Risk Factors for the Rupture of Bifurcation Intracranial Aneurysms Using CT Angiography

Comparison of Woven EndoBridge and stent-assisted coiling for treatment of acutely ruptured wide-neck bifurcation aneurysms: Single-center experience

OBJECTIVE

Treating wide-necked bifurcation aneurysms (WNBA) is challenging. Nevertheless, recent progress in endovascular techniques is promising. Woven EndoBridge devices (WEB) have exhibited outcomes comparable to conventional treatments like stent-assisted coiling (SAC) in treating aneurysms. However, their safety and efficacy in managing acutely ruptured aneurysms remain a topic of interest. This study focuses on this issue.

METHODS

We searched our database from 2020 to 2023 and found 38 patients with acutely (< a week) ruptured WNBA. We extracted radiologic and clinical data from the available medical reports. Favorable functional and radiologic outcomes were assessed using the modified Rankin scale (mRS) and modified Raymond-Roy occlusion classification (MRRC).

RESULTS

Our study population comprised 15 aneurysms treated with WEB and 25 treated with SAC. Operational time was significantly lower in the WEB compared to the SAC group (39.3 vs 66.2 minutes, p value: < 0.001). Immediate (p value=0.64) and the 18th-month (p value=0.42) occlusion rates were comparable between the two groups. Favorable mRS scores in the 3rd month were seen in 100% of SAC patients and 93.3% of WEB patients (p value=0.79). Retreatment (p value=1.0) and complication (p value=0.39) rates were comparable. Vasospasms after the procedure were the most common complication.

CONCLUSIONS

WEB demonstrated comparable safety and efficacy to SAC in patients with acutely ruptured WNBA. Notably, WEB had a shorter procedure duration. Additional studies with extended follow-up periods are necessary for comprehensive evaluation.

Fluid structure Interaction analysis for rupture risk assessment in patients with middle cerebral artery aneurysms

Accurate rupture risk assessment is essential for optimizing treatment decisions in patients with cerebral aneurysms. While computational fluid dynamics (CFD) has provided critical insights into aneurysmal hemodynamics, most analyses focus on blood flow patterns, neglecting the biomechanical properties of the aneurysm wall. To address this limitation, we applied Fluid-Structure Interaction (FSI) analysis, an integrative approach that simulates the dynamic interplay between hemodynamics and wall mechanics, offering a more comprehensive risk assessment. In this study, we used advanced FSI techniques to investigate the rupture risk of middle cerebral artery bifurcation (MCA) aneurysms, analyzing a cohort of 125 patients treated for a MCA aneurysm at Kepler University Hospital, Linz, Austria. Multivariate analysis identified two significant rupture predictors: High Equivalent Stress Area (HESA; p = 0.049), which quantifies stress distribution relative to the aneurysm surface, and Gaussian curvature (GLN; p = 0.031), which captures geometric complexity. We also introduce the HGD index, a novel composite metric combining HESA, GLN, and Maximum Wall Displacement, designed to enhance predictive accuracy. With a threshold of 0.075, the HGD index exhibited excellent diagnostic performance; in internal validation, 24 of 25 ruptured aneurysms surpassed this threshold, yielding a sensitivity of 0.96. In a 5-fold cross validation the reliability of results was confirmed. Our findings demonstrate that the HGD index provides superior rupture risk stratification compared to conventional single-parameter models, offering a more robust tool for the assessment of complex aneurysmal structures. Further multicenter studies are warranted to refine and validate the HGD index, advancing its potential for clinical application and improving patient outcomes.

The relationship between symptomatic status and aneurysm wall enhancement characteristics of single unruptured intracranial aneurysm

OBJECTIVE

We aimed to analyze the aneurysm wall enhancement (AWE) characteristics of a single unruptured intracranial aneurysm (UIA) and observe the relationship between the symptoms of a single UIA and the aneurysm wall.

