Growth and Rupture Risk of Small Unruptured Intracranial Aneurysms: A Systematic Review

Rupture risk of intracranial aneurysms: Comparison between small ruptured intracranial aneurysms and large unruptured intracranial aneurysms

To compare the differences in clinical and morphological features between small ruptured intracranial aneurysms and large unruptured intracranial aneurysms to evaluate the risk factors for the rupture of IAs. The clinical data of 189 consecutive patients with 193 IAs were reviewed. The patients and IAs were divided into ruptured (<5 mm) and unruptured groups (>10 mm). The characteristics of the patients and the intracranial aneurysms (IAs) were compared between the 2 groups, and the risk factors for rupture of IAs were assessed using multiple logistic regression. Patient age (odds ratio [OR], 0.955), IA located at the internal carotid artery (ICA, OR, 0.202), irregular shape (OR, 0.083) and parent vessel diameter (OR, 0.426) were negatively correlated with the risk of IA rupture. IAs located at bifurcations (OR, 6.766) were positively correlated with the risk of IA rupture. In addition to the size of the IAs, regardless of IAs shape, other factors, such as younger age (<63.5 years), location at a bifurcation, IAs located at the ICA and a small parent vessel diameter (<3.25 mm), can influence the risk of IA rupture.

Dimethyl fumarate treatment for unruptured intracranial aneurysms: a study protocol for a double-blind randomised controlled trial

INTRODUCTION

Intracranial aneurysm (IA) is a common cerebrovascular disease. Considering the risks and benefits of surgery, a significant proportion of patients with unruptured IA (UIA) choose conservative observation. Previous studies suggest that inflammation of aneurysm wall is a high-risk factor of rupture. Dimethyl fumarate (DMF) acts as an anti-inflammatory agent by activating nuclear factor erythroid 2-related factor 2 (Nrf2) and other pathways. Animal experiments found DMF reduces the formation and rupture of IAs. In this study, DMF will be evaluated for its ability to reduce inflammation of the aneurysm wall in high-resolution vessel wall imaging.

METHODS AND ANALYSIS

This is a multi-centre, randomised, controlled, double-blind clinical trial. Three hospitals will enrol a total of 60 patients who have UIA with enhanced wall. Participants will be assigned randomly in a 1:1 proportion, taking either 240 mg DMF or placebo orally every day for 6 months. As the main result, aneurysm wall enhancement will be measured by the signal intensity after 6 months of DMF treatment. Secondary endpoints include morphological changes of aneurysms and factors associated with inflammation. This study will provide prospective data on the reduction of UIA wall inflammation by DMF.

ETHICS AND DISSEMINATION

This study has been approved by Medical Ethics Committee of the Beijing Tiantan Hospital, Capital Medical University (approval no: KY2022-064-02). We plan to disseminate our research findings through peer-reviewed journal publication and relevant academic conferences.

TRIAL REGISTRATION NUMBER

NCT05959759.

Prediction of small intracranial aneurysm rupture status based on combined Clinical-Radiomics model

Background

Accumulating small unruptured intracranial aneurysms are detected due to the improved quality and higher frequency of cranial imaging, but treatment remains controversial. While surgery or endovascular treatment is effective for small aneurysms with a high risk of rupture, such interventions are unnecessary for aneurysms with a low risk of rupture. Consequently, it is imperative to accurately identify small aneurysms with a low risk of rupture. The purpose of this study was to develop a clinically practical model to predict small aneurysm ruptures based on a radiomics signature and clinical risk factors.

Methods

A total of 293 patients having an aneurysm with a diameter of less than 5 mm, including 199 patients (67.9 %) with a ruptured aneurysm and 94 patients (32.1 %) without a ruptured aneurysm, were included in this study. Digital subtraction angiography or surgical treatment was required in all cases. Data on the clinical risk factors and the features on computed tomography angiography images associated with the aneurysm rupture status were collected simultaneously. We developed a clinical-radiomics model to predict aneurysm rupture status using multivariate logistic regression analysis. The combined clinical-radiomics model was constructed by nomogram analysis. The diagnostic performance, clinical utility, and model calibration were evaluated by operating characteristic curve analysis, decision curve analysis, and calibration analysis.

Results

A combined clinical-radiomics model (Area Under Curve [AUC], 0.85; 95 % confidence interval [CI], 0.757-0.947) showed effective performance in the operating characteristic curve analysis. In the validation cohort, the performance of the combined model was better than that of the radiomics model (AUC, 0.75; 95 % CI, 0.645-0.865; Delong's test p-value = 0.01) and the clinical model (AUC, 0.74; 95 % CI, 0.625-0.851; Delong's test p-value <0.01) alone. The results of the decision curve, nomogram, and calibration analyses demonstrated the clinical utility and good fitness of the combined model.

Conclusion

Our study demonstrated the effectiveness of a clinical-radiomics model for predicting rupture status in small aneurysms.

A deep learning framework for intracranial aneurysms automatic segmentation and detection on magnetic resonance T1 images

OBJECTIVES

To design a deep learning-based framework for automatic segmentation and detection of intracranial aneurysms (IAs) on magnetic resonance T1 images and test the robustness and performance of framework.

METHODS

A retrospective diagnostic study was conducted based on 159 IAs from 136 patients who underwent the T1 images. Among them, 127 cases were randomly selected for training and validation, and 32 cases were used to assess the accuracy and consistency of our algorithm. We developed and assembled three convolutional neural networks for the segmentation and detection of IAs. The segmentation and detection performance of the model were compared with the ground truth, and various metrics were calculated at the voxel level, IAs level, and patient level to show the performance of our framework.

RESULTS

Our assembled model achieved overall Dice, voxel-level sensitivity, specificity, balanced accuracy, and F1 score of 0.802, 0.874, 0.9998, 0.937, and 0.802, respectively. A coincidence greater than 0.7 between the aneurysms predicted by the model and the ground truth was considered as a true positive. For IAs detection, the sensitivity reached 90.63% with 0.58 false positives per case. The volume of IAs segmented by our model showed a high agreement and consistency with the volume of IAs labeled by experts.

CONCLUSION

The deep learning framework is achievable and robust for IAs segmentation and detection. Our model offers more clinical application opportunities compared to digital subtraction angiography (DSA)-based, CTA-based, and MRA-based methods.

CLINICAL RELEVANCE STATEMENT

Our deep learning framework effectively detects and segments intracranial aneurysms using clinical routine T1 sequences, showing remarkable effectiveness and offering great potential for improving the detection of latent intracranial aneurysms and enabling early identification.

KEY POINTS

•There is no segmentation method based on clinical routine T1 images. Our study shows that the proper deep learning framework can effectively localize the intracranial aneurysms. •The T1-based segmentation and detection method is more universal than other angiography-based detection methods, which can potentially reduce missed diagnoses caused by the absence of angiography images. •The deep learning framework is robust and has the potential to be applied in a clinical setting.

Microsurgical clipping of unruptured intracranial aneurysms by a single surgeon's experience: why should we preserve the neurosurgical skills in our health areas?

BACKGROUND

The long-standing comparison between the endovascular and microsurgical treatment is still ongoing. While not any center avails of a neuroendovascular service, and not every aneurysm is suitable for endovascular treatment, the neurovascular technique is slowly disappearing from our territories, whereas in the current literature, the role of the neurosurgical treatment is being re-appreciated. The aim of this paper was to discuss a single surgeon's clinical and radiological results with the microsurgical management of unruptured intracranial aneurysms (UIA).

METHODS

We retrospectively reviewed the clinical and radiological records of patients treated for UIA, by a single surgeon, in the period ranging between 2015 and 2019. We recorded all the relevant anatomic features of the aneurysm, saliencies of the surgical treatment, such as the need for temporary clipping, intraoperative rupture, or postoperative complications. The results of the clinical and radiological follow-up examinations were recorded either.

RESULTS

Fifty-eight patient undergoing microsurgical clipping were included, harboring a total of 65 UIAs. CTA with 3D reconstructions was sufficient to reach a reliable preoperative planning in 46 patients (76%). A total of 94% of the cases were unchanged or neurologically unremarkable at follow-up. The presence of postoperative complications was associated to the neck size and predictor of a longer hospitalizations, as well as longer hospitalizations are associated to the patients' age, size of the aneurysms and surgical times.

CONCLUSIONS

According to our experience, we believe that microsurgical clipping plays a critical role in the management of UIA, also on the ground of the encouraging results of the relevant literature.

