Morphology of Ruptured and Unruptured Intracranial Aneurysms

Endovascular treatment of ruptured lobulated anterior communicating artery aneurysms: A retrospective study of 24 patients

BACKGROUND

Lobulated intracranial aneurysm is a special type of aneurysm with at least one additional cyst in the neck or body of the aneurysm. Lobulated intracranial aneurysm is a complex aneurysm with complex morphology and structure and weak tumor wall, which is an independent risk factor for rupture and hemorrhage. Lobular aneurysms located in the anterior communicating artery complex account for 36.9% of all intracranial lobular aneurysms. Due to its special anatomical structure, both craniotomy and endovascular treatment are more difficult. Compared with single-capsule aneurysms, craniotomy for lobular intracranial aneurysms has a higher risk and complication rate.

AIM

To investigate the efficacy and safety of endovascular treatment for ruptured lobulated anterior communicating artery aneurysm (ACoAA).

METHODS

Patients with ruptured lobulated ACoAA received endovascular treatment in Sanming First Hospital Affiliated to Fujian Medical University from June 2020 to June 2022 were retrospectively included. Their demographic, clinical and imaging characteristics, endovascular treatment methods and follow-up results were collected.

RESULTS

A total of 24 patients with ruptured lobulated ACoAA were included, including 9 males (37.5%) and 15 females (62.5%). Their age was 56.2 ± 8.9 years old (range 39-74). The time from rupture to endovascular treatment was 10.9 ± 12.5 h. The maximum diameter of the aneurysms was 5.1 ± 1.0 mm and neck width were 3.0 ± 0.7 mm. Nineteen patients (79.2%) were double-lobed and 5 (20.8%) were multilobed. Fisher's grade: Grade 2 in 16 cases (66.7%), grade 3 in 6 cases (25%), and grade 4 in 2 cases (8.3%). Hunt-Hess grade: Grade 0-2 in 5 cases (20.8%), grade 3-5 in 19 cases (79.2%). Glasgow Coma Scale score: 9-12 in 14 cases (58.3%), 13-15 in 10 cases (41.7%). Immediately postprocedural Raymond-Roy grade: grade 1 in 23 cases (95. 8%), grade 2 in 1 case (4.2%). Raymond-Roy grade in imaging follow-up for 2 wk to 3 months: grade 1 in 23 cases (95.8%), grade 2 in 1 case (4.2%). Follow-up for 2 to 12 months showed that 21 patients (87.5%) had good functional outcomes (modified Rankin Scale score ≤ 2), and there were no deaths.

CONCLUSION

Endovascular treatment is a safe and effective treatment for ruptured lobulated AcoAA.

Combining Machine-Measured Morphometric, Geometric, and Hemodynamic Factors to Predict the Risk of Aneurysm Rupture at the Middle Cerebral Artery Bifurcation

BACKGROUND

Middle Cerebral Artery Bifurcation Aneurysm (MbifA) is associated with a high risk of rupture and poor overall prognosis in patients once it ruptures. Morphological, geometric, and hemodynamic parameters have been identified as factors contributing to the rupture of intracranial aneurysms. However, there are no studies that combine these 3 types of parameters to specifically target MbifA rupture.

METHODS

This study enrolled all patients with MbifAs diagnosed at our treatment center from 1 April 2021 to 31 July 2023 who met the study criteria. All patients underwent digital subtraction angiography examination to obtain 3D rotational angiography data. We imported the complete image data into the Aneurysm/Artery Reconstruction and Analysis machine to obtain 13 morphological parameters (Dneck, Ddome, Height, Dmax, Dartery, aspect ratio [AR], size ratio, dome-neck-ratio [DNR], height-artery-ratio, bottleneck factor, Inflow Angle, Incline Angle, Arterial Angle), 5 geometric parameters (V,S,undulation index [UI], ellipticity index [EI],nonsphericity index [NSI]), and 5 hemodynamic parameters (wall shear stress [WSS], the maximum WSS, the parent artery WSS, the normalized WSS [NWSS], oscillatory shear index [OSI]). All the above significant parameters were tested by univariate and multivariate analyses to find out the independent discriminatory factors.

RESULTS

A total of 49 MbifAs (16 ruptured and 33 unruptured) from 44 patients were included in the study. Height (P = 0.033), AR (P = 0.007), DNR (P = 0.011), EI (P = 0.042), NSI(P = 0.030), UI(P = 0.027), WSS(P = 0.033), and NWSS(P = 0.002) were all associated with MbifA rupture in univariate analyses, but only NWSS was an independent risk factor (P = 0.036, OR = 0.046, 95% CI: 0.003-0.815) in multivariate logistic regression analysis.

CONCLUSIONS

Height, AR, DNR, EI, UI, NSI, WSS, and NWSS may be correlated with MbifA rupture, but only NWSS was an independent risk factor. A lower NWSS was associated with a higher risk of MbifA rupture. No significant differences were observed in the angle parameters, including the Inflow Angle, between ruptured and unruptured MbifAs. OSI was significantly increased at the dome of the aneurysm but the mean OSI was not found to be associated with MbifA rupture.

Risk Factors and Location of Intracranial Aneurysm Rupture in a Consecutive Chinese Han Population

OBJECTIVE

The aim of the present study was to retrospectively analyze and investigate the clinical data of 704 cases of ruptured intracranial aneurysms (RIAs) and unruptured intracranial aneurysms (UIAs). The risk factors predicting aneurysm rupture were explored from the perspective of the clinical characteristics of intracranial aneurysm (IA).

METHODS

The clinical data of 704 patients with RIAs (494 patients) and UIAs (210 patients) admitted to the Department of Neurosurgery of Tianjin Medical University General Hospital and Tianjin Fifth Central Hospital between January 2016 and May 2022 were analyzed. A detailed analysis of sex, age, history, personal history, drug intake, and site of aneurysm occurrence was performed. Age was analyzed in segments and strata, and parameters with significant differences in the preliminary analysis results were analyzed by logistic regression to predict factors associated with the risk of aneurysm rupture.

RESULTS

Among 494 patients with RIA (70.2%) and 210 patients with UIA (29.8%), the logistic regression showed that IA location appeared to be the most significant factor associated with RIA (OR, 95% CI: internal carotid artery (ICA), reference; anterior communicating artery,27.864,12.548-61.878; posterior communicating artery,12.408,6.658-23.124; anterior cerebral artery,5.804,2.333-14.440; middle cerebral artery,9.284,4.599-18.744; posterior circulation arteries, 4.224,2.011-8.871). Age was not a significant factor associated with RIA in the model and Hyperlipidemia (OR: 0.365; 95% CI: 0.171-0.779), Atherosclerosis (OR: 0.277; 95% CI: 0.172-0.446) and Multiple aneurysms (OR: 0.275; 95% CI: 0.177-0.425) patients were less likely to have RIA.IA location and age were the best predictors of RIA using the model.

CONCLUSIONS

The present findings indicated that hyperlipidemia and atherosclerosis have a protective effect on aneurysm rupture, and different anatomical sites of IA may be risk factors for the occurrence of IA rupture. Among the anatomical sites of IA, the anterior communicating artery and posterior communicating artery have a higher fracture risk.

Progression from Early Minor Recanalization to Major Recanalization in Ruptured Intracranial Aneurysms After Successful Coil Embolization: Risk Factors and Proposal of a Novel Predicting Variable

BACKGROUND

The risk factors for the progression from early minor recanalization to major recanalization are not well established. Herein, we evaluated ruptured intracranial aneurysms (IAs) with minor recanalization within 1 year of coiling and their progression to major recurrence.

METHODS

We retrospectively reviewed our database of coiled IAs and searched for ruptured saccular IAs that were successfully embolized without residual sacs. We selected IAs with minor recanalization confirmed on radiological studies within 1 year of coil embolization. All the IA cases had a follow-up period longer than 36 months based on the radiological results.

RESULTS

Minor recanalization occurred in 45 IAs within 1 year of coil embolization. Among them, 14 IAs (31.1%) progressed to major recanalization, and 31 remained stable. Progression to major recanalization was detected 12 months after minor recanalization in 2 patients, 24 months in 7 patients, and 36 months in 5 patients. Moreover, the progression to major recanalization occurred more frequently in IAs at the posterior location (P = 0.024, odds ratio 11.20) and IAs with a proportional forced area > 9 mm2 (P = 0.002, odds ratio 17.13), which was a newly proposed variable in the present study.

CONCLUSIONS

Our results showed that approximately one third of the ruptured IAs with early minor recanalization after coiling progressed to major recanalization within 3 years. Physicians should focus on the progression of ruptured IAs from minor to major recanalization, especially those with a posterior circulation location and a proportional forced area >9 mm2.

