title: Establishing final infarct volume: stroke lesion evolution past 30 days is insignificant.
abstract: OBJECTIVE
  Lesion volume measured on MRI has been used as an objective surrogate marker for outcome in clinical trials. However, lesion volumes vary over time because of edema and tissue loss. This study aims to determine if lesion volumes measured at 30 and 90 days after ictus significantly differ.
  
  
  METHODS
  We performed a retrospective study of 18 patients who had acute (<24 hours) DWI and follow-up fluid-attenuated inversion recovery imaging at 5, 30, and 90 days. Two expert readers segmented lesions and the mean volumes of both reads were used in all statistical analyses.
  
  
  RESULTS
  Patient age was 65.8 (SD, 13.7) years and median NIHSS at baseline was 11.5. Inter-rater variability for lesion volume measurements was 3.7 (5.8) mL. Acute DWI volume was 19.3 (17.3) mL. Fluid-attenuated inversion recovery volumes for 5, 30, and 90 days were 34.3 (23.5), 18.6 (14.0), and 15.9 (13.8) mL, respectively. These volumes differed significantly (P<0.001). Linear regression revealed a strong correlation (r=0.96; P<0.001) between lesion volumes at 30 and 90 days with a slope that did not vary significantly from 1.0 (P=0.448).
  
  
  CONCLUSIONS
  Lesions continue to evolve between 5 and 90 days, but by 30 days lesion volume approaches final infarct volume. While clinical response is the most meaningful outcome measure, our findings suggest that lesion volumes measured at 30 days may provide a sufficient approximation for final infarct volume for use in early phase clinical trials.
authors.affiliation: Section on Stroke Diagnostics and Therapeutics, Stroke Branch, National Institute of Neurological Disorders and Stroke, Bethesda, MD 20892, USA.
authors.forename: Martin R
authors.initials: MR
authors.lastname: Gaudinski
authors.forename: Erica C
authors.initials: EC
authors.lastname: Henning
authors.forename: Aaron
authors.initials: A
authors.lastname: Miracle
authors.forename: Marie
authors.initials: M
authors.lastname: Luby
authors.forename: Steven
authors.initials: S
authors.lastname: Warach
authors.forename: Lawrence L
authors.initials: LL
authors.lastname: Latour
mesh_terms: D000368:Aged; D020520:Brain Infarction / Q000209:etiology / Q000473:pathology*; D038524:Diffusion Magnetic Resonance Imaging; D018450:Disease Progression; D006801:Humans; D007091:Image Processing, Computer-Assisted; D015203:Reproducibility of Results; D012189:Retrospective Studies; D020521:Stroke / Q000150:complications / Q000473:pathology*; D013995:Time