Anterior inferior cerebellar artery aneurysm with proximal parent artery stenosis: A case report

Hemodynamic factors are associated with the progression of cerebral aneurysms. We report a 78-year-old woman with an anterior inferior cerebellar artery aneurysm and proximal stenosis of the anterior inferior cerebellar and basilar arteries. The aneurysm exhibited growth on annual follow-up imaging. Aneurysmal rupture occurred 4 years after diagnosis. Coil embolization resulted in aneurysm occlusion with parent artery preservation. Aneurysms adjacent to a more proximal region of severe stenosis in the parent vessel should be considered at high risk for growth or rupture. Such aneurysms require careful monitoring. Particular attention should be paid to posterior circulation aneurysms that occur at anatomically vulnerable sites.

Is oral Streptococcus mutans with collagen-binding protein a risk factor for intracranial aneurysm rupture or formation?

OBJECTIVE

Streptococcus mutans (SM) with the collagen-binding protein Cnm is a unique member of the oral resident flora because it causes hemorrhagic vascular disorders. In the multicenter study, we examined the relationship between Cnm-positive SM (CP-SM) and intracranial aneurysm (IA) rupture, which remains unknown.

METHODS

Between May 2013 and June 2018, we collected whole saliva samples from 431 patients with ruptured IAs (RIAs) and 470 patients with unruptured IAs (UIAs). Data were collected on age, sex, smoking and drinking habits, family history of subarachnoid hemorrhage, aneurysm size, number of teeth, and comorbidities of lifestyle disease.

RESULTS

There was no difference in the positivity rate of patients with CP-SM between the patients with RIAs (17.2%) and those with UIAs (19.4%). The rate of positivity for CP-SM was significantly higher in all IAs <5 mm than in those ≥10 mm in diameter (P=0.0304). In the entire cohort, the rate of positivity for CP-SM was lower in larger aneurysms than in smaller aneurysms (P=0.0393).

CONCLUSIONS

The rate of positivity for CP-SM was lower among patients with large UIAs. These findings are consistent with the hypothesis that CP-SM plays a role in the formation of vulnerable IAs that tend to rupture before becoming larger.

Safety and efficacy of dual antiplatelet drugs for stent-assisted embolization on risk of stroke and prognosis in patients with ruptured intracranial aneurysms: One center results of CIAP-5 clinical trial

BACKGROUND

Although stent-assisted coiling embolization (SAC) has been associated with a higher risk of ischemic and hemorrhagic complications, the use of SAC continues to rise for treating ruptured intracranial aneurysms (RIAs). This study aims to assess the safety and effectiveness of dual antiplatelet therapy (DAPT) in the context of RIAs.

METHODS

We conducted a retrospective analysis at a single center, involving patients with aneurysmal subarachnoid hemorrhage (aSAH) between May 1, 2017 and December 31, 2021. Patients were categorized into two groups: the SAC group and the non-SAC (NSC) group. Patients in the SAC group received DAPT. We compared modified Rankin Scale (mRS) score, along with hemorrhagic and ischemic complications, between the two groups to evaluate the safety and efficacy of DAPT for SAC.

RESULTS

The study included a total of 541 patients, of whom 38 (7.0%) experienced hemorrhagic complications and 48 (8.9%) developed ischemic complications. Additionally, 99 (18.3%) and 84 (15.5%) had poor clinical outcomes at discharge and 6 months, respectively. However, no statistically significant differences were observed between the two groups. Our analysis revealed that aneurysm location in the posterior circulation was a significant risk factor for an unfavorable prognosis when antiplatelet drugs were used following SAC (p = 0.025).

CONCLUSIONS

Administering antiplatelet drugs after SAC for RIAs has demonstrated both safety and effectiveness. However, caution should be exercised when considering this treatment strategy for RIAs located in the posterior circulation due to the potentially elevated risk.

Dynamic evaluation of unruptured intracranial aneurysms by 4D-CT angiography: comparison with digital subtraction angiography (DSA) and surgical findings

BACKGROUND

This study was to prospectively investigate the feasibility of four-dimensional computed tomography angiography (4D-CTA) with electrocardiogram-gated (ECG) reconstruction for preoperative evaluation of morphological parameters, and compared with digital subtraction angiography (DSA). We also aimed to detect pulsation in unruptured intracranial aneurysms (UIAs) by using 4D-CTA, as a potential predicting factor of growth or rupture.

MATERIALS

64 patients with 64 UIAs underwent ECG-gated dynamic 4D-CTA imaging before treatment, of which 46 patients additionally underwent DSA. Original scanning data were reconstructed to produce 20 data sets of cardiac cycles with 5%-time intervals. The extent of agreement on UIAs morphological features assessed with 4D-CTA and DSA was estimated using the k coefficient of the Kappa test. The radiation doses were also calculated and compared between 4D-CTA and DSA. In the aneurysmal surgically treated in our institution, we were able to compare the surgical findings of the aneurysm wall with 4D-CTA images. We performed long-term follow-up on untreated patients.

RESULTS

The morphological characteristics detected by 4D-CTA and DSA were consistent in aneurysm location (k = 1.0), shape (k = 0.76), maximum diameter (k = 0.94), aneurysm neck (k = 0.79) and proximity to parent and branch vessels (k = 0.85). 4D-CTA required lower radiation doses (0.32 ± 0.11 mSv) than DSA (0.84 ± 0.37 mSv, P < 0.001). Pulsation was detected in 26 of the 64 unruptured aneurysms, and all underwent neurosurgical clipping or interventional embolization. In aneurysms surgically treated in our hospital, we observed a significant correlation between 4D-CTA findings and surgical evaluation of the aneurysmal wall, in particular the irregular pulsations detected on 4D-CTA have demonstrated to correspond to dark-reddish thinner wall at surgery.

CONCLUSIONS

In this proof-of-concept study, 4D-CTA provided real-time, non-invasive preoperative assessments of UIAs comparable to DSA. Moreover, optimal correlation between the irregular pulsation detected by 4D-CTA and the surgical findings support a possible role of this technique to identify aneurysms with a higher risk of rupture.

American College of Radiology Appropriateness Criteria®: a bibliometric analysis of panel members

OBJECTIVE

To assess the features of panel members involved in the writing of the ACR-AC and identify alignment with research output and topic-specific research publications.

METHODS

A cross-sectional analysis was performed on the research output of panel members of 34 ACR-AC documents published in 2021. For each author, we searched Medline to record total number of papers (P), total number of ACR-AC papers (C) and total number of previously published papers that are relevant to the ACR-AC topic (R).

RESULTS

Three hundred eighty-three different panel members constituted 602 panel positions for creating 34 ACR-AC in 2021 with a median panel size of 17 members. Sixty-eight (17.5%) of experts had been part of ≥10 previously published ACR-AC papers and 154 (40%) were members in ≥ 5 published ACR-AC papers. The median number of previously published papers relevant to the ACR-AC topic was 1 (IQR: 0-5). 44% of the panel members had no previously published paper relevant to the ACR-AC topic. The proportion of ACR-AC papers (C/P) was higher for authors with ≥ 5 ACR-AC papers (0.21) than authors with < 5 ACR-AC papers (0.11, p < 0.0001); however, proportion of relevant papers per topic (R/P) was higher for authors with < 5 ACR-AC papers (0.10) than authors with ≥ 5 ACR-AC papers (0.07).

CONCLUSION

The composition of the ACR Appropriateness Criteria panels reflects many members with little or no previously published literature on the topic of consideration. Similar pool of experts exists on multiple expert panels formulating imaging appropriateness guidelines.

KEY POINTS

There were 68 (17.5%) panel experts on ≥ 10 ACR-AC panels. Nearly 45% of the panel experts had zero median number of relevant papers. Fifteen panels (44%) had > 50% of members having zero relevant papers.

Malpractice Litigation Related to Diagnosis and Treatment of Intracranial Aneurysms

BACKGROUND AND PURPOSE

Approaches to management of intracranial aneurysms are inconsistent, in part due to apprehension relating to potential malpractice claims. The purpose of this article was to review the causes of action underlying medical malpractice lawsuits related to the diagnosis and management of intracranial aneurysms and to identify the factors associated and their outcomes.

MATERIALS AND METHODS

We consulted 2 large legal databases in the United States to search for cases in which there were jury awards and settlements related to the diagnosis and management of patients with intracranial aneurysms in the United States. Files were screened to include only those cases in which the cause of action involved negligence in the diagnosis and management of a patient with an intracranial aneurysm.

RESULTS

Between 2000 and 2020, two hundred eighty-seven published case summaries were identified, of which 133 were eligible for inclusion in the analysis. Radiologists constituted 16% of 159 physicians sued in these lawsuits. Failure to diagnose was the most common medical malpractice claim referenced (100/133 cases), with the most common subgroups being "failure to include cerebral aneurysm as a differential and thus perform adequate work-up" (30 cases), and "failure to correctly interpret aneurysm evidence on CT or MR imaging" (16 cases). Only 6 of these 16 cases were adjudicated at trial, with 2 decided in favor of the plaintiff (awarded $4,000,000 and $43,000,000, respectively).

