Background: Material/Methods: Results: Conclusions: O R I G I N A L A R T I C L E The hyperdense posterior cerebral artery sign in CT is related to larger ischemic lesion volume Wojciech Ambrosius1,2, Varsha Gupta1, Radoslaw Kazmierski3, Agnieszka Hellmann2, GuoYu Qian1, Wieslaw L. Nowinski1 1 Biomedical Imaging Lab, Agency for Science Technology and Research, Singapore 2 Department of Neurology Poznań University of Medical Sciences, Poznań, Poland 3 Department of Neurology and Cerebrovascular Disorders, Poznań University of Medical Sciences, L. Bierkowski Hospital, Poznań, Poland Author’s address: Wojciech Ambrosius, Department of Neurology, Poznan University of Medical Sciences, Przybyszewskiego 49 Str., 60-645, Poznań, Poland, e-mail: wambrosius@ump.edu.pl Source of support: This study is a part of the joined Singaporean-Polish project focused on development of the computer- aided decision support system for assessment of thrombolytic therapy in acute ischemic stroke in Emergency Department funded by Agency for Science, Technology and Research, Singapore and Ministry of Science and Higher Education, Poland (project no. 072-134 0049) Summary Hyperdensity of the middle cerebral artery (MCA) on unenhanced CT is a recognized sign associated with brain’s early ischemia. The number of studies which showed a hyperdense posterior cerebral artery (HPCA) sign in posterior circulation infarct is relatively small. We investigated the prevalence of the HPCA sign, correlations with ischemic lesion volume, and stroke risk factors. We also determined the association with prothrombotic and inflammatory markers which have not been studied before. In the group of 376 patients with a first acute stroke consecutively admitted to Emergency Department, early signs of brain infarction were visible in 221 (58%) cases. Fifty five (25%) subjects had ischemic lesions in the brain supplied by the posterior circulation. We analyzed the unenhanced CT scans, calculated the density of the posterior cerebral arteries, infarct volume, and assessed the relation of the HPCA sign to other factors. The HPCA sign appeared on CT scans of 12 (22%) patients with evidence of the posterior circulation infarct. The density (in Hounsfield units) of the affected PCA was 46.5 comparing to 20.2 of an intact vessel (p<0.0001). The stroke volume was larger when the HPCA sign was observed (medians: 17.6 vs. 4.3 cm3, p=0.02); in multivariate analysis this association was still significant (OR=1.07; 95% CI, 0.99–1.13). The C-reactive protein and fibrinogen levels were significantly higher (p=0.02 for both factors) in patients with the HPCA sign in the univariate analysis. The HPCA may be considered as an additional marker of early brain infarct, especially with large lesion volume. Signature: © Pol J Radiol, 2011; 76(2): 13-17 Received: 2011.04.12 Accepted: 2011.05.11 Key words: stroke • imaging • computed tomography • hyperdense artery sign PDF file: http://www.polradiol.com/fulltxt.php?ICID=881814 Background Visualization of acute signs of ischemic stroke is still a challenging aspect of neuroimaging. Every year new sophisticated imaging methods are introduced and their results are published showing brain ischemic lesions much more accurately. Most of these trials employ MRI techni- ques [1,2]. Practically, in routine emergency neurological 13