METHODS

In our hospital, 85 patients diagnosed with a single UIA using computed tomography angiography (CTA) were retrospectively analyzed. The patients were divided into symptomatic and asymptomatic groups, including 46 asymptomatic and 39 symptomatic aneurysms. High-resolution magnetic resonance imaging of the vascular wall (HR-MR-VWI) was utilized to ascertain the presence, degree, and extent of AWE and thick-wall enhancement. In addition to AWE characteristics, morphological parameters of aneurysms, such as maximal size, shape, height, neck width, aspect ratio (AR), and size ratio (SR), were scanned using CTA. The differences in the parameters of a single UIA between the two groups were compared. An investigation explored the correlation between the symptom status of a single UIA and AWE.

RESULTS

We observed a correlation between symptom status and maximal size, height, and neck width for a single UIA, the presence or absence of AWE, and the levels and boundaries of AWE and thick-wall reinforcement. This study found that the AWE range was independently correlated with symptom status in the multivariate regression analysis.

CONCLUSION

A larger AWE range was an independent risk factor for the onset of symptoms in a single UIA.

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.

Different Hemodynamic Characteristics and Resulting in Different Risks of Rupture Between Wide-Neck and Narrow-Neck Aneurysms

Objective

This study aimed to determine the ruptured rate and hemodynamic difference between wide-neck aneurysms (WNAs) and narrow-neck aneurysms (NNAs), as well as the hemodynamic parameters of risk factors for aneurysm rupture.

Methods

A total of 121 cases of intracranial aneurysms (IAs) were studied retrospectively between January 2019 and April 2021 at Renmin Hospital of Wuhan University. Intracranial aneurysms were classified into four types: ruptured wide-neck aneurysms (RWNAs), unruptured wide-neck aneurysms (UWNAs), ruptured narrow-neck aneurysms (RNNAs), and unruptured narrow-neck aneurysms (UNNAs). The Chi-square test was used to compare differences in rupture ratios. The clinical characteristics and hemodynamics were analyzed statistically to reveal the rupture risk factors. Moreover, significant parameters were subjected to binary logistic regression analysis to identify the independent predictive factors. The receiver operating characteristic (ROC) curve was performed to obtain cutoff values.

Results

WNAs ruptured more frequently than NNAs (P = 0.033). Ruptured intracranial aneurysms (RIAs) were characterized by significantly higher intra-aneurysmal pressure (IAP), wall shear stress (WSS), wall shear stress gradient (WSSG), and lower normalized wall shear stress (NWSS) than unruptured intracranial aneurysms (UIAs). RWNAs had higher IAP, WSS, and lower NWSS than UWNAs (P < 0.05). RNNAs had higher IAP, Streamwise WSSG and lower NWSS compared to UNNAs (P < 0.05). Binary logistic regression revealed that IAP and WSS were independent predictive risk factors for WNAs rupture, with cut-off values of 405.5 and 6.66 Pa, respectively. Also, IAP was an independent predictive risk factor for NNA rupture, with a cut-off value of 255.3 Pa.

Conclusions

Wide-neck aneurysms and narrow-neck aneurysms have diverse hemodynamics, which prompts a higher rupture ratio for WNAs. IAP could characterize the rupture risk in both WNAs and NNAs independently, but WSS could only predict the rupture risk in WNAs. This research might assist neurosurgeons with fostering a more sensible strategy for the treatment of IAs.

U-Shaped Association of Aspect Ratio and Single Intracranial Aneurysm Rupture in Chinese Patients: A Cross-Sectional Study