CONCLUSIONS

Incorrect interpretation of imaging is relatively infrequent as a cause of malpractice litigation compared with failure to diagnose aneurysms in the clinical setting by neurosurgeons, emergency physicians, and primary care providers.

Rupture discrimination of multiple small (< 7 mm) intracranial aneurysms based on machine learning-based cluster analysis

BACKGROUND

Small multiple intracranial aneurysms (SMIAs) are known to be more prone to rupture than are single aneurysms. However, specific recommendations for patients with small MIAs are not included in the guidelines of the American Heart Association and American Stroke Association. In this study, we aimed to evaluate the feasibility of machine learning-based cluster analysis for discriminating the risk of rupture of SMIAs.

METHODS

This multi-institutional cross-sectional study included 1,427 SMIAs from 660 patients. Hierarchical cluster analysis guided patient classification based on patient-level characteristics. Based on the clusters and morphological features, machine learning models were constructed and compared to screen the optimal model for discriminating aneurysm rupture.

RESULTS

Three clusters with markedly different features were identified. Cluster 1 (n = 45) had the highest risk of subarachnoid hemorrhage (SAH) (75.6%) and was characterized by a higher prevalence of familiar IAs. Cluster 2 (n = 110) had a moderate risk of SAH (38.2%) and was characterized by the highest rate of SAH history and highest number of vascular risk factors. Cluster 3 (n = 505) had a relatively mild risk of SAH (17.6%) and was characterized by a lower prevalence of SAH history and lower number of vascular risk factors. Lasso regression analysis showed that compared with cluster 3, clusters 1 (odds ratio [OR], 7.391; 95% confidence interval [CI], 4.074-13.150) and 2 (OR, 3.014; 95% CI, 1.827-4.970) were at a higher risk of aneurysm rupture. In terms of performance, the area under the curve of the model was 0.828 (95% CI, 0.770-0.833).

CONCLUSIONS

An unsupervised machine learning-based algorithm successfully identified three distinct clusters with different SAH risk in patients with SMIAs. Based on the morphological factors and identified clusters, our proposed model has good discrimination ability for SMIA ruptures.

Optimal Cost-Effective Screening Strategy for Unruptured Intracranial Aneurysms in Female Smokers

BACKGROUND

The prevalence of intracranial aneurysms among female cigarette smokers was shown to be high in previous studies, yet the cost-effectiveness of screening them has never been explored.

OBJECTIVE

To explore the most cost-effective screening strategy for female smokers.

METHODS

A decision analytical study was performed with a Markov model to compare different screening strategies with no screening and to explore the most optimal screening strategy for female smokers. Input data for the model were extracted from literature. A single screening at different ages and multiple screening every 15 years, 10 years, 5 years, and 2 years were performed for female smokers in different age ranges. Deterministic and probabilistic sensitivity analyses were performed to evaluate the robustness of the model. Finally, value of information analysis was performed to investigate the value of collecting additional data.

RESULTS

Screening female smokers for unruptured intracranial aneurysm is cost-effective. All screening strategies yield extra quality-adjusted life years. Screening at younger age brings more health benefit at lower cost. Frequent screening strategies decrease rupture rate of aneurysms more with higher costs per quality-adjusted life year. Screening after age 70 years and frequent screening (every 2 years) after age 60 years is not optimal. Among all the parameters in the model, collecting additional data on utility of the unscreened population would be most valuable.

CONCLUSION

Screening female smokers for intracranial aneurysms once at younger age is most optimal. However, in clinical practice, the duration and intensity of exposure to cigarettes should be taken into consideration.

Stent-assisted coiling vs. coiling alone of ruptured tiny intracranial aneurysms: A contemporary cohort study in a high-volume center

Objective

This study aims to compare the safety and efficacy of stent-assisted coiling (SAC) with those of coiling alone (CA) for the treatment of ruptured tiny intracranial aneurysms.

Methods

We enrolled 245 patients with ruptured tiny intracranial aneurysms treated with coil embolization. Patients were grouped into SAC and CA groups. Baseline characteristics, periprocedural complications, clinical outcomes, and angiographic results were compared between the two groups. In addition, a subgroup analysis was conducted in the SAC group, and patients were regrouped into low-profile visualized intraluminal support (LVIS) and laser-cut groups to compare the perioperative procedure-related complications and clinical and angiographic follow-up outcomes.

Results

All baseline characteristics were equivalent between the two groups except for aneurysm size and dome-to-neck aspect ratio. The rates of overall procedure-related complications, intraprocedural rupture, postoperative early rebleeding, intraprocedural thrombosis, postprocedural thrombosis, and procedure-related mortality were comparable between the two groups (P = 0.105, 0.145, 0.308, 1.000, 1.000, 0.160, respectively). Nevertheless, the rate of hemorrhagic complication in the SAC group was significantly higher (P = 0.023). The angiographic follow-up outcomes showed that the SAC group had a higher complete occlusion rate and lower recurrence rate (88.2 vs. 67.1%, 5.4 vs. 15.2%, P = 0.001). The clinical outcomes at discharge and follow-up between the two groups demonstrated no significant differences (P = 0.192 and P = 0.085, respectively). For subgroup analysis, LVIS stents were associated with a significantly higher rate of complete occlusion (P = 0.014) and a lower rate of intraprocedural rupture (p = 0.021). Moreover, multivariate analysis showed that there were no predictors for the overall, hemorrhagic, and ischemic procedure-related complications, while Raymond class was an independent predictor of retreatment (OR = 3.508, 95% CI 1.168-11.603; P = 0.029).

Conclusion

Stent-assisted coiling may increase the incidence of hemorrhagic events with favorable angiographic results and comparable clinical outcomes compared with stand-alone coiling. Nevertheless, LVIS stent could improve the safety compared with lazer-cut stent. Simultaneously, considering the better long-term effect, LVIS stent-assisted coiling may be a preferable choice for ruptured tiny intracranial aneurysms.

Neuroform atlas stent-assisted coiling of tiny wide-necked intracranial aneurysms

Objective

To investigate the safety and efficacy of Neuroform Atlas stent-assisted coiling for the treatment of tiny wide-necked intracranial aneurysms and evaluate risk factors associated with procedure-related complications.

Methods

We retrospectively examined 46 patients with 46 tiny wide-necked aneurysms who were treated using Atlas stent-assisted coiling at our institution from August 2020 to May 2022. Patient and aneurysm characteristics, procedural details, procedure-related complications, and angiographic and clinical outcomes were analyzed.

Results

A total of 10 patients presented with aneurysmal rupture. Atlas stent placement was successful in all patients. Angiography immediately after the procedure showed complete occlusion in 38 patients (82.6%), neck remnant in 7 (15.2%), and partial occlusion in 1 (2.2%). The mean angiographic follow-up was 8.4 months (range, 6–16). At the last follow-up, angiography showed complete occlusion in 41 patients (89.1%) and neck remnant in 5 (10.9%). No aneurysm recurrence or in-stent stenosis occurred. Incidence of procedure-related complications was 10.8% (intraprocedural aneurysm rupture, two cases; acute thrombosis, two cases; and coil migration, one case); only one patient (2.2%) experienced procedural neurological morbidity. The mean clinical follow-up was 9.7 months. A favorable outcome was achieved in 45 patients (97.8%). In univariate logistic regression analysis, aneurysm size (odds ratio, 4.538; P = 0.045) was significantly associated with procedure-related complications. However, multivariate analysis found no independent risk factors.

Conclusion

Atlas stent-assisted coiling of tiny wide-necked intracranial aneurysms is feasible and effective. Outcomes and occlusion rates are favorable and morbidity is low. The complication rate may be higher in larger tiny aneurysms.

Cost-effectiveness analysis on small (< 5 mm) unruptured intracranial aneurysm follow-up strategies

OBJECTIVE

Unruptured intracranial aneurysms are frequently detected during routine clinical diagnostic processes. A significant portion are small aneurysms less than 5 mm in diameter. While follow-up of patients with small aneurysms has been advocated, the cost-effectiveness of such care and the optimal follow-up interval remain unknown. This study aimed to explore the most cost-effective follow-up interval for small (< 5 mm) unruptured intracranial aneurysms.

