion-weighted imaging lesions would have more penumbral salvage and better clinical outcomes following endovascular reperfusion than patients with rapidly expanding diffusion-weighted imaging lesions.
  
  
  METHODS
  In the first part of this substudy of DEFUSE 2, growth curves were constructed for patients with >90% reperfusion and <10% reperfusion. Next, the initial growth rate was determined in all patients with a clearly established time of symptom onset, assuming a lesion volume of 0 ml just prior to symptom onset. Patients who achieved reperfusion (>50% reduction in perfusion-weighted imaging after endovascular therapy) were categorized into tertiles according to their initial diffusion-weighted imaging growth rates. For each tertile, penumbral salvage [comparison of final volume to the volume of perfusion-weighted imaging (Tmax > 6 s)/diffusion-weighted imaging mismatch prior to endovascular therapy], favorable clinical response (National Institutes of Health Stroke Scale improvement of ≥8 points or 0-1 at 30 days), and good functional outcome (90-day modified Rankin score of ≤2) were calculated. A multivariate model assessed whether infarct growth rates were an independent predictor of clinical outcomes.
  
  
  RESULTS
  Sixty-five patients were eligible for this study; the median initial growth rate was 3·1 ml/h (interquartile range 0·7-10·7). Target mismatch patients (n = 42) had initial growth rates that were significantly slower than the growth rates in malignant profile (n = 9 patients, P < 0·001). In patients who achieved reperfusion (n = 38), slower early diffusion-weighted imaging growth rates were associated with better clinical outcomes (P < 0·05) and a trend toward more penumbral salvage (n = 31, P = 0·103). A multivariate model demonstrated that initial diffusion-weighted imaging growth rate was an independent predictor of achieving a 90-day modified Rankin score of ≤2.
  
  
  CONCLUSIONS
  The growth rate of early diffusion-weighted imaging lesions in acute stroke patients is highly variable; malignant profile patients have higher growth rates than patients with target mismatch. A slower rate of early diffusion-weighted imaging growth is associated with a greater degree of penumbral salvage and improved clinical outcomes following endovascular reperfusion.
authors.affiliation: Stanford Stroke Center, Stanford University School of Medicine, Stanford, CA, USA.
authors.forename: Hayley M
authors.initials: HM
authors.lastname: Wheeler
authors.affiliation: Stanford Stroke Center, Stanford University School of Medicine, Stanford, CA, USA.
authors.forename: Michael
authors.initials: M
authors.lastname: Mlynash
authors.affiliation: Stanford Stroke Center, Stanford University School of Medicine, Stanford, CA, USA.
authors.forename: Manabu
authors.initials: M
authors.lastname: Inoue
authors.affiliation: Stanford Stroke Center, Stanford University School of Medicine, Stanford, CA, USA.
authors.forename: Aaryani
authors.initials: A
authors.lastname: Tipirnini
authors.affiliation: Stanford Stroke Center, Stanford University School of Medicine, Stanford, CA, USA.
authors.forename: John
authors.initials: J
authors.lastname: Liggins
authors.affiliation: Stanford Stroke Center, Stanford University School of Medicine, Stanford, CA, USA.
authors.forename: Roland
authors.initials: R
authors.lastname: Bammer
authors.affiliation: Stanford Stroke Center, Stanford University School of Medicine, Stanford, CA, USA.
authors.forename: Maarten G
authors.initials: MG
authors.lastname: Lansberg
authors.affiliation: Stanford Stroke Center, Stanford University School of Medicine, Stanford, CA, USA.
authors.forename: Stephanie
authors.initials: S
authors.lastname: Kemp
authors.affiliation: Stanford Stroke Center, Stanford University School of Medicine, Stanford, CA, USA.
authors.forename: Greg
authors.initials: G
authors.lastname: Zaharchuk
authors.affiliation: Stanford Stroke Center, Stanford University School of Medicine, Stanford, CA, USA.
authors.forename: Matus
authors.initials: M
authors.lastname: Straka
authors.affiliation: Stanford Stroke Center, Stanford University School of Medicine, Stanford, CA, USA.
authors.forename: Gregory W
authors.initials: GW
authors.lastname: Albers
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D038524:Diffusion Magnetic Resonance Imaging; D057510:Endovascular Procedures / Q000295:instrumentation / Q000379:methods*; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D015999:Multivariate Analysis; D015424:Reperfusion / Q000379:methods*; D016879:Salvage Therapy / Q000379:methods*; D012720:Severity of Illness Index; D020521:Stroke / Q000188:drug therapy*; D015912:Thrombolytic Therapy / Q000379:methods*; D016896:Treatment Outcome
keywords: MRI; ischemic stroke; lesions; radiology; reperfusion; stroke