Computer predicts aortic aneurysm rupture

A new computer model is expected to assist the medical doctors in saving patients with this potential life threatening condition. Assistant Professor Marie Sand Enevoldsen at the Technical University of Denmark (DTU) has developed a prototype computer model for AAA rupture risk evaluation. Today, the rupture risk evaluation is based on the diameter of the AAA and how fast it dilates. As long as the maximum AAA diameter is below 5-5.5 cm the risk associated with the operation is considered to be larger than the risk of AAA rupture. However, there are smaller AAAs that rupture before reaching the diameter criteria and larger AAAs that stabilize and never rupture. So, more detailed knowledge about the biomechanical properties of AAA is needed. This can only be acquired from a computer model.

But how should this computer model be constructed? This is exactly what Marie Sand Enevoldsen has considered during her three years as a PhD student at DTU. As part of the work she spent six months in the US working with international elite researchers within the field, and the effort has resulted in a prototype model. 
“We hope to be able to use the computer model in the clinical setting within the next couple of years” says Marie Sand Enevoldsen.

The model is meant as a patient-specific model fitted to each individual patient. Thus, the prototype model is based on medical imaging techniques, where image slices of the AAA are used to reconstruct the aneurysm, and then by using a computer program it is possible to simulate the blood flow in the AAA as well as the stress distribution in the fragile AAA wall.
“If you consider blood flow in a straight vessel, the blood will induce stress in the vessel wall in a different way compared to blood flow in a curved vessel. The same principle applies to the aorta, so patient-specific geometry is important to develop a realistic model” says Marie Sand Enevoldsen.

Besides considering the course of the AAA, it is important to feed the model age-matched material parameter describing the biomechanical properties of the wall material, as these properties change significantly with age.

The computer model has, until now, been tested in 12 healthy volunteers, and the results indicate that the current model underestimates the arterial stiffness.Next step in the process will therefore be to validate the results of the model.    

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