METHODS

A decision analysis study was performed using a Markov model with Monte Carlo simulations to simulate patients undergoing follow-up by MRA at different time intervals (1-, 2-, 3-, 5-, and 7-year intervals) for small (< 5 mm) unruptured intracranial aneurysms. Input data for the model were extracted from the current literature, primarily meta-analyses. Probabilistic and deterministic sensitivity analyses were performed to evaluate the robustness of the model.

RESULTS

Given the current literature and the model in this study, following up every 2 years with noninvasive imaging is the most cost-effective strategy (cost $126,996, effectiveness 21.9 quality-adjusted life-years), showing the highest net monetary benefit. The conclusion remains robust in probabilistic and deterministic sensitivity analyses. As the annual growth risk of small aneurysms and annual rupture risk of growing aneurysms increase, following up every year is optimal. When the cost for follow-up with MRA is less than $2223, following up every year is cost-effective.

CONCLUSIONS

The most cost-effective follow-up strategy for small (< 5 mm) unruptured aneurysms using MRA is following up every 2 years. More frequent follow-up strategies or prompt preventive treatment would be more appropriate in patients with higher risk factors for growth and aneurysm rupture.

Protocol and Preliminary Results of the Establishment of Intracranial Aneurysm Database for Artificial Intelligence Application Based on CTA Images

Background and Purpose

Unruptured intracranial aneurysms (UIAs) are increasingly being detected in clinical practice. Artificial intelligence (AI) has been increasingly used to assist diagnostic techniques and shows encouraging prospects. In this study, we reported the protocol and preliminary results of the establishment of an intracranial aneurysm database for AI application based on computed tomography angiography (CTA) images.

Methods

Through a review of picture archiving and communication systems, we collected CTA images of patients with aneurysms between January 2010 and March 2021. The radiologists performed manual segmentation of all diagnosed aneurysms on subtraction CTA as the basis for automatic aneurysm segmentation. Then, AI will be applied to two stages of aneurysm treatment, namely, automatic aneurysm detection and segmentation model based on the CTA image and the aneurysm risk prediction model.

Results

Three medical centers have been included in this study so far. A total of 3,190 cases of CTA examinations with 4,124 aneurysms were included in the database. All identified aneurysms from CTA images that enrolled in this study were manually segmented on subtraction CTA by six readers. We developed a structure of 3D-Unet for aneurysm detection and segmentation in CTA images. The algorithm was developed and tested using a total of 2,272 head CTAs with 2,938 intracranial aneurysms. The recall and false positives per case (FP/case) of this model for detecting aneurysms were 0.964 and 2.01, and the Dice values for aneurysm segmentation were 0.783.

Conclusion

This study introduces the protocol and preliminary results of the establishment of the intracranial aneurysm database for AI applications based on CTA images. The establishment of a multicenter database based on CTA images of intracranial aneurysms is the basis for the application of AI in the diagnosis and treatment of aneurysms. In addition to segmentation, AI should have great potential for aneurysm treatment and management in the future.

A Meta-Analysis of Rupture Risk for Intracranial Aneurysms 10 mm or Less in Size Selected for Conservative Management Without Repair

BACKGROUND

Small unruptured intracranial aneurysms (UIAs) are considered to have low risk of rupture. The proportion of UIAs measuring 10 mm or less in size that rupture when selected for conservative management without repair is not well known. The aim of this study is to determine the proportion of UIAs that rupture by size threshold from ≤10 to ≤3 mm when selected for management without repair and to determine the level of precision and sources of heterogeneity in the rupture risk estimate.

METHODS

This study was prospectively registered with the International Prospective Register of Systematic Reviews (PROSPERO) (CRD42019121522). The Ovid MEDLINE, EMBASE, Web of Science Core Collection, and the Cochrane Central Register of Controlled Trials were searched (inception to August 2020). Studies with longitudinal follow-up of patients with UIAs ( ≤10 mm to ≤3 mm) without endovascular or neurosurgical repair were eligible. We included studies, which provided details of aneurysm size and in which UIA rupture was reported as an outcome. The primary outcome of the pooled proportion of UIA rupture during follow-up was synthesized with random-effects meta-analysis; heterogeneity was explored using meta-regression.

RESULTS

A total of 31 studies that included 13,800 UIAs ≤10 mm in size were eligible for data synthesis. The pooled proportion of ≤10 mm UIAs that ruptured when managed without repair was 1.1% (95% CI 0.8-1.5; I 2 = 52.9%) over 3.7 years. Findings were consistent in sensitivity analyses at all the size stratified thresholds including ≤5 and ≤3 mm; rupture occurred in 1.0% (95% CI 0.8-1.3; I 2 = 0%) of 7,280 ≤5 mm UIAs and 0.8% (95% CI 0.4-1.5; I 2 = 0%) of 1,228 ≤3 mm UIAs managed without repair. In higher quality studies with lower risk of bias, rupture occurred in 1.8% (95% CI 1.5-2.0; I 2 = 0%) over 3.9 years. In meta-regression, aneurysm size, shape, anatomical location, and exposure to prior subarachnoid hemorrhage were not identified as sources of heterogeneity.

CONCLUSION

For every 1,000 UIAs that are 10 mm or less in size and selected for conservative management without repair, between 8 and 15 UIAs are estimated to rupture over 3.7 years. When stratified by size, these pooled rupture risk estimates are consistent and clinically applicable for ≤5 mm UIAs selected for management without repair.

SYSTEMATIC REVIEW REGISTRATION

https://www.crd.york.ac.uk/prospero/, identifier: CRD42019121522.

Optimizing Small, Low-Risk, Unruptured Intracranial Aneurysm Treatment Using Game Theory

The incidental diagnosis of unruptured intracranial aneurysms has been increasing in the past several decades. A significant proportion represent small, low-risk, unruptured intracranial aneurysms for which there is equipoise on whether to offer treatment or conservative management. Given this uncertainty, patients may not always be comfortable with their physicians' recommendations. Herein, we use game theory to study the interactions between physicians and patients to determine how conflict and cooperation affect the management of small, low-risk, unruptured intracranial aneurysms. We constructed a game theory model of the interaction between physicians and patients with respect to decision-making for a small, low-risk, unruptured intracranial aneurysm in an asymptomatic patient when there is perceived equipoise between whether to treat or manage conservatively. Assuming that both the physician and patient are rational and eliciting individual patient preferences is not practical, the physician should play the game based on an ex ante probability of meeting a patient with a certain type of preference. This recommendation means that the expectations of the physician regarding the patient's preferences should guide the decision to offer treatment or conservative management as a first option for a small, asymptomatic, low-risk, unruptured intracranial aneurysm for which there is clinical equipoise.

Management of Unruptured Small Multiple Intracranial Aneurysms in China: A Comparative Effectiveness Analysis Based on Real-World Data

Background

Unruptured small aneurysms with a size of <7 mm were often followed conservatively. However, it is unknown whether unruptured small multiple intracranial aneurysms (MIAs) are better to be prophylactically treated or conservatively followed.

Objective

We aim to compare the effectiveness of different strategies regarding their management.

Methods

A decision-analytic Markov model was built over a entire life cycle. The compared strategies include natural history, treat one aneurysm, treat both aneurysms, annual follow-up, biennial follow-up, and follow-up every 5 years. The inputs for the model were obtained from real-world data and related medical literature. Outcomes were measured in terms of quality-adjusted life-years (QALYs).

Results

Treat both aneurysms had the highest effectiveness of 15.36 QALYs and treat one aneurysm had the second-highest effectiveness of 15.11 QALYs. Probabilistic sensitivity analysis with 10,000 iterations showed that treat both aneurysms and treat one aneurysm were optimal in 67.28 and 17.91% of all cases, respectively. One-way and two-way sensitivity analyses showed that the result was sensitive to the proportion of moderate to severe disability after treating two aneurysms, mortality after treating two aneurysms, proportion of moderate to severe disability after treating one aneurysm, and rupture rate of small growing aneurysm. Either treat both aneurysms or treat one aneurysm would be the optimal strategy under most of the circumstances with the variations of these parameters.

Conclusion

For patients with small unruptured MIAs, prophylactic coiling was superior to conservative management and at least one aneurysm should be treated.

