Aslak Wigdahl Bergersen defended his PhD thesis

On Thursday 27 April 2023 at 13:15, Aslak Wigdahl Bergersen defended his PhD thesis "On software tools and variability in medical image-based computational fluid dynamics". The defence took place in the Hans Petter Langtangen Lecture Hall at Simula KA23.

Main research findings

Intracranial aneurysms are balloon-shaped blobs on blood vessels inside the skull and are more brittle than the surrounding blood vessels, and can rupture, causing a stroke. To predict if an aneurysm is going to rupture, we are interested in the local blood flow inside the aneurysm. However, it is challenging to measure blood flow in the brain with good enough resolution. Progress in numerical simulations, combined with medical images of patients’ blood vessels, has provided new opportunities to model blood flow instead. However, the field has had several contentious areas, some of which could be attributed to the multitude of options and assumptions when performing such simulations. In this thesis I have therefore measured the real-world variability, going from a medical image to final blood flow simulation and rupture prediction, by comparing results across many research groups. I have also developed a new software tool that allows for parametric alteration of blood vessel geometry to study how it impacts blood flow. In medical image-based blood flow modelling for aneurysms, better reproducibility and replicability may help advance blood flow modelling as a robust research tool, which ultimately could assist clinicians in improving treatment strategy and patient outcomes.

Prior to the defence, at 11:15 on the same day, Aslak presented his trial lecture "Medical imaging for flow quantification; current clinical applications, limitations and future possibilities" also in the HPL lecture hall.

Adjudication committee:

  • Principal Research Engineer Jonas Lantz, Department of Health, Medicine and Caring Sciences, Linköping University, Sweden
  • Professor Leif Rune Hellevik, Department of Structural Engineering, Norwegian University of Science and Technology, Norway
  • Professor Ole Christian Lingjærde, Department of Informatics, University of Oslo, Norway


  • Chief Research Scientist Kristian Valen-Sendstad, Department of Computational Physiology, Simula
  • Chief Research Scientist Samuel Wall, Department of Computational Physiology, Simula
  • Chief Research Scientist Joakim Sundnes, Department of Informatics, UiO / Department of Computational Physiology, Simula

Read more at the UiO Department of Informatics web page.

Related employees