PHASES Score for Prediction of Intracranial Aneurysm Growth

Patient-specific cerebral 3D vessel model reconstruction using deep learning

Three-dimensional vessel model reconstruction from patient-specific magnetic resonance angiography (MRA) images often requires some manual maneuvers. This study aimed to establish the deep learning (DL)-based method for vessel model reconstruction. Time of flight MRA of 40 patients with internal carotid artery aneurysms was prepared, and three-dimensional vessel models were constructed using the threshold and region-growing method. Using those datasets, supervised deep learning using 2D U-net was performed to reconstruct 3D vessel models. The accuracy of the DL-based vessel segmentations was assessed using 20 MRA images outside the training dataset. The dice coefficient was used as the indicator of the model accuracy, and the blood flow simulation was performed using the DL-based vessel model. The created DL model could successfully reconstruct a three-dimensional model in all 60 cases. The dice coefficient in the test dataset was 0.859. Of note, the DL-generated model proved its efficacy even for large aneurysms (> 10 mm in their diameter). The reconstructed model was feasible in performing blood flow simulation to assist clinical decision-making. Our DL-based method could successfully reconstruct a three-dimensional vessel model with moderate accuracy. Future studies are warranted to exhibit that DL-based technology can promote medical image processing.

Predicting Intracranial Aneurysm Rupture: A Multifactor Analysis Combining Radscore, Morphology, and PHASES Parameters

RATIONALE AND OBJECTIVES

We aimed at developing and validating a nomogram and machine learning (ML) models based on radiomics score (Radscore), morphology, and PHASES to predict intracranial aneurysm (IA) rupture.

MATERIALS AND METHODS

We collected 440 patients with IAs in our hospital from 2015 to 2023, totaling 475 IAs (214 ruptured and 261 unruptured). A 7:3 random split was utilized to allocate participants into training and testing sets. To optimize the selection of radiomics features extracted from digital subtraction angiography, we employed t-tests and LASSO regression. Subsequently, we built single-factor and multifactor logistic regression (LR) models, alongside a nomogram. Furthermore, we employed four ML algorithms. After a comprehensive evaluation, including area under the curve (AUC), calibration curves, decision curve analysis (DCA), and other metrics, the best model was determined.

RESULTS

The AUCs for LR models P (PHASES), M (Morphology), and R (Radscore) in the testing set were 0.859, 0.755, and 0.803, respectively, while those for multifactor models R+M (Radscore and Morphology), R+P (Radscore and PHASES), and R+M+P (Radscore, Morphology, and PHASES) were 0.818, 0.899, and 0.887, respectively. The AUCs of random forest, extreme gradient boosting, gradient boosting machine, and light gradient boosting machine were 0.880, 0.888, 0.891, and 0.892 in testing set, respectively. In the training set, the LR model showed significant differences in AUCs compared with the four ML models (all p < 0.05). However, in the testing set, no statistically significant differences were found between them (all p > 0.05). Both ML models and the nomogram exhibit excellent performance in DCA and calibration curves.

CONCLUSION

Nomogram and ML models based on Radscore, morphology, and PHASES show high precision in predicting aneurysm rupture.

Gadolinium-enhanced intracranial aneurysm wall imaging and risk of aneurysm growth and rupture: a multicentre longitudinal cohort study

OBJECTIVES

In patients with an unruptured intracranial aneurysm, gadolinium enhancement of the aneurysm wall is associated with growth and rupture. However, most previous studies did not have a longitudinal design and did not adjust for aneurysm size, which is the main predictor of aneurysm instability and the most important determinant of wall enhancement. We investigated whether aneurysm wall enhancement predicts aneurysm growth and rupture during follow-up and whether the predictive value was independent of aneurysm size.

MATERIALS AND METHODS

In this multicentre longitudinal cohort study, individual patient data were obtained from twelve international cohorts. Inclusion criteria were as follows: 18 years or older with ≥ 1 untreated unruptured intracranial aneurysm < 15 mm; gadolinium-enhanced aneurysm wall imaging and MRA at baseline; and MRA or rupture during follow-up. Patients were included between November 2012 and November 2019. We calculated crude hazard ratios with 95%CI of aneurysm wall enhancement for growth (≥ 1 mm increase) or rupture and adjusted for aneurysm size.

RESULTS

In 455 patients (mean age (SD), 60 (13) years; 323 (71%) women) with 559 aneurysms, growth or rupture occurred in 13/194 (6.7%) aneurysms with wall enhancement and in 9/365 (2.5%) aneurysms without enhancement (crude hazard ratio 3.1 [95%CI: 1.3-7.4], adjusted hazard ratio 1.4 [95%CI: 0.5-3.7]) with a median follow-up duration of 1.2 years.

CONCLUSIONS

Gadolinium enhancement of the aneurysm wall predicts aneurysm growth or rupture during short-term follow-up, but not independent of aneurysm size.

CLINICAL RELEVANCE STATEMENT

Gadolinium-enhanced aneurysm wall imaging is not recommended for short-term prediction of growth and rupture, since it appears to have no additional value to conventional predictors.

KEY POINTS

• Although aneurysm wall enhancement is associated with aneurysm instability in cross-sectional studies, it remains unknown whether it predicts risk of aneurysm growth or rupture in longitudinal studies. • Gadolinium enhancement of the aneurysm wall predicts aneurysm growth or rupture during short-term follow-up, but not when adjusting for aneurysm size. • While gadolinium-enhanced aneurysm wall imaging is not recommended for short-term prediction of growth and rupture, it may hold potential for aneurysms smaller than 7 mm.

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

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

Body composition and rupture risk of intracranial aneurysms

BACKGROUND

Rupture of an intracranial aneurysm resulting in a subarachnoid hemorrhage (SAH) is a life-threatening situation. Obesity is an increasing health challenge associated with numerous comorbidities. However, recent studies have shown a surprising decreased risk of SAH with increasing body mass index (BMI). The aim was to explore associations between other anthropometric variables and the rupture risk of an intracranial aneurysm, which to our knowledge is lacking in present literature.

METHODS

Using a bioelectrical impedance analysis device, we performed body composition analyses on 31 patients admitted with aneurysmal SAH (aSAH) and 28 patients with planned intervention on their unruptured aneurysm. We also collected information on comorbidities and relevant risk factors. Logistic regression was used to explore associations between anthropometric variables and patients with ruptured versus unruptured aneurysms.

RESULTS

Unadjusted estimates showed a significant inverse relationship between body fat percent and aneurysmal rupture (OR [95% CI]: 0.92 [0.86, 0.97], P = 0.009), and between body fat mass and aneurysmal rupture (OR [95% CI]: 0.95 [0.90, 0.99], P = 0.047). These risk relationships remained significant in age- and sex-adjusted analyses for body fat percent (OR [95% CI]: 0.93, [0.87, 0.97], P = 0.028), and body fat mass (OR [95% CI]: 0.95 [0.90, 0.99], P = 0.041).

CONCLUSIONS

In recent studies showing a paradoxical relation between aSAH and obesity, BMI was the only parameter investigated. We further explored this "obesity paradox" and found lower body fat in aSAH patients compared to UIA. Future studies should investigate these relationships in larger samples. Clinical Trial Registration NCT04613427, November 3, 2020, retrospectively registered.

Nomogram-based geometric and hemodynamic parameters for predicting the growth of small untreated intracranial aneurysms

Previous studies have shown that the growth status of intracranial aneurysms (IAs) predisposes to rupture. This study aimed to construct a nomogram for predicting the growth of small IAs based on geometric and hemodynamic parameters. We retrospectively collected the baseline and follow-up angiographic images (CTA/ MRA) of 96 small untreated saccular IAs, created patient-specific vascular models and performed computational fluid dynamics (CFD) simulations. Geometric and hemodynamic parameters were calculated. A stepwise Cox proportional hazards regression analysis was employed to construct a nomogram. IAs were stratified into low-, intermediate-, and high-risk groups based on the total points from the nomogram. Receiver operating characteristic (ROC) analysis, calibration curves, decision curve analysis (DCA) and Kaplan-Meier curves were evaluated for internal validation. In total, 30 untreated saccular IAs were grown (31.3%; 95%CI 21.8%-40.7%). The PHASES, ELAPSS, and UIATS performed poorly in distinguishing growth status. Hypertension (hazard ratio [HR] 4.26, 95%CI 1.61-11.28; P = 0.004), nonsphericity index (95%CI 4.10-25.26; P = 0.003), max relative residence time (HR 1.01, 95%CI 1.00-1.01; P = 0.032) were independently related to the growth status. A nomogram was constructed with the above predictors and achieved a satisfactory prediction in the validation cohort. The log-rank test showed significant discrimination among the Kaplan-Meier curves of different risk groups in the training and validation cohorts. A nomogram consisting of geometric and hemodynamic parameters presented an accurate prediction for the growth status of small IAs and achieved risk stratification. It showed higher predictive efficacy than the assessment tools.

Perioperative Antiplatelet Management in the Flow-Diverter Treatment for Unruptured Cerebral Aneurysms: A Single-Center, Retrospective Analysis

BACKGROUND

Although periprocedural antiplatelet therapy for the treatment of unruptured intracranial aneurysms (UIAs) using flow-diverter stents (FDSs) is necessary to avoid thromboembolic complications, a definite antiplatelet therapy has not been established. We aimed to evaluate the safety and efficacy of periprocedural antiplatelet management in UIA treatment with FDS.

