Aneurysm Wall Enhancement Research Articles

There is poor agreement between the subjective and quantitative adjudication of aneurysm wall enhancement.

The determination of Aneurysm wall enhancement (AWE) by human readers on visual inspection alone is subjective and prone to error. A three-dimensional (3D) method for quantifying the aneurysm wall's signal intensity (SI) enables objective determination of AWE. Inter-reader agreement and agreement between subjective and objective determination of AWE were assessed in this study. Patients with saccular intracranial aneurysms (IAs) were imaged with high-resolution MRI. Subjective assessment: Two internal adjudicators visually determined AWE if the degree of enhancement was equal to or higher than the pituitary stalk. An experienced internal neuroradiologist resolved disagreements. This internal adjudication was compared with an external adjudication to assess inter-rater agreement among centers. Objective assessment: The distribution of SI across the aneurysm wall after normalizing the SI to the corpus callosum was determined with an in-house code. The normalized mean SI on post-contrast T1 MRI was defined as 3D-circumferential AWE (3D-CAWE). If the 3D-CAWE value was higher than one, an IA was defined as objectively "enhancing." Inter-rater agreement was analyzed with kappa coefficients. Inter-technique agreement between subjective and objective assessment was performed using kappa statistics. Univariate regressions were performed to identify which morphological characteristics influenced subjective adjudication of enhancement. A total of 113 IAs were analyzed. The agreement of the internal assessment was moderate (k = 0.63), 49.5% of IAs (56) were classified as "enhancing" and 50.5% (57) as "non-enhancing" after consensus. Inter-rater agreement between internal and external adjudication was weak (k = 0.52) for the presence of AWE. There was no agreement between the subjective assessment of AWE and objective 3D-CAWE (k = 0.16, p 0.02). Subjective assessment was less likely to reliably adjudicate enhancement when assessing multiple aneurysms (OR 0.4, 95% CI 0.16 -0.97, p 0.04) and IAs larger than > 7 mm (OR 0.22, 95% CI 0.09 -0.55, p 0.002) despite being objectively "non-enhancing". Subjective adjudication of AWE has poor inter-rater agreement, and no agreement with an objective 3D method of determining AWE. It is also less likely than objective quantification to identify enhancement in aneurysms larger than 7 mm or when multiple aneurysms are present. Objective 3D quantification, such as the technique used in this study, should therefore be considered when assessing AWE, especially in patients with multiple aneurysms and aneurysms larger than 7 mm in size. 3D, three-dimensional; 3D-CAWE, three-dimensional circumferential aneurysm wall enhancement; AWE, aneurysm wall enhancement; Gd, gadolinium; HR-MRI, high resolution MRI; HR 3D T1 VWI, high-resolution 3D T1 weighted black blood vessel wall imaging; IA, intracranial aneurysm; SI, signal intensity.

Does it stable? Intracranial aneurysm wall enhancement might be the warning signals: a meta-analysis of observational studies.

Magnetic resonance vessel wall imaging (MR-VWI) is an emerging imaging technology used to assess the progressive risk of unruptured intracranial aneurysms (UIAs). Unlike the standard evaluation model, MR-VWI is still debatable. This study aims to further define the potential relationship between aneurysm wall enhancement (AWE) and aneurysm stability. Using "intracranial aneurysm", "magnetic resonance", and "enhancement" as keywords, relevant studies were systematically searched in PubMed, Embase, and Cochrane, and the qualified studies were enrolled for further analysis. There were 13 case-control studies, 4 cohort studies, and 2,678 cases of intracranial aneurysms included in the meta-analysis. It was shown that AWE was correlated with intracranial aneurysm rupture (OR = 35.90, 95% CI: 15.58 to 82.75, p < 0.001), growth (OR = 6.69, 95% CI: 2.69 to 16.63, p < 0.001), and presence of symptoms (OR = 14.46, 95% CI: 9.07 to 23.05, p < 0.001). This finding had a high diagnostic value, but the correlation was probably not independent of aneurysm size. The pooled relative risks of the follow-up studies revealed that the risk of UIA progression was approximately 3.33 times higher with AWE than without AWE (RR = 3.33, 95% CI: 2.33 to 4.78, p < 0.001). In addition, the pooled results demonstrated that quantitative indices of VWI enhancement were equally linked with aneurysm stability (OR = 19.61, 95% CI: 10.63 to 36.17, p < 0.001). AWE is an effective imaging method to assess the stability of UIAs, and it can be a marker for the prophylactic treatment of small unruptured intracranial aneurysms in the future, which remains to be validated by prospective studies with large samples.

