Infarct Core Reliability by CT Perfusion is a Time-Dependent Phenomenon

BACKGROUND AND PURPOSE In the setting of an extended time window for endovascular treatment (EVT) for acute stroke patients, computed tomography perfusion (CTP) has become a major tool in patient selection. However, there are some data suggesting that the initial ischemic core may be overestimated by CTP depending on stroke onset time. This study aims to evaluate possible predictors of overestimation of infarct core by CTP. METHODS We studied all consecutive stroke patients undergoing EVT during 1 year who underwent CTP at admission and had a successful recanalization. Admission infarct core was measured on cerebral blood volume maps generated using the Intellispace Portal (Philips Healthcare, Best, the Netherlands) and final infarct was measured on noncontrast follow-up computed tomography at 24 hours. We defined overestimation of the infarct core as initial core minus final infarct >10 mL. RESULTS Out of 107 patients undergoing EVT in the study period, 60 were anterior circulation and had CTP done at our institute, and of them 31 were compatible with the inclusion criteria (known time of onset, no hemorrhagic conversion, and good recanalization). Median National Institute of Health Stroke Scale on admission was 13. Median time from symptoms to CTP was 148 minutes. Seventeen patients were found to have overestimation of the infarct core. Logistic regression analyses showed time from symptom onset to CTP to be inversely related to overestimation with a cutoff of 170 minutes (sensitivity 94% and specificity 43%). CONCLUSION Over estimation of the infarct core by CTP in patients undergoing EVT is time dependent and so CTP results among early arrivers should be interpreted cautiously.