METHODS

A single-center retrospective analysis of consecutive patients with UIAs treated with FDSs between September 2013 and January 2022 was conducted. Patients received dual antiplatelet therapy (DAPT) (aspirin and clopidogrel) for 14-day before and 3-6 months after FDS placement. Platelet aggregation was evaluated prior to treatment using light transmission aggregometry, which was classified into 3 grades; 1-3: promoted, 4-6: appropriate, and 7-9: non-responder, for adenosine diphosphate (ADP) and collagen. By this classification, the antiplatelet regimen was modified. Outcome included hemorrhagic and ischemic events.

RESULTS

193 patients with 200 UIAs underwent 213 FDSs placement. The median platelet aggregability grade before treatment was 5 for ADP and 4 for collagen. Antiplatelet therapy modification was performed in 62 patients (32.1%). The median postoperative DAPT duration was 94 days. Antiplatelet medicine-related hemorrhagic events occurred in 4 patients (2.1%) and ischemic events occurred in 6 patients (3.1%). These patients had no morbido-mortality.

CONCLUSIONS

Periprocedural antiplatelet management based on the value of platelet aggregability was relatively safe and effective for treating UIA with FDS.

Intracranial aneurysm wall displacement depicted by amplified Flow predicts growth

BACKGROUND

Abnormal intracranial aneurysm (IA) wall motion has been associated with IA growth and rupture. Recently, a new image processing algorithm called amplified Flow (aFlow) has been used to successfully track IA wall motion by combining the amplification of cine and four-dimensional (4D) Flow MRI. We sought to apply aFlow to assess wall motion as a potential marker of IA growth in a paired-wise analysis of patients with growing versus stable aneurysms.

METHODS

In this retrospective case-control study, 10 patients with growing IAs and a matched cohort of 10 patients with stable IAs who had baseline 4D Flow MRI were included. The aFlow was used to amplify and extract IA wall displacements from 4D Flow MRI. The associations of aFlow parameters with commonly used risk factors and morphometric features were assessed using paired-wise univariate and multivariate analyses.

RESULTS

aFlow quantitative results showed significantly (P=0.035) higher wall motion displacement depicted by mean±SD 90th% values of 2.34±0.72 in growing IAs versus 1.39±0.58 in stable IAs with an area under the curve of 0.85. There was also significantly (P<0.05) higher variability of wall deformation across IA geometry in growing versus stable IAs depicted by the dispersion variables including 121-150% larger standard deviation ([Formula: see text]) and 128-161% wider interquartile range [Formula: see text].

CONCLUSIONS

aFlow-derived quantitative assessment of IA wall motion showed greater wall motion and higher variability of wall deformation in growing versus stable IAs.

Modeling and evaluation of biomechanics and hemodynamic based on patient-specific small intracranial aneurysm using fluid-structure interaction

BACKGROUND AND OBJECTIVE

Rupture of small intracranial aneurysm (IA) often leads to the development of highly fatal clinical syndromes such as subarachnoid hemorrhage. Due to the patient specificity of small IA, there are many difficulties in evaluating the rupture risk of small IA such as multiple influencing factors, high clinical experience requirements and poor reusability.

METHODS

In this study, clinical methods such as transcranial doppler (TCD) and magnetic resonance imaging (MRI) are used to obtain patient-specific parameters, and the fluid-structure interaction method (FSI) is used to model and evaluate the biomechanics and hemodynamics of patient-specific small IA.

RESULTS

The results show that a spiral vortex stably exists in the patient-specific small IA. Due to the small size of the patient-specific small IA, the blood flow velocity still maintains a high value with maximum reaching 3 m/s. The inertial impact of blood flow and vortex convection have certain influence on hemodynamic and biomechanics parameters. They cause three high value areas of WSSM on the patient-specific small IA with maximum of 180 Pa, 130 Pa and 110 Pa, respectively. They also cause two types of WSS concentration points, positive normal stress peak value areas and negative normal stress peak value areas to appear.

CONCLUSION

This paper found that the factors affecting hemodynamic parameters and biomechanical parameters are different. Unlike hemodynamic parameters, biomechanical parameters are also affected by blood pressure in addition to blood flow velocity. This study reveals the relationship between the flow field distribution and changes of patient-specific small IA, biomechanics and hemodynamics.

Risk factors of unruptured intracranial aneurysms instability in the elderly

BACKGROUND

Presently, a consistent strategy for determining the stability of unruptured intracranial aneurysms (UIAs) in elderly patients is lacking, primarily due to the unique characteristics of this demographic. Our objective was to assess the risk factors contributing to aneurysm instability (growth or rupture) within the elderly population.

METHODS

In this study, we compiled data from follow-up patients with UIAs spanning from November 2016 to August 2021. We specifically focused on patients aged ≥ 60 years. Clinical histories were gathered, and morphological parameters of aneurysms were measured. The growth of aneurysms was determined using the computer-assisted semi-automated measurement (CASAM). Growth and rupture rates of UIAs were calculated, and both univariate and multivariate Cox regression analyses were conducted. Additionally, Kaplan-Meier survival curves were plotted.

RESULTS

A total of 184 patients with 210 aneurysms were enrolled in the study. The follow-up period encompasses 506.6 aneurysm-years and 401.4 patient-years. Among all the aneurysms, 23 aneurysms exhibited growth, with an annual aneurysm growth rate of 11.0%, and 1 (4.5%) experienced rupture, resulting in an annual aneurysm rupture rate of 0.21%. Multivariate Cox analysis identified poorly controlled hypertension (P = 0.011) and high-risk aneurysms (including anterior cerebral artery (ACA), anterior communicating artery (AcoA), posterior communicating artery aneurysm (PcoA), posterior circulation (PC) > 4 mm or distal internal carotid artery (ICAd), middle cerebral artery (MCA), and PC > 7 mm) (P = 0.006) as independent risk factors for the development of unstable aneurysms.

CONCLUSIONS

In the elderly, poorly controlled hypertension and high-risk aneurysms emerge as significant risk factors for aneurysm instability. This underscores the importance of rigorous surveillance or timely intervention in patients presenting with these risk factors.

Risk of unruptured aneurysms in subarachnoid hemorrhage patients with multiple intracranial aneurysms: a multicenter, longitudinal, comparative study from China

BACKGROUND

In aneurysmal subarachnoid hemorrhage patients with multiple intracranial aneurysms (aSAH-MIA patients), the risk of secondary unruptured intracranial aneurysms is inconsistent. This study aimed to explore the risk of unruptured aneurysms in Chinese aSAH-MIA patients.

METHODS

The medical records and angiographic images of aSAH-MIA patients from eight cerebrovascular centers in China were retrospectively reviewed and analyzed. Patients with a single unruptured intracranial aneurysm (UIA) and no prior aSAH were used as controls. Propensity score matching (PSM) was employed to balance the differences in age, gender, aneurysm size, aneurysm site, and follow-up duration between the two groups.

RESULTS

The study included 267 unruptured aneurysms from 204 aSAH-MIA patients and 769 single UIA. After PSM, 201 aneurysms were enrolled in the aSAH-MIA group and 201 aneurysms in the control group. The mean follow-up was 2.2 years. Thirty-four aneurysm instability events (28 growth and 6 rupture, 16.9%) occurred during follow-up in the aSAH-MIA group and 16 instability events (13 growth and 3 rupture, 8%) occurred in the control group. Risk factors for aneurysmal instability were aneurysm irregularity (OR 2.53; 95% CI 1.18 to 4.31), higher size ratio (OR 1.23; 95% CI 1.37 to 4.39), and middle cerebral artery location (OR 1.86; 95% CI 1.03 to 3.17). The risk of aneurysmal instability was substantially elevated in the aSAH-MIA group (HR 2.07; 95% CI 1.12 to 3.02).

CONCLUSIONS

Unruptured aneurysms in Chinese aSAH-MIA patients exhibited higher risks of growth and rupture than in patients with a single UIA. Middle cerebral artery location, higher size ratio and irregular shape were associated with higher risk of growth or rupture.

Prevalence and Characteristics of Intracranial Aneurysms in Hereditary Hemorrhagic Telangiectasia

BACKGROUND AND PURPOSE

The association between hereditary hemorrhagic telangiectasia and intracranial aneurysms remains controversial. This study evaluated the prevalence and characteristics of intracranial aneurysms in patients with hereditary hemorrhagic telangiectasia with brain vascular malformations.

MATERIALS AND METHODS

Between 2007 and 2021, patients enrolled in the Brain Vascular Malformation Consortium with definite hereditary hemorrhagic telangiectasia, the presence of brain vascular malformations, and available angiographic studies of the brain were retrospectively reviewed. Angiographic features of intracranial aneurysms and their relationship to coexisting brain vascular malformations were analyzed. We also examined the association between baseline clinical features and the presence of intracranial aneurysms.

RESULTS

One hundred eighty patients were included. A total of 14 intracranial aneurysms were found in 9 (5%) patients, and 4 intracranial aneurysms were considered flow-related aneurysms. Patients with intracranial aneurysms were significantly older than patients without intracranial aneurysms (mean, 48.1 [SD, 18.2] years versus 33.5 [SD, 21.0] years; P = .042). If we excluded flow-related intracranial aneurysms, the prevalence of intracranial aneurysms was 3.3%. All intracranial aneurysms were in the anterior circulation, were unruptured, and had an average maximal diameter of 3.9 (SD, 1.5) mm. No intracranial aneurysms were found in pediatric patients with hereditary hemorrhagic telangiectasia. No statistically significant correlation was observed among other baseline demographics, hereditary hemorrhagic telangiectasia features, and the presence of intracranial aneurysms.

