Blood Flow Changes Induced by Flow Diverting Stent in a Large Wide-neck Intracranial Aneurysm

Abstract

Purpose Intracranial aneurysm flow diverting stents (FDS) have been used for endovascular treatment. Experience with FDS has shown encouraging results for difficult to treat aneurysms. To further understand the influence of FDS and help treatment planning, many researchers have proposed using computer software to examine and compare aneurysmal flow changes before and after FDS treatment. We implemented an intracranial stent flow mapping (IS FlowMap) program to study a large wide neck aneurysm and to compare the blood flow characteristics before and after treatment. Material and Methods A 19 mm large ICA aneurysm (15.7 mm neck) was treated by FDS. Angiogram images before and after stent implantation were evaluated. The IS FlowMap program was used to evaluate stent-induced blood flow changes in a series of images. Motion-tracking algorithms were utilized to analyze blood flow patterns within the aneurysm and blood flow impingement on the aneurysm wall. Angiogram images with contrast injection before and after the FDS treatment were used as input. Results The large aneurysm treated with the Pipeline FDS had a decrease in flow impingement on the aneurysm wall, especially at the proximal wall. After FDS treatment, blood flow impingement along the reconstructed vessel and stent was observed. Distinct differences in the aneurysmal inflow circulation were found by flow vector analysis. We observed that the original high-impact inflow at the proximal end of the aneurysm changed to the redirected slow inflow penetrating the FDS stent. This suggests that in the large wide neck aneurysm, although the impingement of blood inflow decreases, a larger area of blood inflow from the parent vessel is created due to blood flow penetrating the FDS. Conclusions By analyzing a series of angiogram images, we observed the detailed changes in blood flow induced by FDS treatment. Distinct flow changes after the placement of FDS can be found using regular angiogram images. Further understanding flow changes induced by stents and studying the relationship between such changes and treatment outcome will be helpful to advance treatment strategy.