Procedure-related Complications during Endovascular Treatment of Intracranial Saccular Aneurysms

Retinal artery/arteriole occlusion risks after endovascular treatment for unruptured intracranial aneurysm

BACKGROUND

To evaluate the association between retinal artery/arteriole occlusion (RAO) and unruptured intracranial aneurysm (UIA).

METHODS

Incident UIA patients from a nationwide cohort (n=253 240) were categorised into three groups based on subsequent treatment: observation (n=208 993), microsurgical clipping (n=14 168) and endovascular treatment (EVT) groups (n=30 079). The incidence and the incident time of RAO were analysed. HRs of RAO and associated risk factors were evaluated. Additionally, a hospital cohort comprising 2569 consecutive UIA patients treated at a tertiary hospital was analysed with detailed clinical information of UIAs.

RESULTS

In the nationwide cohort analysis, the incidence of RAO was significantly higher in EVT group than in observation and clipping groups, especially within 60 days (early RAO (within 60 days): HR=4.00, 95% CI: 2.44 to 6.56); delayed RAO (after 60 days): HR=1.74, 95% CI: 1.13 to 2.68). Multivariable analysis showed that the presence of chronic kidney disease (p=0.009) and use of a balloon microcatheter during the procedure (p=0.013) were associated with a higher risk of RAO. In hospital cohort analysis, 11 (0.8%) cases of RAO occurred after EVT, whereas none occurred after microsurgical clipping (p<0.001). Patients with RAO were younger and received balloon microcatheters more frequently than their counterparts. Ten cases of RAO (90.9%) occurred in paraclinoid aneurysms, where EVT was preferred over microsurgical clipping.

CONCLUSIONS

Performing EVT for UIA may increase the risk of subsequent RAO. Care should be taken when treating paraclinoid aneurysms with balloon microcatheters.

Gender Differences in Procedural Clinical Complications and Outcomes of Intracranial Aneurysms: Analysis of the Stroke Thrombectomy and Aneurysm Registry

BACKGROUND AND OBJECTIVES

Some studies have shown that female patients had a poorer prognosis after endovascular treatment for ruptured intracranial aneurysm than male patients. However, data have been sparse regarding differences in the periprocedural and perioperative complication rate with ruptured and unruptured intracranial aneurysms.

METHODS

This retrospective cohort study used data from the Stroke Thrombectomy and Aneurysm Registry, a database of 9 institutions in the United States, Europe, and Asia. The study presented intracranial aneurysms after microsurgical and/or endovascular treatment from January 1, 2013, to December 31, 2022. The primary outcome was incidence of periprocedural cerebral infarction. Secondary outcomes were periprocedural intracranial hemorrhage, periprocedural mortality, perioperative vasospasm, and functional outcome at 90 days after procedure.

RESULTS

Among 3342 patients with aneurysm, 2447 were female and 857 were male, and the mean age of female and male patients was 59.6 and 57.1 years, respectively. Current smoker, family history of aneurysm, and ruptured aneurysm were observed in 23.5% vs 35.7 %, 10.8 % vs 5.7%, and 28.2% vs 40.5% of female and male patients, respectively. In female patients, internal carotid artery aneurysms were more commonly observed (31.1% vs 17.3%); however, anterior cerebral artery aneurysms were less commonly observed (18.5% vs 33.8%) compared with male patients. Periprocedural cerebral infarction rate was lower in female than male patients (2.4% vs 4.4%; P = .002). The adjusted odds ratio of primary outcome of female to male patients was 0.72 (95% CI, 0.46-1.12). Incidence of periprocedural intracranial hemorrhage and periprocedural mortality and perioperative symptomatic vasospasm and functional outcome was similar in both groups. In subgroup analysis, periprocedural cerebral infarction due to microsurgical treatment occurred frequently in male patients while incidence in endovascular treatment was similar in both groups (interaction P = .005).

CONCLUSION

This large multicenter registry of patients undergoing intracranial aneurysm treatment found that female patients were not at increased risk of perioperative complications.