CONCLUSIONS

The prevalence of intracranial aneurysms in this large cohort study is comparable with that in the general population and might be increased slightly due to hemodynamic factors associated with shunting brain vascular malformations.

Endovascular treatment for anterior inferior cerebellar artery-posterior inferior cerebellar artery (AICA-PICA) common trunk variant aneurysms: Technical note and literature review

The Anterior Inferior Cerebellar Artery-Posterior Inferior Cerebellar Artery (AICA-PICA) common trunk is a rare variant of cerebral posterior circulation in which a single vessel originating from either the basilar or vertebral arteries supplies both cerebellum and brainstem territories. We present the first case of an unruptured right AICA-PICA aneurysm treated with flow diversion using a Shield-enhanced pipeline endovascular device (PED, VANTAGE Embolization Device with Shield Technology, Medtronic, Canada). We expand on this anatomic variant and review the relevant literature. A 39-year-old man presented to our treatment center with vertigo and right hypoacusis. The initial head CT/CTA was negative, but a 4-month follow-up MRI revealed a 9 mm fusiform dissecting aneurysm of the right AICA. The patient underwent a repeat head CTA and cerebral angiogram, which demonstrated the presence of an aneurysm on the proximal portion of an AICA-PICA anatomical variant. This was treated with an endovascular approach that included flow diversion via a PED equipped with Shield Technology. The patient's post-procedure period was uneventful, and he was discharged home after two days with an intact neurological status. The patient is still asymptomatic after a 7-month follow-up, with MR angiogram evidence of stable aneurysm obliteration and no ischemic lesions. Aneurysms of the AICA-PICA common trunk variants have a high morbidity risk due to the importance and extent of the territory vascularized by a single vessel. Endovascular treatment with flow diversion proved to be both safe and effective in obliterating unruptured cases.

Morphological characteristics of brain aneurysms among age groups

BACKGROUND

Patient's age is an important factor in determining the risk of aneurysm rupture. However, there is limited data on how aneurysm morphology differs among age groups. We studied morphological characteristics of brain aneurysms among age groups in a large cohort.

METHODS

Aneurysms from the Stroke Thrombectomy and Aneurysm Registry (STAR) were analyzed. The following parameters were included: location, size, neck, width, height, aspect ratio, and regular versus irregular morphology. The risk of rupture presentation was estimated using logistic regression.

RESULTS

A total of 1407 unruptured and 607 ruptured saccular aneurysms were included. The most common locations of ruptured aneurysms in patients younger than 70 years-old were the middle cerebral artery (MCA) and the anterior communicating artery (ACOM). The most common location of ruptured aneurysms in patients older than 70 years-old were the posterior communicating artery (PCOM) and ACOM. The size of unruptured aneurysms increased with age (p < .001). Conversely, the size of ruptured aneurysms was similar among age groups (p = .142). Unruptured and ruptured aneurysms became more irregular at presentation with older age (p < .001 and p .025, respectively). Irregular morphology and location were associated with rupture status across all age groups in multivariate regression.

CONCLUSIONS

Younger patients have small unruptured and ruptured aneurysms, and ruptured aneurysms are mostly located in the MCA and ACOM. Older patients have larger and more irregular unruptured aneurysms, and ruptured aneurysms are mostly located in the PCOM and ACOM. An irregular morphology increases the risk of rupture in all age groups.

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.

Mathematical Analysis of the Effectiveness of Screening for Intracranial Aneurysms in First-Degree Relatives of Persons with Subarachnoid Hemorrhage

OBJECTIVE

Population screening for aneurysms in patients with risk factors and preventive surgical treatment are beneficial according to numerous studies. One of the most significant risk factors is heredity, namely, the presence of first-degree relatives (FDR) with aneurysmal subarachnoid hemorrhage (aSAH). Nevertheless, there are still no generally accepted approaches or evidence bases regarding the benefits of the aneurysm screening strategy.

METHODS

Mathematical modeling of the dynamics of aneurysm development in the population was carried out using an algorithm implementing a discrete Markov's chain. To implement the model, all probabilities of events and distributions are taken from available literature sources. Three-dimensional time of flight noncontrast magnetic resonance angiography was chosen as a screening method. Patients underwent preventive surgical treatment if an aneurysm was detected.

RESULTS

Screening and preventive treatment in the general population reduces the prevalence of aneurysms by 1.74% (3.44% in the FDR group) and the prevalence of aSAH by 14.36% (37.48% in the FDR group). Mortality due to aSAH was reduced by 14.44%. The number of disabilities also decreases. The occurrence of deep disability was reduced by 20.2% in the FDR group. Economic analysis of the part of the population consisting of FDRs showed annual savings of ies also decr CONCLUSIONS: The mathematical model demonstrated that screening and preventive treatment of cerebral aneurysms can reduce aSAH-associated morbidity and mortality. In the FDR group, there was decrease in the prevalence of aSAH and decrease in associated mortality. Screening for cerebral aneurysms is cost-effective.

A Pragmatic Randomized Trial Comparing Surgical Clipping and Endovascular Treatment of Unruptured Intracranial Aneurysms

BACKGROUND AND PURPOSE

Surgical clipping and endovascular treatment are commonly used in patients with unruptured intracranial aneurysms. We compared the safety and efficacy of the 2 treatments in a randomized trial.

MATERIALS AND METHODS

Clipping or endovascular treatments were randomly allocated to patients with one or more 3- to 25-mm unruptured intracranial aneurysms judged treatable both ways by participating physicians. The study hypothesized that clipping would decrease the incidence of treatment failure from 13% to 4%, a composite primary outcome defined as failure of aneurysm occlusion, intracranial hemorrhage during follow-up, or residual aneurysms at 1 year, as adjudicated by a core lab. Safety outcomes included new neurologic deficits following treatment, hospitalization of >5 days, and overall morbidity and mortality (mRS > 2) at 1 year. There was no blinding.

RESULTS

Two hundred ninety-one patients were enrolled from 2010 to 2020 in 7 centers. The 1-year primary outcome, ascertainable in 290/291 (99%) patients, was reached in 13/142 (9%; 95% CI, 5%-15%) patients allocated to surgery and in 28/148 (19%; 95% CI, 13%-26%) patients allocated to endovascular treatments (relative risk: 2.07; 95% CI, 1.12-3.83; P = .021). Morbidity and mortality (mRS >2) at 1 year occurred in 3/143 and 3/148 (2%; 95% CI, 1%-6%) patients allocated to surgery and endovascular treatments, respectively. Neurologic deficits (32/143, 22%; 95% CI, 16%-30% versus 19/148, 12%; 95% CI, 8%-19%; relative risk: 1.74; 95% CI, 1.04-2.92; P = .04) and hospitalizations beyond 5 days (69/143, 48%; 95% CI, 40%-56% versus 12/148, 8%; 95% CI, 5%-14%; relative risk: 0.18; 95% CI, 0.11-0.31; P < .001) were more frequent after surgery.

CONCLUSIONS

Surgical clipping is more effective than endovascular treatment of unruptured intracranial aneurysms in terms of the frequency of the primary outcome of treatment failure. Results were mainly driven by angiographic results at 1 year.

Characteristics and Distribution of Intracranial Aneurysms in Patients with Autosomal Dominant Polycystic Kidney Disease Compared with the General Population: A Meta-Analysis

Key Points

IAs location distribution in patients with ADPKD differ from the ones in non-ADPKD patients IAs in patients with ADPKD are more commonly located in the anterior circulation and in large caliber arteries Because of IA multiplicity and singular IA distribution, patients with ADPKD represent a special population who need to be closely followed

Background

Autosomal dominant polycystic kidney disease (ADPKD) is the most common genetic condition associated with intracranial aneurysms (IAs). The associated pathophysiology remains unknown, but an association with wall shear stress is suspected. Cerebral arterial location is the principal factor influencing IA natural history. This study aims to compare IA location-specific distribution between ADPKD and non-ADPKD patients.

Methods

The ADPKD group comprised data from a systematic review of the literature (2016–2020, N =7) and three cohorts: integrated biomedical informatics for the management of cerebral aneurysms, Novosibirsk, and Unruptured Cerebral Aneurysms Study. The non-ADPKD group was formed from the integrated biomedical informatics for the management of cerebral aneurysms, Unruptured Cerebral Aneurysms Study, International Stroke Genetics Consortium, and the Finnish cohort from the literature. Patients and IAs characteristics were compared between ADPKD and non-ADPKD groups, and a meta-analysis for IA locations was performed.

Results

A total of 1184 IAs from patients with ADPKD were compared with 21,040 IAs from non-ADPKD patients. In total, 78.6% of patients with ADPKD had hypertension versus 39.2% of non-ADPKD patients. A total of 32.4% of patients with ADPKD were smokers versus 31.5% of non-ADPKD patients. In total, 30.1% of patients with ADPKD had a positive family history for IA versus 15.8% of the non-ADPKD patients. Patients with ADPKD showed a higher rate of IA multiplicity (33.2% versus 23.1%). IAs from patients with ADPKD showed a significant predominance across the internal carotid and middle cerebral arteries. Posterior communicating IAs were more frequently found in the non-ADPKD group. The meta-analysis confirmed a predominance of IAs in the patients with ADPKD across large caliber arteries (odds ratio [95% confidence interval]: internal carotid artery: 1.90 [1.10 to 3.29]; middle cerebral artery: 1.18 [1.02–1.36]). Small diameter arteries, such as the posterior communicating, were observed more in non-ADPKD patients (0.21 [0.11–0.88]).