Predictive nomogram models for unfavorable prognosis after aneurysmal subarachnoid hemorrhage: Analysis from a prospective, observational cohort in China

AIM

The aim of the study was to identify predictors for 3-month poor functional outcome or death after aSAH and develop precise and easy-to-use nomogram models.

METHODS

The study was performed at the department of neurology emergency in Beijing Tiantan Hospital. A total of 310 aSAH patients were enrolled between October 2020 and September 2021 as a derivation cohort, while a total of 208 patients were admitted from October 2021 to March 2022 as an external validation cohort. Clinical outcomes included poor functional outcome defined as modified Rankin Scale score (mRS) of 4-6 or all-cause death at 3 months. Least absolute shrinkage and selection operator (LASSO) analysis, as well as multivariable regression analysis, were applied to select independent variables associated with poor functional outcome or death and then to construct two nomogram models. Model performance were evaluated through discrimination, calibration, and clinical usefulness in both derivation cohort and external validation cohort.

RESULTS

The nomogram model to predict poor functional outcome included seven predictors: age, heart rate, Hunt-Hess grade on admission, lymphocyte, C-reactive protein (CRP), platelet, and direct bilirubin levels. It demonstrated high discrimination ability (AUC, 0.845; 95% CI: 0.787-0.903), satisfactory calibration curve, and good clinical usefulness. Similarly, the nomogram model combining age, neutrophil, lymphocyte, CRP, aspartate aminotransferase (AST) levels, and treatment methods to predict all-cause death also revealed excellent discrimination ability (AUC, 0.944; 95% CI: 0.910-0.979), satisfactory calibration curve, and clinical effectiveness. Internal validation showed the bias-corrected C-index for poor functional outcome and death was 0.827 and 0.927, respectively. When applied to the external validation dataset, both two nomogram models exhibited high discrimination capacity [poor functional outcome: AUC = 0.795 (0.716-0.873); death: AUC = 0.811 (0.707-0.915)], good calibration ability, and clinical usefulness.

CONCLUSIONS

Nomogram models constructed for predicting 3-month poor functional outcome or death after aSAH are precise and easily applicable, which can help physicians to identify patients at risk, guide decision-making, and provide new directions for future studies to explore the novel treatment targets.

Correlation between the rate of morphological changes and rupture of intracranial aneurysms during one cardiac cycle analyzed by 4D-CTA

Objective

This study aimed to analyze the relationship between the rate of morphological changes and intracranial aneurysm rupture during the cardiac cycle.

Methods

Eighty-four patients with intracranial aneurysms were retrospectively analyzed and divided into the rupture (42 cases) and unruptured (42 cases) groups. Four-dimensional computed tomography angiography (4D-CTA) was performed to collect quantitative parameters of aneurysm morphology and calculate the morphological change rate. The potential factors associated with aneurysm rupture were determined by comparing the general clinical data and rate of change in the location and morphology of the aneurysm between the two groups.

Results

Each morphological change rate in the rupture group was generally higher than that of the unruptured group. The rate of dome height change and aneurysm volume change were independent factors associated with aneurysm rupture. ROC curve analysis revealed that the diagnostic accuracy of the aneurysm volume change rate was higher. When the volume change rate was 12.33%, the sensitivity and specificity of rupture were 90.5 and 55.8%, respectively.

Conclusion

The rate of change in dome height and volume of intracranial aneurysms during one cardiac cycle were independent factors associated with aneurysm rupture.

A framework for intracranial aneurysm detection and rupture analysis on DSA

BACKGROUND

Intracranial aneurysm is a severe cerebrovascular disease that can result in subarachnoid hemorrhage (SAH), leading to high incidence and mortality rates. Computer-aided detection of aneurysms can assist doctors in enhancing diagnostic accuracy. The analysis of aneurysm imaging holds considerable predictive value for aneurysm rupture. This paper presents a method for the detection of aneurysms and analysis of ruptures using digital subtraction angiography (DSA).

METHODS

A total of 263 aneurysms were analyzed, with 125 being ruptured and 138 being unruptured. Firstly, a filter based on the eigenvalues of the Hessian matrix was proposed for aneurysm detection. The filter's detection parameters can be automatically obtained through Bayesian optimization. Aneurysms were detected based on their structure and the response of the filter. Secondly, considering the variations in blood flow and morphology among aneurysms in DSA, intensity, texture, and blood perfusion features were extracted from the ruptured aneurysms and unruptured aneurysms. Subsequently, a sparse representation (SR) method was utilized to classify unruptured and ruptured aneurysms.

RESULTS

The experimental results for aneurysm detection showed that the F1-score was 94.1%. In the classification of ruptured and unruptured aneurysms, the accuracy, sensitivity, specificity, and area under curve (AUC) were 96.1%, 94.4%, 97.5%, and 0.982, respectively.

CONCLUSION

This paper presents a scheme combining an aneurysm detection filter and machine learning, offering a reliable solution for the diagnosis and prediction of aneurysm rupture.

On the major role played by the lumen curvature of intracranial aneurysms walls in determining their mechanical response, local hemodynamics, and rupture likelihood

The properties of intracranial aneurysms (IAs) walls are known to be driven by the underlying hemodynamics adjacent to the IA sac. Different pathways exist explaining the connections between hemodynamics and local tissue properties. The emergence of such theories is essential if one wishes to compute the mechanical response of a patient-specific IA wall and predict its rupture. Apart from the hemodynamics and tissue properties, one could assume that the mechanical response also depends on the local morphology, more specifically, the curvature of the luminal surface, with larger values at highly-curved wall portions. Nonetheless, this contradicts observations of IA rupture sites more often found at the dome, where the curvature is lower. This seeming contradiction indicates a complex interaction between the hemodynamics adjacent to the aneurysm wall, its morphology, and mechanical response, which warrants further investigation. This was the main goal of this work. We accomplished this by analyzing the stress and stretch fields in different regions of the wall for a sample of IAs, which have been classified based on particular hemodynamics conditions and lumen curvature. Pulsatile numerical simulations were performed using the one-way fluid-solid interaction strategy implemented in OpenFOAM (solids4foam toolbox). We found that the variable best correlated with regions of high stress and stretch was the lumen curvature. Additionally, our data suggest a connection between the local curvature and particular hemodynamics conditions adjacent to the wall, indicating that the lumen curvature is a property that could be used to assess both mechanical response and hemodynamic conditions, and, moreover, suggest new rupture indicators based on the curvature.

A deep-learning method for the end-to-end prediction of intracranial aneurysm rupture risk

It is critical to accurately predict the rupture risk of an intracranial aneurysm (IA) for timely and appropriate treatment because the fatality rate after rupture is 50 % . Existing methods relying on morphological features (e.g., height-width ratio) measured manually by neuroradiologists are labor intensive and have limited use for risk assessment. Therefore, we propose an end-to-end deep-learning method, called TransIAR net, to automatically learn the morphological features from 3D computed tomography angiography (CTA) data and accurately predict the status of IA rupture. We devise a multiscale 3D convolutional neural network (CNN) to extract the structural patterns of the IA and its neighborhood with a dual branch of shared network structures. Moreover, we learn the spatial dependence within the IA neighborhood with a transformer encoder. Our experiments demonstrated that the features learned by TransIAR are more effective and robust than handcrafted features, resulting in a 10 % - 15 % improvement in the accuracy of rupture status prediction.

Reproducibility of the computational fluid dynamic analysis of a cerebral aneurysm monitored over a decade

Computational fluid dynamics (CFD) simulations are increasingly utilised to evaluate intracranial aneurysm (IA) haemodynamics to aid in the prediction of morphological changes and rupture risk. However, these models vary and differences in published results warrant the investigation of IA-CFD reproducibility. This study aims to explore sources of intra-team variability and determine its impact on the aneurysm morphology and CFD parameters. A team of four operators were given six sets of magnetic resonance angiography data spanning a decade from one patient with a middle cerebral aneurysm. All operators were given the same protocol and software for model reconstruction and numerical analysis. The morphology and haemodynamics of the operator models were then compared. The segmentation, smoothing factor, inlet and outflow branch lengths were found to cause intra-team variability. There was 80% reproducibility in the time-averaged wall shear stress distribution among operators with the major difference attributed to the level of smoothing. Based on these findings, it was concluded that the clinical applicability of CFD simulations may be feasible if a standardised segmentation protocol is developed. Moreover, when analysing the aneurysm shape change over a decade, it was noted that the co-existence of positive and negative values of the wall shear stress divergence (WSSD) contributed to the growth of a daughter sac.

