The effect of aneurysm geometry on the intra-aneurysmal flow condition

Various anatomical parameters affect on intra-aneurysmal hemodynamics. Nevertheless, how the shapes of real patient aneurysms affect on their intra-aneurysmal hemodynamics remains unanswered. Quantitative computational fluid dynamics simulation was conducted using eight patients’ angiograms of internal carotid artery–ophthalmic artery aneurysms. The mean size of the intracranial aneurysms was 11.5 mm (range 5.8 to 19.9 mm). Intra-aneurysmal blood flow velocity and wall shear stress (WSS) were collected from three measurement planes in each aneurysm dome. The correlation coefficients (r) were obtained between hemodynamic values (flow velocity and WSS) and the following anatomical parameters: averaged dimension of aneurysm dome, the largest aneurysm dome dimension, aspect ratio, and dome–neck ratio. Negative linear correlations were observed between the averaged dimension of aneurysm dome and intra-aneurysmal flow velocity (r = −0.735) and also WSS (r = −0.736). The largest dome diameter showed a negative correlation with intra-aneurysmal flow velocity (r = −0.731) and WSS (r = −0.496). The aspect ratio demonstrated a weak negative correlation with the intra-aneurysmal flow velocity (r = −0.381) and WSS (r = −0.501). A clear negative correlation was seen between the intra-aneurysmal flow velocity and the dome–neck ratio (r = −0.708). A weak negative correlation is observed between the intra-aneurysmal WSS and the dome–neck ratio (r = −0.392). The aneurysm dome size showed a negative linear correlation with intra-aneurysmal flow velocity and WSS. Wide-necked aneurysm geometry was associated with faster intra-aneurysmal flow velocity

Computational Hemodynamics Framework for the Analysis of Cerebral Aneurysms

Assessing the risk of rupture of intracranial aneurysms is important for clinicians because the natural rupture risk can be exceeded by the small but significant risk carried by current treatments. To this end numerous investigators have used image‐based computational fluid dynamics models to extract patient‐specific hemodynamics information, but there is no consensus on which variables or hemodynamic characteristics are the most important. This paper describes a computational framework to study and characterize the hemodynamic environment of cerebral aneurysms in order to relate it to clinical events, such as growth or rupture. In particular, a number of hemodynamic quantities are proposed to describe the most salient features of these hemodynamic environments. Application to a patient population indicates that ruptured aneurysms tend to have concentrated inflows, concentrated wall shear stress distributions, high maximal wall shear stress, and smaller viscous dissipation ratios than unruptured aneurysms. Furthermore, these statistical associations are largely unaffected by the choice of physiologic flow conditions. This confirms the notion that hemodynamic information derived from image‐based computational models can be used to assess aneurysm rupture risk, to test hypotheses about the mechanisms responsible for aneurysm formation, progression, and rupture, and to answer specific clinical questions

Intermittent Orbital Pain due to Hemodynamic Collapse of an Orbital Varix: A Case Report

Orbital varices typically present with symptoms related to dilation or thrombosis. We describe a rare presentation of an orbital varix with pain caused by hemodynamic collapse of the varix. A woman in the third decade presented with position-dependent orbital pain and enophthalmos. She was found to have an intraorbital varix and a separate pterygoid varix. The patient underwent endovascular treatment of the pterygoid varix using coils and sclerosing agents which altered the venous outflow from the orbital varix. The patient had immediate resolution of symptoms after the procedure. Our findings suggest that extraorbital venous outflow abnormalities may be the cause of symptoms in selected cases of orbital varices. By understanding the venous structures on cerebral angiography and treating the extraorbital component, orbital intervention may be avoided, reducing the risk of complications

Abstract Number ‐ 169: Intraprocedural angiographic sign for assessing the stent‐clot interaction during mechanical thrombectomy

Introduction The characteristics of the occlusive clot affect the clot integration with a stent retriever (SR). This relationship, stent‐clot interaction, is considered to be a major factor in the technical success of mechanical thrombectomy. To date, numerous studies analyzing the retrieved clots have shown that both soft erythro‐rich clots and hard fibrin‐rich clots make clot retrieval challenging. Several studies have successfully obtained information on this interaction using three‐dimensional (3D) rotational angiography. However, these 3D imaging technologies have not been utilized in clinical practice due to the time‐consuming nature of image acquisition and processing. Our previous clinical study demonstrated that the angiographic findings about the deployed stent morphology obtained from conventional two‐dimensional (2D) angiography could predict recanalization (1). The greater stent expansion at the occlusion was strongly associated with recanalization after the procedure. This intraprocedural angiographic sign allows us to know the stiffness of the clots in real‐time and to choose the optimal technique. The purpose of this study was to evaluate whether the stent expansion assessed by a 2D angiographical image reflects the actual stent dilation at the occlusion (Figure). We investigated the correlations between 2D images and 3D structures of the deployed SR using an experimental occlusion model. Methods Using occlusion models created with pseudo‐clot with 9 hardness levels (n = 3/clot type), images of the deployed Trevo SR were obtained by cone‐beam computed tomography.As the measurement metric for the 2D images, we used the degree of stent expansion obtained from a plane along the long axis of the device. In clinical practice, however, this 2‐D image is usually obtained from one viewing angle. Therefore, to investigate the difference in measurement by viewing angle, different angle 2D images were created to evaluate the stent expansion. For the 3D structures, we used the stent area obtained from the short‐axis plane of the vascular model, considering this as a surrogate for actual stent expansion. We evaluated the correlation between the 2D images and the 3D structure. Results A total of 27 model image sets were obtained, showing graduated stent expansion (range: 21–79%) depending on the clot type. The median variation in the degree of stent expansion for each model measured at different angles, which means the differences by viewing angles, was 9% (range: 5–20%). The median degree of stent expansion was strongly correlated with the stent area (Pearson’s coefficient: 0.98), indicating that the degree of stent expansion could reflect the 3D structure. Conclusions This study showed that the stent expansion on 2D angiography, even assessed from one direction, could be used as the approximation of the actual stent dilatation at the occlusion. This angiographic sign provides real‐time feedback on the clot characteristics at the occlusion