Conclusion

This analysis shows that IAs diagnosed in patients with ADPKD are more often localized in large caliber arteries from the anterior circulation in comparison with IAs in non-ADPKD patients. It shows that primary cilia driven wall shear stress vessel remodeling to be more critical in cerebral anterior circulation large caliber arteries.

A survey of the radiological follow-up of unruptured intracranial aneurysms in the United Kingdom

OBJECTIVE

Unruptured intracranial aneurysms (UIA) are common. For many the treatment risks outweigh their risk of subarachnoid haemorrhage and patients undergo surveillance imaging. There is little data to inform if and how to monitor UIAs resulting in widely varying practices. This study aimed to determine the current practice of unruptured UIA surveillance in the United Kingdom.

METHODS

A questionnaire was designed to address the themes of surveillance protocols for UIA including when surveillance is initiated, how frequently it is performed, and when it is terminated. Additionally, how aneurysm growth is managed and how clinically meaningful growth is defined were explored. The questionnaire was distributed to members of the British Neurovascular Group using probability-based cluster and non-probability purposive sampling methods.

RESULTS

Responses were received from 30 of the 30 (100.0%) adult neurosurgical units in the United Kingdom of which 27 (90.0%) routinely perform surveillance for aneurysm growth. Only four units had a unit policy. The mean patient age up to which a unit would initiate follow-up of a low-risk UIA was 65.4 ± 9.0 years. The time points at which imaging is performed varied widely. There was an even split between whether units use a fixed duration of follow-up or an age threshold for terminating surveillance. Forty percent of units will follow-up patients more than 5 years from diagnosis. The magnitude in the change in size that was felt to constitute growth ranged from 1 to 3mm. No units routinely used vessel wall imaging although 27 had access to 3T MRI capable of performing it.

CONCLUSIONS

There is marked heterogeneity in surveillance practices between units in the United Kingdom. This study will help units better understand their practice relative to their peers and provide a framework forplanning further research on aneurysm growth.

Morphological Factors affecting Coil-Only Embolization of Small Unruptured Aneurysms

Objective When small unruptured aneurysms (SUA) are embolized by coils, manipulation of the microcatheter and coil is limited because of their small size. Previous studies suggested that the morphology of the artery and aneurysm is important. In the present study, we clarified the morphological factors affecting coil-only embolization of SUA.

Patients and Methods We retrospectively identified 17 patients who underwent embolization for unruptured aneurysm with a maximum diameter less than 5 mm. We investigated the following: (1) the relationships among dome/neck ratio (D/N), height/neck ratio (H/N), height/dome ratio (H/D), projection of aneurysm-parent artery, and adverse events, (2) immediate and late occlusion, and (3) number of coils.

Results (1) Adverse events developed in three cases in which the H/D was smaller than 1 (p < 0.02). There was a significant difference in the rate of adverse events by projection of the aneurysm-parent artery (p < 0.03), (2) Occlusion rate: Immediately after coil embolization, 71% (12/17) were neck remnant; however, 88% (15/17) of SUA became complete occlusion in the follow-up term, and (3) 1.5 ± 0.6 coils were used.

Conclusion To achieve successful coil-only embolization in SUAs, it is important to select aneurysms for which the projection of the parent artery is suitable for embolizing and the H/D ratio is larger than 1. In SUAs, occlusion develops naturally after coil embolization.

Integrating oculomics with genomics reveals imaging biomarkers for preventive and personalized prediction of arterial aneurysms

Objective

Arterial aneurysms are life-threatening but usually asymptomatic before requiring hospitalization. Oculomics of retinal vascular features (RVFs) extracted from retinal fundus images can reflect systemic vascular properties and therefore were hypothesized to provide valuable information on detecting the risk of aneurysms. By integrating oculomics with genomics, this study aimed to (i) identify predictive RVFs as imaging biomarkers for aneurysms and (ii) evaluate the value of these RVFs in supporting early detection of aneurysms in the context of predictive, preventive and personalized medicine (PPPM).

Methods

This study involved 51,597 UK Biobank participants who had retinal images available to extract oculomics of RVFs. Phenome-wide association analyses (PheWASs) were conducted to identify RVFs associated with the genetic risks of the main types of aneurysms, including abdominal aortic aneurysm (AAA), thoracic aneurysm (TAA), intracranial aneurysm (ICA) and Marfan syndrome (MFS). An aneurysm-RVF model was then developed to predict future aneurysms. The performance of the model was assessed in both derivation and validation cohorts and was compared with other models employing clinical risk factors. An RVF risk score was derived from our aneurysm-RVF model to identify patients with an increased risk of aneurysms.

Results

PheWAS identified a total of 32 RVFs that were significantly associated with the genetic risks of aneurysms. Of these, the number of vessels in the optic disc ('ntreeA') was associated with both AAA (β = -0.36, P = 6.75e-10) and ICA (β = -0.11, P = 5.51e-06). In addition, the mean angles between each artery branch ('curveangle_mean_a') were commonly associated with 4 MFS genes (FBN1: β = -0.10, P = 1.63e-12; COL16A1: β = -0.07, P = 3.14e-09; LOC105373592: β = -0.06, P = 1.89e-05; C8orf81/LOC441376: β = 0.07, P = 1.02e-05). The developed aneurysm-RVF model showed good discrimination ability in predicting the risks of aneurysms. In the derivation cohort, the C-index of the aneurysm-RVF model was 0.809 [95% CI: 0.780-0.838], which was similar to the clinical risk model (0.806 [0.778-0.834]) but higher than the baseline model (0.739 [0.733-0.746]). Similar performance was observed in the validation cohort, with a C-index of 0.798 (0.727-0.869) for the aneurysm-RVF model, 0.795 (0.718-0.871) for the clinical risk model and 0.719 (0.620-0.816) for the baseline model. An aneurysm risk score was derived from the aneurysm-RVF model for each study participant. The individuals in the upper tertile of the aneurysm risk score had a significantly higher risk of aneurysm compared to those in the lower tertile (hazard ratio = 17.8 [6.5-48.8], P = 1.02e-05).

Conclusion

We identified a significant association between certain RVFs and the risk of aneurysms and revealed the impressive capability of using RVFs to predict the future risk of aneurysms by a PPPM approach. Our finds have great potential to support not only the predictive diagnosis of aneurysms but also a preventive and more personalized screening plan which may benefit both patients and the healthcare system.

Graphical abstract

Supplementary Information

The online version contains supplementary material available at 10.1007/s13167-023-00315-7.

Association of elevated neutrophil-to-lymphocyte ratio with increased intracranial aneurysm stability scores and aneurysm growth

BACKGROUND AND PURPOSE

Inflammation involves in the progression of intracranial aneurysms (IAs). However, whether the neutrophil-to-lymphocyte ratio (NLR) as an inflammatory marker links to IAs stability is unidentified. This study was performed to assess the association of the NLR with IAs stability.

METHODS

We retrospectively reviewed the medical records of patients diagnosed with unruptured IAs from January 2014 to June 2018. According to the quartiles of the NLR, patients with unruptured IAs were categorized into four groups. We evaluated the association between the NLR and IAs stability scores and IAs growth. Multiple logistic regression models were used in the analysis.

RESULTS

A significant dose-response association was found between the NLR with IAs stability scores and IAs growth. After adjustment for potential confounders, an elevated NLR (fourth quartile) was associated with increased PHASES score (>5) (adjusted odds ratio [OR], 2.007; 95% confidence interval [CI], 1.361-2.960; p<0.001 [p for trend <0.001]), increased ELAPSS score (>15) (adjusted OR, 1.581; 95% CI, 1.074-2.328; p=0.020 [p for trend =0.001]), increased JAPAN 3-year rupture risk score (>5) (adjusted OR, 1.512; 95% CI, 1.033-2.215; p=0.034 [p for trend <0.001]), and IAs growth (adjusted OR, 16.759; 95% CI, 3.022-92.928; p=0.001 [p for trend <0.001]).

CONCLUSION

An elevated NLR was associated with increased IAs stability scores and IAs growth. The association between NLR and IAs stability need further investigate.

Inflow Angle Impacts Morphology, Hemodynamics, and Inflammation of Side-wall Intracranial Aneurysms

BACKGROUND

Aneurysm inflow angle has been shown to be associated with hemodynamic changes by computational fluid dynamics. However, these studies were based on single aneurysm model and were limited to side-wall aneurysms.

PURPOSE

To investigate the association between inflow angle and morphology, hemodynamic, and inflammation of intracranial side-wall and bifurcation aneurysms.

STUDY TYPE

Prospective.

POPULATION

A total of 62 patients (aged 58.34 ± 12.39, 44 female) with 59 unruptured side-wall aneurysms and 17 unruptured bifurcation aneurysms were included.

