Can DWI-ASPECTS Substitute for Lesion Volume in Acute Stroke?

Background and Purpose— The extent of diffusion lesion on pretreatment imaging is a risk factor for poor outcome and hemorrhagic transformation after thrombolysis, and volumes of 70 to 100 mL have been advocated as cut-offs. However, estimating diffusion-weighted imaging (DWI) lesion volume (VolDWI) in the acute setting may be cumbersome. We aimed to determine whether the DWI-Alberta Stroke Program Early CT Score (DWI-ASPECTS) can substitute for VolDWI. Methods— DWI-ASPECTS and VolDWI were measured retrospectively on pretreatment MRI (median onset-to-MRI delay=122 minutes) in 330 consecutively treated patients with middle cerebral artery stroke. Results— DWI-ASPECTS and VolDWI were strongly correlated (&rgr;=−0.82), but each DWI-ASPECTS point corresponded to a wide range of VolDWI. All patients with DWI-ASPECTS ≥7 (n=207) had VolDWI <70 mL, whereas 32 of the 34 patients with DWI-ASPECTS <4 had VolDWI >100 mL. However, intermediate DWI-ASPECTS (4–6; n=89) corresponded to highly variable VolDWI (median, 66 mL; interquartile range, 40–98). Conclusions— Although each DWI-ASPECTS point corresponds to a wide range of volumes, DWI-ASPECTS <4 or ≥7 may be used as reliable surrogates of VolDWI >100 or <70 mL, respectively.