Perfusion-derived metrics to calculate cerebral infarct growth rate, "ultrafast progressor" phenotype, and neuroprotection.

Cerebral infarct growth rate (IGR) varies widely in ischemic stroke, and this has important clinical implications. In their recent article, Lin et al. explored IGR characteristics and treatment modification in so-called "ultrafast progressors". We comment on the study's methodology for calculating IGR and its interpretation, arguing that perfusion-derived metrics should probably not be adjusted for the time between symptom onset and imaging. Time-independent metrics may better characterize ultrafast progressors by avoiding assumptions about the linearity of infarct growth curves. These results could inform future studies, as ultrafast progressors might benefit the most from neuroprotection interventions.