FIELD STRENGTH/SEQUENCE

A 3.0 T; 3D fast field echo sequence (TOF-MRA); free-breathing, 3D radio-frequency-spoiled, multi-shot turbo field echo sequence (4D-flow MRI); 3D black-blood T1-weighted volumetric turbo spin echo acquisition sequence (T₁ -VISTA) ASSESSMENT: Two neuroradiologists assessed the inflow angle and size for intracranial aneurysms in 3D space with TOF-MRA images. The average and maximum inflow velocity (V_avg-IA , V_max-IA ), blood flow (Flow_avg-IA , Flow_max-IA ), and average wall shear stress (WSS_avg-IA ) for aneurysms were assessed from 4D-flow MRI in regions of interest drawn by two neuroradiologists. The aneurysmal wall enhancement (AWE) grades between precontrast and postcontrast T₁ -VISTA images were evaluated by three neuroradiologists.

STATISTICAL TESTS

Kruskal-Wallis H test, χ² test, Pearson's correlation coefficient, scatter plots and regression lines, multivariate logistic regression analysis (partial correlation r) were performed. A P < 0.05 was considered statistically significant.

RESULTS

The WSS_avg-IA (0.52 ± 0.34 vs. 0.27 ± 0.22) and AWE grades (1.38 ± 1.04 vs. 2.02 ± 0.68) between the two inflow angle subgroups of side-wall aneurysms were significantly different. The aneurysm size (r_s  = 0.31), WSS_avg-IA (r_s  = -0.45), and AWE grades (r_s  = 0.45) were significantly correlated with inflow angle in side-wall aneurysms. While in bifurcation aneurysms, there were no significant associations between inflow angle and size (P = 0.901), V_avg-IA (P = 0.699), V_max-IA (P = 0.482), Flow_avg-IA (P = 0.550), Flow_max-IA (P = 0.689), WSS_avg-IA (P = 0.573), and AWE grades (P = 0.872).

DATA CONCLUSION

A larger aneurysm size, a lower WSS and a higher AWE grade were correlated with a larger inflow angle in side-wall aneurysms.

EVIDENCE LEVEL

3 TECHNICAL EFFICACY: Stage 2.

Deep learning-based semantic vessel graph extraction for intracranial aneurysm rupture risk management

PURPOSE

Intracranial aneurysms are vascular deformations in the brain which are complicated to treat. In clinical routines, the risk assessment of intracranial aneurysm rupture is simplified and might be unreliable, especially for patients with multiple aneurysms. Clinical research proposed more advanced analysis of intracranial aneurysm, but requires many complex preprocessing steps. Advanced tools for automatic aneurysm analysis are needed to transfer current research into clinical routine.

METHODS

We propose a pipeline for intracranial aneurysm analysis using deep learning-based mesh segmentation, automatic centerline and outlet detection and automatic generation of a semantic vessel graph. We use the semantic vessel graph for morphological analysis and an automatic rupture state classification.

RESULTS

The deep learning-based mesh segmentation can be successfully applied to aneurysm surface meshes. With the subsequent semantic graph extraction, additional morphological parameters can be extracted that take the whole vascular domain into account. The vessels near ruptured aneurysms had a slightly higher average torsion and curvature compared to vessels near unruptured aneurysms. The 3D surface models can be further employed for rupture state classification which achieves an accuracy of 83.3%.

CONCLUSION

The presented pipeline addresses several aspects of current research and can be used for aneurysm analysis with minimal user effort. The semantic graph representation with automatic separation of the aneurysm from the parent vessel is advantageous for morphological and hemodynamical parameter extraction and has great potential for deep learning-based rupture state classification.

Hemodynamics and bio-mechanics of morphologically distinct saccular intracranial aneurysms at bifurcations: Idealised vs Patient-specific geometries

Understanding the factors that influence the rupture of aneurysms is of primary concern to the clinicians, who are grappled with patient management. It is important to know how the relation between morphological features of the cerebral aneurysm, and the mechanical stresses on the containing arterial walls are influenced by the hemodynamic forces. Present study investigates three different shapes, which have been identified correspondingly in patient-specific scenarios as well. The primary objective is to categorize the bifurcation aneurysms into standard shapes such as, spherical, beehive and pear-shaped, based on patient-specific clinical studies and further compare and contrast the model aneurysms with the patient specific configurations, for their hemodynamic factors as well as the attendant stresses on the wall. MethodsComputational fluid dynamic simulations are performed accounting for the fluid-structure interaction (FSI) effects between the flowing fluid and the containing vessel wall. Blood is assumed to be Newtonian, while the arterial walls are assumed to be linearly elastic. A commercial solver is used for performing detailed calculations. Hemodynamic and bio-mechanical rupture predictions are carried out for the three different shapes. Observations derived from the idealised simulations are compared and contrasted against their patient-specific counterparts. ResultsFrom detailed numerical simulations, it was observed that pear-shaped aneurysms exhibit large re-circulation bubble and flow stagnation zone, with higher residence time for the particles, which may lead to atherosclerotic lesions. Beehive shape allows for maximum flow into the aneurysmal sac with concentrated jet impinging on the dome, leading to high values of maximum WSS (MWSS) resulting in great propensity to form a secondary bleb. However, flow field inside a spherical aneurysm is found to be stable with fewer vortices, and nearly uniform distribution of wall stresses are observed though-out the sac, which perhaps signifies hemodynamically and bio-mechanically stable condition. ConclusionCategorizing patient-specific intracranial aneurysms into standard shapes viz, spherical, beehive and pear could generalize the process of prediction of hemodynamic and bio-mechanical rupture indicators. Comparative assessment of the flow field and stresses reported from the simulations on idealised models, with corresponding patient-specific simulations reveal that, these studies could aid in understanding the generalised shape dependence of hemodynamic and bio-mechanical behaviour of aneurysms.

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.

Association Between Aneurysmal Hemodynamics and Rupture Risk of Unruptured Intracranial Aneurysms

Background

Assessing rupture risk in patients with unruptured intracranial aneurysms (UIAs) remains challenging. Hemodynamics plays an important role in the natural history of intracranial aneurysms. This study aimed to compare aneurysmal hemodynamic features between patients with different rupture risk as determined by PHASES score.

Methods

We retrospectively examined 238 patients who harbored a solitary saccular UIA. Patients were stratified by rupture risk into low-, intermediate-, and high-risk groups according to PHASES score. Flow simulations were performed to compare differences in hemodynamics among the groups.

Results

Aneurysmal time-averaged wall shear stress (WSSa) and normalized WSS (WSSn) decreased progressively as PHASES score increased. WSSa and WSSn significantly differed among the low-, intermediate-, and high-risk groups (p < 0.001). WSSa was significantly lower in the high-risk group than the low-risk group (p < 0.001) and the intermediate-risk group (p = 0.004). WSSn was also significantly lower in the high-risk group than the low-risk group (p < 0.001) and the intermediate-risk group (p = 0.001).

Conclusions

Low WSS was significantly associated with higher risk of intracranial aneurysm rupture as determined by PHASES score, indicating that hemodynamics may play an important role in aneurysmal rupture. In the future, a multidimensional rupture risk prediction model that includes hemodynamic parameters should be investigated.

Skeletal muscle atrophy and myosteatosis are not related to long-term aneurysmal subarachnoid hemorrhage outcome

The prognosis of aneurysmal subarachnoid hemorrhage (aSAH) is highly variable. This study aims to investigate whether skeletal muscle atrophy and myosteatosis are associated with poor outcome after aSAH. In this study, a cohort of 293 consecutive aSAH-patients admitted during a 4-year period was retrospectively analyzed. Cross-sectional muscle measurements were obtained at the level of the third cervical vertebra. Muscle atrophy was defined by a sex-specific cutoff value. Myosteatosis was defined by a BMI-specific cutoff value. Poor neurological outcome was defined as modified Rankin Scale 4-6 at 2 and 6-month follow-up. Patient survival state was checked until January 2021. Generalized estimating equation was performed to assess the effect of muscle atrophy / myosteatosis on poor neurological outcome after aSAH. Cox regression was performed to analyze the impact of muscle atrophy and myosteatosis on overall survival. The study found that myosteatosis was associated with poor neurological condition (WFNS 4-5) at admission after adjusting for covariates (odds ratio [OR] 2.01; 95%CI 1.05,3.83; P = .03). It was not associated with overall survival (P = .89) or with poor neurological outcomes (P = .18) when adjusted for other prognostic markers. Muscle atrophy was not associated with overall survival (P = .58) or neurological outcome (P = .32) after aSAH. In conclusion, myosteatosis was found to be associated with poor physical condition directly after onset of aSAH. Skeletal muscle atrophy and myosteatosis were however irrelevant to outcome in the Western-European aSAH patient. Future studies are needed to validate these finding.

Artificial Intelligence Applications in Intracranial Aneurysm: Achievements, Challenges and Opportunities

Intracranial aneurysms present in about 3% of the general population and the number of detected aneurysms is continuously rising with the advances in imaging techniques. Intracranial aneurysm rupture carries a high risk of death or permanent disabilities; therefore assessment of the intracranial aneurysm along the entire course is of great clinical importance. Given the outstanding performance of artificial intelligence (AI) in image-based tasks, many AI-based applications have emerged in recent years for the assessment of intracranial aneurysms. In this review we will summarize the state-of-the-art of AI applications in intracranial aneurysms, emphasizing the achievements, and exploring the challenges. We will also discuss the future prospects and potential opportunities. This article provides an updated view of the AI applications in intracranial aneurysms and may act as a basis for guiding the related future works.