Diagnosis and Treatment of Unruptured Intracranial Aneurysms and Aneurysmal Subarachnoid Hemorrhage

Unruptured intracranial aneurysms (UIAs) are commonly acquired vascular lesions that form an outpouching of the arterial wall due to wall thinning. The prevalence of UIAs in the general population is 3.2%. In contrast, an intracranial aneurysm may be manifested after rupture with classic presentation of a thunderclap headache suggesting aneurysmal subarachnoid hemorrhage (SAH). Previous consensus suggests that although small intracranial aneurysms (<7 mm) are less susceptible to rupture, aneurysms larger than 7 mm should be treated on a case-by-case basis with consideration of additional risk factors of aneurysmal growth and rupture. However, this distinction is outdated. The PHASES score, which comprises data pooled from several prospective studies, provides precise estimates by considering not only the aneurysm size but also other variables, such as the aneurysm location. The International Study of Unruptured Intracranial Aneurysms is the largest observational study on the natural history of UIAs, providing the foundation to the current guidelines for the management of UIAs. Although SAH accounts for only 3% of all stroke subtypes, it is associated with considerable burden of morbidity and mortality. The initial management is focused on stabilizing the patient in the intensive care unit with close hemodynamic and serial neurologic monitoring with endovascular or open surgical aneurysm treatment to prevent rebleeding. Since the results of the International Subarachnoid Aneurysm Trial, treatment of aneurysmal SAH has shifted from surgical clipping to endovascular coiling, which demonstrated higher odds of survival free of disability at 1 year after SAH. Nonetheless, aneurysmal SAH remains a public health hazard and is associated with high rates of disability and death.

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.

Atorvastatin and growth, rupture of small unruptured intracranial aneurysm: results of a prospective cohort study

Background and aims:

The role of statins in unruptured intracranial aneurysm (UIA) growth and rupture remains ambiguous. This study sought to determine whether atorvastatin is associated with aneurysm growth and rupture in patients harboring UIA <7 mm.

Methods:

This prospective, multicenter cohort study consecutively enrolled patients with concurrent UIA <7 mm and ischemic cerebrovascular disease from four hospitals between 2016 and 2019. Baseline and follow-up patient information was recorded. Because of the strong anti-inflammatory effect of aspirin, patients using aspirin were excluded. Patients taking atorvastatin 20 mg daily were atorvastatin users. The primary and exploratory endpoints were aneurysm rupture and growth, respectively.

Results:

Among the 1087 enrolled patients, 489 (45.0%) took atorvastatin, and 598 (55%) took no atorvastatin. After a mean follow-up duration of 33.0 ± 12.5 months, six (1.2%) and five (0.8%) aneurysms ruptured in atorvastatin and non-atorvastatin groups, respectively. In the adjusted multivariate Cox analysis, UIA sized 5 to <7 mm, current smoker, and uncontrolled hypertension were associated with aneurysm rupture, whereas atorvastatin [adjusted hazard ratio (HR) 1.495, 95% confidence interval (CI) 0.417–5.356, p = 0.537] was not. Of 159 patients who had follow-up imaging, 34 (21.4%) took atorvastatin and 125 (78.6%) took no atorvastatin. Aneurysm growth occurred in five (14.7%) and 21 (16.8%) patients in atorvastatin and non-atorvastatin groups (mean follow-up: 20.2 ± 12.9 months), respectively. In the adjusted multivariate Cox analysis, UIAs sized 5 to <7 mm and uncontrolled hypertension were associated with a high growth rate; atorvastatin (adjusted HR 0.151, 95% CI 0.031–0.729, p = 0.019) was associated with a reduced growth rate.

Conclusions:

We conclude atorvastatin use is associated with a reduced risk of UIA growth, whereas atorvastatin is not associated with UIA rupture.

Machine Learning-Based Prediction of Small Intracranial Aneurysm Rupture Status Using CTA-Derived Hemodynamics: A Multicenter Study

BACKGROUND AND PURPOSE

Small intracranial aneurysms are being increasingly detected while the rupture risk is not well-understood. We aimed to develop rupture-risk models of small aneurysms by combining clinical, morphologic, and hemodynamic information based on machine learning techniques and to test the models in external validation datasets.

MATERIALS AND METHODS

From January 2010 to December 2016, five hundred four consecutive patients with only small aneurysms (<5 mm) detected by CTA and invasive cerebral angiography (or surgery) were retrospectively enrolled and randomly split into training (81%) and internal validation (19%) sets to derive and validate the proposed machine learning models (support vector machine, random forest, logistic regression, and multilayer perceptron). Hemodynamic parameters were obtained using computational fluid dynamics simulation. External validation was performed in other hospitals to test the models.

RESULTS

The support vector machine performed the best with areas under the curve of 0.88 (95% CI, 0.85-0.92) and 0.91 (95% CI, 0.74-0.98) in the training and internal validation datasets, respectively. Feature ranks suggested hemodynamic parameters, including stable flow pattern, concentrated inflow streams, and a small (<50%) flow-impingement zone, and the oscillatory shear index coefficient of variation, were the best predictors of aneurysm rupture. The support vector machine showed an area under the curve of 0.82 (95% CI, 0.69-0.94) in the external validation dataset, and no significant difference was found for the areas under the curve between internal and external validation datasets (P = .21).

CONCLUSIONS

This study revealed that machine learning had a good performance in predicting the rupture status of small aneurysms in both internal and external datasets. Aneurysm hemodynamic parameters were regarded as the most important predictors.

Risk of Rupture of Small Intracranial Aneurysms (≤5 mm) Among the Chinese Population

OBJECTIVE

We sought to develop a model to predict the risk of small intracranial aneurysm (SIA; ≤5 mm) rupture among Chinese adults and to compare the score predicted by our model with the PHASES (population, hypertension, age, size, earlier subarachnoid hemorrhage, aneurysm site) score.

METHODS

From August 2011 to June 2015, 366 patients with 394 SIAs were retrospectively evaluated and followed up for ≥5 years. The clinical characteristics of the patients were reviewed from their medical records, and the SIA features were evaluated from the imaging studies. The independent risk factors for SIA rupture were studied using multiple Cox proportional hazards regression analysis. The diagnostic value of the PHASES score for the prediction of SIA rupture was also calculated.

RESULTS

Six SIAs in 6 different patients had ruptured during a mean follow-up of 6.4 years. An irregular shape (odds ratio [OR], 31.464), a high aspect ratio (OR, 40.573), and a high size ratio (OR, 20.541) increased the risk of rupture. The predictive score incorporated these three factors. The threshold was 1.5, and the area under the curve, sensitivity, and specificity were 0.986, 100%, and 94.6%, respectively. For the PHASES score, the area under the curve, sensitivity, and specificity were 0.702, 83.3%, and 62.1%, respectively.

CONCLUSIONS

An irregular shape, a high aspect ratio, and a high size ratio were associated with SIA rupture in the Chinese population. Our predictive score is of great value in predicting the risk of SIA rupture.

Current Management of Small Unruptured Intracranial Aneurysms in the United States: Results of a National Survey

OBJECTIVE

To understand how physicians in the United States manage patients with small unruptured intracranial aneurysms and factors that influence the management.

METHODS

An online survey questionnaire was designed through SurveyMonkey and distributed electronically to The Society of Interventional Surgery, American Association of Neurological Surgeons/Congress of Neurological Surgeons Joint Section of Cerebrovascular Surgery, American Academy of Neurology, and Massachusetts Neurologic Association. All participations were voluntary and anonymous.

RESULTS

Among all the participants, 53.8% of them were neurosurgeons, 33.0% were neurointerventional radiologists, and 13.2% were neurologists. For management of aneurysms 2-4 mm, 87.8% of respondents favored routine surveillance with imaging follow-up, 3.8% preferred routine treatment, and 8.5% recommended routine treatment or follow-up only for high risk patients. In total, 25.5% preferred annual follow-up, and 67.9% liked follow-up once in a year and then space out at various intervals. For aneurysms between 5 and 7 mm, 73.6% supported routine treatment, 20.8% favored surveillance with imaging follow-up, and 5.7% recommended treating or follow-up only high-risk groups. In total, 58.5% preferred annual follow-up, whereas 34.9% liked follow-up once in a year and then space out at various intervals. For routine follow-up, 64.1% of the physicians chose magnetic resonance angiography without contrast, and 40.6% preferred computed tomography angiography.

CONCLUSIONS

For aneurysms 2-4 mm, majority of the physicians preferred regular follow-up, whereas for aneurysms 5-7 mm, the majority favor treatment. There remains heterogeneity in practice among physicians in the United States regarding follow-up strategies for small unruptured aneurysms. Further studies are needed to evaluate the optimal management strategy, follow-up frequency and duration of imaging for small unruptured intracranial aneurysms.

