PT - JOURNAL ARTICLE AU - A. Rodríguez-Vázquez AU - C. Laredo AU - A. Renú AU - S. Rudilosso AU - L. Llull AU - S. Amaro AU - V. Obach AU - V. Vera AU - A. Páez AU - L. Oleaga AU - X. Urra AU - Á. Chamorro TI - Optimizing the Definition of Ischemic Core in CT Perfusion<span class="sc">:</span> Influence of Infarct Growth and Tissue<span class="sc">-</span>Specific Thresholds AID - 10.3174/ajnr.A7601 DP - 2022 Sep 01 TA - American Journal of Neuroradiology PG - 1265--1270 VI - 43 IP - 9 4099 - http://www.ajnr.org/content/43/9/1265.short 4100 - http://www.ajnr.org/content/43/9/1265.full SO - Am. J. Neuroradiol.2022 Sep 01; 43 AB - BACKGROUND AND PURPOSE: CTP allows estimating ischemic core in patients with acute stroke. However, these estimations have limited accuracy compared with MR imaging. We studied the effect of applying WM- and GM-specific thresholds and analyzed the infarct growth from baseline imaging to reperfusion.MATERIALS AND METHODS: This was a single-center cohort of consecutive patients (n = 113) with witnessed strokes due to proximal carotid territory occlusions with baseline CT perfusion, complete reperfusion, and follow-up DWI. We segmented GM and WM, coregistered CTP with DWI, and compared the accuracy of the different predictions for each voxel on DWI through receiver operating characteristic analysis. We assessed the yield of different relative CBF thresholds to predict the final infarct volume and an estimated infarct growth–corrected volume (subtracting the infarct growth from baseline imaging to complete reperfusion) for a single relative CBF threshold and GM- and WM-specific thresholds.RESULTS: The fixed threshold underestimated lesions in GM and overestimated them in WM. Double GM- and WM-specific thresholds of relative CBF were superior to fixed thresholds in predicting infarcted voxels. The closest estimations of the infarct on DWI were based on a relative CBF of 25% for a single threshold, 35% for GM, and 20% for WM, and they decreased when correcting for infarct growth: 20% for a single threshold, 25% for GM, and 15% for WM. The combination of 25% for GM and 15% for WM yielded the best prediction.CONCLUSIONS: GM- and WM-specific thresholds result in different estimations of ischemic core in CTP and increase the global accuracy. More restrictive thresholds better estimate the actual extent of the infarcted tissue.ICCintraclass correlation coefficientIGinfarct growthIQRinterquartile rangerCBFrelative CBF