Augmenting Prediction of Intracranial Aneurysms' Risk Status Using Velocity-Informatics: Initial Experience

Our primary goal here is to demonstrate that innovative analytics of aneurismal velocities, named velocity-informatics, enhances intracranial aneurysm (IA) rupture status prediction. 3D computer models were generated using imaging data from 112 subjects harboring anterior IAs (4-25 mm; 44 ruptured and 68 unruptured). Computational fluid dynamics simulations and geometrical analyses were performed. Then, computed 3D velocity vector fields within the IA dome were processed for velocity-informatics. Four machine learning methods (support vector machine, random forest, generalized linear model, and GLM with Lasso or elastic net regularization) were employed to assess the merits of the proposed velocity-informatics. All 4 ML methods consistently showed that, with velocity-informatics metrics, the area under the curve and prediction accuracy both improved by approximately 0.03. Overall, with velocity-informatics, the support vector machine's prediction was most promising: an AUC of 0.86 and total accuracy of 77%, with 60% and 88% of ruptured and unruptured IAs being correctly identified, respectively.

Can we explain machine learning-based prediction for rupture status assessments of intracranial aneurysms?

Although applying machine learning (ML) algorithms to rupture status assessment of intracranial aneurysms (IA) has yielded promising results, the opaqueness of some ML methods has limited their clinical translation. We presented the first explainability comparison of six commonly used ML algorithms: multivariate logistic regression (LR), support vector machine (SVM), random forest (RF), extreme gradient boosting (XGBoost), multi-layer perceptron neural network (MLPNN), and Bayesian additive regression trees (BART). A total of 112 IAs with known rupture status were selected for this study. The ML-based classification used two anatomical features, nine hemodynamic parameters, and thirteen morphologic variables. We utilized permutation feature importance, local interpretable model-agnostic explanations (LIME), and SHapley Additive exPlanations (SHAP) algorithms to explain and analyze 6 Ml algorithms. All models performed comparably: LR area under the curve (AUC) was 0.71; SVM AUC was 0.76; RF AUC was 0.73; XGBoost AUC was 0.78; MLPNN AUC was 0.73; BART AUC was 0.73. Our interpretability analysis demonstrated consistent results across all the methods; i.e., the utility of the top 12 features was broadly consistent. Furthermore, contributions of 9 important features (aneurysm area, aneurysm location, aneurysm type, wall shear stress maximum during systole, ostium area, the size ratio between aneurysm width, (parent) vessel diameter, one standard deviation among time-averaged low shear area, and one standard deviation of temporally averaged low shear area less than 0.4 Pa) were nearly the same. This research suggested that ML classifiers can provide explainable predictions consistent with general domain knowledge concerning IA rupture. With the improved understanding of ML algorithms, clinicians' trust in ML algorithms will be enhanced, accelerating their clinical translation.

Three-dimensional printing-assisted precision microcatheter shaping in intracranial aneurysm coiling

Optimal microcatheter shaping is essential for successful endovascular coiling procedures which is sometimes challenging. Our aim was not only to introduce a new shaping method using three-dimensional (3D) printed vessel models but also to prove its feasibility, efficiency and superiority. This was a retrospective cohort study. From September 2019 to March 2021, 32 paraclinoid aneurysms managed with endovascular coiling were retrospectively included and identified. Sixteen aneurysms were coiled using 3D microcatheter shaping method (3D shaping group), and traditional manual shaping method using shaping mandrels was adopted for another 16 patients (control group). The cost and angiographical and clinical outcomes between the two groups were compared, and the feasibility and effectiveness of the new 3D shaping method were evaluated and described in detail. With technical success achieved in 93.75%, most of the 16 shaped microcatheters using new shaping method could be automatically navigated into the target aneurysms without the assistance of microguidewires and could be assessed with favorable accessibility, positioning and stability. Twenty-seven out of 32 aneurysms (84.38%) were completely occluded with the rate of perioperative complications being 12.50%. Although there was no significant difference between the occlusion rates and complication rates of the two groups, the new shaping method could dramatically decrease the number of coils deployed and reduce the overall procedure time. Patient specific shaping of microcatheters using 3D printing may facilitate easier and safer procedures in coil embolization of intracranial aneurysms with shorter surgery time and less coils deployed.