Update on Vessel Wall Imaging of Intracranial Aneurysm

Intracranial aneurysms occur frequently; however, only a few of these rupture to cause subarachnoid hemorrhage. This presents a dilemma regarding the course of appropriate treatment. In the last decade, the wide utilization of magnetic resonance imaging-based vessel wall imaging(VWI) has facilitated the assessment of aneurysm wall enhancement(AWE), which has garnered significant attention. In 2013, initial reports highlighted that AWE was characteristic of ruptured aneurysms whereas, in 2014, AWE was identified as a characteristic feature of unruptured aneurysms with a high risk of rupture. Several studies have supported these findings since then. VWI, a novel modality that visualizes the inflammation of the aneurysmal wall, is considered highly useful for the diagnosis of aneurysms. This review discusses the key literature on AWE. Long-term prospective studies are warranted to determine whether AWE is an independent risk factor for aneurysmal progression.

Aneurysm Wall Enhancement Can Predict Rupture Point in Intracranial Aneurysms With Multiple Blebs.

Ruptured aneurysms visualized by vessel wall MRI (VW-MRI) exhibit characteristic aneurysm wall enhancement (AWE). A secondary bulge of the aneurysmal wall, called a bleb, is often the site of rupture in ruptured aneurysms. We hypothesized that a higher degree of AWE would identify the rupture point in aneurysms with multiple blebs. AWE was quantitatively analyzed in consecutive ruptured intracranial aneurysms with multiple blebs (31 aneurysms with a total of 72 blebs) using VW-MRI. A 3-dimensional T1-weighted fast spin-echo sequence was obtained after contrast media injection, and the contrast ratio of the aneurysm wall against the pituitary stalk (CRstalk) was calculated as the AWE indicator. Bleb characteristics, including CRstalk and wall shear stress (WSS), were compared between ruptured and unruptured blebs. Odds ratios with 95% confidence intervals for ruptures were calculated by conditional logistic regression analysis. Ruptured blebs had a higher CRstalk and lower WSS compared with unruptured blebs. CRstalk remained significantly associated with the bleb rupture status in the conditional logistic regression (adjusted odds ratio 3.9, 95% CIs 1.6-9.7). AWE is associated with the bleb rupture status independent of WSS. Contrast-enhanced VW-MRI may be a useful noninvasive tool for identifying the rupture point and guiding the treatment strategy.

Aneurysmal Wall Enhancement of Non-Ruptured Intracranial Aneurysms after Endovascular Treatment Correlates with Higher Aneurysm Reperfusion Rates, but Only in Large Aneurysms.