Relationship between 3D Morphologic Change and 2D and 3D Growth of Unruptured Intracranial Aneurysms

BACKGROUND AND PURPOSE

Untreated unruptured intracranial aneurysms are usually followed radiologically to detect aneurysm growth, which is associated with increased rupture risk. The ideal aneurysm size cutoff for defining growth remains unclear and also whether change in morphology should be part of the definition. We investigated the relationship between change in aneurysm size and 3D quantified morphologic changes during follow-up.

MATERIALS AND METHODS

We performed 3D morphology measurements of unruptured intracranial aneurysms on baseline and follow-up TOF-MRAs. Morphology measurements included surface area, compactness, elongation, flatness, sphericity, shape index, and curvedness. We investigated the relation between morphologic change between baseline and follow-up scans and unruptured intracranial aneurysm growth, with 2D and 3D growth defined as a continuous variable (correlation statistics) and a categoric variable (t test statistics). Categoric growth was defined as ≥1-mm increase in 2D length or width. We assessed unruptured intracranial aneurysms that changed in morphology and the proportion of growing and nongrowing unruptured intracranial aneurysms with statistically significant morphologic change.

RESULTS

We included 113 patients with 127 unruptured intracranial aneurysms. Continuous growth of unruptured intracranial aneurysms was related to an increase in surface area and flatness and a decrease in the shape index and curvedness. In 15 growing unruptured intracranial aneurysms (12%), curvedness changed significantly compared with nongrowing unruptured intracranial aneurysms. Of the 112 nongrowing unruptured intracranial aneurysms, 10 (9%) changed significantly in morphology (flatness, shape index, and curvedness).

CONCLUSIONS

Growing unruptured intracranial aneurysms show morphologic change. However, nearly 10% of nongrowing unruptured intracranial aneurysms change in morphology, suggesting that they could be unstable. Future studies should investigate the best growth definition including morphologic change and size to predict aneurysm rupture.

Radiologic assessment of rupture risk in small (<5 mm) posterior communicating artery aneurysms

Although previous studies have investigated the predictors of posterior communicating artery (PCoA) aneurysm rupture with clinical and radiologic parameters, the accessibility of "small PCoA aneurysms (<5 mm)" has rarely been reported. Here, we designed a study to identify the factors which are thought to be risky and prone to rupture in small PCoA aneurysms (<5 mm).A total of 114 patients diagnosed with PCoA aneurysm under 5 mm in size on digital subtraction angiography were retrospectively enrolled and divided into ruptured (n = 51) and unruptured (n = 63) groups. Clinical variables were reviewed, and 10 radiologic parameters were obtained, including maximum diameter, height, width, neck width, aspect ratio, dome-to-neck ratio, bleb formation, size ratio, presence of fetal-type PCoA, and inflow angle. Statistical analyses were conducted to compare the groups (ruptured vs unruptured) and identify the risk factors for rupture.High rupture rate of small PCoA aneurysm is noted (51/114, 44.7%). In the comparison analysis, parameters of size ratio (P = .045), aspect ratio (P = .001), and bleb formation (P = .015) were significantly different between the 2 groups. In the regression model, the aspect ratio (P = .045) and bleb formation (P = .004) were significantly associated with the rupture of aneurysm.In respect of small (<5 mm) PCoA aneurysms of our cohort, morphologic parameters of "bleb formation" and "a high aspect ratio" are present more often in ruptured aneurysms as compared to unruptured aneurysms.

A Deep Learning Model with High Standalone Performance for Diagnosis of Unruptured Intracranial Aneurysm

PURPOSE

This study aimed to investigate whether a deep learning model for automated detection of unruptured intracranial aneurysms on time-of-flight (TOF) magnetic resonance angiography (MRA) can achieve a target diagnostic performance comparable to that of human radiologists for approval from the Korean Ministry of Food and Drug Safety as an artificial intelligence-applied software.

MATERIALS AND METHODS

In this single-center, retrospective, confirmatory clinical trial, the diagnostic performance of the model was evaluated in a predetermined test set. After sample size estimation, the test set consisted of 135 aneurysm-containing examinations with 168 intracranial aneurysms and 197 aneurysm-free examinations. The target sensitivity and specificity were set as 87% and 92%, respectively. The patient-wise sensitivity and specificity of the model were analyzed. Moreover, the lesion-wise sensitivity and false-positive detection rate per case were also investigated.

RESULTS

The sensitivity and specificity of the model were 91.11% [95% confidence interval (CI): 84.99, 95.32] and 93.91% (95% CI: 89.60, 96.81), respectively, which met the target performance values. The lesion-wise sensitivity was 92.26%. The overall false-positive detection rate per case was 0.123. Of the 168 aneurysms, 13 aneurysms from 12 examinations were missed by the model.

CONCLUSION

The present deep learning model for automated detection of unruptured intracranial aneurysms on TOF MRA achieved the target diagnostic performance comparable to that of human radiologists. With high standalone performance, this model may be useful for accurate and efficient diagnosis of intracranial aneurysm.

Hemodynamic changes after intracranial aneurysm growth

OBJECTIVE

For accurate risk assessment of unruptured intracranial aneurysms, it is important to understand the underlying mechanisms that lead to rupture. It is known that hemodynamic anomalies contribute to aneurysm growth and rupture, and that growing aneurysms carry higher rupture risks. However, it is unknown how growth affects hemodynamic characteristics. In this study, the authors assessed how hemodynamic characteristics change over the course of aneurysm growth.

METHODS

The authors included patients with observed aneurysm growth on longitudinal MRA in the period between 2012 and 2016. Patient-specific vascular models were created from baseline and follow-up images. Subsequently, intraaneurysmal hemodynamic characteristics were computed using computational fluid dynamics. The authors computed the normalized wall shear stress, oscillatory shear index, and low shear area to quantify hemodynamic characteristics. Differences between baseline and follow-up measurements were analyzed using paired t-tests.

RESULTS

Twenty-five patients with a total of 31 aneurysms were included. The aneurysm volume increased by a median (IQR) of 26 (9-39) mm3 after a mean follow-up period of 4 (range 0.4-10.9) years. The median wall shear stress decreased significantly after growth. Other hemodynamic parameters did not change significantly, although large individual changes with large variability were observed.

CONCLUSIONS

Hemodynamic characteristics change considerably after aneurysm growth. On average, wall shear stress values decrease after growth, but there is a large variability in hemodynamic changes between aneurysms.

Aspirin and growth, rupture of unruptured intracranial aneurysms: A systematic review and meta-analysis

OBJECTIVES

Aspirin has been suggested as a potential therapeutic strategy to prevent the growth and rupture of unruptured intracranial aneurysms (UIAs), but there is still controversy. The aim of this systematic review and meta-analysis is to determine the association between aspirin use and growth, rupture of UIAs.

METHODS

We performed a systematic literature search of electronic databases to identify cohort and case-control studies investigating the relationship between aspirin use and growth or rupture of UIAs. Pooled odds ratio (OR) with corresponding 95% confidence interval (CI) were calculated using a random effects model. Heterogeneity among studies was quantified using the I² statistic, and potential publication bias was assessed using funnel plots. Sensitivity analysis was performed to verify the robustness of the intention-to-treat results. Subgroup analysis was conducted according to the frequency of aspirin use.

RESULTS

We identified 8 studies comprising 10,518 participants. The risk of bias was low to moderate. The pooled estimate showed that aspirin use was associated with a lower likelihood of growth of UIAs (OR = 0.25, 95% CI = 0.11-0.55; p = 0.0005) without statistical heterogeneity (p for Cochran Q statistic = 0.62, I² = 0%). Likewise, aspirin intake also significant decreased 58% risk of intracranial aneurysms rupture (OR = 0.42, 95% CI = 0.29-0.60; p < 0.00001) with moderate heterogeneity (p for Cochran Q statistic = 0.005, I² = 66%). Similar results were observed in the sensitivity analysis. Pooled OR of aspirin frequency subgroup analysis for less than or equal to 2 times per week was 0.82 (95%CI = 0.40-1.72; I² = 0%), for at least 3 times per week to daily was 0.25 (95%CI = 0.12-053; I² = 0%), for daily was 0.59 (95%CI: 0.47-0.74; I² = 0%), and for unknown was 0.26 (95%CI: 0.15-0.45; I² = 51%).

CONCLUSIONS

The results of this systematic review and meta-analysis indicates a beneficial effect of aspirin on growth and rupture of UIAs.

Risk factors for the progression of unruptured intracranial aneurysms in patients followed by CT/MR angiography

Background

The progression of an unruptured intracranial aneurysm (UIA) is associated with a higher rupture risk. The aim of this study was to identify the risk factors for the progression of UIAs among Chinese adults and compare them with the ELAPSS (Earlier subarachnoid hemorrhage, IA Location, Age, Population, IA Size and Shape) score.

Methods

Four hundred thirty-eight consecutive patients with 491 UIAs were followed and reviewed retrospectively from August 2011 to November 2019. Follow-up images of the UIAs were used to determine changes in IA size and shape. Patients and IAs were divided into non-progression and progression groups. In addition to the clinical characteristics of the patients, the features of the IAs (e.g., size and shape) were evaluated by computed tomography angiography (CTA) or magnetic resonance angiography (MRA). Independent risk factors for UIA progression were studied using multiple Cox proportional hazards regression analysis. In addition, the diagnostic value of the ELAPSS score for the prediction of UIA progression was calculated.

