Advanced imaging determinants of intracranial aneurysm growth and rupture

Treatment decision-making in unruptured intracranial aneurysms is a real clinical problem. We can use several patient and imaging characteristics to make this decision. However, for many rupture risk associated characteristics the clinical value is still uncertain, and their relation with aneurysm growth (and thus overall instability) is unknown. Therefore, the aim of this thesis was to evaluate the determinants of aneurysm instability (growth and rupture).
This thesis starts with a study on a new, relatively unexplored, hemodynamic characteristic and its association with aneurysm rupture. Subsequently, we validate commonly used imaging markers: the aneurysm size and the presence of wall enhancement. The thesis ends with an evaluation of several morphological, hemodynamical and wall characteristics in relation to aneurysm growth.
This thesis showed that several characteristics (such as the particle residence time and vessel wall enhancement) are not associated with aneurysm instability. As a result, predicting which aneurysm becomes instable is difficult. The process of growth and rupture is a complex interplay between morphology, hemodynamics and the vessel wall. During growth, the risk profile, and characteristics keep changing which requires repeated assessment. The size and direction of change are not consistent within the total population. However, after growth grown aneurysms have a hemodynamic environment that is associated with higher rupture risks. The phantom study and MRA agreement study in this thesis are a step towards validating the used methods. Both studies show that the new imaging methods can have additional value, but further improvements are needed.