Baseline CT imaging included brain non-contrast CT, CTP, and CTA, obtained with different CT scanners (64, 128, 256, or 320 detectors, with Toshiba [Tokyo, Japan], Siemens [Munich, Germany], or GE [Cleveland, OH, USA] scanners). The axial coverage ranged from 80 to 160 mm.
The CTP data were processed by commercial software MIStar (Apollo Medical Imaging Technology, Melbourne, Vic, Australia). CTP parameters were generated by applying the mathematical algorithm of singular value decomposition with delay and dispersion correction (20 (link), 21 (link)). The following four CTP parameters were generated: cerebral blood flow (CBF), cerebral blood volume (CBV), mean transit time (MTT), and delay time (DT). The penumbra and core volume were measured on acute CTP with dual threshold setting (22 (link)): DT at the threshold of 3 s for whole ischemic lesion volume and CBF at the threshold setting of 30% for acute core volume. The collateral index was defined by the ratio of DT >6 s/DT >2 s volume.
The CTP data were processed by commercial software MIStar (Apollo Medical Imaging Technology, Melbourne, Vic, Australia). CTP parameters were generated by applying the mathematical algorithm of singular value decomposition with delay and dispersion correction (20 (link), 21 (link)). The following four CTP parameters were generated: cerebral blood flow (CBF), cerebral blood volume (CBV), mean transit time (MTT), and delay time (DT). The penumbra and core volume were measured on acute CTP with dual threshold setting (22 (link)): DT at the threshold of 3 s for whole ischemic lesion volume and CBF at the threshold setting of 30% for acute core volume. The collateral index was defined by the ratio of DT >6 s/DT >2 s volume.
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