Simultaneous measurement of regional cerebral blood flow by perfusion CT and stable xenon CT: A validation study

BACKGROUND AND PURPOSE: Knowledge of cerebral blood how (CBF) alterations i n cases of acute stroke could be valuable in the early management of these cases. Among imaging techniques affording evaluation of cerebral perfusion, perfusion CT studies involve sequential acquisition of cerebral CT section s obtained in an axial mode during the IV administration of iodinated contr ast material. They are thus very easy to perform in emergency settings, Per fusion CT values of CBF hare proved to be accurate in animals, and perfusio n CT affords plausible values in humans, The purpose of this study was to v alidate perfusion CT studies of CBF by comparison with the results provided by stable xenon CT, which have been reported to be accurate, and to evalua te acquisition and processing modalities of CT data, notably the possible d econvolution methods and the selection of the reference artery. METHODS: Twelve stable xenon CT and perfusion CT cerebral examinations were performed within an interval of a few minutes in patients with various cer ebrovascular diseases, CBF maps were obtained from perfusion CT data by dec onvolution using singular value decomposition and least mean square methods . The CBF were compared with the stable xenon CT results in multiple region s of interest through linear regression analysis and bilateral t tests for matched variables. RESULTS: Linear regression analysis showed good correlation between perfusi on CT and stable xenon CT CBF values (singular value decomposition method: R-2 = 0.79, slope = 0.87; least mean square method: R-2 = 0.67, slope = 0.8 3). Bilateral t tests for matched variables did not identify a significant difference between the two imaging methods (P > .1), Both deconvolution met hods were equivalent (P > .1). The choice of the reference artery is a majo r concern and has a strong influence on the final perfusion CT CBF map. CONCLUSION: Perfusion CT studies of CBF achieved with adequate acquisition parameters and processing lead to accurate and reliable results.