Aneurysm characteristics, coil packing, and post-coiling hemodynamics affect long-term treatment outcome

Risk factors for recanalization after coil embolization for cerebral aneurysms: importance of the first coil and prediction model

BACKGROUND

Endovascular coil embolization for cerebral aneurysms is a well-established treatment; however, postoperative recanalization remains a risk. This study aimed to clarify risk factors for cerebral aneurysm recanalization after coil embolization and to develop a predictive model for assessing risks.

METHODS

This retrospective study included patients with cerebral saccular aneurysms who underwent initial coil embolization at our hospital in Tokyo, Japan between 2012 and 2023. The following cases were excluded: follow-up of <1 year, re-treatment and use of bioactive coils. Outcomes included aneurysm characteristics and postoperative Raymond-Roy Occlusion Classification (RROC). Univariate and multivariate Cox proportional hazards models were used to identify independent predictors. A simplified risk score was constructed using LASSO logistic regression and β-coefficients from multivariable analysis. Internal validity was assessed by bootstrap resampling. External validation was performed using an independent cohort and model performance was evaluated in terms of discrimination and calibration.

RESULTS

Among the 150 patients with aneurysms, 79 were analyzed after applying exclusion criteria. Multivariate analysis identified four independent predictors of recanalization: rupture status, aneurysm size ≥7 mm, RROC without class I, and first volume embolization ratio <8 %. These variables were incorporated into an integer-based risk score ranging from 0 to 7. The model demonstrated strong discrimination in the internal validation cohort (C-statistic: 0.89), which remained acceptable in the external validation cohort (C-statistic: 0.81, 95 % CI: 0.74-0.89). Risk stratification showed increasing recanalization rates of 1.8 %, 13.5 %, and 41.5 % in low- (0-2), intermediate- (3-4), and high-risk (5-7) groups, respectively. Calibration in the external cohort showed slight overestimation of risk in high-score patients.

CONCLUSION

This study identified four significant risk factors for recanalization after coil embolization and proposed a practical, externally validated risk score. The model provides clinically relevant risk stratification and may support individualized follow-up strategies.

Imaging of Intracranial Aneurysms: A Review of Standard and Advanced Imaging Techniques

The treatment of intracranial aneurysms is dictated by its risk of rupture in the future. Several clinical and radiological risk factors for aneurysm rupture have been described and incorporated into prediction models. Despite the recent technological advancements in aneurysm imaging, linear length and visible irregularity with a bleb are the only radiological measure used in clinical prediction models. The purpose of this article is to summarize both the standard imaging techniques, including their limitations, and the advanced techniques being used experimentally to image aneurysms. It is expected that as our understanding of advanced techniques improves, and their ability to predict clinical events is demonstrated, they become an increasingly routine part of aneurysm assessment. It is important that neurovascular specialists understand the spectrum of imaging techniques available.

A novel neutrophil extracellular traps related diagnostic signature for intracranial aneurysm

Neutrophil extracellular traps (NETs) released by neutrophils can exacerbate inflammation, leading to rupture of intracranial aneurysms (IA). This study aims to explore potential NETs-related genes in IA. RNA sequencing data for IA were downloaded from the Gene Expression Omnibus database. NETs-related genes were screened using weighted gene co-expression network analysis (WGCNA) and differentially expressed gene (DEG) analyses. Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment analyses were performed. LASSO Cox regression analysis identified optimal genes for model construction. Immune cell infiltration in IA was studied using CIBERSORT. Five NETs-related hub genes were identified in IA, involved in pathways like neutrophil chemotaxis, Toll-like receptor signaling, and regulation of inflammatory response. A risk score model was developed based on TLR7, TLR2, IL1B, ENTPD4, and FPR1. Immune cell infiltration analysis showed significant variations between low-risk-IA and high-risk-IA groups. Monocytes and neutrophils infiltration proportions were significantly positively correlated with the risk score. The ROC analysis showed AUC values exceeding 0.85 for both training and validation sets, confirming the model's excellent performance. A novel NETs-related diagnostic signature for IA was created, offering new insights into the pathogenesis and diagnosis of IA.

Exploration of the effect of morphology and location on hemodynamics of small aneurysms: a variable-controlled study based on two cases with tandem aneurysms

INTRODUCTION

Small aneurysms are usually treated with a flow diverter alone, without coils. However, some continue to exhibit incomplete occlusion after treatment, even after an extended period. This study aimed to investigate the effects of aneurysm morphology and location on the hemodynamic parameters related to poor outcomes.

METHODS

Two patients with tandem aneurysms were enrolled. Flow diverter deployment was simulated, and preoperative and postoperative hemodynamics were analyzed using computational fluid dynamics. The preoperative and postoperative hemodynamics of the actual surgical plan were simulated using finite element analysis and computational fluid dynamics. The correlation between morphology, hemodynamics, and incomplete occlusion was evaluated by calculating the hemodynamics of aneurysm models with different heights and neck widths, adjusted according to the original geometry.

RESULTS

Simulation of the actual surgical plan showed that the incompletely occluded aneurysm had a larger postoperative velocity at the sac and neck region (va and vneck) and residual flow volume than the occluded aneurysm in both cases. The inflow rate (Qinflow), inflow concentration index (ICI), va, and residual flow volume increased when the aneurysm neck width was expanded; with the increase in height, Qinflow and ICI increased up to a certain point, while va and residual flow volume showed a decreasing trend. Aneurysms located on the superior wall of the internal carotid artery ophthalmic segment had a larger vneck than those on the inferior wall.

CONCLUSION

Aneurysms located on the superior wall of the internal carotid artery ophthalmic segment or with a larger neck or height present a more severe hemodynamic environment, requiring careful consideration when planning surgery. This study provides hemodynamic evidence demonstrating how morphology affects aneurysm progression.

