This document describes a visualization tool called VarVis that was presented at the EuroVis 2016 conference. VarVis uses a graph-based representation to visualize and compare anatomical variations in branching structures. It represents variations as node-link graphs and allows interactive exploration of similarities and differences between variations. An evaluation with domain experts found that VarVis improved task performance over traditional illustrations and that the summary tree abstraction was useful. The tool could be expanded in the future to build patient-specific models based on medical imaging data.

1. EuroVis 2016
18th EG/VGTC Conference on Visualization
6-10 June 2016, Groningen, the Netherlands
VarVis: Visualizing Anatomical Variation
in Branching Structures
Noeska Smit1, Annelot Kraima2, Daniel Jansma2, Marco
DeRuiter2, Elmar Eisemann1 and Anna Vilanova1
1Delft University of Technology
2Leiden University Medical Center

2. EuroVis 2016 Noeska Smit - VarVisEuroVis 2016
Brachydactyly Type D

3. EuroVis 2016 Noeska Smit - VarVisEuroVis 2016
Anatomical Variation
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Vesalius, A. Fabrica, 1543 Thompson, A. Third annual report of the committee of the collective investigation of
the Anatomical Society of Great Britain and Ireland for the year 1891-92. J. Anat.
Physiol. 27: 183-194, 1893.

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Anatomical Variation Example
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Relevance
• Correct diagnose and safe treatment
• For anyone performing interventional procedures:
• Radiologists
• Vascular surgeons
• Transplantation surgeons
• Neurosurgeons
• …
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Relevance
• What types of variations exist?
• How often do they occur?
• Similarity and differences amongst variations?
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Current representation
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Current representation
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Glasser, S.T. An anatomic study of venous variations at the fossa ovalis.
Arch. Surg. 46:289-295, 1943.

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Spot the differences?
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Improved visualization?
• Simple overlay?
• Summarize?
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Why not graph theory?
• Represent branching structures as graphs
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Graph representation: tree
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Graph matching

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Graph matching
• Label nodes based on endpoints they feed
• Traverse pair of trees from every endpoint to the root:
• If labels match: continue
• If labels do not match: merge nodes
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A
B
C
BC
ABC
A
B
C
Graph Matching
ABC ABC

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Graph matching: summary tree
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Topology similarity measure
• Given two graphs, how similar is the topology?
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Source data: 15 variations
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Global view: Topology similarity
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Local view
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Local view
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VarVis
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Evaluation
• Three domain experts:
• Task performance
• User experience
• Improved task performance over illustrations alone
• Summary tree abstraction
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Conclusion
• VarVis: interactive application
visualizing anatomical
variations
• Future work:
build patient-specific graph
representations based on medical
imaging
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Thank you!
• http://medvis.org - the blog on all things medical visualization
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@_Noeska_
@medvisorg
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