Deep learning-based recognition and segmentation of intracranial aneurysms under small sample size

The manual identification and segmentation of intracranial aneurysms (IAs) involved in the 3D reconstruction procedure are labor-intensive and prone to human errors. To meet the demands for routine clinical management and large cohort studies of IAs, fast and accurate patient-specific IA reconstruction becomes a research Frontier. In this study, a deep-learning-based framework for IA identification and segmentation was developed, and the impacts of image pre-processing and convolutional neural network (CNN) architectures on the framework's performance were investigated. Three-dimensional (3D) segmentation-dedicated architectures, including 3D UNet, VNet, and 3D Res-UNet were evaluated. The dataset used in this study included 101 sets of anonymized cranial computed tomography angiography (CTA) images with 140 IA cases. After the labeling and image pre-processing, a training set and test set containing 112 and 28 IA lesions were used to train and evaluate the convolutional neural network mentioned above. The performances of three convolutional neural networks were compared in terms of training performance, segmentation performance, and segmentation efficiency using multiple quantitative metrics. All the convolutional neural networks showed a non-zero voxel-wise recall (V-Recall) at the case level. Among them, 3D UNet exhibited a better overall segmentation performance under the relatively small sample size. The automatic segmentation results based on 3D UNet reached an average V-Recall of 0.797 ± 0.140 (3.5% and 17.3% higher than that of VNet and 3D Res-UNet), as well as an average dice similarity coefficient (DSC) of 0.818 ± 0.100, which was 4.1%, and 11.7% higher than VNet and 3D Res-UNet. Moreover, the average Hausdorff distance (HD) of the 3D UNet was 3.323 ± 3.212 voxels, which was 8.3% and 17.3% lower than that of VNet and 3D Res-UNet. The three-dimensional deviation analysis results also showed that the segmentations of 3D UNet had the smallest deviation with a max distance of +1.4760/-2.3854 mm, an average distance of 0.3480 mm, a standard deviation (STD) of 0.5978 mm, a root mean square (RMS) of 0.7269 mm. In addition, the average segmentation time (AST) of the 3D UNet was 0.053s, equal to that of 3D Res-UNet and 8.62% shorter than VNet. The results from this study suggested that the proposed deep learning framework integrated with 3D UNet can provide fast and accurate IA identification and segmentation.

Rupture Risk Assessment for Anterior Communicating Artery Aneurysms Using Decision Tree Modeling

Background

Although anterior communicating artery (ACoA) aneurysms have a higher risk of rupture than aneurysms in other locations, whether to treat unruptured ACoA aneurysms incidentally found is a dilemma because of treatment-related complications. Machine learning models have been widely used in the prediction of clinical medicine. In this study, we aimed to develop an easy-to-use decision tree model to assess the rupture risk of ACoA aneurysms.

Methods

This is a retrospective analysis of rupture risk for patients with ACoA aneurysms from two medical centers. Morphologic parameters of these aneurysms were measured and evaluated. Univariate analysis and multivariate logistic regression analysis were performed to investigate the risk factors of aneurysm rupture. A decision tree model was developed to assess the rupture risk of ACoA aneurysms based on significant risk factors.

Results

In this study, 285 patients were included, among which 67 had unruptured aneurysms and 218 had ruptured aneurysms. Aneurysm irregularity and vessel angle were independent predictors of rupture of ACoA aneurysms. There were five features, including size ratio, aneurysm irregularity, flow angle, vessel angle, and aneurysm size, selected for decision tree modeling. The model provided a visual representation of a decision tree and achieved a good prediction performance with an area under the receiver operating characteristic curve of 0.864 in the training dataset and 0.787 in the test dataset.

Conclusion

The decision tree model is a simple tool to assess the rupture risk of ACoA aneurysms and may be considered for treatment decision-making of unruptured intracranial aneurysms.

Single-Center Experience Using a 3D4K Digital Operating Scope System for Aneurysm Surgery

BACKGROUND

In recent years, 3D4K exoscope systems (EXs) have been introduced to microneurosurgery and reported to be an alternative to conventional operating microscopes (OMs). This study reviews our single-center experience using an 3D4K EX in intracranial aneurysm surgery.

OBJECTIVE

To investigate the applicability of a novel 3D4K EX for intracranial aneurysm surgery.

METHODS

A retrospective analysis of patients who underwent microsurgical repair of incidentally or ruptured cerebral aneurysms between August 2018 and August 2020 was performed. Patient and aneurysm characteristics and technical features, including 3-dimensional indocyanine green fluorescence, were evaluated. Data on surgery duration were statically assessed for a time trend and comparability with the OM cohort.

RESULTS

Overall, we collected 185 aneurysm cases in which the exoscope was used in 44 cases. The mean duration of surgery using the EX was in similar range to those using the OM (165.5 ± 45.8 minutes vs 160.5 ± 39.2 minutes, P > .05). Routine postoperative computed tomography angiography showed comparable rates of complete aneurysm occlusion (95.5% vs 92.2%, P > .05) and postoperative complications (9.1% vs 9.7%, P > .05). There was no necessity to revert to the OM from the EX. Three-dimensional indocyanine green fluorescence was used in all procedures without any malfunction.

CONCLUSION

The 3D4K EX for vascular microsurgical cases proved to be as useful as the OM. Because of the ease of use and comparable surgical results, the EX has the potential to become an accepted and additional visualization tool in vascular microsurgery next to the OM.

Intracranial Aneurysm Rupture Risk Estimation With Multidimensional Feature Fusion

The rupture of aneurysms is the main cause of spontaneous subarachnoid hemorrhage (SAH), which is a serious life-threatening disease with high mortality and permanent disability rates. Therefore, it is highly desirable to evaluate the rupture risk of aneurysms. In this study, we proposed a novel semiautomatic prediction model for the rupture risk estimation of aneurysms based on the CADA dataset, including 108 datasets with 125 annotated aneurysms. The model consisted of multidimensional feature fusion, feature selection, and the construction of classification methods. For the multidimensional feature fusion, we extracted four kinds of features and combined them into the feature set, including morphological features, radiomics features, clinical features, and deep learning features. Specifically, we applied the feature extractor 3D EfficientNet-B0 to extract and analyze the classification capabilities of three different deep learning features, namely, no-sigmoid features, sigmoid features, and binarization features. In the experiment, we constructed five distinct classification models, among which the k-nearest neighbor classifier showed the best performance for aneurysm rupture risk estimation, reaching an F2-score of 0.789. Our results suggest that the full use of multidimensional feature fusion can improve the performance of aneurysm rupture risk assessment. Compared with other methods, our method achieves the state-of-the-art performance for aneurysm rupture risk assessment methods based on CADA 2020.

Analysis of Risk Factors for Anterior Communicating Artery Aneurysm Rupture: A Single-Center Study

BACKGROUND

Congenital hypoplasia or aplasia of the A1 segment of the anterior cerebral artery is associated with an increased incidence of berry aneurysms at the anterior communicating artery (ACoA) complex. We analyzed the factors contributing to ACoA aneurysm rupture.

METHODS

We retrospectively analyzed the data of patients with ACoA aneurysms who had undergone cerebral angiography from July 2008 to January 2020. The risk factors for rupture were identified using univariate and multivariate logistic regression models. We used the imaging data of patients without intracranial aneurysms as the control population.

RESULTS

We confirmed 253 aneurysms in 253 patients, including 137 men (54.2%) and 116 women (45.8%), with a mean age of 54.6 ± 12.7 years. Of the 253 aneurysms, 218 (86.2%) were ruptured and 35 (13.8%) were unruptured, with a mean diameter of 4.56 ± 1.96 mm and 3.24 ± 1.79 mm, respectively. Of the 253 aneurysms, 176 (69.6%) were <5 mm in diameter, 146 (83%) of which were ruptured. Of the 253 patients, 141 (55.7%) exhibited A1 segment hypoplasia or aplasia: 106 (41.9%) on the right side of the circle of Willis and 35 (13.8%) on the left. Multivariate logistic regression analysis identified the aneurysm diameter (odds ratio, 4.11; 95% confidence interval, 1.601-16.07; P = 0.003) and age <65 years (odds ratio, 0.17; 95% confidence interval, 0.062-0.48; P < 0.001) as independent predictors of rupture.

CONCLUSIONS

ACoA aneurysms are small (<5 mm) and have a high risk of rupture. A1 segment hypoplasia or aplasia is a risk factor for ACoA aneurysm formation; however, it was uncorrelated with aneurysm diameter or rupture risk. The strongest independent risk factors for rupture were age <65 years and aneurysm diameter.