Background: Previous studies have analyzed the association of aspect ratio (AR) on the ruptured intracranial aneurysm (IA), but the findings are inconclusive and controversial. Therefore, the study aimed to derive a more detailed estimation of this association between AR and ruptured IA in Chinese IA patients. Methods: The present work was a cross-sectional study. We retrospectively collected 1,588 Chinese patients with a single IA from January 2010 to November 2017. The relationship was examined between AR at diagnosis and ruptured IA. Covariates included data of demographics, morphological parameters, lifestyle habits, clinical features, and comorbidities. Binary logistic regression and two-piecewise linear models were used to analyze independent associations of AR with ruptured IA. Results: The results suggest that the association between AR and IA rupture was U-shaped. In the AR range of 1.08-1.99, the prevalence of IA rupture was 13% lower for each 0.1-unit increment in AR [odds ratio 0.87, 95% confidence interval (CI) 0.80-0.98]. Conversely, for every 0.1-unit increase in AR, the prevalence of IA rupture increased by ~3% (odds ratio 1.03, 95% CI 1.01-1.06) in the AR range of 3.42-4.08. Conclusion: The relationship between AR and ruptured IA was U-shaped, with the negative association at AR of 1.08-1.99 and positive association at AR of 3.42-4.08.

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

BACKGROUND

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

METHODS

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

RESULTS

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

CONCLUSIONS

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

Intracranial aneurysm management in patients with late-onset Pompe disease (LOPD)

Pompe disease is a rare hereditary metabolic disorder caused by α-glucosidase (GAA) deficiency. The late-onset form of the disease (LOPD) is considered a multisystemic disorder which could involve vascular system with cerebrovascular abnormalities such as intracranial aneurysms or dolichoectasia. Intracranial aneurysm rupture may represent a life-threatening emergency. A possible treatment of unruptured intracranial aneurysms (UIAs) should consider both aneurysm-related (aneurysmal size, shape, localization, numbers and hemodynamic factors) and patient-related risk factors (patient's age and sex, hypertension, smoke exposure). Moreover, UIAs management of LOPD patients needs also to take into account the altered blood vessels integrity and elasticity, whose consistency is likely weakened by the deficient GAA activity as a further potential risk factor. We herein present our approach for of UIAs management in three patients with LOPD. Among them, only one patient with a left saccular UIA of the anterior communicating artery, after careful consideration of risk factors, underwent the endovascular treatment. The other two patients were scheduled for a 1-year follow-up, according to radiological, clinical, and risk evaluation features. Finally, we would like to suggest some general recommendations for UIAs management. In particular, if no risk factors are identified, a cautious yearly follow-up is suggested; otherwise, if risk factors are present, endovascular treatment should be considered.

Current Treatment of Anterior Communicating Artery Aneurysms: Single Center Study

INTRODUCTION

Anterior communicating artery aneurysms (ACoAAs) are the most frequent intracranial aneurysms treated at neurosurgical departments with a vascular program.

MATERIAL AND METHODS

We reviewed patients with ACoAAs in a single institution over ten years (2008-2017). The focus was on the final outcome; complications, age, and clinical condition with respect to modalities were analyzed.

RESULTS

A total of 198 patients treated during this period was included in the study: 176 patients had a ruptured ACoAA and 22 had an unruptured ACoAA. Then, 127 (71%) were treated surgically and 51 (29%) by endovascular means. Out of the whole series, a good recovery occurred in 123 patients (62%), moderate disability in 11 (5.5%), severe disability in 19 (10%), vegetative state in 11 (5.5%), and death in 34 (17%). In the 157 patients (72.5%) with a subarachnoid hemorrhage (SAH), both modalities had a favorable outcome: 27.5% had an unfavorable outcome, 12% had complications in surgery versus 17.6% during endovascular treatment. No statistical difference in outcome, complications, and age was noted between modalities. Surgical treatment was more frequently adopted for patients in a better clinical condition (p ≤ 0.05).

CONCLUSION

More than two thirds of the patients (72.5%) reached a favorable outcome. There was no difference in age between the treatment modalities. Risks of complications are present and specific for both modalities.

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

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

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

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

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

Therapeutic evaluation of a patient with ruptured intracranial aneurysm without subarachnoid hemorrhage by CT imaging: a case report

Background

The majority of ruptured intracranial aneurysms are combined with subarachnoid hemorrhage, but patients with only intracerebral hematoma without any subarachnoid hemorrhage are extremely rare.