Postoperative Time-of-Flight Magnetic Resonance Angiography Classification is a Predictor of Postoperative Recanalization of Unruptured Cerebral Aneurysms

BACKGROUND

Endovascular treatment has become the preferred approach for managing unruptured cerebral aneurysms, with simple and balloon-assisted coil embolization as the standard first-line therapy. However, recanalization after coil embolization remains a major clinical concern. This study aimed to evaluate the predictive factors for recanalization using time-of-flight magnetic resonance (TOF-MR) angiography.

METHODS

This retrospective multicenter study analyzed data from 241 patients with unruptured cerebral aneurysms who underwent coil embolization at 5 stroke centers. Aneurysms were evaluated using TOF-MR angiography within 7 days postprocedure and at follow-up. The study investigated the role of aneurysm characteristics and the Postoperative TOF-MR Angiography (PTMA) classification in predicting recanalization.

RESULTS

Of the 241 aneurysms analyzed, 79 (32.7%) exhibited recanalization, and 15 (6.2%) required retreatment. Aneurysms with a maximum diameter of ≥10 mm were associated with a higher risk of recanalization (odds ratio, 3.27; 95% confidence interval (CI), 1.38-7.75; P < 0.01). The PTMA classification, which indicated incomplete occlusion (small residual neck/residual neck/partial occlusion), also showed a significant association with recanalization (odds ratio, 4.82; 95% confidence interval, 2.17-10.7; P < 0.01). The modified Raymond-Roy classification (Class IIIb) also contributed to the prediction of recanalization (odds ratio, 3.09; 95% confidence interval, 1.50-6.38; P < 0.01).

CONCLUSIONS

Aneurysm size, the modified Raymond-Roy classification, and PTMA classification within 7 days of coil embolization were significant predictors of recanalization. This study suggests that TOF-MR angiography may be accurate, and that PTMA classification may serve as an appropriate predictor of aneurysm recanalization. Further prospective studies with larger cohorts are required to validate our findings.

Hemodynamic Evaluation of Residual Cavity Growth in a Basilar-Tip Cerebral Aneurysm Post-coiling Using Silent Magnetic Resonance Angiography (MRA): A Case Report

Coil embolization of cerebral aneurysms often encounters challenges in achieving complete filling of the aneurysm sac due to complex shapes and hemodynamic factors, frequently resulting in the formation of a residual cavity (RC) at the aneurysm neck. The hemodynamic mechanisms underlying RC formation and growth, however, remain poorly understood. Computational fluid dynamics (CFD) analysis, combined with silent MRA free from contrast agents and metal artifacts, offers a promising approach to elucidate these mechanisms, potentially enhancing the clinical management of cerebral aneurysms post-coiling. Herein, we report a case of a basilar-tip aneurysm treated with coil embolization, where sequential silent MRA and CFD analysis were employed to investigate hemodynamic factors driving rapid RC growth. Initial RC formation was attributed to coil compaction driven by flow impingement at the aneurysm neck onto the neo-endothelial surface, contributing to vertical growth. In contrast, secondary flows detached from the main inflow jet were observed in distal regions of the RC, leading to flow stagnation, wall vulnerability, and subsequent horizontal expansion of the aneurysmal wall. This case highlights the role of secondary detached flows in RC enlargement, emphasizing their potential to weaken the aneurysm wall and drive sac expansion. CFD analysis using silent MRA is a valuable tool for understanding RC hemodynamics and post-coiling management for cerebral aneurysms.

Mid-term safety and efficacy in small intracranial aneurysm coiling: results from TARGET® nano prospective independent core lab adjudicated multicenter registry

Background

The primary objective is to evaluate the safety and effectiveness of Stryker second generation Target® Nano Coils in the treatment of ruptured and unruptured small (<7 mm) intracranial aneurysms.

Methods

The TARGET Registry is a prospective, two-arm study with independent medical event monitoring and core-lab adjudication. This paper describes the second arm of the TARGET registry. Patients with de novo intracranial aneurysms were embolized with 2nd generation TARGET Nano coils in 12 US centers. The primary efficacy outcome was adequate aneurysm occlusion (RR occlusion grade I-II) on follow-up. Primary safety outcome was treatment-related morbidity and mortality. Secondary outcomes included aneurysm packing density immediately post-procedure, immediate adequate occlusion, aneurysm re-access rate, retreatment rate and clinical outcomes using modified ranking scale. A secondary analysis investigated the influence of using Nano-predominant coils (≥2/3 of total coil-length) vs. non-Nano-predominant coils (<2/3 of total length).

Results

150 patients with 155 aneurysms met the inclusion and exclusion criteria. (31%) patients with ruptured and (69%) with unruptured aneurysms were treated using TARGET coils. Median age was 58.8 (SD 12.7), 74.7% were females, and 80% were Caucasians. Mean follow-up was 5.23 (SD 2.27) months. Peri-procedural mortality was seen in 2.0% of patients. Good outcome at discharge (mRS 0-2) was seen in 81.3% of the cohort. The median packing density (SD) was 29.4% (14.9). Mid-term complete/near complete occlusion rate was seen in 96% of aneurysms and complete obliteration was seen in 75.2% of aneurysms. Patients treated predominantly with Nano coils had higher PD (32.6% vs. 26.1%, p < 0.001). There was no significant difference in clinical and angiographic outcomes. The mid-term mRS0-2 was achieved in 106/109 (97.2%) patients. All-cause mortality was 5/115 (4.3%).

Conclusion

In the multicenter TARGET Registry, 75.8% of aneurysms achieved mid-term complete occlusion, and 96% achieved complete/near complete occlusion with excellent independent functional outcome.