Management of Unruptured Intracranial Aneurysms

Unruptured intracranial aneurysms (UIAs) are common and are being detected with increasing frequency given the improved quality and higher frequency of cross-sectional imaging. The long-term natural history of UIAs remains poorly understood. To date, there is relative lack of clear guidelines for selection of patients with UIAs for treatment. Surveillance imaging for untreated UIAs is frequently performed, but frequency, duration, and modality of surveillance imaging need clearer guidelines. The authors review the current evidence on prevalence, natural history, role of treatment, and surveillance and screening imaging and highlight the areas for further research.

Morphological Irregularity of Unruptured Intracranial Aneurysms is More Related with Aneurysm Size Rather Than Cerebrovascular Atherosclerosis: A Case-Control Study

Objective

It remains unclear whether irregular morphological features of intracranial aneurysms (IAs) are associated with atherosclerosis. We investigated the effect of cerebrovascular atherosclerosis stenosis (CAS) on irregular morphology of IAs.

Patients and Methods

This single-center case-control study included consecutive patients with IAs at our institution from September 2011 to September 2018. Cases were patients with irregular IAs, and age- and location-matched controls were patients with regular IAs. Conditional logistic regression models were used to assess the relationship between angiographic variables of CAS and aneurysmal irregularity.

Results

A total of 140 cases of irregular IAs and 140 controls were included in the analysis. Sixteen patients with irregular IAs (11.4%) and eleven patients with regular IAs (7.9%) had >50% parent artery stenosis; however, the differences were not statistically significant between these two groups. In addition, no significant between-group differences were observed in distributions of the cerebrovascular stenosis, number of arterial stenoses, and location of the stenosis. In the final adjusted conditional logistic regression model, only aneurysm size (≥7 mm) was significantly associated with irregular IA morphology (P = 0.022). Moreover, 89 cases of irregular IAs and 89 controls were included in the analysis of unruptured IAs (UIAs). In the final adjusted conditional logistic regression model, only aneurysm size (≥7 mm) was significantly associated with irregular UIA morphology (P = 0.020).

Conclusion

Our findings indicate that the morphological irregularity of unruptured intracranial aneurysms is more related with aneurysm size rather than cerebrovascular atherosclerosis. Further studies are needed to use prospective data to identify causative factors responsible for aneurysmal irregularity.

Comparison of clinical and histopathological characteristics of short-term progressive and non-progressive blood blister-like aneurysms

BACKGROUND

Many blood blister aneurysms (BBAs) have been documented with a rapid progression history in repeated angiography. The underlying mechanism and clinical significance remained elusive. This current study aims to clarify the clinical and histopathological differences between short-term progressive BBA and non-progressive BBAs.

METHODS AND MATERIALS

Eighty-one patients with BBAs were consecutively included for this single-center retrospective analysis. Clinical and radiological data on these patients were retrieved from 2017 to 2019. BBAs were defined as either progressive or non-progressive based on observed growth based on repeated imaging. Histopathological examinations of a saccular aneurysm, a progressive BBA, and a non-progressive BBA were conducted using representative aneurysm samples.

RESULTS

Among all enrolled patients, 26 of the them were identified with progressive BBAs, while the other 55 with non-progressive BBAs. Progressive BBAs were diagnosed significantly earlier in angiography (3.36 ± 0.61 vs. 6.53 ± 1.31 days, p < 0.05) and showed a higher presence rate of daughter sacs (61.5 vs. 38.2%, p < 0.05). Three different progression patterns were identified. BBAs that developed daughter sac enlargement are diagnosed significantly later than BBAs exhibiting other progression patterns. Patients with progressive and non-progressive BBAs exhibited similar overall clinical outcomes and incidence for complications. For patients with non-progressive BBAs, microsurgery appears to be inferior to endovascular treatment, while for patients with progressive BBAs, the short-term outcomes between microsurgery and endovascular treatment were identical. Histopathological analysis revealed that both subtypes shared a similar pseudoaneurysms structure, but non-progressive BBAs had more histologically destructed aneurysm wall with less remnant fibrillar collagen in adventitia.

CONCLUSIONS

Progressive and non-progressive BBAs may not be distinct pathological lesions but represent different stages during the BBA development. Early intervention, regardless of treatment methods, is recommended for salvageable patients with progressive BBAs, but microsurgery should be performed with caution for non-progressive BBAs due to increased surgical risk.

Using a Convolutional Neural Network and Convolutional Long Short-term Memory to Automatically Detect Aneurysms on 2D-DSA Images (Preprint)

Background

It is hard to distinguish cerebral aneurysms from overlapping vessels in 2D digital subtraction angiography (DSA) images due to these images’ lack of spatial information.

Objective

The aims of this study were to (1) construct a deep learning diagnostic system to improve the ability to detect posterior communicating artery aneurysms on 2D DSA images and (2) validate the efficiency of the deep learning diagnostic system in 2D DSA aneurysm detection.

Methods

We proposed a 2-stage detection system. First, we established the region localization stage to automatically locate specific detection regions of raw 2D DSA sequences. Second, in the intracranial aneurysm detection stage, we constructed a bi-input+RetinaNet+convolutional long short-term memory (C-LSTM) framework to compare its performance for aneurysm detection with that of 3 existing frameworks. Each of the frameworks had a 5-fold cross-validation scheme. The receiver operating characteristic curve, the area under the curve (AUC) value, mean average precision, sensitivity, specificity, and accuracy were used to assess the abilities of different frameworks.

Results

A total of 255 patients with posterior communicating artery aneurysms and 20 patients without aneurysms were included in this study. The best AUC values of the RetinaNet, RetinaNet+C-LSTM, bi-input+RetinaNet, and bi-input+RetinaNet+C-LSTM frameworks were 0.95, 0.96, 0.92, and 0.97, respectively. The mean sensitivities of the RetinaNet, RetinaNet+C-LSTM, bi-input+RetinaNet, and bi-input+RetinaNet+C-LSTM frameworks and human experts were 89% (range 67.02%-98.43%), 88% (range 65.76%-98.06%), 87% (range 64.53%-97.66%), 89% (range 67.02%-98.43%), and 90% (range 68.30%-98.77%), respectively. The mean specificities of the RetinaNet, RetinaNet+C-LSTM, bi-input+RetinaNet, and bi-input+RetinaNet+C-LSTM frameworks and human experts were 80% (range 56.34%-94.27%), 89% (range 67.02%-98.43%), 86% (range 63.31%-97.24%), 93% (range 72.30%-99.56%), and 90% (range 68.30%-98.77%), respectively. The mean accuracies of the RetinaNet, RetinaNet+C-LSTM, bi-input+RetinaNet, and bi-input+RetinaNet+C-LSTM frameworks and human experts were 84.50% (range 69.57%-93.97%), 88.50% (range 74.44%-96.39%), 86.50% (range 71.97%-95.22%), 91% (range 77.63%-97.72%), and 90% (range 76.34%-97.21%), respectively.

Conclusions

According to our results, more spatial and temporal information can help improve the performance of the frameworks. Therefore, the bi-input+RetinaNet+C-LSTM framework had the best performance when compared to that of the other frameworks. Our study demonstrates that our system can assist physicians in detecting intracranial aneurysms on 2D DSA images.

Predictors of Intraoperative Aneurysm Rupture, Aneurysm Remnant, and Brain Ischemia following Microsurgical Clipping of Intracranial Aneurysms: Single-Center, Retrospective Cohort Study

BACKGROUND AND STUDY AIMS

 Complete microsurgical clip occlusion of an aneurysm is one of the most important challenges in cerebrovascular surgery. Incorrect position of clip blades as well as intraoperative aneurysm rupture can expose the patient to serious complications such as rebleeding in case of aneurysm remnant and cerebral ischemia in case of occlusion of branching arteries or perforators. The aim of this study was to identify independent predictors of surgery-derived complications (aneurysm remnant and brain ischemia) as well as intraoperative aneurysm rupture in an institutional series of patients.

MATERIAL AND METHODS

 This is a single-institution, retrospective cohort study including 147 patients with 162 aneurysms that were selected for microsurgical clipping due to intracranial aneurysm in a 5-year period. Bivariate and multivariate analyses were performed to identify independent predictors among demographic, clinical, and radiographic factors.

RESULTS

 Increasing aneurysm size with a cutoff value at 9 mm (p = 0.009; odds ratio [OR]: 0.644) and irregular dome shape (p = 0.003; OR: 4.242) were independently associated with brain ischemia and aneurysm remnants that occurred in 13.6 and 17.3% of patients in our group, respectively. Intraoperative rupture was encountered in 27% of patients and its predictors were patient's age (p = 0.002; OR: 1.073) and increasing aneurysm size with a cutoff value at 7 mm (p = 0.003; OR: 1.205).

CONCLUSION

 Aneurysm size, patient's age, and irregular dome shape were the most important risk factors of aneurysm remnant, brain ischemia, and intraoperative aneurysm rupture in our series of patients. We were not able to define a cutoff value for patient's age, but our results showed that with increasing age the risk of intraoperative aneurysm rupture increased.