Results

Seventy-two IAs in 68 patients progressed during a mean follow-up time of 24.2±19.68 months. IAs located at the bifurcation [odds ratio (OR) 2.600], with an irregular shape (OR 2.981) or having a high aspect ratio (AR, OR 2.430) were correlated with progression. Based on these three factors, the threshold value of our predictive score was 0.5, and the area under the curve (AUC), sensitivity and specificity were 0.756, 93.1% and 40.6%, respectively, while the AUC, sensitivity and specificity of the ELAPSS score were 0.711, 55.6%, and 75.2%, respectively.

Conclusions

IAs located at the bifurcation, with an irregular shape and with an elevated AR are risk factors for UIA progression in the Chinese population. Our predictive score is of great value in predicting the risk of UIA progression.

Reliability and Agreement of 2D and 3D Measurements on MRAs for Growth Assessment of Unruptured Intracranial Aneurysms

BACKGROUND AND PURPOSE

Reliable and reproducible measurement of unruptured intracranial aneurysm growth is important for unruptured intracranial aneurysm rupture risk assessment. This study aimed to compare the reliability and reproducibility of 2D and 3D growth measurements of unruptured intracranial aneurysms.

MATERIALS AND METHODS

2D height, width, and neck and 3D volume measurements of unruptured intracranial aneurysms on baseline and follow-up TOF-MRAs were performed by two observers. The reliability of individual 2D and 3D measurements and of change (growth) between paired scans was assessed (intraclass correlation coefficient) and stratified for aneurysm location. The smallest detectable change on 2D and 3D was determined. Proportions of growing aneurysms were compared, and Bland-Altman plots were created.

RESULTS

Seventy-two patients with 84 unruptured intracranial aneurysms were included. The interobserver reliability was good-to-excellent for individual measurements (intraclass correlation coefficient  > 0.70), poor for 2D change (intraclass correlation coefficient < 0.5), and good for 3D change (intraclass correlation coefficient = 0.76). For both 2D and 3D, the reliability was location-dependent and worse for irregularly shaped aneurysms. The smallest detectable changes for 2D height, width, and neck and 3D volume measurements were 1.5 , 2.0, and 1.9 mm and 0.06 mL, respectively. The proportion of growing unruptured intracranial aneurysms decreased from 10% to 2%, depending on the definition of growth (1 mm or the smallest detectable changes for 2D and 3D).

CONCLUSIONS

The interobserver reliability of the size measurements of individual 2D and 3D unruptured intracranial aneurysms was good-to-excellent but lower for 2D and 3D growth measurements. For growth assessment, 3D measurements are more reliable than 2D measurements. The smallest detectable change for 2D measurements was larger than 1 mm, the current clinical definition of unruptured intracranial aneurysm growth.

Aneurysm morphological prediction of intracranial aneurysm rupture in elderly patients using four-dimensional CT angiography

OBJECTIVE

The natural history of unruptured intracranial aneurysms (UIAs) in elderly patients remains poorly understood, and the treatment of UIAs is controversial. The presence of irregular pulsation detected by four-dimensional CT angiography (4D-CTA) is associated with ruptured aneurysms. We aimed to investigate the morphological predictors of irregular pulsation of aneurysms in elderly patients.

PATIENTS AND METHODS

We performed a prospective study of intracranial aneurysms detected by 4D-CTA. Elderly patients were defined as those more than 60 years of age. The irregular pulsation was defined as a focal protuberance during a cardiac cycle. We performed multivariate analyses to determine the associations of clinical characteristics and aneurysm morphologies with the irregular pulsation of aneurysms.

RESULTS

A total of 128 elderly patients with 166 intracranial aneurysms was included. The irregular pulsation occurred in 71 (42.8%) aneurysms. The multivariate analysis showed that a large size ratio (p = 0.006), posterior circulation aneurysms (p = 0.033), the presence of a daughter dome (p = 0.006), and aneurysm rupture (p = 0.032) were independently associated with the irregular pulsation. The multivariate analysis of predictors of irregular pulsation of unruptured aneurysms showed that size ratio (p = 0.01) and the presence of a daughter dome (p = 0.016) were independent predictors of irregular pulsation.

CONCLUSION

A large size ratio, posterior circulation aneurysms, the presence of a daughter dome, and aneurysm rupture were independent predictors of the irregular pulsation of aneurysms in elderly patients. The morphological characteristics detected by 4D-CTA may be helpful to evaluate the risk of rupture of aneurysms.

Warning Signs in the Era of Unruptured Intracranial Aneurysms: Report on 2 Cases of Fatal Aneurysmal Hemorrhage

Introduction

The timing of treatment remains unresolved for patients with unruptured intracranial aneurysms (UIAs) and headaches, particularly when the pain is short term, localized, and related to the aneurysm site. We lack evidence to support the notion that when a headache accompanies an aneurysm, it elevates the risk of rupture.

Results

We describe 2 cases of fatal subarachnoid hemorrhage in patients with a history of headache and known aneurysms. Both of these patients had good indications for treatment: a young age and an aneurysm >7 mm, and both were qualified for elective surgery. However, both patients died of fatal aneurysm ruptures before the planned surgery.

Conclusion

These cases suggested that treatment should be started as soon as possible, when a UIA is diagnosed based on a short-term period of severe headaches or when a UIA is observed and then severe headaches appear. There is no straightforward guideline for treatment timing in these patients. However, in this era of UIAs, the significance of sentinel headaches should be reevaluated. Given the incidence of headaches in the general population and the very low risk of aneurysm rupture, there may be a tendency to neglect the role of headache as a possible warning sign.

Deep Shape Features for Predicting Future Intracranial Aneurysm Growth

Introduction: Intracranial aneurysms (IAs) are a common vascular pathology and are associated with a risk of rupture, which is often fatal. Aneurysm growth is considered a surrogate of rupture risk; therefore, the study aimed to develop and evaluate prediction models of future artificial intelligence (AI) growth based on baseline aneurysm morphology as a computer-aided treatment decision support.

Materials and methods: Follow-up CT angiography (CTA) and magnetic resonance angiography (MRA) angiograms of 39 patients with 44 IAs were classified by an expert as growing and stable (25/19). From the angiograms vascular surface meshes were extracted and the aneurysm shape was characterized by established morphologic features and novel deep shape features. The features corresponding to the baseline aneurysms were used to predict future aneurysm growth using univariate thresholding, multivariate random forest and multi-layer perceptron (MLP) learning, and deep shape learning based on the PointNet++ model.

Results: The proposed deep shape feature learning method achieved an accuracy of 0.82 (sensitivity = 0.96, specificity = 0.63), while the multivariate learning and univariate thresholding methods were inferior with an accuracy of up to 0.68 and 0.63, respectively.

Conclusion: High-performing classification of future growing IAs renders the proposed deep shape features learning approach as the key enabling tool to manage rupture risk in the “no treatment” paradigm of patient follow-up imaging.

Low Carotid Flow Pulsatility Index Correlates With the Presence of Unruptured Intracranial Aneurysms

Background

We assessed cases of incidental unruptured intracranial aneurysm (UIA) discovered on screening magnetic resonance angiography to identify hemodynamic and atherosclerotic risk factors.

Methods and Results

The data of 1376 healthy older subjects (age range, 31–91 years) without cerebro‐ or cardiovascular diseases who underwent brain magnetic resonance angiography as part of a medical checkup program at a health screening center were examined retrospectively. We looked for an increase in classical risk factors for UIAs (age, sex, hypertension, and smoking) and laboratory data related to lifestyle diseases among subjects with UIAs. Brachial‐ankle pulse wave velocity, central systolic blood pressure, radial augmentation index, and carotid flow pulsatility index were also compared between those with and without UIAs. We found UIAs in 79 (5.7%) of the subjects. Mean age was 67.1±9.0 years, and 55 (70%) were women. Of the 79 aneurysms, 75 (95%) were in the anterior circulation, with a mean diameter of 3.1 mm (range, 2.0–8.0 mm). Subjects with UIAs were significantly older and had more severe hypertension. The carotid flow pulsatility index was significantly lower in subjects with UIAs and negatively and independently correlated with UIAs. Tertile analysis stratified by carotid flow pulsatility index revealed that subjects with lower indices had higher levels of low‐density lipoprotein cholesterol.

Conclusions

The presence of UIAs correlated with lower carotid flow pulsatility index and elevated low‐density lipoprotein cholesterol in the data from a population of healthy older volunteers. A reduced carotid flow pulsatility index may affect low‐density lipoprotein cholesterol elevation by some molecular pathways and influence the development of cerebral aneurysms. This may guide aneurysm screening indications for institutions where magnetic resonance angiography is not routine.