Abstract Number ‐ 96: The COGNITIVE study: Cognition and Imaging with Tigertriever

Introduction Results of systematic reviews and studies evaluating treatment effects of cerebrovascular interventions on the prevalence of post‐stroke cognitive impairment vary likely due to heterogeneity in populations, sample size, variable treatment effect, and time and methods of cognitive examination. Like thrombolytic therapy, endovascular therapy (EVT) in large vessel occlusion (LVO) stroke is strongly associated with successful reperfusion, reduced mortality, and good clinical outcomes. Nevertheless, the effect of successful reperfusion after EVT on cognitive function remains unexplored. Methods Four hundred (400) patients aged 18–75 will be enrolled in the USA and outside USA clinical centers. The primary endpoint will be the association between successful reperfusion, defined as eTICI ≥ 2b50, and cognitive benefit, defined as delta Montreal Cognitive Assessment (MoCA) from 4 days to 180 days post‐EVT or MoCA ≥ 26 at 180 days post‐EVT. Secondary endpoints will include first pass successful revascularization, reduction in hypoperfusion volumes within 24 h, functional evaluations (NIHSS, mRS), MoCA and cognitive battery evaluations, and QOLs at various timepoints, baseline to 180 days post‐EVT. The correlation between cognitive function and stroke characteristics, imaging variables, functional ability, and demographic and socio‐behavioral factors will be explored. Safety endpoints will include all‐cause mortality, symptomatic intracranial hemorrhage within 24 h, and device‐related serious adverse events. Key inclusion criteria are per instructions for use (IFU) and pre‐stroke mRS ≤1. Key exclusion criteria are per IFU, prior hemorrhage or stroke within 3 months, and pre‐existing cognitive impairment and/or dementia. Results More study details including the statistical analysis plan and study status will be discussed. Conclusions COGNITIVE is a very first multi‐center, post‐market, prospective, single‐arm EVT study to evaluate whether successful reperfusion with the Tigertriever device is associated with cognitive benefit in subjects with LVO. The study is a superiority design to evaluate whether Tigertriever treatment significantly reduces cognitive impairment

Flow-directed micro-catheterisation technique over a detachable coil

Embolisation of neonatal arteriovenous shunts poses several challenges: tortuous and fragile vessels, limited contrast volume and few specialised paediatric endovascular devices. In a 9-day-old patient with a choroidal type vein of Galen malformation we encountered an extremely tortuous posterior choroidal artery pedicle during endovascular treatment. After attempted selection using a traditional over-the-wire technique, we advanced a platinum coil through the micro-catheter. High flow within the feeder directed the soft and malleable coil anterograde. We then advanced the catheter over the coil's pusher wire in a facile manner to an ideal position for embolisation. This approach may be especially useful in cases requiring coil/vinyl-based liquid embolics, given that the only flow-directed micro-catheter available to most operators is compatible with n-Butyl cyanoacrylate alone. Moreover, the soft distal portion of coil may impart a safety benefit over traditional guidewires in easily perforated neonatal vasculature

Structural Analysis for Wingspan Stent in a Perforator Model

Perforator infarction represents a critical problem after intracranial Wingspan stent. To explore the mechanism of perforator infarction, we simulated the stent-artery interaction at an atheromatous plaque with perforator. Structural deformation and biomechanical stress distribution after stenting were analyzed. High radial stress values were located along the stent struts, which surrounded the area with high circumferential stress. Stretched perforator orifice in a circumferential direction after stenting was simulated. These results show that structural deformation could play a role in the mechanism of perforator occlusion after Wingspan stenting

Structural Analysis for Wingspan Stent in a Perforator Model

Perforator infarction represents a critical problem after intracranial Wingspan stent. To explore the mechanism of perforator infarction, we simulated the stent-artery interaction at an atheromatous plaque with perforator. Structural deformation and biomechanical stress distribution after stenting were analyzed. High radial stress values were located along the stent struts, which surrounded the area with high circumferential stress. Stretched perforator orifice in a circumferential direction after stenting was simulated. These results show that structural deformation could play a role in the mechanism of perforator occlusion after Wingspan stenting