Elucidating key immunological biomarkers and immune microenvironment dynamics in aging-related intracranial aneurysm through integrated multi-omics analysis

BACKGROUND

The exact cause of intracranial aneurysms (IA) is still unclear. However, pro-inflammatory factors are known to contribute to IA progression. The specific changes in the immune microenvironment of IAs remain largely unexplored.

METHODS

This study analyzed single-cell sequencing data from a male mouse model of brain aneurysm, focusing on samples before and after elastase-induced Willis aneurysms. The data helped identify eight distinct cell subpopulations: fibroblasts, macrophages, NK cells, endothelial cells, B cells, granulocytes, and monocytes. The study also involved bulk RNA sequencing of 97 IA samples, utilizing ssGSEA and CIBERSORT algorithms for analysis. Intercellular communication among these cells was inferred to understand the immune dynamics in IA.

RESULTS

The study found that fibroblasts and macrophages are predominant in various disease states of IA. Notably, the onset of IA was marked by a significant increase in fibroblasts and a decrease in macrophages. There was a marked increase in cellular interactions, especially involving macrophages, at the onset of the disease. Through enrichment analysis, 12 potential immunogenic biomarkers were identified. Of these, Rgs1 emerged as a critical molecule in IA formation, confirmed through secondary validation in a single-cell sequencing dataset.

CONCLUSION

This comprehensive analysis of immune cell composition and intercellular communication in IA tissues highlights the significant roles of macrophages and the molecule Rgs1. These findings shed light on the physiological and pathological conditions of IA, offering new insights into its immune microenvironment.

Hemodynamic study on the therapeutic effects of varying diameter embolic coils in the treatment of intracranial aneurysms

Endovascular coiling is the predominant method for treating cerebral aneurysms. Extensive reports on selecting coil length, hardness, and material are available. However, the impact of coil diameter on postoperative outcomes remains unclear. This study enrolled six personalized geometric models of intracranial aneurysms: three bifurcation aneurysms and three sidewall aneurysms. Four coil models were constructed by changing the coil diameter. Coil embolization was simulated using the finite element method. Computational fluid dynamics was used to characterize hemodynamics in the aneurysms after embolization. Evaluation parameters included velocity reduction, wall shear stress (WSS), low WSS (LWSS), oscillatory shear index (OSI), relative residence time (RRT), and residual flow volume in the aneurysms. At the peak time (t = 0.17 s), the proportion of LWSS area in bifurcation aneurysms increase with the rise in coil diameter: 0.8D, 71.28 ± 12.62% versus 1D, 74.97 ± 19.17% versus 1.2D, 78.88 ± 18.56% versus 1.4D, 84.00 ± 11.53% (mean ± SD). The proportion of high OSI area decreases as the coil diameter increases: 0.8D, 4.41% ± 2.82% versus 1.0D, 3.78 ± 3.33% versus 1.2D, 2.28% ± 1.77% versus 1.4D, 1.58% ± 1.11% (mean ± SD). The proportion of high RRT area increases as the coil diameter rises: 0.8D, 3.40% ± 1.68% versus 1.0D, 7.67 ± 4.12% versus 1.2D, 9.84% ± 9.50% versus 1.4D, 22.29% ± 14.28% (mean ± SD). Side wall aneurysms do not exhibit the aforementioned trend. Bifurcation aneurysms plugged with a coil of 1.4 times the diameter have the largest RFVs (<10 mm/s) within the group. Aforementioned patterns are not found in sidewall aneurysms. In the treatment of aneurysms with coiling, varying coil diameters can result in different hemodynamic environments within the aneurysm. Larger coil diameters have improved hemodynamic performance for bifurcation aneurysms. However, coil diameter and embolization effectiveness have no significant relationship for sidewall aneurysms.

Experimental study using phantom models of cerebral aneurysms and 4D-DSA to measure blood flow on 3D-color-coded images

BACKGROUND

The current 3D-iFlow application can only measure the arrival time of contrast media through intensity values. If the flow rate could be estimated by 3D-iFlow, patient-specific hemodynamics could be determined within the scope of normal diagnostic management, eliminating the need for additional resources for blood flow rate estimation.

OBJECTIVE

The aim of this study is to develop and validate a method for measuring the flow rate by data obtained from 3D-iFlow images - a prototype application in Four-dimensional digital subtraction angiography (4D-DSA).

METHODS

Using phantom model and experimental circuit with circulating glycerin solution, an equation for the relationship between contrast media intensity and flow rate was developed. Applying the equation to the aneurysm phantom models, the derived flow rate was evaluated.

RESULTS

The average errors between the derived flow rate and setting flow rate became larger when the glycerin flow and the X-rays from the X-ray tube of the angiography system were parallel to each other or when the measurement point included overlaps with other contrast enhanced areas.

CONCLUSION

Although the error increases dependent on the imaging direction and overlap of contrast enhanced area, the developed equation can estimate the flow rate using the image intensity value measured on 3D-iFlow based on 4D-DSA.

