Influence of the Arterial Input Function on Absolute and Relative Perfusion-Weighted Imaging Penumbral Flow Detection

Background and Purpose—Perfusion-weighted imaging maps are used to identify critical hypoperfusion in acute stroke. However, quantification of perfusion may depend on the choice of the arterial input function (AIF). Using quantitative positron emission tomography we evaluated the influence of the AIF location on maps of absolute and relative perfusion-weighted imaging to detect penumbral flow (PF; <20 mL/100 g/min on positron emission tomographyCBF) in acute stroke. Methods—In 22 patients with acute stroke the AIF was placed at 7 sites (M1, M2, M3 ipsi- and contralateral and internal carotid artery–M1 contralateral to the infarct). Comparative 15O-water positron emission tomography and AIF-dependent perfusion-weighted imaging (cerebral blood flow, cerebral blood volume, mean transit time, and time to maximum) were performed. A receiver operating characteristic curve analysis described the threshold independent performance (area under the curve) of the perfusion-weighted maps for all 7 AIF locations and id...