Radiological surveillance of small unruptured intracranial aneurysms: a systematic review, meta-analysis, and meta-regression of 8428 aneurysms

With the widespread use of imaging techniques, the possibility that an asymptomatic unruptured intracranial aneurysm (UIA) is detected has increased significantly. There is no established consensus regarding follow-up, duration, and frequency of such imaging surveillance. The objectives of this study include assessing the growth rate and rupture risk of small (less than 7mm) UIAs, identifying associated risk factors and providing an aneurysm surveillance protocol in appropriately selected patients. Systematic searches of Medline, Embase, and Cochrane Central were undertaken from database inception to March 2020 for published studies reporting the growth and rupture risks of small UIAs. Twenty-one studies reporting 8428 small UIAs were included in our meta-analysis. The pooled mean age was 61 years (95% CI: 55-67). The mean follow-up period for growth and rupture ranged from 11 to 108 months, with the pooled mean follow-up period across 14 studies being 42 months (95% CI: 33-51). Pooled overall growth rate was 6.0% (95% CI: 3.8-8.7). Pooled growth rates for aneurysms < 5mm and < 3 mm were 5.2% (95% CI: 3.0-7.9) and 0.8% (95% CI: 0.0-6.1), respectively. Pooled overall rupture rate was 0.4% (95% CI: 0.2-0.7). From the meta-regression analysis, having multiple aneurysms, smoking, hypertension, and personal history of SAH did not significantly predict growth, and a personal history of SAH, smoking, hypertension, and multiple aneurysms were not statistically significant predictors of rupture. Our findings suggest that small UIAs have low growth and rupture rates and very small UIAs have little or no risk for rupture. In the setting of incidental small UIAs, patients with multiple and/or posterior circulation aneurysms require more regular radiological monitoring.

Characteristics of patients with ruptured very small intracranial aneurysm sized less than 3 mm

Objective

If the size of an intracranial aneurysm is below 3 mm, clinicians rarely treat them because of the low risk of rupture. But subarachnoid hemorrhage (SAH) due to the rupture of very small intracranial aneurysm (VSIA) (saccular aneurysm sized less than 3 mm) may lead to many critical neurological complications. So we analyzed the characteristics and differences between the ruptured VSIA group and the ruptured non-VSIA group.

Methods

421 saccular aneurysms from patients with SAH between January 2016 and December 2019 were included. Patient information including age, sex, and medical history and information about the aneurysm including location, size, aspect ratio, inflow angle, and height-width ratio were collected. And we compared the VSIA group with non-VSIA group about these characteristics

Results

12.1% (51/421) of the aneurysms were included in the VSIA group, while the non-VSIA group consisted of 87.9% of the aneurysms (370/421). The female predominance was significantly higher in the VSIA group than that in the non-VSIA group (p=0.011). No significant difference was observed in location, medical history, height-width ratio between the groups. The mean value of the inflow angle in the VSIA group was much lower than that in the non-VSIA group, but no statistically significant association between rupture risk and the inflow angle was observed. The average aspect ratio was significantly lower than that in the non-VSIA group.

Conclusions

Ruptured VSIA group has higher percentage of females and lower aspect ratio than ruptured non-VSIA group. Further studies regarding the characteristics of ruptured and unruptured VSIA patients is required for assistance in clinical decision related to treatment of VSIA group before the aneurysmal sac rupture.

Safety of Aspirin Use in Patients With Stroke and Small Unruptured Aneurysms

OBJECTIVE

We initiated a multicenter, prospective cohort study to test the hypothesis that aspirin is safe for patients with ischemic cerebrovascular disease (ICVD) harboring unruptured intracranial aneurysms (UIAs) <7 mm.

METHODS

This prospective, multicenter cohort study consecutively enrolled 1,866 eligible patients with ICVD harboring UIAs <7 mm in diameter from 4 hospitals between January 2016 and August 2019. Baseline and follow-up patient information, including the use of aspirin, was recorded. The primary endpoint was aneurysm rupture.

RESULTS

After a total of 4,411.4 person-years, 643 (37.2%) patients continuously received aspirin treatment. Of all included patients, rupture occurred in 12 (0.7%). The incidence rate for rupture (IRR) was 0.27 (95% confidence interval [CI] 0.15-0.48) per 100 person-years. The IRRs were 0.39 (95% CI 0.21-0.72) and 0.06 (95% CI 0.010-0.45) per 100 person-years for the nonaspirin and aspirin groups, respectively. In the multivariate analysis, uncontrolled hypertension and UIAs 5 to <7 mm were associated with a high rate of aneurysm rupture, whereas aspirin use was associated with a low rate of aneurysm rupture. Compared with other groups, the high-risk group (UIAs 5 to <7 mm with concurrent uncontrolled hypertension) without aspirin had higher IRRs.

CONCLUSION

Aspirin is a safe treatment for patients with concurrent small UIAs and ICVD. Patients who are not taking aspirin in the high-risk group warrant intensive surveillance.

CLINICALTRIALSGOV IDENTIFIER

NCT02846259.

CLASSIFICATION OF EVIDENCE

This study provides Class III evidence that for patients harboring UIAs <7 mm with ICVD, aspirin does not increase the risk of aneurysm rupture.

Introducing the Rupture Criticality Index to Compare Risk Factor Combinations Associated With Aneurysmal Rupture

BACKGROUND

Relative risk is insufficient to guide treatment decision-making for unruptured intracranial aneurysms. Our objective was to introduce a novel risk assessment methodology called the Rupture Criticality Index (RCI), which allows for concurrent evaluation of groups of risk factors (RFs).

METHODS

From a retrospective database of saccular aneurysms, we identify 915 patients and delineate 50 potential RFs for aneurysms in 11 unique locations. RF combinations for multivariable analysis were defined by aneurysm size, location, and a third variable from the study design. Data analysis was performed by applying frequency distribution methods to define the RCI of each RF combination.

RESULTS

RF combinations at greatest risk were small (4.8-8.2 mm) or medium (8.3-14.5 mm) anterior communicating aneurysms (ACoA) in male individuals (RCI 9.87-10), small ACoA in those ≤37 years or 38-55 years (RCI 8.67-8.99), medium basilar tip aneurysms (BTAs) in male individuals (RCI 10), and large (14.6-22.5 mm) BTA in Caucasians or those aged 38-55 years (RCI 9.25, 9.35, respectively).

CONCLUSIONS

We introduce the concept of RCI and compare how RF combinations are associated with aneurysmal rupture. This novel approach to aneurysmal rupture identifies high-risk clinical presentations and can be used to guide clinical decision-making in patients with non-traditional risks.

Aspirin and Growth of Small Unruptured Intracranial Aneurysm

Background and Purpose:

The role of aspirin in unruptured intracranial aneurysm (UIA) growth remains largely unknown. We aim to identify whether aspirin is associated with a lower rate of UIA growth in patients with UIA <7 mm.

Methods:

This prospective cohort study consecutively enrolled patients with UIAs <7 mm with ischemic cerebrovascular disease between January 2016 and December 2019. Baseline and follow-up patient information, including the use of aspirin and blood pressure level, were recorded. Patients were considered aspirin users if they took aspirin, including standard- and low-dose aspirin, ≥3× per week. The primary end point was aneurysm growth in any direction or an indisputable change in aneurysm shape.

Results:

Among the 315 enrolled patients, 272 patients (86.3%) underwent imaging examinations during follow-up (mean follow-up time, 19.6±12.7 months). A total of 113 patients were continuously treated with aspirin. UIA growth occurred in 31 (11.4%) patients. In the multivariate Cox analysis, specific aneurysm locations (anterior communicating artery, posterior communicating artery, or middle cerebral artery; hazard ratio, 2.89 [95% CI, 1.22–6.88]; P =0.016) and a UIA size of 5 to <7 mm (hazard ratio, 7.61 [95% CI, 3.02–19.22]; P <0.001) were associated with a high risk of UIA growth, whereas aspirin and well-controlled blood pressure were associated with a low risk of UIA growth (hazard ratio, 0.29 [95% CI, 0.11–0.77]; P =0.013 and hazard ratio, 0.25 [95% CI, 0.10–0.66]; P =0.005, respectively). The cumulative annual growth rates were as high as 40.0 and 53.3 per 100 person-years in the high-risk patients (>1 risk factor) with and without aspirin, respectively.

Conclusions:

Aspirin therapy and well-controlled blood pressure are associated with a low risk of UIA growth; the incidence of UIA growth in high-risk patients in the first year is high, warranting intensive surveillance in this patient group.

Registration:

URL: https://www.clinicaltrials.gov . Unique identifier: NCT02846259.

Screening for Intracranial Aneurysms in Coarctation of the Aorta: A Decision and Cost-Effectiveness Analysis

BACKGROUND

Patients with coarctation of the aorta have a high prevalence of intracranial aneurysms (IA) and suffer subarachnoid hemorrhage (SAH) at younger ages than the general population. American Heart Association/American College of Cardiology guidelines recommend IA screening, but appropriate age and interval of screening and its effectiveness remain a critical knowledge gap.