Case presentation

The patient was hospitalized due to sudden dizziness combined with slurred speech. The patient showed considerable decreased physical activity without any nuchal rigidity. Head CT showed hematoma in the left temporal lobe, and the shape of hematoma was extremely irregular. MRI indicated the absence of any vascular malformations. The patient was diagnosed with middle cerebral artery bifurcation aneurysm in the left by head CTA. Intracranial aneurysm clip and removal of hematoma in the left temporal lobe were performed under general anesthesia. The patient did not show any significant neurological dysfunction after the surgery and was followed up for 4 months after discharge with GOS score of 5 points.

Conclusions

Intracranial hematoma with irregular morphology around the lateral fissure of the brain should be considered critical in order to avoid misdiagnosis and any possibility of missed diagnosis of vascular lesions, so as to ensure an exact therapeutic strategy with good prognosis for the patients.

Analysis of Anterior Cerebral Artery Tortuosity: Association with Anterior Communicating Artery Aneurysm Rupture

BACKGROUND

Many researchers have found a correlation between tortuous arteries and development of aneurysms in cerebral arteries. However, there are no studies analyzing the impact of tortuosity on risk of subarachnoid hemorrhage (SAH) occurrence. Therefore, we decided to determine whether tortuosity of the anterior cerebral artery can be related to the rupture of anterior communicating artery aneurysm and to severity and treatment outcome of SAH.

METHODS

We retrospectively analyzed anterior cerebral artery anatomy of 121 patients with anterior communicating artery aneurysms. From patients' medical records, we obtained their history including previous and current diseases and medications. For each patient we calculated relative length, sum of angle metrics, triangular index, product of angle distance, and inflection count metrics.

RESULTS

Patients with SAH had significantly higher relative length (0.70 ± 0.19 vs. 0.63 ± 0.22; P = 0.03) and significantly lower inflection count metrics (0.10 ± 0.08 vs. 0.16 ± 0.19; P < 0.01), respectively. In multivariate logistic regression analysis, after adjustment of all possible confounders, diabetes mellitus (odds ratio [OR], 0.154; 95% confidence interval [CI], 0.032-0.553; P < 0.01) and higher inflection count metrics (OR, 0.604; 95% CI, 0.357-0.909; P = 0.042) remained independently associated with lower risk of SAH. We also found an independent correlation between aneurysm dome size (R = -0.289; P = 0.02) and triangular index (R = 0.273; P = 0.03) and Glasgow Coma Scale score on admission.

CONCLUSIONS

Higher anterior cerebral artery tortuosity might be a protective factor against anterior communicating artery aneurysm rupture.

Risk factors for ruptured intracranial aneurysms

Background & objectives

The treatment of unruptured intracranial aneurysms (IAs) remains controversial; the ability to predict the risk of rupture for an aneurysm would be of clinical value. The aim of this study was to determine and evaluate the predictive value of the risk factors of IA rupture.

Methods

This retrospective study involved 379 consecutive patients with 441 aneurysms between August 2011 and July 2014. Based on clinical data and computed tomography angiography findings, the potential of risk factors to predict the aneurysmal rupture was assessed using statistical methods.

Results

Age, hypertension, heart disease, diabetes mellitus, cerebral atherosclerosis, aneurysms located at the internal carotid artery (ICA) and neck width (N) correlated negatively with rupture risk. Aneurysms located at the anterior communicating artery, bifurcation, irregularity, with a daughter sac, aneurysm height, maximum size, aspect ratio (AR), height-to-width ratio and bottleneck factor were significantly and positively correlated with rupture risk. The multivariate logistic regression model revealed that bifurcation aneurysm, irregular aneurysm and high AR increased the rupture risk, while cerebral atherosclerosis, aneurysm located on the ICA and greater N decreased the risk. Receiver operating characteristic analysis of AR curve values differed according to circumstances.

