Cerebral Perfusion Analysis via CTP

As previous studies revealed, CTP scans were performed with the 64-slice detector CT scanner (Philips, Best, the Netherlands) and followed with injection of diluted nonionic contrast material. CTP data were then transferred to a postprocessing workstation (Extended Brilliance Workstation v 3.0, Philips Medical Systems) [22 (link)]. Cerebral blood volume (CBV), cerebral blood flow (CBF), mean transit time (MTT), and time to peak (TTP) were calculated using a deconvolution operation (Extend Brilliance Workstation v 3.0, Philips Medical Systems, USA). Absolute values of CTP parameters are subject to the area of regions of interest (ROIs) and are influenced by physiologic factors such as blood pressure [23 (link), 24 (link)]. Hence, we used the ratio of the values measured in the ipsilateral hemisphere to those in the contralateral hemisphere for CBV, CBF, MTT, and TTP (rCBV, rCBF, rMTT, and rTTP). Four absolute values obtained from 4 consecutive layers of a given territory were averaged to obtain the mean of CBV, CBF, MTT, and TTP in both ipsilateral and contralateral side. ROIs in both hemispheres including frontal lobe, occipital lobe, temporal lobe, and basal ganglia were manually outlined according to the maps of Damasio [25 (link)].