how they can be used to communicate depth. Section \[sec:implementation\] provides implementation details for a GPU-based real-time visualization of VSS. Section \[sec:userstudy\] discusses the results of our user study, whereas derived insights and limitations of VSS are discussed in Section \[sec:discussion\]. Finally, we will conclude in Section \[sec:conclusions\] and summarize our contributions and findings.

Related Work {#sec:relatedwork}
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In this section, we describe the work related to vessel visualization and depth perception enhancement in medical visualization. Since providing a comprehensive review of these topics is beyond our scope, we would like to refer the reader to the state-of-the-art report published by Preim et al. [@Preim2016] which details many of these concepts.

**Medical visualization.** Several techniques have been proposed to improve the perception of medical visualizations. Global illumination techniques, for example, have been proven to improve the perception of surface features in volume visualization [@Zheng2014]. Ropinski et al. [@Ropinski2008] and Diaz et al. [@Diaz2010b] for instance developed different techniques to approximate ambient occlusion in volumetric datasets in order to improve shape and depth perception. In a more general setup, Wanger et al. [@Wanger1992] demonstrate how shadows can significantly improve the perception of the relative position of objects in a scene. Solteszova 