Improving the accuracy of computational fluid dynamics simulations of coiled cerebral aneurysms using finite element modeling

Cerebral aneurysms are a serious clinical challenge, with ∼half resulting in death or disability. Treatment via endovascular coiling significantly reduces the chances of rupture, but the techniquehas failure rates of ∼20 %. This presents a pressing need to develop a method fordetermining optimal coildeploymentstrategies. Quantification of the hemodynamics of coiled aneurysms using computational fluid dynamics (CFD) has the potential to predict post-treatment outcomes, but representing the coil mass in CFD simulations remains a challenge. We use the Finite Element Method (FEM) for simulating patient-specific coil deployment for n = 4 ICA aneurysms for which 3D printed in vitro models were also generated, coiled, and scanned using ultra-high resolution synchrotron micro-CT. The physical and virtual coil geometries were voxelized onto a binary structured grid and porosity maps were generated for geometric comparison. The average binary accuracy score is 0.8623 and the average error in porosity map is 4.94 %. We then conduct patient-specific CFD simulations of the aneurysm hemodynamics using virtual coils geometries, micro-CT generated oil geometries, and using the porous medium method to represent the coil mass. Hemodynamic parameters including Neck Inflow Rate (Qneck) and Wall Shear Stress (WSS) were calculated for each of the CFD simulations. The average relative error in Qneck and WSS from CFD using FEM geometry were 6.6 % and 21.8 % respectively, while the error from CFD using a porous media approximation resulted in errors of 55.1 % and 36.3 % respectively; demonstrating a marked improvement in the accuracy of CFD simulations using FEM generated coil geometries.

Randomized, prospective, multicenter trial assessing the numen coil embolization system in the endovascular treatment of small intracranial aneurysms: outcomes from the CATCH Trial

BACKGROUND AND PURPOSE

The CATCH (Coil Application Trial in China) trial was designed to assess the safety and efficacy of the Numen Coil Embolization System in the treatment of intracranial aneurysms in comparison with the Axium coil (ev3/Medtronic). Although the endovascular treatment of small (< 5 mm) intracranial aneurysms has been reported with favorable long-term clinical and angiographic outcomes, randomized trials are still lacking. Data for aneurysms smaller than 5 mm were extracted from the CATCH trial.

MATERIALS AND METHODS

A randomized, prospective, multicenter trial was conducted at ten centers throughout China. Enrolled subjects with small intracranial aneurysms were randomly assigned to receive treatment with the Numen Coil or the Axium coil. The primary outcome was successful aneurysm occlusion at the 6-month follow-up. In contrast, the secondary outcomes included complete aneurysm occlusion, recurrence rate, clinical deterioration, and safety data at the 6-month and 12-month follow-ups.

RESULTS

A total of 124 patients were enrolled in the study. Overall, 58 patients were assigned to the Numen group, and 66 were assigned to the Axium group. At the 6-month follow-up, the successful aneurysm occlusion rate was 93.1% (54/58) in the MicroPort NeuroTech group and 97.0% (64/66) in the Axium group, with a common odds ratio of 0.208 (95% confidence interval, 0.023-1.914; P = 0.184). Complications were comparable between the groups.

CONCLUSIONS

Compared with the Aixum coil, the Numen coil is safe and effective in treating small intracranial aneurysms.

TRIAL REGISTRATION

(13/12/2016, NCT02990156).

Safety and efficacy of endovascular treatment for tiny ruptured intracranial aneurysms with low-profile visualized intraluminal support stents

BACKGROUND

Endovascular treatment for tiny ruptured intracranial aneurysms is known to be technically challenging. Thus, we aimed to investigate the safety and efficacy of low-profile visualized intraluminal support (LVIS) stents in the treatment of tiny ruptured intracranial aneurysms.

METHODS

From April 2014 to June 2019, among 90 patients with tiny ruptured aneurysms who were treated at our institution endovascularly, 28 underwent stent-assisted coiling with LVIS stents. The clinical and angiographic results were reviewed.

RESULTS

In the LVIS group, complete occlusion was achieved in 27 patients (96.4%). Intraprocedural thrombus formation occurred in 3 patients (10.7%). Follow-up angiography in 24 patients at 6-12 months showed complete occlusion in 23 patients (95.8%) and no aneurysm recurrence. In the coiling-only group, complete occlusion was achieved in 58 patients (93.5%). Intraprocedural aneurysm rupture occurred in 2 patients (3.2%), and postprocedural ischemia occurred in 4 patients (6.5%), with a complication rate of 9.7%. Follow-up angiography in 52 patients at 6-12 months showed complete occlusion in 43 patients (82.7%) and aneurysm recurrence in 7 patients (9.2%). No significant (p > 0.05) differences existed between the two groups.

CONCLUSIONS

The LVIS stent is safe and effective in the treatment of tiny ruptured intracranial aneurysms.

An attention residual u-net with differential preprocessing and geometric postprocessing: Learning how to segment vasculature including intracranial aneurysms

OBJECTIVE

Intracranial aneurysms (IA) are lethal, with high morbidity and mortality rates. Reliable, rapid, and accurate segmentation of IAs and their adjacent vasculature from medical imaging data is important to improve the clinical management of patients with IAs. However, due to the blurred boundaries and complex structure of IAs and overlapping with brain tissue or other cerebral arteries, image segmentation of IAs remains challenging. This study aimed to develop an attention residual U-Net (ARU-Net) architecture with differential preprocessing and geometric postprocessing for automatic segmentation of IAs and their adjacent arteries in conjunction with 3D rotational angiography (3DRA) images.

METHODS

The proposed ARU-Net followed the classic U-Net framework with the following key enhancements. First, we preprocessed the 3DRA images based on boundary enhancement to capture more contour information and enhance the presence of small vessels. Second, we introduced the long skip connections of the attention gate at each layer of the fully convolutional decoder-encoder structure to emphasize the field of view (FOV) for IAs. Third, residual-based short skip connections were also embedded in each layer to implement in-depth supervision to help the network converge. Fourth, we devised a multiscale supervision strategy for independent prediction at different levels of the decoding path, integrating multiscale semantic information to facilitate the segmentation of small vessels. Fifth, the 3D conditional random field (3DCRF) and 3D connected component optimization (3DCCO) were exploited as postprocessing to optimize the segmentation results.