Interpretation & conclusions

Cerebral atherosclerosis, location in the ICA and larger N were the protective factors against aneurysm rupture, and IAs located at bifurcations, irregular shape and increased AR indicated a greater rupture risk.

Morphological characteristics associated with the rupture risk of mirror posterior communicating artery aneurysms

Objective

Patient related clinical factors and intracranial aneurysms (IAs) at different locations may lead to statistical bias when investigating the rupture risk of IAs. Thus the purpose of this study was to identify the morphological parameters that are related to the rupture of mirror posterior communicating artery aneurysms (PComAAs).

Methods

Between August 2011 and July 2017, 68 patients with mirror PComAAs and aneurysmal subarachnoid hemorrhage were diagnosed by CT angiography at three medical centers. Morphological characteristics for PComAAs included bifurcation, shape, neck width, width, depth, maximum size, flow angle, parent vessel diameter, aspect ratio (AR), depth/width ratio, bottleneck factor, and size ratio (SR). Multiple logistic regression analysis was performed to determine the independent risk factors for rupture. Receiver operating characteristic curve analysis was performed to obtain the optimal thresholds.

Results

AR (OR 5.623) and SR (OR 5.570) were more commonly observed in the ruptured cohort. The threshold values of AR and SR were 0.98 and 1.21, respectively.

Conclusions

Mirror PComAAs are a useful model to investigate the rupture risk of PComAAs. AR (≥0.98) and SR (≥1.21) are better predictors of ruptured PComAAs.

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

Background:

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

Methods:

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

Results:

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

Conclusion:

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

Anterior Communicating Artery Aneurysm Morphology and the Risk of Rupture

BACKGROUND

Recently, with improvements in computed tomography angiography and digital subtraction angiography, the assessment of certain morphologic traits of anterior communicating artery aneurysms (ACoAA) has drawn great attention. The determination of specific factors associated with rupture would provide much-needed guidance for the treatment of unruptured intracranial aneurysms, such as surgical clipping or endovascular coiling. Morphologic factors include, but are not limited to, aneurysm size, number, shape, dome direction, neck/dome ratio, and relationship of the aneurysm to the surrounding vessels. However, the results of previous investigations concerning morphologic parameters have yielded inconsistent results.

METHODS

This review presents and analyzes the literature on the morphology of ACoAAs and risk of rupture.

RESULTS

This literature review reveals that the strongest predictors of ACoAA rupture are size ratio, direction of the dome, and fenestration. These were the only factors that were either unanimously or near unanimously found to be predictive of rupture across multiple studies.

CONCLUSIONS

The size ratio, direction of the dome, and fenestration should be examined most meticulously when deciding when to treat an ACoAA.

Wall enhancement ratio and partial wall enhancement on MRI associated with the rupture of intracranial aneurysms

Objectives

To evaluate the risk factors for rupture of intracranial aneurysms (IAs) using high resolution MRI (HRMRI).

Methods

91 consecutive patients with 106 IAs were reviewed from February 2016 to April 2017. Patients and IAs were divided into ruptured and unruptured groups. In addition to the clinical characteristics of the patients, the features of IAs (eg, shape) were evaluated by CT angiography, whereas wall thickness, enhanced patterns, and enhancement ratio (ER) were evaluated by MRI. Multiple logistic regression analysis was used to identify independent risk factors associated with the rupture of IAs. Receiver operating characteristic curve analysis was performed on the final model, and the optimal thresholds were obtained.

Results

ER (OR 6.638) and partial wall enhancement (PWE) (OR 6.710) were not markers of aneurysms more prone to rupture, but simply were more commonly found in the ruptured aneurysm cohort. The threshold value for ER was 61.5%.

Conclusions

ER (≥61.5%) and IAs with PWE are better predictors of rupture. Increased attentions should be paid to these factors during assessment of IA rupture.

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

BACKGROUND AND OBJECTIVE

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

METHODS

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

RESULTS

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

CONCLUSIONS

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