Risk Factors for Higher Volume of Hemorrhage in Ruptured Anterior Circulation Intracranial Aneurysms

Purpose: To explore the influencing factors of volume hemorrhage in ruptured anterior circulation aneurysms, so as to identify the characteristics of anterior circulation aneurysms with high volume of hemorrhage, and to provide advice for clinical diagnosis and treatment for those aneurysms. Methods: We retrospectively reviewed 437 cases of ruptured anterior intracranial aneurysms in our center between the years 2012 and 2017. According to the inclusion criteria, a total of 100 qualified patients were screened out. We collected demographic characteristics, environmental exposure, and admission status of enrolled patients. In addition, morphological parameters and location of aneurysms were also included. The semiautomatic threshold method was used to measure the volume of hemorrhage. According to the results, the patients were divided into the group with high blood volume and low blood volume. Univariate and multivariate logistic regression analyses were used to discover the related factors affecting the bleeding volume. Results: In univariable analysis, pulse pressure (P = 0.014) showed a significant difference at the P < 0.05 test level. In terms of aneurysm morphology, the irregular shape (P < 0.001), calcification (P = 0.001), and flow angle (P = 0.006) showed significant statistical differences between the two groups at the P < 0.01 level (P < 0.01). Multivariate logistic regression analysis showed that irregular shape (OR = 5.370 P = 0.002 < 0.05), large flow angle (OR = 1.033 P = 0.016 < 0.05), and calcification (OR = 5.460 P = 0.003 < 0.05) were risk factors for volume of hemorrhage in ruptured anterior circulation aneurysms. The influence of hypertension history was at critical state (OR = 2.877 P = 0.051 > 005). Conclusions: According to our analysis results, intracranial anterior circulation aneurysms with irregular shapes, calcifications, and large flow angle are more dangerous. Aneurysms with these characteristics often have a large amount of hemorrhage, requiring timely treatment in clinical practice.

Clinical features of and risk factors for intracranial aneurysms associated with moyamoya disease

BACKGROUND

The clinical features of aneurysms associated with moyamoya disease (MMD) and risk factors for the formation and rupture of aneurysms are not well defined.

AIMS

In this study, we retrospectively analyzed clinical data of MMD patients and examined the potential risk factors for the formation and rupture of aneurysms in these patients.

METHODS

The medical records of all MMD patients in our hospital from April 2012 to May 2019 were reviewed. The logistic regression analysis was used to determine the independent association between various potential risk factors and the presence or rupture of intracranial aneurysms in MMD patients.

RESULTS

Of 2230 MMD patients, 182 (8.2%) cases had intracranial aneurysms. The mean age of onset in patients with aneurysms was 47.2 years, which was significantly higher when compared with those without aneurysms (p < 0.001). In logistic regression analysis, age of onset remained significantly associated with the presence of intracranial aneurysms, while female gender, hypertension, diabetes mellitus, and coronary artery disease were not. Besides, intracranial aneurysms were significantly associated with intracranial hemorrhage in MMD patients (odds ratio [OR] = 5.19; 95% confidence interval [CI], 3.80-7.09). About 60% aneurysms >5 mm in size, and 62.1% aneurysms with irregularly shaped morphology were ruptured. Aneurysms located in basilar tip, collateral or moyamoya vessels were more likely to present with rupture.

CONCLUSIONS

Age was an important risk factor for intracranial aneurysms formation in MMD patients. Aneurysms increased the risk of intracerebral hemorrhage in MMD patients, and their ruptures were correlated with aneurysms size, location, and morphology.

Clinical characteristics associated with sentinel headache in patients with unruptured intracranial aneurysms

OBJECTIVE

Sentinel headache (SH) is considered as a signal of the impending rupture of an aneurysm. However, it is difficult to diagnose whether the headaches of patients are associated with unstable aneurysms. Therefore, there is some doubt about the importance of headaches in patients with unruptured intracranial aneurysms (UIAs). This study was performed to explore the existence and clinical characteristics of SH associated with aneurysms.

METHODS

Thirty-six patients with a single UIA were collected in this study. Patients were symptomatically categorized into two groups: SH and non-SH. The PHASES scores and patient and aneurysm characteristics were analyzed. Two independent MRI experts who were blinded to the patients' clinical history conducted the analysis of the SWI results.

RESULTS

There were 15 patients with sentinel headache. No significant difference was found in patient's basic information and history. The SH group had a higher PHASES score than the non-SH group (P < 0.05). In univariable analysis, abnormal SWI signals were significantly more frequent in the SH group (P < 0.01) and the inflow angle was significantly lower in the non-SH group (P < 0.05). In multivariable analysis, abnormal signals in SWI were an independent factor associated with SH (P < 0.01).

CONCLUSIONS

SH exists in patients with UIAs and may indicate a high risk of aneurysm rupture. Abnormal signals on SWI may serve as a clinical feature to identify aneurysm-related SH and be helpful for the formulation of therapeutic strategy. Aneurysm geometry may also be related to SH but need further studies in the future.

Impact of aneurysm shape and neck configuration on cerebral infarction during microsurgical clipping of intracranial aneurysms

OBJECTIVE

Cerebral infarction is a significant cause of morbidity and mortality related to microsurgical clipping of intracranial aneurysms. The objective of this study was to determine the impact of aneurysm shape and neck configuration on cerebral infarction after aneurysm surgery.

METHODS

The authors retrospectively reviewed consecutive cases of ruptured and unruptured aneurysms treated with microsurgical clipping at their institution between 2010 and 2018. Three-dimensional reconstructions from preoperative computed tomography and digital subtraction angiography were used to determine aneurysm shape (regular/complex) and neck configuration (regular/irregular). Morphological and procedure-related risk factors for cerebral infarction were identified using univariate and multivariate statistical analyses.

RESULTS

Among 243 patients with 252 aneurysms (148 ruptured, 104 unruptured), the overall cerebral infarction rate was 17.1%. Infarction tended to occur more often in aneurysms with complex shape (p = 0.084). Likewise, aneurysms with an irregular neck had a significantly higher rate of infarction (37.5%) than aneurysms with regular neck configuration (10.1%, p < 0.001). Aneurysms with an irregular neck were associated with a higher rate of intraoperative rupture (p = 0.003) and temporary parent artery occlusion (p = 0.037). In the multivariate analysis, irregular neck configuration was identified as an independent risk factor for infarction (OR 4.2, 95% CI 1.9-9.4, p < 0.001), whereas the association between aneurysm shape and infarction was not significant (p = 0.966).

CONCLUSIONS

Irregular aneurysm neck configuration represents an independent risk factor for cerebral infarction during microsurgical clipping of both ruptured and unruptured aneurysms.

Intracranial vessel wall imaging: applications, interpretation, and pitfalls

Vessel wall imaging (VWI) is being increasingly used as a non-invasive diagnostic method to evaluate the intra- and extracranial vascular bed. Whereas conventional vascular imaging primarily assesses the vessel lumen, VWI changes the focus of analysis toward the vessel wall. As the technical challenges of high spatial resolution, signal-to-noise ratio, and contrast-to-noise ratio and long scans times are addressed, interest in the clinical applications of this technique has steadily increased over the years. In this review, the authors will discuss the various applications of VWI as well as principles of interpretation and common imaging findings, focusing on intracranial atherosclerosis, vascular dissection, vasculitides (such as primary angiitis of the central nervous system (PACNS) and neurosarcoidosis), vasculopathies (such as reversible cerebral vasoconstriction syndrome (RCVS), cocaine-induced vasculopathy, moyamoya disease, and radiation-induced arteriopathy), aneurysms, and post-thrombectomy changes. The authors will also discuss the potential pitfalls of VWI and helpful cues to avoid being tricked.

Machine Learning Classification of Cerebral Aneurysm Rupture Status with Morphologic Variables and Hemodynamic Parameters

Purpose

To construct a classification model of rupture status and to clarify the importance of morphologic variables and hemodynamic parameters on rupture status by applying a machine learning (ML) algorithm to morphologic and hemodynamic data of cerebral aneurysms.

Materials and Methods

Between 2011 and 2019, 226 (112 ruptured and 114 unruptured) cerebral aneurysms in 188 consecutive patients were retrospectively analyzed with computational fluid dynamics (CFD). A random forest ML algorithm was applied to the results to create three classification models consisting of only morphologic variables (model 1), only hemodynamic parameters (model 2), and both morphologic variables and hemodynamic parameters (model 3). The accuracy of rupture status classification and the importance of each variable or parameter in the models were computed.