RESULTS

Comprehensive experimental assessments validated the effectiveness of our ARU-Net. The proposed ARU-Net model achieved comparable or superior performance to the state-of-the-art methods through quantitative and qualitative evaluations. Notably, we found that ARU-Net improved the identification of arteries connecting to an IA, including small arteries that were hard to recognize by other methods. Consequently, IA geometries segmented by the proposed ARU-Net model yielded superior performance during subsequent computational hemodynamic studies (also known as "patient-specific" computational fluid dynamics [CFD] simulations). Furthermore, in an ablation study, the five key enhancements mentioned above were confirmed.

CONCLUSIONS

The proposed ARU-Net model can automatically segment the IAs in 3DRA images with relatively high accuracy and potentially has significant value for clinical computational hemodynamic analysis.

Non-contrast enhanced silent MR angiography to evaluate hemodynamics and morphology of unruptured intracranial aneurysms: a comparative computational fluid dynamics study

BACKGROUND

Silent MR angiography (silent MRA) is a new generation of non-contrast enhanced angiography with outstanding advantages in visualizing cerebrovascular lesions and the follow-up after endovascular treatment for intracranial aneurysms (IAs). This study aims to investigate the reliability of silent MRA-based three-dimensional (3D) geometric description and hemodynamic calculation of IAs.

METHODS

19 patients with 23 unruptured IAs, who underwent both silent MRA and 3D rotational angiography (3DRA), were included in this study. Computational fluid dynamics simulations were performed on all patient-specific 3D reconstruction images to compare the morphology and hemodynamics of the two different imaging models for IAs.

RESULTS

Silent MRA models had smaller maximum and perpendicular height (mm), aneurysmal surface area (mm²), and aneurysmal volume (mm³) than 3DRA (p<0.05); the differences of the above parameters between the two models were 9.0±6.2%, 7.7±7.4%, 15.9±13.0%, and 21.4±17.5%, respectively. However, correlation analysis of morphological parameters in various dimensions and model comparison showed good overall consistency in geometrical characteristics between the two models. Moderate coherence was observed between models in time-averaged wall shear stress of aneurysm and parent vessel (TAWSS, PAWSS), aneurysm velocity (AV), parent vessel velocity, and oscillatory shear index (OSI). However, strong correlations were observed among normalized aneurysm wall shear stress (NWSS), low shear area (LSA), inflow concentration index (ICI), and normalized aneurysm velocity (NAV).

CONCLUSION

Both morphological and hemodynamic assessments of IAs for silent MRA are comparable to 3DRA. Additionally, normalized indicators such as NWSS, LSA, ICI, and NAV were better than TAWSS, AV, and OSI in silent MRA-related hemodynamic evaluation.

Risk Factors for Recurrence of Intracranial Aneurysm After Coil Embolization: A Meta-Analysis

Intracranial aneurysm is a severe cerebral disorder involving complicated risk factors and endovascular coiling is a common therapeutic selection for intracranial aneurysm. The recurrence is a clinical challenge in intracranial aneurysms after coil embolization. With this study, we provided a meta-analysis of the risk factors for the recurrence of intracranial aneurysm after coil embolization. Nine studies were included with a total of 1,270 studies that were retrieved from the database. The sample size of patients with intracranial aneurysms ranged from 241 to 3,530, and a total of 9,532 patients were included in the present meta-analysis. The intracranial aneurysms that occurred in middle cerebral artery (MCA) (OR = 1.09, 95% CI: 1.03–1.16, P = 0.0045) and posterior circulation (OR = 2.01, 95% CI: 1.55–2.60, P = 0.000) presented the significantly higher risk of recurrence after coil embolization. Meanwhile, intracranial aneurysms of size > 7 mm (OR = 5.38, 95%CI: 3.76–7.70, P = 0.000) had a significantly higher risk of recurrence after coil embolization. Moreover, ruptured aneurysm (OR = 2.86, 95% CI: 2.02–4.04, P = 0.000) and subarachnoid hemorrhage (SAH) (OR = 1.57, 95% CI: 1.20–2.06, P = 0.001) was positively correlated with the risk of recurrence after coil embolization. In conclusion, this meta-analysis identified the characteristics of intracranial aneurysms with MCA, posterior circulation, size > 7 mm, ruptured aneurysm, and SAH as the risk factors of recurrence after coil embolization for intracranial aneurysms.

Transcriptome-Based Dissection of Intracranial Aneurysms Unveils an “Immuno-Thermal” Microenvironment and Defines a Pathological Feature-Derived Gene Signature for Risk Estimation

Immune inflammation plays an essential role in the formation and rupture of intracranial aneurysm (IA). However, the current limited knowledge of alterations in the immune microenvironment of IA has hampered the mastery of pathological mechanisms and technological advances, such as molecular diagnostic and coated stent-based molecular therapy. In this study, seven IA datasets were enrolled from the GEO database to decode the immune microenvironment and relevant biometric alterations. The ssGSEA algorithm was employed for immune infiltration assessment. IAs displayed abundant immune cell infiltration, activated immune-related pathways, and high expression of immune-related genes. Several immunosuppression cells and genes were also coordinately upregulated in IAs. Five immune-related hub genes, including CXCL10, IL6, IL10, STAT1, and VEGFA, were identified from the protein-protein interaction network and further detected at the protein level. CeRNA networks and latent drugs targeting the hub genes were predicted for targeted therapy reference. Two gene modules recognized via WCGNA were functionally associated with contractile smooth muscle loss and extracellular matrix metabolism, respectively. In blood datasets, a pathological feature-derived gene signature (PFDGS) for IA diagnosis and rupture risk prediction was established using machine learning. Patients with high PFDGS scores may possess adverse biological alterations and present with a high risk of morbidity or IA rupture, requiring more vigilance or prompt intervention. Overall, we systematically unveiled an “immuno-thermal” microenvironment characterized by co-enhanced immune activation and immunosuppression in IA, which provides a novel insight into molecular pathology. The PFDGS is a promising signature for optimizing risk surveillance and clinical decision-making in IA patients.

