Abstract
In this thesis we have aimed to improve rupture risk assessment for intracranial aneurysms. We have focused on two techniques that allow assessment of aneurysm wall related characteristics: computational fluid dynamics (CFD) for the assessment of hemodynamics along the wall and imaging of the vessel wall itself using magnetic resonance vessel wall imaging (VWI).
In chapter 2 we show that flow-rates, velocity-magnitudes, and pulsatility indices differ among parent artery locations, but also that anatomical variations of the CoW have significant effects on the flow. In Chapter 3, we demonstrate that important hemodynamic characteristics—flow complexity, stability, and concentration—changed in two-thirds of our population due to a changing morphology before, during, or just after rupture. In Chapter 4, hemodynamic changes after aneurysm growth were investigated using longitudinal imaging. Large hemodynamic changes with a large variability between aneurysms have been observed in our population. In Chapter 5, we analyze the effect of neurovascular stents on the peri-aneurysmal geometry and resulting intra-aneurysmal hemodynamics. In our study we showed that the tortuosity of the peri-aneurysmal vasculature decreased with more than 50% in cases where stents were located in the intradural space, resulting in inconsistent intra-aneurysmal hemodynamic changes.
The aneurysm wall can be visualized non-invasively using MR-VWI, and is frequently presented as a valuable tool for assessing the stability of the aneurysm wall. In Chapter 6, we analyze different imaging modalities in conjunction with VWI to assess underlying mechanisms that may have contributed to vessel wall enhancement. We identified multiple underlying sources that may have contributed to enhancement: e.g. atherosclerosis, intramural hematoma, and slow flow. In Chapter 7, a phantom-setup was designed to quantify the contribution of slow flow to vessel wall enhancement. We demonstrated that wall-like signals—originating from slow flow along the wall—were visible in VWI both with and without preparation pulses, although preparation pulses did improve slow-flow suppression. The MR-signal became more apparent after contrast-administration, and higher signal intensities were observed for low inflow-rates.
In chapter 2 we show that flow-rates, velocity-magnitudes, and pulsatility indices differ among parent artery locations, but also that anatomical variations of the CoW have significant effects on the flow. In Chapter 3, we demonstrate that important hemodynamic characteristics—flow complexity, stability, and concentration—changed in two-thirds of our population due to a changing morphology before, during, or just after rupture. In Chapter 4, hemodynamic changes after aneurysm growth were investigated using longitudinal imaging. Large hemodynamic changes with a large variability between aneurysms have been observed in our population. In Chapter 5, we analyze the effect of neurovascular stents on the peri-aneurysmal geometry and resulting intra-aneurysmal hemodynamics. In our study we showed that the tortuosity of the peri-aneurysmal vasculature decreased with more than 50% in cases where stents were located in the intradural space, resulting in inconsistent intra-aneurysmal hemodynamic changes.
The aneurysm wall can be visualized non-invasively using MR-VWI, and is frequently presented as a valuable tool for assessing the stability of the aneurysm wall. In Chapter 6, we analyze different imaging modalities in conjunction with VWI to assess underlying mechanisms that may have contributed to vessel wall enhancement. We identified multiple underlying sources that may have contributed to enhancement: e.g. atherosclerosis, intramural hematoma, and slow flow. In Chapter 7, a phantom-setup was designed to quantify the contribution of slow flow to vessel wall enhancement. We demonstrated that wall-like signals—originating from slow flow along the wall—were visible in VWI both with and without preparation pulses, although preparation pulses did improve slow-flow suppression. The MR-signal became more apparent after contrast-administration, and higher signal intensities were observed for low inflow-rates.
| Original language | English |
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| Qualification | Doctor of Philosophy |
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| Award date | 8 Apr 2021 |
| Place of Publication | Enschede |
| Publisher | |
| Print ISBNs | 978-94-6332-748-0 |
| DOIs | |
| Publication status | Published - 8 Apr 2021 |