Aneurysmal wall enhancement (AWE) of non-ruptured sacular intracranial aneurysms (IA) after endovascular treatment (ET) is a frequently observed imaging finding using AWE-sequences in brain magnetic resonance imaging (MRI). So far, its value remains unclear. We aimed to investigate the effect of AWE on aneurysm reperfusion rates in a longitudinal cohort. This is a retrospective MRI study over the timespan of up to 5 years, assessing the correlation of increased AWE of non-ruptured IAs and events of aneurysm reperfusion and retreatment, PHASES Score and grade of AWE. T1 SPACE fat saturation (FS) and T1 SE FS blood suppression sequences after contrast administration were used for visual interpretation of increased AWE. The IAs' sizes were assessed via the biggest diameter. The grade of enhancement was defined in a grading system from grade 1 to grade 3. 127 consecutive non ruptured IA-patients (58.9 ± 9.0 years, 94 female, 33 male) who underwent elective aneurysm occlusion were included. AWE was observed in 40.2% of patients (51/127) after ET, 6 patients already showed AWE before treatment. In large IAs (which were defined as a single maximum diameter of over 7.5 mm), AWE was significantly associated with aneurysm reperfusion in contrast to large aneurysm without AWE). All grades of AWE were significantly associated with reperfusion. Our data suggests that in patients with initially large IAs, AWE is correlated with aneurysm reperfusion.

Radiomics-Based Predictive Nomogram for Assessing the Risk of Intracranial Aneurysms.

Aneurysm wall enhancement (AWE) has the potential to be used as an imaging biomarker for the risk stratification of intracranial aneurysms (IAs). Radiomics provides a refined approach to quantify and further characterize AWE's textural features. This study examines the performance of AWE quantification combined with clinical information in detecting symptomatic IAs. Ninety patients harboring 104 IAs (29 symptomatic and 75 asymptomatic) underwent high-resolution magnetic resonance imaging (HR-MRI). The assessment of AWE was performed using two different methods: 3D-AWE mapping and composite radiomics-based score (RadScore). The dataset was split into training and testing subsets. The testing set was used to build two different nomograms using each modality of AWE assessment combined with patients' clinical information and aneurysm morphological data. Finally, each nomogram was evaluated on an independent testing set. A total of 22 radiomic features were significantly different between symptomatic and asymptomatic IAs. The 3D-AWE mapping nomogram achieved an area under the curve (AUC) of 0.77 (63% accuracy, 78% sensitivity, and 58% specificity). The RadScore nomogram exhibited a better performance, achieving an AUC of 0.83 (77% accuracy, 89% sensitivity, and 73% specificity). The comprehensive analysis of IAs with the quantification of AWE data through radiomic analysis, patient clinical information, and morphological aneurysm metrics achieves a high accuracy in detecting symptomatic IA status.

A multidimensional pre-operative planning method of unruptured vertebral artery dissecting aneurysms using three-dimensional AWE mapping and hemodynamic simulation

ObjectiveHigh-resolution magnetic resonance imaging (HR-MRI) can provide valuable insights into the evaluation of vascular pathological conditions, and 3D digital subtraction angiography (3D-DSA) offers clear visualization of the vascular morphology and hemodynamics. This study aimed to investigate the potential of a multimodal method to treat unruptured vertebral artery dissection aneurysms (u-VADAs) by fusing image data from HR-MRI and 3D-DSA. MethodsThis observational study enrolled 5 patients diagnosed with u-VADAs, who were scheduled for interventional treatment. The image data of HR-MRI and 3D-DSA were merged by geometry software, resulting in a multimodal model. Quantified values of aneurysm wall enhancement (AWE), wall shear stress (WSS), neck velocity, inflow volume, intra-stent flow velocity (ISvelocity), and intra-aneurysmal velocity (IAvelocity) were calculated from the multimodal method. ResultsWe found the actual lengths of u-VADAs in the multimodal model were longer than the 3D-DSA model. We formulated surgical plannings based on the WSS, IA velocity, and neck velocity. The post-operative value of IAvelocity, neck velocity, and follow-up quantified values of AWE were decreased compared with the pre-operative condition. After that, u-VADAs were complete occlusion in four patients and near-complete occlusion in one patient during the 6th-month follow-up after surgery. ConclusionThe multidimensional method combining HR-MRI with 3D-DSA may provide more valuable information for treating VADAs, with the potential to develop effective surgical planning.

Optimizing timing for quantification of intracranial aneurysm enhancement: a multi-phase contrast-enhanced vessel wall MRI study.