Results

The accuracy was 77.0% in model 1, 71.2% in model 2, and 78.3% in model 3. The three most important features were projection ratio, size ratio, and aspect ratio in model 1; low shear area ratio, oscillatory shear index, and oscillatory velocity index in model 2; and projection ratio, irregular shape, and size ratio in model 3.

Conclusion

Classification models of rupture status of cerebral aneurysms were constructed by applying an ML algorithm to morphologic variables and hemodynamic parameters. The model worked with relatively high accuracy, in which projection ratio, irregular shape, and size ratio were important for the discrimination of ruptured aneurysms.Supplemental material is available for this article.© RSNA, 2020.

Identifying Predictors for Aneurysm Remnants After Clipping by Morphometric Analysis and Proposal of a Novel Risk Score

OBJECTIVE

Although the risk of aneurysm remnants after microsurgical clipping is generally low, complete aneurysm occlusion is not always guaranteed. We performed a morphometric analysis of intracranial aneurysms to identify predictors for aneurysm remnants and to propose a novel risk score.

METHODS

This is a retrospective, single-center analysis of consecutive patients with ruptured and unruptured aneurysms who underwent microsurgical clipping and postoperative digital subtraction angiography between 2010 and 2018. Based on preoperative rotational angiography, distinct morphologic aneurysm characteristics were determined and correlated with postoperative angiographic results. Factors predictive in the univariate and multivariate analyses were determined to establish a risk score for postoperative remnants after aneurysm clipping.

RESULTS

Among 140 patients with 166 clipped aneurysms, aneurysm remnants were present in 19.9%. In the multivariate analysis, ruptured aneurysm status (odds ratio [OR], 7.8; 95% confidence interval [CI], 1.7-36; P < 0.01) and increased aspect ratio (OR, 1.9; 95% CI, 1.0-4.0; P = 0.07) were associated with postoperative aneurysm remnants. Anterior communicating artery location (P = 0.02), internal carotid artery location (P = 0.06), increased aneurysm inclination angle (P < 0.01), and irregular aneurysm shape (P = 0.07) were further predictors for aneurysm remnants in the univariate analysis. These factors were weighted and included into a risk sum score for postoperative aneurysm remnants (range, 0-8 points), which performed with good accuracy (area under the curve = 0.807).

CONCLUSIONS

After external validation of the proposed risk score, it could help identify cases requiring angiographic control after aneurysm surgery.

Automatic detection on intracranial aneurysm from digital subtraction angiography with cascade convolutional neural networks

Background

An intracranial aneurysm is a cerebrovascular disorder that can result in various diseases. Clinically, diagnosis of an intracranial aneurysm utilizes digital subtraction angiography (DSA) modality as gold standard. The existing automatic computer-aided diagnosis (CAD) research studies with DSA modality were based on classical digital image processing (DIP) methods. However, the classical feature extraction methods were badly hampered by complex vascular distribution, and the sliding window methods were time-consuming during searching and feature extraction. Therefore, developing an accurate and efficient CAD method to detect intracranial aneurysms on DSA images is a meaningful task.

Methods

In this study, we proposed a two-stage convolutional neural network (CNN) architecture to automatically detect intracranial aneurysms on 2D-DSA images. In region localization stage (RLS), our detection system can locate a specific region to reduce the interference of the other regions. Then, in aneurysm detection stage (ADS), the detector could combine the information of frontal and lateral angiographic view to identify intracranial aneurysms, with a false-positive suppression algorithm.

Results

Our study was experimented on posterior communicating artery (PCoA) region of internal carotid artery (ICA). The data set contained 241 subjects for model training, and 40 prospectively collected subjects for testing. Compared with the classical DIP method which had an accuracy of 62.5% and an area under curve (AUC) of 0.69, the proposed architecture could achieve accuracy of 93.5% and the AUC of 0.942. In addition, the detection time cost of our method was about 0.569 s, which was one hundred times faster than the classical DIP method of 62.546 s.

Conclusion

The results illustrated that our proposed two-stage CNN-based architecture was more accurate and faster compared with the existing research studies of classical DIP methods. Overall, our study is a demonstration that it is feasible to assist physicians to detect intracranial aneurysm on DSA images using CNN.

Differential Subsampling with Cartesian Ordering for Ultrafast High-Resolution MRA in the Assessment of Intracranial Aneurysms

BACKGROUND AND PURPOSE

We aimed to evaluate the feasibility of an ultrafast whole head contrast-enhanced MRA (CE-MRA) in morphometric assessment of intracranial aneurysms in comparison to routinely used time-of-flight (TOF)-MRA.

METHODS

In this prospective single institutional study, patients with known untreated intracranial aneurysm underwent MRA. Routine multislab TOF-MRA was obtained with a 3D voxel sizes of .6 × .6 × 1 (6-minute acquisition time). CE-MRA of whole head was obtained using Differential Subsampling with Cartesian Ordering (DISCO) and 2D Auto-calibrating Reconstruction for Cartesian imaging with a 3D voxel-sizes of .75 × .75 × 1 mm³ during a 6-second temporal resolution. Morphometric features of intracranial aneurysms, including size, aneurysm sac morphology, and the presence of intraluminal thrombosis, were assessed on both techniques. Statistical analysis was performed using a combination of Kappa test, Bland-Altman, and correlation coefficient analysis.

RESULTS

A total of 34 aneurysms in 28 patients were included. Aneurysm size measurements (mean ± SD) were similar between DISCO-MRA (4.1 ± 2.3 mm) and TOF-MRA (4.3 ± 2.8 mm) (P = .27). Bland-Altman analysis showed a mean difference of .4 mm and there was excellent correlation r = .91 (95% CI: .87-.96). In six aneurysms (17.6%), TOF-MRA was nonconfidant to exclude intraluminal thrombosis. In seven aneurysms (20%), TOF-MRA was unable or nonconfidant in depicting aneurysm sac morphology.

CONCLUSIONS

Described ultrafast high spatial-resolution MRA is superior to routinely used TOF-MRA in assessment of morphometric features of intracranial aneurysms, such as intraluminal thrombosis and aneurysm morphology, and is obtained in a fraction of the time (6 seconds).

Aneurysm morphology in patients with autosomal dominant polycystic kidney disease: A case-control study

PURPOSE

Approximately 8% of patients with autosomal dominant polycystic kidney disease (ADPKD) develop intracranial aneurysms. The reason for development of intracranial aneurysms in ADPKD patients might be related to interactions between the presence of hypertension and the basic mechanism underlying the disease, which leads to weakness of the connective tissue. In this study, we aimed to identify differences in aneurysm morphology between ADPKD patients and a location-matched set of controls.

METHODS

A total of 42 ADPKD patients and 49 control patients with 122 aneurysms were included. Aneurysm size, location, and morphology were evaluated by two neuroradiologists. Aneurysm morphology was classified into one of three groups: regular saccular, irregular saccular, and fusiform. Continuous variables were compared with chi-squared tests and categorical variables were compared with student's t-test.

RESULTS

When considering all patients, there was no significant difference in aneurysm morphology or size (4.5 ± 2.6 mm vs 5.4 ± 2.9 mm; p = 0.09) between the ADPKD and control group. In a subgroup analysis of medium and large aneurysms (n = 61), there was a significantly lower incidence of regular saccular aneurysms (28% vs. 56%; p = 0.03) and higher incidence of fusiform aneurysms (12% vs 0%; p = 0.03) in the ADPKD group compared to a control group.

CONCLUSION

When excluding categorically "small" aneurysms, there is a reduced incidence of regular saccular aneurysms and increased incidence of fusiform aneurysms in ADPKD patients compared to a control group. Further study of this population of patients is warranted to better understand their risks of aneurysm rupture and indications for treatment.

A Simple Scoring Model for Prediction of Rupture Risk of Anterior Communicating Artery Aneurysms

Background: The rupture risk of anterior communicating artery aneurysms (ACoAAs) has been known to be higher than that of aneurysms at other locations. Thus, the aim of this study is to investigate the clinical and morphological characteristics associated with risk factors for the rupture of ACoAAs.

Methods: In total, 361 consecutive patients with 361 ACoAAs between August 2011 and December 2017 were retrospectively reviewed. Patients and ACoAAs were divided into ruptured and unruptured groups. In addition to clinical characteristics, ACoAA characteristics were evaluated by CT angiography (CTA). A multiple logistic regression analysis was used to identify the independent risk factors associated with ACoAA rupture. The assignment score of these variables depends on the β coefficient. A receiver operating characteristic (ROC) curve analysis was used to calculate the optimal thresholds.