Endovascular treatment for large (> 10 mm) basilar tip aneurysms: a retrospective case series

PURPOSE

To report the long-term clinical and angiographic outcomes of the endovascular treatment of large/giant basilar tip aneurysms (BTAs) in our institutions.

METHODS

We retrospectively reviewed cases of BTA larger than 10 mm that received endovascular treatment between January 2009 and December 2019. Data on the demographic and clinical characteristics and radiologic severity were obtained from the patients' medical records. The collected clinical follow-up data included neurological evaluation. Magnetic resonance angiography (MRA) was performed 6 to 12 months after the procedure, followed by once every 1 to 2 years as needed.

RESULTS

A total of 12 patients with BTA were included in this study. The median age was 60.08 years (27-80 years), and the mean clinical follow-up was 66.78 months (19.00-142.87 months). Almost half of the patients presented with unruptured BTAs (58.33%, n = 7). The median maximum aneurysm diameter was 13.00 mm (10.46-20.90 mm) and the mean neck size was 8.34 mm (4.82-13.04 mm). A Modified Raymond Roy Classification (MRRC1) of 1 or 2 was observed in 66.67% of the patients (n = 8) immediately after the first procedure. Procedural morbidity and mortality were 33.33% and 8.33%, respectively. Major recanalization occurred in two patients, one of whom underwent additional coiling with the other being merely observed due to older age.

CONCLUSION

It is very difficult to cure a large BTA completely at once and recanalization occurred often after endovascular treatment. Conducting long-term follow-up studies at short intervals is warranted, as well as improving existing treatment methods and developing new approaches.

Hemodynamic mechanism of pulsatile tinnitus caused by venous diverticulum treated with coil embolization

BACKGROUND AND OBJECTIVE

Coil embolization has become a new treatment method for pulsatile tinnitus (PT) caused by sigmoid sinus diverticulum (SSD). Although this therapy has achieved good results in clinical reports, the hemodynamic mechanism of coils in the treatment of PT in SSD remained unclear.

METHODS

Finite element method (FEM) and computational fluid dynamics (CFD) were combined to explore the hemodynamic mechanism of coil embolization in SSD treatment. Three personalized geometric models of sigmoid sinus were established according to the CTA data of patients. Coil model were established by FEM, and the hemodynamic differences of SSD before and after coiling were compared by transient CFD method.

RESULTS

Velocity streamlines disappeared in the SSD after coiling. At the peak time (t1 = 0.22 s), the SSD-average velocity decreased in every patient. The average value of the decreased in three patients was 0.154 ± 0.028 m/s (mean ± SD). Wall average pressure (P_avg) also showed a decline in every patient. Average of decrements of three patients was 17.69 ± 4.91 Pa (mean ± SD). Average WSS (WSS_avg) was also reduced in every patient. The average value of WSS drop was 9.74 ± 3.02 Pa (mean ± SD). After coiling, the proportion of low-velocity region in the sigmoid sinus cortical plate dehiscence (SSCPD) area increased. Average of increments was 22.1 ± 5.36% (mean ± SD).

CONCLUSIONS

A reduction in SSD-average velocity, wall pressure, and WSS were the short-term hemodynamic mechanism of coil embolization for PT. Coil embolization increased the proportion of low-velocity region in the SSCPD area, thereby creating a hemodynamic environment that easily produced thrombus and protects blood vessels from the impact of blood flow. This phenomenon was the long-term effect of coil embolization.

Hemodynamic analysis for endovascular treatment in small unruptured intracranial aneurysms: a matched comparison study of flow diverter versus LVIS

BACKGROUND

We compared the treatment of small unruptured intracranial aneurysms (UIAs) with flow diverter and LVIS-assisted coiling to determine the effects of hemodynamic changes caused by different stent and coil packing in endovascular treatment.

METHODS

Fifty-one UIAs in 51 patients treated with pipeline embolization device (PED) were included in this study and defined as the PED group. We matched controls 1:1 and enrolled 51 UIAs who were treated with LVIS stent, which were defined as the LVIS group. Computational fluid dynamics were performed to assess hemodynamic alterations between PED and LVIS. Clinical analysis was also performed between these two groups after the match.

RESULTS

There was no difference in procedural complications between the two groups (P = 0.558). At the first angiographic follow-up, the complete occlusion rate was significantly higher in the LVIS group compared with that in the PED group (98.0% vs. 82.4%, P = 0.027). However, during the further angiographic follow-up, the complete occlusion rate in the PED group achieved 100%, which was higher than that in the LVIS group (98.0%). Compared with the LVIS group after treatment, cases in the PED group showed a higher value of velocity in the aneurysm (0.03 ± 0.09 vs. 0.01 ± 0.01, P = 0.037) and WSS on the aneurysm (2.32 ± 5.40 vs. 0.33 ± 0.47, P = 0.011). Consequently, the reduction ratios of these two parameters also showed statistical differences. These parameters in the LVIS group showed much higher reduction ratios. However, the reduction ratio of the velocity on the neck plane was comparable between two groups.

CONCLUSIONS

Both LVIS and PED were safe and effective for the treatment of small UIAs. However, LVIS-assisted coiling produced greater hemodynamic alterations in the aneurysm sac compared with PED. The hemodynamics in the aneurysm neck may be a key factor for aneurysm outcome.