METHODS AND RESULTS

To evaluate the benefits and cost-effectiveness of magnetic resonance angiography screening for IA in patients with coarctation of the aorta, we developed and calibrated a Markov model to match published IA prevalence estimates. The primary outcome was the incremental cost-effectiveness ratio. Secondary outcomes included lifetime cumulative incidence of prophylactic IA treatment and mortality and SAH deaths prevented. Using a payer perspective, a lifetime horizon, and a willingness-to-pay of $150 000 per quality-adjusted life-year gained, we applied a 3% annual discounting rate to costs and effects and performed 1-way, 2-way, and probabilistic sensitivity analyses. In a simulated cohort of 10 000 patients, no screening resulted in a 10.1% lifetime incidence of SAH and 183 SAH-related deaths. Screening at ages 10, 20, and 30 years led to 978 prophylactic treatments for unruptured aneurysms, 19 procedure-related deaths, and 65 SAH-related deaths. Screening at ages 10, 20, and 30 years was cost-effective compared with screening at ages 10 and 20 years (incremental cost-effectiveness ratio $106 841/quality-adjusted life-year). Uncertainty in the outcome after aneurysm treatment and quality of life after SAH influenced the preferred screening strategy. In probabilistic sensitivity analysis, screening at ages 10, 20, and 30 years was cost-effective in 41% of simulations and at ages 10 and 20 in 59% of simulations.

CONCLUSIONS

Our model supports the American Heart Association/American College of Cardiology recommendation to screen patients with coarctation of the aorta for IA and suggests screening at ages 10 and 20 or at 10, 20, and 30 years would extend life and be cost-effective.

Hemodynamics of Cerebral Aneurysms: Connecting Medical Imaging and Biomechanical Analysis

In the last two decades, numerous studies have conducted patient-specific computations of blood flow dynamics in cerebral aneurysms and reported correlations between various hemodynamic metrics and aneurysmal disease progression or treatment outcomes. Nevertheless, intra-aneurysmal flow analysis has not been adopted in current clinical practice, and hemodynamic factors usually are not considered in clinical decision making. This review presents the state of the art in cerebral aneurysm imaging and image-based modeling, discussing the advantages and limitations of each approach and focusing on the translational value of hemodynamic analysis. Combining imaging and modeling data obtained from different flow modalities can improve the accuracy and fidelity of resulting velocity fields and flow-derived factors that are thought to affect aneurysmal disease progression. It is expected that predictive models utilizing hemodynamic factors in combination with patient medical history and morphological data will outperform current risk scores and treatment guidelines. Possible future directions include novel approaches enabling data assimilation and multimodality analysis of cerebral aneurysm hemodynamics.

Perioperative rupture risk of unruptured intracranial aneurysms in cardiovascular surgery

Although unruptured intracranial aneurysms are increasingly being diagnosed incidentally, perioperative rupture risk of unruptured intracranial aneurysm in patients undergoing cardiovascular surgery remains unclear. Therefore, we conducted an observational study to assess the prevalence and perioperative rupture risk of unruptured intracranial aneurysm in patients undergoing cardiovascular surgery. Adult patients (n = 4864) who underwent cardiovascular surgery between January 2010 and December 2016 were included. We assessed the prevalence of unruptured intracranial aneurysms in these patients using preoperative neurovascular imaging. The incidence of postoperative 30-day subarachnoid haemorrhage from aneurysmal rupture was investigated in patients undergoing cardiovascular surgery with unruptured intracranial aneurysm. Postoperative outcomes were compared between patients with unruptured intracranial aneurysm and those without unruptured intracranial aneurysm. Of the 4864 patients (39.6% females; mean ± standard deviation age, 62.3 ± 11.3 years), 353 patients had unruptured intracranial aneurysms (prevalence rate, 7.26%; 95% confidence interval, 6.52-8.06%). Of these, eight patients received surgical or endovascular treatment before surgery and 345 patients underwent cardiovascular surgery with unruptured intracranial aneurysms. Within 30 days postoperatively, subarachnoid haemorrhage occurred only in one patient, and the cumulative postoperative 30-day subarachnoid haemorrhage incidence was 0.29% (95% confidence interval, 0.01% to 1.61%). The Kaplan-Meier estimated subarachnoid haemorrhage probabilities according to the unruptured intracranial aneurysm rupture risk scores were not higher than the previously reported risk in the general population. There were no significant differences in postoperative subarachnoid haemorrhage-free survival, haemorrhagic stroke-free survival, in-hospital mortality, and hospital length of stay between patients with unruptured intracranial aneurysm and those without unruptured intracranial aneurysm. In conclusion, the prevalence of unruptured intracranial aneurysm in patients undergoing cardiovascular surgery is higher than in the general population. However, incidentally detected unruptured intracranial aneurysms are not linked to an increased risk of subarachnoid haemorrhage or adverse postoperative outcomes. These findings may help determine the optimal management of unruptured intracranial aneurysms before cardiovascular surgery.

Comparative effectiveness analysis of Pipeline device versus coiling in unruptured aneurysms smaller than 10 mm

OBJECTIVE

Both endovascular coiling and the Pipeline embolization device (PED) have been shown to be safe and clinically effective for treatment of small (< 10 mm) aneurysms. The authors conducted a comparative effectiveness analysis to compare the utility of these treatment methods in terms of health benefits.

METHODS

A decision-analytical study was performed with Markov modeling methods to simulate patients with small unruptured aneurysms undergoing endovascular coiling, stent-assisted coiling (SAC), or PED placement for treatment. Input probabilities were derived from prior literature, and 1-way, 2-way, and probabilistic sensitivity analyses were performed to assess model and input parameter uncertainty.

RESULTS

The base case calculation for a 50-year-old man reveals PED to have a higher health benefit (17.48 quality-adjusted life years [QALYs]) than coiling (17.44 QALYs) or SAC (17.36 QALYs). PED is the better option in 6020 of the 10,000 iterations in probabilistic sensitivity analysis. When the retreatment rate of PED is lower than 9.53%, and the coiling retreatment is higher than 15.6%, PED is the better strategy. In the 2-way sensitivity analysis varying the retreatment rates from both treatment modalities, when the retreatment rate of PED is approximately 14% lower than the retreatment rate of coiling, PED is the more favorable treatment strategy. Otherwise, coiling is more effective. SAC may be better than PED when the unfavorable outcome risk of SAC is lower than 70% of its reported current value.

CONCLUSIONS

With the increasing use of PEDs for treatment of small unruptured aneurysms, the current study indicates that these devices may have higher health benefits due to lower rates of retreatment compared to both simple coiling and stent-assisted techniques. Longer follow-up studies are needed to document the rates of recurrence and retreatment after coiling and PED to assess the cost-effectiveness of these strategies.

Rupture risk of small unruptured cerebral aneurysms

OBJECTIVE

The annual rupture rate of small (3-4 mm) unruptured cerebral aneurysms (UCAs) is 0.36% per year, however, the proportion of small ruptured aneurysms < 5 mm is 35%. This discrepancy is explained by the hypothesis that most acute subarachnoid hemorrhage (SAH) is from recently formed, unscreened aneurysms, but this hypothesis is without definitive proof. The authors aimed to clarify the actual number of screened, ruptured small aneurysms and risk factors for rupture.

METHODS

The Unruptured Cerebral Aneurysm Study Japan, a project of the Japan Neurosurgical Society, was designed to clarify the natural course of UCAs. From January 2001 through March 2004, 6697 UCAs among 5720 patients were prospectively registered. At registration, 2839 patients (49.6%) had 3132 (46.8%) small UCAs of 3-4 mm. The registered, treated, and rupture numbers of these small aneurysms and the annual rupture rate were investigated. The rate was assessed per aneurysm. The characteristics of patients and aneurysms were compared to those of larger unruptured aneurysms (≥ 5 mm). Cumulative rates of SAH were estimated per aneurysm. Risk factors underwent univariate and multivariate analysis.

RESULTS

Treatment and rupture numbers of small UCAs were 1132 (37.1% of all treated aneurysms) and 23 (20.7% of all ruptured aneurysms), respectively. The registered, treated, rupture number, and annual rupture rates were 1658 (24.8%), 495 (16.2%), 11 (9.9%), and 0.30%, respectively, among 3-mm aneurysms, and 1474 (22.0%), 637 (20.9%), 12 (10.8%), and 0.45%, respectively, among 4-mm aneurysms. Multivariate risk-factor analysis revealed that a screening brain checkup (hazard ratio [HR] 4.1, 95% confidence interval [CI] 1.2-14.4), history of SAH (HR 10.8, 95% CI 2.3-51.1), uncontrolled hypertension (HR 5.2, 95% CI 1.8-15.3), and location on the anterior communicating artery (ACoA; HR 5.0, 95% CI 1.6-15.5) were independent predictors of rupture.