Results: The multiple logistic regression model revealed that A1 dominance [odds ratio (OR) 3.034], an irregular shape (OR 3.358), and an aspect ratio ≥1.19 (AR; OR 3.163) increased the risk of rupture, while cerebral atherosclerosis (OR 0.080), and mean diameters ≥2.48 mm (OR 0.474) were negatively correlated with ACoAA rupture. Incorporating these five factors, the ROC analysis revealed that the threshold value of the multifactors was one, the sensitivity was 88.3%, and the specificity was 66.0%.

Conclusions: The scoring model is a simple method that is based on A1 dominance, irregular shape, aspect ratio, cerebral atherosclerosis, and mean diameters from CTA and is of great value in the prediction of the rupture risk of ACoAAs.

Dynamic Volume Change Rate and Aspect Ratio Are Correlated to the Formation of an Irregular Morphology of Unruptured Intracranial Aneurysm

OBJECTIVE

The aim of this research was to study the factors influencing the formation of intracranial aneurysms with irregular morphology by observing the dynamic volume change rate of intracranial unruptured aneurysms and other aneurysm characteristics.

METHOD

Sixty-five unruptured intracranial aneurysms of 51 consecutive patients from 1 center were included in this study. All patients underwent a dual-source computed tomography electrocardiogram-gated 4-dimensional computed tomography angiography examination. The original data at the end of the scan were reconstructed, and 20 sets of data packages through a cardiac cycle with 5% interval were obtained. Data packages were processed by a 3-dimensional software workstation to obtain 20 sets of images and dynamic diagrams. The volume of each aneurysm in the 20 sets of images was measured, and the volume change was calculated by a specific formula. The other data features of the aneurysm such as aneurysm neck, aneurysm height, aspect ratio (AR), location at bifurcation, and clinical features such as age, sex, hypertension history, type 2 diabetes history, smoking history, family history, multiple aneurysm history, and subarachnoid hemorrhage history, were documented in detail. After single factor analysis data, logistic regression analysis of the meaningful indicator was conducted to study the predictive factors of irregular aneurysms.

RESULTS

Of the 65 aneurysms, 25 possessed an irregular shape and 40 were of regular shape; 51 were anterior circulatory aneurysms and 14 were posterior circulatory aneurysms. Single factor analysis showed that AR (P = 0.001), volume change rate (P = 0.002), and location of aneurysm at the bifurcation (P = 0.038) of the vessel were significantly correlated with irregular aneurysms, but not correlated with age, sex, hypertension history, type 2 diabetes history, smoking history, family history, multiple aneurysm history, and subarachnoid hemorrhage history. Multifactor analysis showed that volume change rate greater than 30% (P = 0.008; odds ratio, 6.934) and AR greater than 1.4 (P = 0.004; odds ratio, 8.258) were independent correlative factors of the formation of intracranial aneurysm with irregular shape.

CONCLUSION

The volume change rate and AR are independent correlative factors of the formation of intracranial aneurysm with irregular shape.

Quantification of hemodynamic irregularity using oscillatory velocity index in the associations with the rupture status of cerebral aneurysms

BACKGROUND

Complex and unstable flow patterns are reported to be associated with the rupture status of cerebral aneurysms, while their evaluation depends on qualitative analysis of streamlines of bloodflow. Oscillatory velocity index (OVI) is a hemodynamic parameter to quantify flow patterns. The aim of this study is to elucidate the associations between OVI and the rupture status of cerebral aneurysms.

METHODS

One hundred and twenty-nine ruptured and unruptured cerebral aneurysms were analyzed with computational fluid dynamics under pulsatile flow conditions. With the use of median value of OVI, all aneurysms were divided into high and low OVI groups. Statistical analysis was performed to compare rupture status, and morphological and hemodynamic parameters between the two groups.

RESULTS

The median value of OVI was 0.006. High OVI was more likely observed in ruptured aneurysms (P=0.028) and associated with irregular shape, complex flow patterns, and unstable flow patterns (P<0.001, respectively). In morphological parameters, maximum size, aspect, projection, size, and volume-to-ostium area ratios were significantly higher in the high OVI group (P<0.001, respectively). In hemodynamic parameters, wall shear stress and wall shear stress gradient were significantly lower, and oscillatory shear index and gradient oscillatory number were significantly higher in the high OVI group (P<0.001, respectively).

CONCLUSION

High OVI was associated with rupture status, and morphological and hemodynamic characteristics of ruptured aneurysms. These results indicate that OVI may serve as a valuable hemodynamic parameter for diagnosing rupture status and risks of aneurysms.

Impact of aneurysm shape on morbidity after clipping of unruptured intracranial aneurysms

BACKGROUND

Complex aneurysm shape is a predominant risk factor for aneurysm rupture but its impact on clinical outcome after clipping remains unclear. The objective of the present study was to compare complications and morbidity after clipping of unruptured single-sac aneurysms (SSAs) and aneurysms with multiple sacs (MSAs).

METHODS

A retrospective, single-center study was conducted for patients that were treated between 2010 and 2018. We analyzed surgical parameters, treatment-related complications, and morbidity, defined as any increase in the modified Rankin scale at 3-month follow-up.

RESULTS

We identified 101 patients (mean age: 52.9 ± 10.5 years) that underwent clipping for 57 SSAs and 44 MSAs. The two groups were comparable regarding aneurysm size and neck width. Clipping of MSAs was associated with a longer operation time (p = 0.008) and increased use of intraoperative indocyanine green (p = 0.016) than SSAs. Complications occurred more often in the MSA group (29.5%) than in the SSA group (14.0%; p = 0.057). Morbidity was significantly higher in the MSA group (20.5%) than in the SSA group (3.5%, p = 0.009). In the univariate analysis, the odds of morbidity were 7.1 times greater for MSAs than for SSAs (95% CI 1.4-34.7).

CONCLUSIONS

Morbidity after microsurgical clipping is significantly increased in MSAs as compared to SSAs. This may be attributed to a more difficult clip placement with stronger manipulation of the aneurysm dome and the surrounding brain tissue.

The role of inflammation and potential pharmacological therapy in intracranial aneurysms

Intracranial aneurysms remain important clinical concern. There is relatively low risk of rupture of symptomless aneurysms incidentally found in MRA or CTA performed due to other indications. Not all of the intracranial aneurysms should or can be treated with neurosurgery intervention or endovascular embolization. Clinical strategy for small, symptomless, unruptured aneurysms is still questionable. Mechanisms underlying aneurysms formation, progression and rupture are poorly understood. Inflammation is one of the factors suspected to participate in these processes. Therefore the aim of this manuscript is to present current state of knowledge about the role of inflammation in the formation and progression of intracranial aneurysms and in their rupture process. Current knowledge about possible pharmacological treatment of intracranial aneurysms will also be presented. Macrophages infiltration seems to participate in the formation of intracranial aneurysms. Inhibition of signals sent by macrophages may prevent the aneurysms formation. Inflammation present in the wall of the aneurysm seems to be also related to the aneurysm's rupture risk. However it does not seem to be the only cause of the degeneration, but it can be a possible target of drug therapy. Some preliminary studies in humans indicate the potential role of aspirin as a factor that decrease the level of inflammation and lower the risk of rupture of intracranial aneurysms. However further research including a greater number of subjects and a prospective randomized design are necessary to assess the role of aspirin in preventing strategy for small, symptomless, unruptured intracranial aneurysms.

Morphological parameters and anatomical locations associated with rupture status of small intracranial aneurysms

Characterization of the rupture risk factors for small intracranial aneurysms (SIAs, ≤5 mm) is clinically valuable. The present study aims to identify image-based morphological parameters and anatomical locations associated with the rupture status of SIAs. Two hundred and sixty-three patients with single SIAs (128 ruptured, 135 unruptured) were included, and six morphological parameters, including size, aspect ratio (AR), size ratio (SR), height–width ratio (H/W), flow angle (FA) and aneurysm width–parent artery diameter ratio, and the aneurysm locations were evaluated using three-dimensional geometry, and were used to identify a correlation with aneurysm rupture. Statistically significant differences were observed between ruptured and unruptured groups for AR, SR, H/W, FA, and aneurysm locations, from univariate analyses. Logistic regression analysis further revealed that AR (p = 0.034), SR (p = 0.004), H/W (p = 0.003), and FA (p < 0.001) had the strongest independent correlation with ruptured SIAs after adjustment for age, gender and other clinical risk factors. A future study on a larger SIA cohort need to establish to what extent the AR, SR, H/W and FA increase the risk of rupture in patients with unruptured SIAs in terms of absolute risks.

Current Perspectives in Imaging Modalities for the Assessment of Unruptured Intracranial Aneurysms: A Comparative Analysis and Review

BACKGROUND

Intracranial aneurysms (IAs) are pathologic dilatations of cerebral arteries. This systematic review summarizes and compares imaging techniques for assessing unruptured IAs (UIAs). This review also addresses their uses in different scopes of practice. Pathophysiologic mechanisms are reviewed to better understand the clinical usefulness of each imaging modality.

