Early CT perfusion mismatch in acute stroke is not time-dependent but relies on collateralization grade

Introduction Factors that determine the extent of the penumbra in the initial diagnostic workup using whole brain CT Perfusion (WB-CTP) remain unclear. The purpose of the current study was to determine a possible dependency of the initial mismatch size between cerebral blood flow (CBF) and cerebral blood volume (CBV) from time after symptom onset, leptomeningeal collateralization, and occlusion localization in acute middle cerebral artery (MCA) infarctions. Methods Out of an existing cohort of 992 consecutive patients receiving multiparametric CT scans including WB-CTP due to suspected stroke, we included patients who had (1) a witnessed time of symptom onset, (2) an infarction of the MCA territory as documented by follow-up imaging, and (3) an initial CBF volume of >10 ml. CBF and CBV lesion sizes, collateralization grade, and the site of occlusion were determined. Results We included 103 patients. Univariate analysis showed that time from symptom onset (168 +/− 91.2 min) did not correlate with relative or absolute mismatch volumes ( p = 0.458 and p = 0.921). Higher collateralization gradings were associated with small absolute mismatch volumes ( p = 0.004 and p