Aneurysm identification by analysis of the blood-vessel skeleton Josef Kohout, Alessandro Chiarini, Gordon J. Clapworthy, Gregor Klajnšek  Computer Methods and Programs in Biomedicine  Volume 109, Issue 1, Pages 32-47 (January 2013) DOI: 10.1016/j.cmpb.2012.08.018 Copyright © 2012 Elsevier Ireland Ltd Terms and Conditions

Fig. 1 The @neurIST processing toolchain: from medical images, increasingly sophisticated computer models are built. As complexity increases, more predictive information is extracted, whereas the confidence decreases as additional computational steps are involved. Computer Methods and Programs in Biomedicine 2013 109, 32-47DOI: (10.1016/j.cmpb.2012.08.018) Copyright © 2012 Elsevier Ireland Ltd Terms and Conditions

Fig. 2 Visualisation of curvatures: Gaussian (left) and mean (right). Computer Methods and Programs in Biomedicine 2013 109, 32-47DOI: (10.1016/j.cmpb.2012.08.018) Copyright © 2012 Elsevier Ireland Ltd Terms and Conditions

Fig. 3 Classification of surface points – each colour represents one group. (For interpretation of the references to colour in this figure legend, the reader is referred to the web version of the article.) Computer Methods and Programs in Biomedicine 2013 109, 32-47DOI: (10.1016/j.cmpb.2012.08.018) Copyright © 2012 Elsevier Ireland Ltd Terms and Conditions

Fig. 4 Comparison of the narrowest place and the neck of aneurysm. Computer Methods and Programs in Biomedicine 2013 109, 32-47DOI: (10.1016/j.cmpb.2012.08.018) Copyright © 2012 Elsevier Ireland Ltd Terms and Conditions

Fig. 5 Blood vessels and their skeleton. Computer Methods and Programs in Biomedicine 2013 109, 32-47DOI: (10.1016/j.cmpb.2012.08.018) Copyright © 2012 Elsevier Ireland Ltd Terms and Conditions

Fig. 6 Blood vessels and their skeleton created by various method. Computer Methods and Programs in Biomedicine 2013 109, 32-47DOI: (10.1016/j.cmpb.2012.08.018) Copyright © 2012 Elsevier Ireland Ltd Terms and Conditions

Fig. 7 The underlying skeleton, split into two parts: one (yellow) corresponding to the healthy blood vessels, the other (green) corresponding to the aneurysm. (For interpretation of the references to colour in this figure legend, the reader is referred to the web version of the article.) Computer Methods and Programs in Biomedicine 2013 109, 32-47DOI: (10.1016/j.cmpb.2012.08.018) Copyright © 2012 Elsevier Ireland Ltd Terms and Conditions

Fig. 8 Skeleton edges and their region of support on the surface. Computer Methods and Programs in Biomedicine 2013 109, 32-47DOI: (10.1016/j.cmpb.2012.08.018) Copyright © 2012 Elsevier Ireland Ltd Terms and Conditions

Fig. 9 Illustration of skeleton partitioning: some surface vertices belong to the healthy blood vessel, although they are supported by the edge CP of the aneurysm part of the skeleton – see the text. Computer Methods and Programs in Biomedicine 2013 109, 32-47DOI: (10.1016/j.cmpb.2012.08.018) Copyright © 2012 Elsevier Ireland Ltd Terms and Conditions

Fig. 10 Illustration of the calculation of the probabilities pd(V) and ps(V, E, P) – see text. Left: the calculation of pd(V); green edges belong to the set SA, yellow edges belong to the set SB, thick edges belong to subsets EA (green) or EB (yellow) – for the sake of simplicity, there is only one edge in each subset (all other edges are considered to be too far from the point V), VA and VB are points of edges from EA and EB, respectively, that are closest to the point V. Right: the calculation of ps(V, EA, P); V′ is the point closest to the point V that lies on an edge from EA, red is the shortest path from the point V′ to the point P. (For interpretation of the references to colour in this figure legend, the reader is referred to the web version of the article.) Computer Methods and Programs in Biomedicine 2013 109, 32-47DOI: (10.1016/j.cmpb.2012.08.018) Copyright © 2012 Elsevier Ireland Ltd Terms and Conditions

Fig. 11 Aneurysm probability map without (left) and with (right) post-processing adjustment. The identified neck of the aneurysm is the red contour. (For interpretation of the references to colour in this figure legend, the reader is referred to the web version of the article.) Computer Methods and Programs in Biomedicine 2013 109, 32-47DOI: (10.1016/j.cmpb.2012.08.018) Copyright © 2012 Elsevier Ireland Ltd Terms and Conditions