Stiff coils enhance shape retention and pressure resistance in an aneurysm model even at low volume

PURPOSE

To elucidate the characteristics of 3 D frame coils and identify the optimal coil for visceral aneurysms.

MATERIAL AND METHODS

Using a vascular model, we compared the postembolization coil distribution and repulsive force of three coils: Guglielmi detachable coil (GDC; stock wire diameter, 0.004 in; primary diameter, 0.015 in), Target XL (0.003, 0.014), and Target XXL (0.003, 0.017). Additionally, the coil area, roundness, and center of gravity were quantitatively compared. The coil repulsive force was measured by compressing the postembolization vessel model with a digital force gauge.

RESULTS

There were no significant differences in the coil area and roundness among the three coil types. Compared with the Target coils, the GDC deployed evenly along the vessel wall, its center of gravity was less displaced, and although it had the lowest embolic density, its repulsive force was greater regardless of the number of coils used.

CONCLUSIONS

GDC coils with a larger stock wire diameter and a smaller primary diameter unfolded evenly along the wall and had a greater repulsive force. Coil stiffness contributes to coil stability and shape retention, indicating the possibility of preventing recurrence by selecting a frame coil with a focus on coil stiffness.

Quantitative analysis of flow vortices: differentiation of unruptured and ruptured medium-sized middle cerebral artery aneurysms

BACKGROUND

Surgical intervention for unruptured intracranial aneurysms (IAs) carries inherent health risks. The analysis of "patient-specific" IA geometric and computational fluid dynamics (CFD) simulated wall shear stress (WSS) data has been investigated to differentiate IAs at high and low risk of rupture to help clinical decision making. Yet, outcomes vary among studies, suggesting that novel analysis could improve rupture characterization. The authors describe a CFD analytic method to assess spatiotemporal characteristics of swirling flow vortices within IAs to improve characterization.

METHODS

CFD simulations were performed for 47 subjects harboring one medium-sized (4-10 mm) middle cerebral artery (MCA) aneurysm with available 3D digital subtraction angiography data. Alongside conventional indices, quantified IA flow vortex spatiotemporal characteristics were applied during statistical characterization. Statistical supervised machine learning using a support vector machine (SVM) method was run with cross-validation (100 iterations) to assess flow vortex-based metrics' strength toward rupture characterization.

RESULTS

Relying solely on vortex indices for statistical characterization underperformed compared with established geometric characteristics (total accuracy of 0.77 vs 0.80) yet showed improvements over wall shear stress models (0.74). However, the application of vortex spatiotemporal characteristics into the combined geometric and wall shear stress parameters augmented model strength for assessing the rupture status of middle cerebral artery aneurysms (0.85).

CONCLUSIONS

This preliminary study suggests that the spatiotemporal characteristics of flow vortices within MCA aneurysms are of value to improve the differentiation of ruptured aneurysms from unruptured ones.

Cilioretinal Artery Occlusion after Endovascular Coil Embolization for Anterior Communicating Artery

Unruptured intracranial aneurysms have a risk of rupture, so coil embolization is widely practiced as it preserves a patent artery. There are complications of coil procedures, such as patent artery occlusion and thromboembolism, which can result in retinal artery occlusion. We report onretinal artery occlusion following coil embolization of anterior communicating artery aneurysm. This is a rare case of a combination of cilioretinal and branch retinal artery occlusion, and is unusual in showing a functional recovery.

Comparison of Treatment Results by Coil Embolization Procedures for Ruptured Cerebral Aneurysms

Objective

In coil embolization of ruptured cerebral aneurysms, intraoperative cerebral aneurysm re-rupture and thromboembolism are of concern. A good embolic condition can be expected by adjunctive techniques, but there is an increased risk of complications. We investigated the treatment results by coil embolization procedures for ruptured cerebral aneurysms.

Methods

Between January 2016 and December 2019, 75 ruptured saccular cerebral aneurysms were treated by coil embolization at our hospital. The background factors, results of aneurysm embolization, intraoperative re-rupture, symptomatic cerebral embolism, and other factors were investigated retrospectively. We compared and examined these factors based on the procedure.

