University of Groningen Development and validation of intracranial thrombus segmentation on CT angiography in patients with acute ischemic stroke Santos,

Background and Purpose: Thrombus characterization is increasingly considered important in predicting treatment success for patients with acute ischemic stroke. The lack of intensity contrast between thrombus and surrounding tissue in CT images makes manual delineation a difficult and time consuming task. Our aim was to develop an automated method for thrombus measurement on CT angiography and validate it against manual delineation. Materials and Methods: Automated thrombus segmentation was achieved using image intensity and a vascular shape prior derived from the segmentation of the contralateral artery. In 53 patients with acute ischemic stroke due to proximal intracranial arterial occlusion, automated length and volume measurements were performed. Accuracy was assessed by comparison with inter-observer variation of manual delineations using intraclass correlation coefficients and Bland–Altman analyses. Results: The automated method successfully segmented the thrombus for all 53 patients. The intraclass correlation of automated and manual length and volume measurements were 0.89 and 0.84. Bland-Altman analyses yielded a bias (limits of agreement) of 20.4 (28.8, 7.7) mm and 8 (2126, 141) mm for length and volume, respectively. This was comparable to the best interobserver agreement, with an intraclass correlation coefficients of 0.90 and 0.85 and a bias (limits of agreement) of 20.1 (211.2, 10.9) mm and 217 (2216, 185) mm. Conclusions: The method facilitates automated thrombus segmentation for accurate length and volume measurements, is relatively fast and requires minimal user input, while being insensitive to high hematocrit levels and vascular calcifications. Furthermore, it has the potential to assess thrombus characteristics of low-density thrombi. Citation: Santos EMM, Marquering HA, Berkhemer OA, van Zwam WH, van der Lugt A, et al. (2014) Development and Validation of Intracranial Thrombus Segmentation on CT Angiography in Patients with Acute Ischemic Stroke. PLoS ONE 9(7): e101985. doi:10.1371/journal.pone. 0101985 Editor: Jean-Claude Baron, INSERM U894, Centre de Psychiatrie et Neurosciences, Hopital Sainte-Anne and Université Paris 5, France Received March 13, 2014; Accepted June 13, 2014; Published July 17, 2014 Copyright: 2014 Santos et al. This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited. Data Availability: The authors confirm that, for approved reasons, some access restrictions apply to the data underlying the findings. The analysis data will be available upon request to Emilie M. M. Santos (Depts. of Radiology and Medical Informatics, Erasmus MC, Rotterdam, the Netherlands; e.santos@erasmusmc.nl) to all researchers who meet the criteria for access to confidential data. Funding: Technology Foundation STW under Grant 11632, MRCLEAN (Dutch Heart Foundation). http://www.carisma-airspace.nl. ITEA3 project MEDUSA under grant number 10004. https://itea3.org/project/medusa.html. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript. Competing Interests: The authors have declared that no competing interests exist. * Email: e.santos@erasmusmc.nl " MR CLEAN investigators are provided in the Acknowledgments.