Fig. 12 Aneurysm probability map without (left) and with (right) post-processing adjustment. The identified neck of the aneurysm is the red contour. (For interpretation of the references to colour in this figure legend, the reader is referred to the web version of the article.) Computer Methods and Programs in Biomedicine 2013 109, 32-47DOI: (10.1016/j.cmpb.2012.08.018) Copyright © 2012 Elsevier Ireland Ltd Terms and Conditions

Fig. 13 Aneurysm probability map with smoothing: (left) no smoothing, (centre) 10 times, (right) 100 times. The post-processing adjustment is used in all cases. Computer Methods and Programs in Biomedicine 2013 109, 32-47DOI: (10.1016/j.cmpb.2012.08.018) Copyright © 2012 Elsevier Ireland Ltd Terms and Conditions

Fig. 14 An example of cutting of the triangle ABC. Computer Methods and Programs in Biomedicine 2013 109, 32-47DOI: (10.1016/j.cmpb.2012.08.018) Copyright © 2012 Elsevier Ireland Ltd Terms and Conditions

Fig. 15 The detected aneurysm (green) and its neck (red and blue contours). The skeleton point P was chosen at a junction. Default settings were used. (For interpretation of the references to colour in this figure legend, the reader is referred to the web version of the article.) Computer Methods and Programs in Biomedicine 2013 109, 32-47DOI: (10.1016/j.cmpb.2012.08.018) Copyright © 2012 Elsevier Ireland Ltd Terms and Conditions

Fig. 16 The detected aneurysm (green) and its neck (blue). The skeleton point P was chosen on a branch. The default settings were used but the post-processing adjustment was not performed. (For interpretation of the references to colour in this figure legend, the reader is referred to the web version of the article.) Computer Methods and Programs in Biomedicine 2013 109, 32-47DOI: (10.1016/j.cmpb.2012.08.018) Copyright © 2012 Elsevier Ireland Ltd Terms and Conditions

Fig. 17 The sensitivity of the accuracy of the identification of neck (red contour) to the choice of the skeleton point P (blue ball). The post-processing adjustment was not performed. (For interpretation of the references to colour in this figure legend, the reader is referred to the web version of the article.) Computer Methods and Programs in Biomedicine 2013 109, 32-47DOI: (10.1016/j.cmpb.2012.08.018) Copyright © 2012 Elsevier Ireland Ltd Terms and Conditions

Fig. 18 Blood vessels with aneurysms excised – before and after the hole filling operation. Computer Methods and Programs in Biomedicine 2013 109, 32-47DOI: (10.1016/j.cmpb.2012.08.018) Copyright © 2012 Elsevier Ireland Ltd Terms and Conditions

Fig. 19 The blood vessel from Fig. 18 after the smoothing operation. Computer Methods and Programs in Biomedicine 2013 109, 32-47DOI: (10.1016/j.cmpb.2012.08.018) Copyright © 2012 Elsevier Ireland Ltd Terms and Conditions

Fig. 20 An illustration of the sensitivity of our method on the quality of the skeleton. Computer Methods and Programs in Biomedicine 2013 109, 32-47DOI: (10.1016/j.cmpb.2012.08.018) Copyright © 2012 Elsevier Ireland Ltd Terms and Conditions

Fig. 21 The result of detection of aneurysm for dataset from Fig. 20 after improving the quality of the skeleton. Computer Methods and Programs in Biomedicine 2013 109, 32-47DOI: (10.1016/j.cmpb.2012.08.018) Copyright © 2012 Elsevier Ireland Ltd Terms and Conditions

Fig. 22 An illustration of the sensitivity of our method on the quality of the skeleton for a complex case. Left – original corrupted skeleton and the detected aneurysm for this skeleton, right – manually edited skeleton and the corresponding detected aneurysm. Computer Methods and Programs in Biomedicine 2013 109, 32-47DOI: (10.1016/j.cmpb.2012.08.018) Copyright © 2012 Elsevier Ireland Ltd Terms and Conditions

Fig. 23 Comparison of aneurysms detected by our method with default options (green – above) with those extracted manually by an expert (red – below). (For interpretation of the references to colour in this figure legend, the reader is referred to the web version of the article.) Computer Methods and Programs in Biomedicine 2013 109, 32-47DOI: (10.1016/j.cmpb.2012.08.018) Copyright © 2012 Elsevier Ireland Ltd Terms and Conditions