Results

The mean age was 62.8 and there were 57 female patients (76.0%). The single catheter technique (SCT) was used in 44 cases (58.7%) and the adjunctive technique was used in 31 cases (41.3%). Complete obliteration (CO) was achieved in 24 cases (32.0%), there was a neck remnant (NR) in 23 (30.7%), body filling (BF) was observed in 28 (37.3%), intraoperative re-rupture occurred in 7 (9.3%), and symptomatic cerebral embolism developed in 6 (8.0%), but no postoperative re-rupture was observed. Retreatment was required in only three cases of SCT. On comparison by procedure, the incidence of symptomatic cerebral embolism was significantly lower in SCT group than in the adjunctive technique group (2.3% vs 16.1%, p = 0.04).

Conclusion

Among the cases of coil embolization for ruptured cerebral aneurysms at our hospital, SCT resulted in a lower incidence of symptomatic cerebral embolism than adjunctive techniques. It is essential to select an appropriate procedure in each case by understanding the characteristics of each procedure.

Success Rate of Simple Coil Embolization in Wide-Neck Aneurysm with Aneurysmal Shoulder

Background and Objective:

Wide-necked intracranial aneurysm (WIA) is one of the challenging diseases for neuro-interventionist to treat by simple coiling technique. The purpose of this study is to identify the morphology associated with successful simple coil embolization in wide neck aneurysm patients.

Materials and Methods:

Between January 2002 and August 2018, 102 patients with total 115 ruptured or unruptured WIA which received endovascular treatment were retrospective reviewed. Data were analyzed including demographics, aneurysm morphology, endovascular technique, angiographic outcome, complication, regrowth, and retreatment rate.

Results:

The mean age of patients was 61.6 years with female predominant (72.5%). Ruptured WIA was diagnosed in 71 patients (61.7%). Majority of aneurysms were located in an anterior circulation which were 74 cases (64.3%), mainly paraclinoid aneurysm (30/115). Endovascular treatment was successful in 113 cases (98.3%) which can be mainly divided into simple coil embolization 50 cases (43.5%), balloon-assisted coil embolization 26 cases (22.6%), and stent-assisted coil embolization 32 cases (27.8%). Complete, subtotal, and incomplete occlusion of WIA was achieved in 32 cases (27.8%), 62 cases (53.9%), and 18 cases (15.7%), respectively. There was 9.6% complication occurred. Regrowth and retreatment were found 20% and 15.7%, respectively.

Conclusion:

WIA with two-sided aneurysmal shoulder or neck width <3.6 mm. are significantly associated with successful coil embolization using simple coiling technique.

In-vitro pliability assessment of embolization coils for intracranial aneurysm treatment

BACKGROUND

Embolization coils have routinely been used to treat intracranial aneurysms via an endovascular approach. Soft coils are typically viewed as the best design for filling and finishing the aneurysms to achieve a higher packing density and are hypothesized to exert a lower force against the aneurysm wall during deployment. We report here an in vitro pliability test method to assess clinically relevant coil softness and compare these metrics for two commercially available framing and finishing coil products.

METHODS

A force measurement sensor was affixed onto a side-wall synthetic aneurysm model to continuously measure forces on the aneurysm wall during coil deployment at a fixed delivery rate. A quantitative overall energy metric (average work number or AWN) was calculated from the force-displacement graph representing coil delivery into the aneurysm. Two groups of coils were evaluated: (a) finish coil group (N = 20 ea.): Axium™ Prime Extra Soft coil (ES) and Target™ 360 Nano coil (Nano), and (b) frame coil group (N = 20 ea.): Axium™ Prime FC coil (FC) and Target™ 360 Standard coil (Standard).

RESULTS

(a) In the finish coil group, AWN was measured as: ES (0.53 ± 0.09 gf-cm) and Nano (0.99 ± 0.21 gf-cm). (b) In the frame coil group, AWN was measured as FC (2.54 ± 0.53 gf-cm) and Standard (4.48 ± 0.52 gf-cm). In both groups, Axium Prime coils had statistically lower measures of AWN and therefore higher pliability compared to Target coils (p < .001).

CONCLUSIONS

The in-vitro pliability test method offers quantitative metrics to assess coil softness during deployment in a clinically relevant aneurysm model.