METHODS

A literature review was performed using PubMed with these search terms: "intracranial aneurysm," "cerebral aneurysm," "magnetic resonance angiography (MRA)," computed tomography angiography (CTA)," "catheter angiography," "digital subtraction angiography," "molecular imaging," "ferumoxytol," and "myeloperoxidase". Only studies in English were cited.

RESULTS

Since the development and improvement of noninvasive diagnostic imaging (computed tomography angiography and magnetic resonance angiography), many prospective studies and meta-analyses have compared these tests with gold standard digital subtraction angiography (DSA). Although computed tomography angiography and magnetic resonance angiography have lower detection rates for UIAs, they are vital in the treatment and follow-up of UIAs. The reduction in ionizing radiation and lack of endovascular instrumentation with these modalities provide benefits compared with DSA. Novel molecular imaging techniques to detect inflammation within the aneurysmal wall with the goal of stratifying risk based on level of inflammation are under investigation.

CONCLUSIONS

DSA remains the gold standard for preoperative planning and follow-up for patients with IA. Newer imaging modalities such as ferumoxytol-enhanced magnetic resonance imaging are emerging techniques that provide critical in vivo information about the inflammatory milieu within aneurysm walls. With further study, these techniques may provide aneurysm rupture risk and prediction models for individualized patient care.

Difference in aneurysm characteristics between ruptured and unruptured aneurysms in patients with multiple intracranial aneurysms

Background:

The risk of aneurysmal rupture is dependent upon numerous factors, however, there are inconsistencies in the results between studies, which may be due to confounding factors. This can be avoided by comparing the characteristics of ruptured and unruptured aneurysms within the same patient. We sought to analyze the aneurysm characteristics of patients with acute aneurysmal subarachnoid hemorrhage (SAH) and multiple intracranial aneurysms.

Methods:

We reviewed our prospectively maintained institutional database, between 01/10/2007 and 01/01/2017, for all patients with confirmed SAH and >1 aneurysm. We recorded the size, location, and morphology and calculated secondary geometric indices such as bottleneck factor and aspect ratio.

Results:

During the study period, a total of 694 patients with aneurysmal SAH were admitted to our institution. We identified 113 patients (74.3% female, average age 51.7 ± 12.3). The majority of patients had only one associate unruptured aneurysm (79.6%). The average unruptured aneurysm was 3.1 ± 1.5 mm and the average ruptured aneurysm was 5.7 ± 2.7 mm (P < 0.001). In the multivariate analysis, aneurysm location, aneurysm morphology, and size were independently associated with rupture. A complex aneurysm morphology was the strongest risk factor for rupture (OR, 29.27; 95% CI 14.33–59.78; P < 0.001) with size >7 mm (OR, 17.74; 95% CI 4.07–77.35; P < 0.001), and AcomA location also showing a strong independent association.

Conclusion:

Size plays an important part in determining rupture risk, however, other factors such as location and in particular morphology must also be considered. We believe that the introduction of vessel wall imaging will help to risk stratify aneurysms.

[Cerebral vascular syndrome of connective tissue dysplasia as a cause of subarachnoid hemorrhage in young patients]

AIM

To clarify the role of connective tissue dysplasia (CTD) in the development and course of intracranial arterial aneurysm (IAA) and arteriovenous malformation (AVM) in young patients.

MATERIAL AND METHODS

The first stage of the study was a prospective 7-year follow-up of 549 patients with CDT signs, aged from 18 to 45 years, mean 23.51±8.67 years. The first stage included a comparative analysis of clinical characteristics of patients with DST with asymptomatic pathology of cerebral vessels and patients with DST without this pathology. At the second stage, there was a comparative study in 2 groups of patients with symptomatic pathology of cerebral vessels (AAA and/or AVM): with CTD (n=58) and without CTD (n=135).

RESULTS

Symptomatic AAA and/or AVM were identified in 10.56% of young people with CTD including 37 patients with subarachnoid hemorrhages (SAH). The age of clinical manifestations was 25.55±8.13 years. Expressed manifestations of CTD were more frequent in the group of patients with cerebral vascular pathology compared to patients without CTD (p=0.008). The majority of patients had CTD manifestations of 3 or more systems, less than 2 systems were not involved, 12 patients had small abnormalities and/or malformations of the heart and other vessels. Hypertension, pathology of the vertebral arteries, skin, spine, veins, fully open Willis circle were independent risk factors for symptomatic pathology of cerebral vessels in patients with CTD. AVM and AAA in young patients with CTD compared with patients without CTD were characterized by the manifestation at an earlier age (25.55±8.13 years and 36.10±10.58 years, respectively; p=0.000), a more frequent combination with a fully open Willis circle (56.90 and 25.19%, respectively; df=1; p=0.000), more frequent multiple pathologies (15.52 and 4.44%, respectively, p=0.008), EAA in the posterior vascular bed (15.52 and 3.70%, respectively, p=0.004), SAH (63.79 and 35.56%, respectively, p=0.000) with lesser effects of general population risk factors.

CONCLUSION

EAA and AVM in patients with CTD are likely to be considered in the context of vascular syndrome of connective tissue dysmorphogenesis, and CTD as a factor of adverse prognosis of IAA and AVM.

The Size of Ruptured Intracranial Aneurysms : A 10-Year Series from a Single Center

PURPOSE

There is a controversy concerning the risk of rupture of small intracranial aneurysms. We sought to determine the size and morphological features of ruptured intracranial aneurysms.

MATERIAL AND METHODS

The hospital files and images from all patients referred during one decade (2007-2016) to a specialized neurovascular center were retrospectively reviewed. Neck diameter, fundus depth and width as well as neck width based on catheter angiography were measured. Aneurysm morphology was classified as either regular, lobulated, irregular or fusiform.

RESULTS

A total of 694 consecutive patients with aneurysmal subarachnoid hemorrhage (aSAH) were identified (65.9% female, median age 54.3 years). The anterior communicating artery (AcomA) was the most frequent location of ruptured aneurysms. The medians for aneurysm depth, width and neck diameter were 5 mm, 4.5 mm and 3 mm, respectively. A regular contour of the aneurysm sac was found in 19%.

CONCLUSION

The majority of aSAH are caused by small intracranial aneurysms. There is no safety margin in terms of small aneurysm size of regular shape without daughter aneurysms. Treatment should also be offered to patients with small, regularly shaped intracranial aneurysms, together with an empirical risk-benefit assessment.

Bifurcation Location and Growth of Aneurysm Size Are Significantly Associated with an Irregular Shape of Unruptured Intracranial Aneurysms

BACKGROUND AND OBJECTIVE

Previous studies firmly proved that an irregular aneurysmal shape was associated strongly with intracranial aneurysm (IA) rupture, but it is unclear how irregularly shaped IAs form. We aimed to identify the factors related to irregular shape of IAs.

METHODS

We retrospectively analyzed of consecutive patients evaluated or treated for IA at our institution from June 2015 to July 2016. According to the imaging morphology of aneurysm, the enrolled patients were divided into irregular and regular group. Demographic data and imaging data of the 2 groups were compared to identify the factors related to aneurismal irregular shape.

RESULTS

There were 429 aneurysms (180 irregular and 249 regular aneurysms), including 315 unruptured aneurysms and 114 ruptured aneurysms. Most unruptured aneurysms occurred in the internal carotid arteries (53.3%), anterior communicating artery (10.8%), and posterior communicating artery (10.8%), anterior cerebral artery (5.4%), middle cerebral artery (9.8%), and posterior circulation (9.8%). In univariate analysis, for unruptured aneurysm, irregular aneurysmal shape was significantly related to aneurysm size (P = 0.009), aspect ratio (P = 0.003), size ratio (P = 0.002), and location at the bifurcation (P = 0.009) but not with smoking status, hypertension, hyperlipidemia, or diabetes mellitus. In multivariate logistic analysis, irregular aneurysms occurred mainly in unruptured aneurysms with a larger size (diameter ≥5 mm; odds ratio [OR] 2.106; 95% confidence interval [CI] 1.183-3.749; P = 0.011); location at a bifurcation (OR 2.017; 95% CI 1.191-3.413; P = 0.006), and aspect ratio (≥0.8; OR 4.992; 95% CI 1.318-18.915; P = 0.018).

CONCLUSIONS

Location at a bifurcation, an increased aneurysm size, and greater aspect ratio are significant independent factors associated with an irregular shape in unruptured IAs but not with smoking status, hypertension, hyperlipidemia, or diabetes mellitus.