Simulation of stent retriever thrombectomy in acute ischemic stroke by finite element analysis

Stent retriever thrombectomy has become an effective method for treating acute ischemic stroke. Successful recanalization cannot be achieved for all patients. The outcome of mechanical thrombectomy may be associated with some mechanical factors, requiring efficient tools that are able to assess the interaction between stent retrievers and clots. In this study, a simulation by finite element analysis was developed to evaluate the outcome of stent retriever thrombectomy for clots of different sizes and frictional properties. The deployment and retrieval of the stent retriever were conducted in a middle cerebral artery model. The recanalization, deformation of the clot and stent retriever and the stress induced in the clot were assessed. The results showed that higher friction could lead to failed recanalization and increased stress in the clot. The simulation method can be used to characterize the mechanical behaviour of stent retrievers and clots, offering a potential tool for the optimization of device design and the selection of surgical strategies.

Development and assessment of machine learning models for predicting recurrence risk after endovascular treatment in patients with intracranial aneurysms

Intracranial aneurysms (IAs) remain a major public health concern and endovascular treatment (EVT) has become a major tool for managing IAs. However, the recurrence rate of IAs after EVT is relatively high, which may lead to the risk for aneurysm re-rupture and re-bleed. Thus, we aimed to develop and assess prediction models based on machine learning (ML) algorithms to predict recurrence risk among patients with IAs after EVT in 6 months. Patient population included patients with IAs after EVT between January 2016 and August 2019 in Hunan Provincial People's Hospital, and an adaptive synthetic (ADASYN) sampling approach was applied for the entire imbalanced dataset. We developed five ML models and assessed the models. In addition, we used SHapley Additive exPlanations (SHAP) and local interpretable model-agnostic explanation (LIME) algorithms to determine the importance of the selected features and interpret the ML models. A total of 425 IAs were enrolled into this study, and 66 (15.5%) of which recurred in 6 months. Among the five ML models, gradient boosting decision tree (GBDT) model performed best. The area under curve (AUC) of the GBDT model on the testing set was 0.842 (sensitivity: 81.2%; specificity: 70.4%). Our study firstly demonstrated that ML-based models can serve as a reliable tool for predicting recurrence risk in patients with IAs after EVT in 6 months, and the GBDT model showed the optimal prediction performance.

Hemodynamic and Morphological Factors Related to Coil Compaction in Basilar Artery Tip Aneurysms

PURPOSE

Coil compaction is directly related to the degree of cerebral aneurysmal recanalization. The Degree of Recanalization (DoR) was quantified by measuring the volume vacated by coil deformation. The purpose of this study was to clarify the hemodynamic and morphological factors associated with coil compaction.

METHODS

Computational fluid dynamics (CFD) simulations were performed on 28 middle size (5-10 mm), unruptured basilar artery tip aneurysms. The DoR was measured by comparing the coil mass shape obtained from three-dimensional digital subtraction angiography data immediately after coil embolization and again within 1 to 2 years of follow-up. Deployed coils were modeled using a virtual coiling technique for CFD simulations. Hemodynamic and morphological factors to predict the DoR were derived using multiple linear regression.

RESULTS

Aneurysmal neck area, the maximum pressure generated on the neck surface after coil embolization, and the high-pressure position on the neck surface predicted DoR with statistical significance (p<0.001, p<0.001, p=0.004, respectively). DoR tended to increase when the neck area was large, the pressure generated on the coils was high, and the high-pressure position was close to the center of the neck surface. The volume embolization ratio was not statistically relevant for the DoR in the cases of this study.

CONCLUSIONS

Coil compaction occurs in cerebral aneurysms with a wide neck, high pressure generated on the coils, and high pressure in the center of the neck surface. Establishing the DoR can contribute to the prediction of recanalization after coil embolization.

The Application of "Stilted Building" Technique in the Embolization of Aneurysms with Secondary Branches

Objective

Many intracranial aneurysms often have branch arteries, and it is especially important to protect them during embolization. The purpose of the present study was to evaluate the curative effect and safety of the “stilted building” technique.

Methods

25 patients with intracranial aneurysms with branch arteries that have been treated by coil embolization with the “stilted building” technique were retrospectively reviewed. Clinical follow-up was performed after endovascular treatment.

Results

All 25 patients successfully underwent aneurysm embolization. During the operation, the ruptured sac and most of the body of the aneurysm were embolized using the “stilted building” technique. Immediate imaging showed that the blood flow to the branch arteries from the neck or sidewall of the aneurysm was unobstructed. The mRS scores of the 25 patients during the follow-up period were mRS 0 for twenty-one patients, mRS 1 for three patients, and mRS 6 for one patient. No aneurysms recurred among the patients who completed the follow-up.

Conclusions

In an aneurysm with a branch artery, when a balloon or stent cannot be effectively used to protect the branch artery, the use of “stilted building” embolization can achieve good therapeutic effects, and the short-term follow-up results are satisfactory; the technique can effectively protect branch arteries originating from aneurysms.

Fast virtual coiling algorithm for intracranial aneurysms using pre-shape path planning

To aid in predicting and improving treatment outcome of endovascular coiling of intracranial aneurysms, simulation of patient-specific coil deployment should be both accurate and fast. We developed a fast virtual coiling algorithm called Pre-shape Path Planning (P3). It captures the mechanical propensity of a released coil to restore its pre-shape for bending energy minimization, producing coils without unrealistic kinks and bends. A coil is discretized into finite-length segments and extruded from the delivery catheter segment-by-segment following a generic coil pre-shape. With the release of each segment, coil-wall and coil-coil collisions are detected and resolved. Modeling of each case took seconds to minutes. To test the algorithm, we evaluated its output against the literature, experiments, and patient angiograms. The periphery-to-core ratio of coils deployed by P3 decreased with increasing coil packing density, consistent with observations in the literature. Coils deployed by P3 compared well with in vitro experiments, free from unphysical kinks and loops that arose from previous virtual coiling algorithms. Simulations of coiling in four patient-specific aneurysms agreed well with the patient angiograms. To test the influence of coil pre-shape on P3, we performed hemodynamic simulations in aneurysms with coils deployed by P3 using the generic pre-shape, P3 using a coil-specific pre-shape, and full finite-element-method simulation. We found that the generic pre-shape was sufficient to produce results comparable to virtual coiling by finite element modeling. Based on these findings, P3 can rapidly simulate coiling in patient-specific aneurysms with good accuracy and is thus a potential candidate for clinical treatment planning.