Comparing methods of detecting and segmenting unruptured intracranial aneurysms on TOF-MRAS: The ADAM challenge

Accurate detection and quantification of unruptured intracranial aneurysms (UIAs) is important for rupture risk assessment and to allow an informed treatment decision to be made. Currently, 2D manual measures used to assess UIAs on Time-of-Flight magnetic resonance angiographies (TOF-MRAs) lack 3D information and there is substantial inter-observer variability for both aneurysm detection and assessment of aneurysm size and growth. 3D measures could be helpful to improve aneurysm detection and quantification but are time-consuming and would therefore benefit from a reliable automatic UIA detection and segmentation method. The Aneurysm Detection and segMentation (ADAM) challenge was organised in which methods for automatic UIA detection and segmentation were developed and submitted to be evaluated on a diverse clinical TOF-MRA dataset. A training set (113 cases with a total of 129 UIAs) was released, each case including a TOF-MRA, a structural MR image (T1, T2 or FLAIR), annotation of any present UIA(s) and the centre voxel of the UIA(s). A test set of 141 cases (with 153 UIAs) was used for evaluation. Two tasks were proposed: (1) detection and (2) segmentation of UIAs on TOF-MRAs. Teams developed and submitted containerised methods to be evaluated on the test set. Task 1 was evaluated using metrics of sensitivity and false positive count. Task 2 was evaluated using dice similarity coefficient, modified hausdorff distance (95^th percentile) and volumetric similarity. For each task, a ranking was made based on the average of the metrics. In total, eleven teams participated in task 1 and nine of those teams participated in task 2. Task 1 was won by a method specifically designed for the detection task (i.e. not participating in task 2). Based on segmentation metrics, the top two methods for task 2 performed statistically significantly better than all other methods. The detection performance of the top-ranking methods was comparable to visual inspection for larger aneurysms. Segmentation performance of the top ranking method, after selection of true UIAs, was similar to interobserver performance. The ADAM challenge remains open for future submissions and improved submissions, with a live leaderboard to provide benchmarking for method developments at https://adam.isi.uu.nl/.

Readmission Trends Related to Unruptured Intracranial Aneurysm Treatment

Background and Purpose: Aneurysmal subarachnoid hemorrhage (SAH) is associated with high mortality. Prophylactic treatment of the unruptured intracranial aneurysm (UIA) is considered in a select group of patients thought to be at high for aneurysmal rupture. Hospital readmission rates can serve as a surrogate marker for the safety and cost-effectiveness of treatment options for UIAs; we present an analysis of the 30-day rehospitalization rates and predictors of readmission following UIA treatment with surgical and endovascular approaches. Methods: We retrospectively analyzed data from the National Readmission Database (NRD) derived from the Healthcare Cost and Utilization Project for the year 2014. The cohort included patients with a primary discharge diagnosis of a treated unruptured aneurysm. The primary outcome variable was the 30-day readmission rate in open surgical vs. endovascularly treated groups. The secondary outcomes included predictors of readmissions, and causes of 30-day readmissions in these two groups. Results: The 30-day readmission rate for the surgical group was 8.37% compared to 4.87% for the endovascular group. The index hospitalization duration was longer in the surgical group. A larger proportion of the patients readmitted following surgical treatment were hypertensive (76.35, vs. 63.43%), but the prevalence of other medical comorbidities was comparable in the two treatment groups. Conclusions: There is a higher likelihood for 30-day readmission, longer duration of initial hospitalization and a lower likelihood of discharge home following surgical treatment of UIAs when compared to endovascular treatment. These findings, however, do not demonstrate long-term superiority of one specific treatment modality.

Knowledge framework and emerging trends in intracranial aneurysm magnetic resonance angiography: a scientometric analysis from 2004 to 2020

Background

As magnetic resonance angiography (MRA) has been increasingly used in the follow-up of intracranial aneurysms (IAs) as a non-invasive technique, the knowledge framework and areas of research interest in intracranial aneurysms magnetic resonance angiography (IAMRA) change approximately every 10 years. However, few studies have quantitatively analyzed the published literature in this field. In the present study, we used scientometrics to survey the knowledge field, development trends, and research focus of IAMRA with the aim of providing a reference for further study.

Methods

We collected articles on IAMRA published from 2004 (Jan 1, 2004) to 2020 (May 24, 2020). Web of Science Core Collection databases (WoSCCd) including the Science Citation Index Expanded were searched. An experienced staff member from the Department of Radiology at Southern Medical University, assisted in screening articles for relevant articles. We used ArcGIS (a mapping and location analytics platform) to perform geographic visualization. Excel 2016 was used to analyze the literature data, including number of publications, impact factor (IF), and publication year. CiteSpace V was used to conduct a series of literature feature clustering, including author co-citation analysis, reference co-citation analysis (RCA), and burst keywords analysis.

Results

A total of 1,272 articles on IAMRA published between 2004 and 2020 were included. Of 257 journals, American Journal of Neuroradiology (IF 2018: 3.256) published the most IAMRA articles (109 publications, 8.57%), followed by Journal of Neurosurgery (IF 2018: 4.131, 51 publications, 4.16%), and Neuroradiology (IF 2018: 2.504, 51 publications, 4.01%). Of 56 countries, the USA published the most, with 347 articles [27.28%, IF: 3.14 (average IF of all journals in the country)], followed by Japan (242 articles, 19.03%, IF: 2.38), Germany (135 articles, 10.61%, IF: 3.21), and China (101 articles, 7.94%, IF: 2.86). A total of 1387 institutions published articles, with the Mayo Clinic publishing the most (33 articles, 2.59%), followed by Shanghai Jiao Tong University (25 article, 1.97%), Seoul National University (23 articles, 1.81%), and University Medical Center Utrecht (19 articles, 1.49%). Of 399 authors, Rinkel ranked first with 19 articles, followed by Li MH (18 articles), Uchino A (15 articles), and Saito N (13 articles). Cluster RCA showed that the first cluster was "#0 growth", followed by "#1 Guglielmi detachable coils". Timeline views showed that the time span of "#0 growth" was the closest to today. The modularity value was 0.6971, and the mean silhouette value was 0.5477. According to the burst keyword analysis, "risk factors associated to rupture" was the topic with the strongest burst since 2017. Studies conducted in several countries suggested that age is inversely related to the risk of rupture, which implies the importance of MRA follow-up for patients of different age.

Conclusions

From 2004 to 2020, the number of published IAMRA-related articles gradually increased. The USA and Western Europe lead in the field, with a concentration of cutting-edge talents and high-level scientific research institutions. A synthesis of the clustering results of RCA and burst keyword analysis indicated that unruptured IA growth, stent-assisted coil embolization, and risk factors associated to rupture were the current hotspots in IAMRA 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.

Wall Redness of Enlarged Unruptured Cerebral Aneurysm

OBJECTIVES

The wall of enlarged unruptured cerebral aneurysm (EUCA) is thought to be reddish, thin, and fragile. This study aimed to evaluate the EUCA wall redness based on quantitative signal intensity method and to compare the clinical and radiological characteristics between EUCA and non-EUCA.

MATERIALS & METHODS

In this retrospective analysis, red (R), green (G), blue (B), and RGB signal intensities of aneurysm were quantitatively measured using an intraoperative digital picture in 150 cases. Color intensities were measured by two independent investigators. Aneurysm redness was defined as an R/RGB ratio since the brightness of the operative field differed by each surgery or angle of the microscope.

RESULTS

The median aneurysm size was 4.9 mm (IQR 3.9-5.9 mm). Median color intensity of R, G, B, RGB, and R/RGB ratio were 206 (185-215), 129 (107-150), 136 (115-157), 157 (140-174), and 1.26 (1.20-1.38), respectively. The intraclass correlation coefficient for R/RGB ratio was 0.73 (P<0.0001). The proportion of female sex was significantly higher for EUCA (p = 0.019). Median R/RGB ratio in GUCA was significantly larger than that of non-EUCA (OR 1.25, 95% CI 1.19-1.35) (p = 0.035). Even after adjustment of female sex, a R/RGB ratio ≧1.36 was related to EUCA (OR 3.02, 95% CI 1.30-7.02).

CONCLUSIONS

The present study showed that a R/RGB ratio could be calculated easily and a larger R/RGB ratio was related to EUCA. When EUCA is managed by surgical treatment, more careful manipulation should be needed compared to non-EUCA due to a "red" wall of EUCA.

CT Angiography-Based Radiomics for Classification of Intracranial Aneurysm Rupture

Background: Intracranial aneurysm rupture is a devastating medical event with a high morbidity and mortality rate. Thus, timely detection and management are critical. The present study aimed to identify the aneurysm radiomics features associated with rupture and to build and evaluate a radiomics classification model of aneurysm rupture. Methods: Radiomics analysis was applied to CT angiography (CTA) images of 393 patients [152 (38.7%) with ruptured aneurysms]. Patients were divided at a ratio of 7:3 into retrospective training (n = 274) and prospective test (n = 119) cohorts. A total of 1,229 radiomics features were automatically calculated from each aneurysm. The feature number was systematically reduced, and the most important classifying features were selected. A logistic regression model was constructed using the selected features and evaluated on training and test cohorts. Radiomics score (Rad-score) was calculated for each patient and compared between ruptured and unruptured aneurysms. Results: Nine radiomics features were selected from the CTA images and used to build the logistic regression model. The radiomics model has shown good performance in the classification of the aneurysm rupture on training and test cohorts [area under the receiver operating characteristic curve: 0.92 [95% confidence interval CI: 0.89-0.95] and 0.86 [95% CI: 0.80-0.93], respectively, p < 0.001]. Rad-score showed statistically significant differences between ruptured and unruptured aneurysms (median, 2.50 vs. -1.60 and 2.35 vs. -1.01 on training and test cohorts, respectively, p < 0.001). Conclusion: The results indicated the potential of aneurysm radiomics features for automatic classification of aneurysm rupture on CTA images.