CONCLUSIONS

Although the annual rupture rate of small aneurysms was low, the actual number of ruptures was not low. Small aneurysms that ruptured during follow-up could be detected, screened, and managed based on each risk factor. Possible selection criteria for treating small UCAs include a history of SAH, uncontrolled hypertension, location on the ACoA, and young patients. Further large prospective and longitudinal trials are needed.Clinical trial registration no.: C000000418 (https://www.umin.ac.jp/ctr).

Librarians as methodological peer reviewers for systematic reviews: results of an online survey

BACKGROUND

Developing a comprehensive, reproducible literature search is the basis for a high-quality systematic review (SR). Librarians and information professionals, as expert searchers, can improve the quality of systematic review searches, methodology, and reporting. Likewise, journal editors and authors often seek to improve the quality of published SRs and other evidence syntheses through peer review. Health sciences librarians contribute to systematic review production but little is known about their involvement in peer reviewing SR manuscripts.

METHODS

This survey aimed to assess how frequently librarians are asked to peer review systematic review manuscripts and to determine characteristics associated with those invited to review. The survey was distributed to a purposive sample through three health sciences information professional listservs.

RESULTS

There were 291 complete survey responses. Results indicated that 22% (n = 63) of respondents had been asked by journal editors to peer review systematic review or meta-analysis manuscripts. Of the 78% (n = 228) of respondents who had not already been asked, 54% (n = 122) would peer review, and 41% (n = 93) might peer review. Only 4% (n = 9) would not review a manuscript. Respondents had peer reviewed manuscripts for 38 unique journals and believed they were asked because of their professional expertise. Of respondents who had declined to peer review (32%, n = 20), the most common explanation was "not enough time" (60%, n = 12) followed by "lack of expertise" (50%, n = 10).The vast majority of respondents (95%, n = 40) had "rejected or recommended a revision of a manuscript| after peer review. They based their decision on the "search methodology" (57%, n = 36), "search write-up" (46%, n = 29), or "entire article" (54%, n = 34). Those who selected "other" (37%, n = 23) listed a variety of reasons for rejection, including problems or errors in the PRISMA flow diagram; tables of included, excluded, and ongoing studies; data extraction; reporting; and pooling methods.

CONCLUSIONS

Despite being experts in conducting literature searches and supporting SR teams through the review process, few librarians have been asked to review SR manuscripts, or even just search strategies; yet many are willing to provide this service. Editors should involve experienced librarians with peer review and we suggest some strategies to consider.

Management of Tiny Unruptured Intracranial Aneurysms: A Comparative Effectiveness Analysis

Importance

Unruptured intracranial aneurysms (UIAs) are relatively common in the general population and are being increasingly diagnosed; a significant proportion are tiny (≤3 mm) aneurysms. There is significant heterogeneity in practice and lack of clear guidelines on the management of incidental, tiny UIAs. It is important to quantify the implications of different management strategies in terms of health benefits to patients.

Objective

To evaluate the effectiveness of routine treatment (aneurysm coiling) vs 3 strategies for imaging surveillance compared with no preventive treatment or routine follow-up of tiny UIAs.

Design, Setting, and Participants

A decision-analytic model-based comparative effectiveness analysis was conducted from May 1 to June 30, 2017, using inputs from the medical literature. PubMed searches were performed to identify relevant literature for all key model inputs, each of which was derived from the clinical study with the most robust data and greatest applicability. Analysis included 10 000 iterations simulating adult patients with incidental detections of UIAs 3 mm or smaller and no history of subarachnoid hemorrhage.

Interventions

The following 5 management strategies for tiny UIAs were evaluated: annual magnetic resonance angiography (MRA) screening, biennial MRA screening, MRA screening every 5 years, aneurysm coiling and follow-up, and no treatment or preventive follow-up.

Main Outcomes and Measures

A Markov decision model for lifetime rupture was constructed from a societal perspective per 10 000 patients with incidental, tiny UIAs. Outcomes were assessed in terms of quality-adjusted life-years. Probabilistic, 1-way, and 2-way sensitivity analyses were performed.

Results

In this analysis of 10 000 iterations simulating adult patients with a mean age of 50 years, the base-case calculation shows that the management strategy of no treatment or preventive follow-up has the highest health benefit (mean [SD] quality-adjusted life-years, 19.40 [0.31]). Among the management strategies that incorporate follow-up imaging, MRA every 5 years is the best strategy with the next highest effectiveness (mean [SD] quality-adjusted life-years, 18.05 [0.62]). The conclusion remains robust in probabilistic and 1-way sensitivity analyses. No routine follow-up remains the optimal strategy when the annual growth rate and risk of rupture of growing aneurysms are varied. When the annual risk of rupture of nongrowing UIAs is less than 1.7% (0.23% in base case scenario), no follow-up is the optimal strategy. If annual risk of rupture is more than 1.7%, coiling should be performed directly.

Conclusions and Relevance

Given the current literature, no preventive treatment or imaging follow-up is the most effective strategy in patients with aneurysms that are 3 mm or smaller, resulting in better health outcomes. More aggressive imaging surveillance for aneurysm growth or preventive treatment should be reserved for patients with a high risk of rupture. Given these findings, it is important to critically evaluate the appropriateness of current clinical practices, and potentially determine specific guidelines to reflect the most effective management strategy for patients with incidental, tiny UIAs.

Incidental Microaneurysms During Microvascular Surgery: Incidence, Treatment, and Significance

BACKGROUND

Although new imaging tools have been developed for the detection of smaller aneurysms, angiographically negative microaneurysms are still encountered during cerebral microsurgery. Currently, only limited information regarding incidence and efficacy of treatment of these microaneurysms is available.

METHODS

We investigated the incidence and treatment of incidental microaneurysms (IMAs) in the last 5 years. IMAs are unidentifiable and invisible on preoperative angiography, but are detected during microvascular surgery. The inclusion criteria were aneurysm cases treated with microsurgery via transsylvian approaches, and those undergoing preoperative digital subtraction angiography.

RESULTS

This study enrolled 484 surgical cases (248 cases of subarachnoid hemorrhage and 236 cases of unruptured aneurysms) in 460 patients, and 33 tiny aneurysms were found in 31 operative cases (6.4% incidence per operation). The most typical type was located on another branching site of the middle cerebral artery found during neck clipping of the middle cerebral artery bifurcation aneurysm. A patient with multiple aneurysms presented a statistically significant risk (375/78 vs. 15/16; P < 0.001) of IMA identification. IMAs were treated by clipping and wrapping in 18 and 15 cases, respectively, without complications.

CONCLUSIONS

This study revealed a 6.4% incidence of IMAs; however, this could be underestimated because of the limited range of inspection. Early detection of an IMA through careful inspection during microvascular surgery could be beneficial, especially in patients with multiple aneurysms.

Cost-Effectiveness of Computed Tomography Angiography in Management of Tiny Unruptured Intracranial Aneurysms in the United States

Background and Purpose—

Our study aims to evaluate the cost-effectiveness of computed tomography angiography (CTA) for surveillance of tiny unruptured intracranial aneurysms and the impact of CTA radiation-induced brain tumor on the overall effectiveness of CTA.

Methods—

A Markov decision model was constructed from a societal perspective starting with patients 30-, 40-, or 50-year-old, with incidental detection of unruptured intracranial aneurysm ≤3 mm and no prior history of subarachnoid hemorrhage. Five different management strategies were assessed (1) annual CTA surveillance, (2) biennial CTA, (3) CTA follow-up every 5 years, (4) coiling and subsequent magnetic resonance imaging follow-up, and (5) annual CTA surveillance for the first 2 years, followed by every 5-year CTA follow-up. Probabilistic, 1-way, and 2-way sensitivity analyses were performed.

Results—

The base case calculation shows every 5-year CTA follow-up to be the most cost-effective strategy, and the conclusion remains robust in probabilistic sensitivity analysis. It remains the dominant strategy when the annual rupture risk of nongrowing unruptured intracranial aneurysms is smaller than 2.66% or the rupture risk in growing aneurysms is <57.4%. The radiation-induced brain cancer risk is relatively low, and sensitivity analysis shows that the radiation-induced cancer risk does not influence the conclusions unless the risk exceeds 663-fold of the base case values.

Conclusions—

Given the current literature, every 5-year CTA imaging follow-up is the cost-effective strategy in patients with aneurysms ≤3 mm, resulting in better health outcomes and lower healthcare spending. Patients with aneurysms at high risk of rupture might need more aggressive management.