title: Development and validation of intracranial thrombus segmentation on CT angiography in patients with acute ischemic stroke.
abstract: OBJECTIVE
  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.
  
  
  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 -0.4 (-8.8, 7.7) mm and 8 (-126, 141) mm3 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 -0.1 (-11.2, 10.9) mm and -17 (-216, 185) mm3.
  
  
  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.
authors.affiliation: Dept. of Radiology, Erasmus MC, Rotterdam, the Netherlands; Dept. of Medical Informatics, Erasmus MC, Rotterdam, the Netherlands; Dept. of Radiology, AMC, Amsterdam, the Netherlands; Dept. of Biomedical Engineering and Physics, AMC, Amsterdam, the Netherlands.
authors.forename: Emilie M M
authors.initials: EM
authors.lastname: Santos
authors.affiliation: Dept. of Radiology, AMC, Amsterdam, the Netherlands; Dept. of Biomedical Engineering and Physics, AMC, Amsterdam, the Netherlands.
authors.forename: Henk A
authors.initials: HA
authors.lastname: Marquering
authors.affiliation: Dept. of Radiology, AMC, Amsterdam, the Netherlands.
authors.forename: Olvert A
authors.initials: OA
authors.lastname: Berkhemer
authors.affiliation: Dept. of Radiology, Maastricht University Medical Centre, Maastricht, the Netherlands.
authors.forename: Wim H
authors.initials: WH
authors.lastname: van Zwam
authors.affiliation: Dept. of Radiology, Erasmus MC, Rotterdam, the Netherlands.
authors.forename: Aad
authors.initials: A
authors.lastname: van der Lugt
authors.affiliation: Dept. of Radiology, AMC, Amsterdam, the Netherlands.
authors.forename: Charles B
authors.initials: CB
authors.lastname: Majoie
authors.affiliation: Dept. of Radiology, Erasmus MC, Rotterdam, the Netherlands; Dept. of Medical Informatics, Erasmus MC, Rotterdam, the Netherlands; Faculty of Applied Sciences, Delft University of Technology, Delft, the Netherlands.
authors.forename: Wiro J
authors.initials: WJ
authors.lastname: Niessen
mesh_terms: D002533:Cerebral Angiography / Q000379:methods*; D005260:Female; D006801:Humans; D020767:Intracranial Thrombosis / Q000175:diagnosis / Q000000981:diagnostic imaging* / Q000628:therapy; D008297:Male; D008875:Middle Aged; D015588:Observer Variation; D010363:Pattern Recognition, Automated / Q000379:methods; D011856:Radiographic Image Enhancement / Q000379:methods; D011857:Radiographic Image Interpretation, Computer-Assisted / Q000379:methods*; D015203:Reproducibility of Results; D012189:Retrospective Studies; D020521:Stroke / Q000175:diagnosis / Q000000981:diagnostic imaging* / Q000628:therapy; D014057:Tomography, X-Ray Computed / Q000379:methods*