Tailored Sac Embolization During EVAR for Preventing Persistent Type II Endoleak

BACKGROUND

Persistent type II endoleaks (ELIIp) occur in 8-23% of patients submitted to endovascular aneurysm repair (EVAR) and may lead to aneurysm progression and rupture. Intraoperative embolization of the abdominal aortic aneurysm (AAA) sac is effective to prevent their occurrence, however a method to achieve complete sac thrombosis has not been standardized yet. Aim of our study was to identify factors associated with prevention of ELIIp after intraoperative embolization, in order to optimize technical details.

METHODS

Patients at high risk for ELIIp, who underwent EVAR with AAA - sac coil embolization were prospectively collected into a dedicated database from January 2012 to March 2015. The endoluminal residual sac volume (ERV), not occupied by the endograft [ERV= AAA total volume (TV) - (AAA-thrombus volume (THV) + endograft volume (EgV)] was calculated on preoperative computed tomography and the concentration of coils implanted (CCoil= n coils implanted/ERV) for each patient was evaluated. AAA volumetric evaluation was conducted by dedicated vessels analysis software (3Mensio). ELIIp presence was evaluated by contrast-enhanced ultrasound at 6 and 12-month. Patients with ELIIp at 12 months (Group 1) were clustered and compared to patients without ELIIp (Group 2), in order to evaluate the incidence of ELIIp in patients undergone to preventive AAA-sac embolization, and identify the predictors of ELIIp prevention. Morphological potential risk factors for ELIIp such as TV, THV, VR% and EgV were also considered in all patients. Statistical correlation was assessed by Fisher Exact Test.

RESULTS

Among 326 patients undergone to standard EVAR, 61 (19% - M: 96.7%, median age: 72 [IQR: 8] years, median AAA diameter: 57 [IQR: 7] mm) were considered at high risk for ELIIp and were submitted to coil embolization. The median AAA total volume (TV) and median ERV were 156 (IQR: 59) cc and 46 (IQR: 26) cc, respectively. The median number and concentration of coils (IMWCE-38-16-45 Cook M-Ray) positioned in AAA-sac were 5 (IQR: 1) coils and 0.17 coil/cm³ (range 0.02-1.20). Among this high-risk population, the incidence of ELIIp was 29.5% and 23% at 6 and 12-month, respectively. Fourteen patients (23%) were clustered in Group1 and 47 (77%) in Group 2. Both groups were homogeneous for clinical characteristics and preoperative morphological risk factors. There were no differences in the preoperative median TV, AAA-thrombus volume (THV), %VR, EgV and number of implanted coils between Group1 and Group2. Patients in Group1 had a significantly higher ERV (59 [IQR: 13] cm³ vs. 42 [IQR: 27] cm³, P = 0.002) and lower CCoil (0.09 [IQR: 0.03] vs. 0.18 [IQR: 0.21], P = 0.006) than patients of Group2. ELIIp was significantly related to the presence of ERV > 49 cm³ (86 % vs. 42 %, Group1 and Group2 respectively, P = 0.006) and CCoil < 0.17coil/ cm³ (100% vs. 68%, Group1 e Group2 respectively, P = 0.014).

CONCLUSION

According with our results, Coil concentration and endoluminal residual volume can affect the efficacy of the AAA - sac embolization in the prevention of ELIIp, moreover CCoil ≥0.17coil/ cm³ maight be considered to determine the tailored number of coils.

Five-year results of randomized bioactive versus bare metal coils in the treatment of intracranial aneurysms: the Matrix and Platinum Science (MAPS) Trial

BACKGROUND

No randomized trial of intracranial aneurysm coiling has compared long-term efficacy of polymer-modified coils to bare metal coils (BMCs). We report 5-year results comparing Matrix² coils to BMCs. The primary objective was to compare the rates of target aneurysm recurrence (TAR) at 12 months. Secondary objectives included angiographic outcomes at TAR or 12 months and TAR at 5 years.

METHODS

A total of 626 patients were randomized to BMCs or Matrix² coils. Detailed methods and 1-year results have been published previously.

RESULTS

Of 580 patients eligible for 5-year follow-up, 431 (74.3%) completed follow-up or reached TAR. Matrix² coils were non-inferior to BMCs (P=0.8) but did not confer any benefit. Core lab reported post-treatment residual aneurysm filling (Raymond III) correlated with TAR (P<0.0001) and with aneurysm hemorrhage after treatment (P<0.008). Repeat aneurysmal hemorrhage after treatment, but before hospital discharge, occurred in three patients treated for acutely ruptured aneurysms. Additionally, two patients treated for unruptured aneurysms experienced a first hemorrhage during follow-up. All five hemorrhages resulted from aneurysms with Raymond III residual aneurysm filling persisting after initial treatment. After 5 years follow-up, 2/626 (0.3%) patients are known to have had target aneurysm rupture following hospital discharge. The annualized rate of delayed hemorrhage after coiling was 2/398/5=0.001 (0.1%) per year for unruptured aneurysms and 0 for ruptured aneurysms.

CONCLUSIONS

After 5 years Matrix² coils were non-inferior to BMCs but no benefit was demonstrated. Post-treatment residual angiographic aneurysm filling (Raymond III) is strongly associated with TAR (P<0.0001) and post-treatment aneurysmal hemorrhage (P=0.008).