Aneurysm wall enhancement (AWE) on high-resolution contrast-enhanced vessel wall MRI (VWMRI) is an emerging biomarker for intracranial aneurysms (IAs) stability. Quantification methods of AWE in the literature, however, are variable. We aimed to determine the optimal post-contrast timing to quantify AWE in both saccular and fusiform IAs. Consecutive patients with unruptured IAs were prospectively recruited. VWMRI was acquired on 1 pre-contrast and 4 consecutive post-contrast phases (each phase was 9 min). Signal intensity values of cerebrospinal fluid (CSF) and aneurysm wall on pre- and 4 post-contrast phases were measured to determine the aneurysm wall enhancement index (WEI). AWE was also qualitatively analyzed on post-contrast images using previous grading criteria. The dynamic changes of AWE grade and WEI were analyzed for both saccular and fusiform IAs. Thirty-four patients with 42 IAs (27 saccular IAs and 15 fusiform IAs) were included. The changes in AWE grade occurred in 8 (30%) saccular IAs and 6 (40%) in fusiform IAs during the 4 post-contrast phases. The WEI of fusiform IAs decreased 22.0% over time after contrast enhancement (p = 0.009), while the WEI of saccular IAs kept constant during the 4 post-contrast phases (p > 0.05). When performing quantitative analysis of AWE, acquiring post-contrast VWMRI immediately after contrast injection achieves the strongest AWE for fusiform IAs. While the AWE degree is stable for 36 min after contrast injection for saccular IAs. The standardization of imaging protocols and analysis methods for AWE will be helpful for imaging surveillance and further treatment decisions of patients with unruptured IAs. Imaging protocols and measurements of intracranial aneurysm wall enhancement are reported heterogeneously. Aneurysm wall enhancement for fusiform intracranial aneurysms (IAs) is strongest immediately post-contrast, and stable for 36 min for saccular IAs. Future multi-center studies should investigate aneurysm wall enhancement as an emerging marker of aneurysm growth and rupture.

Risk Factors and Clinical Significance of Ultra-Long-Term Microischemia After Intracranial Aneurysm Embolization.

This study aimed to explore influencing factors and clinical significance of ultra-long-term microischemia following intracranial aneurysm (IA) embolization and establish a theoretical foundation for reducing both the incidence of ultra-long-term microischemia and cognitive dysfunction in patients post embolization. A retrospective analysis was conducted on data from 147 patients who received endovascular treatment for IAs. Patients were categorized into microischemic and control (non-microischemic) groups on the based on the findings of high-resolution magnetic resonance vessel wall imaging (HR-VWI) examinations performed 3days postoperatively and 6months postoperatively. Risk factors for the occurrence of ultra-long-term microischemia were determined by univariate analysis and multivariate logistic regression analysis. Out of 147 patients included in the study, 51 (34.69%) developed microischemia while the remaining 96 (65.31%) did not experience this condition. Analysis revealed that factors such as sex, age, history of underlying diseases (hypertension, diabetes mellitus), aneurysmal site characteristics, the presence or absence of stenosis in the aneurysm-bearing artery, modified Fisher score at admission, Barthel's index at discharge, immunoinflammatory index at 3days postoperatively and at the 6-month follow-up, the presence or absence of aneurysmal wall enhancement, and the presence or absence of aneurysmal lumen showed no statistically significant differences between the two groups (all P > 0.05). By contrast, variables like in operative time, rupture status of the aneurysm before surgery according to World Federation of Neurologic Surgeons (WFNS) grade, aneurysm size, number of stents used, number of guidewires and catheters used, and Evans index between the two groups were found to have statistically significant disparities between those who developed microischemia and those who did not (P < 0.05). A subsequent multivariate analysis revealed that aneurysm size, Evans index, and the number of stents used were independent risk factors for the occurrence of ultra-long-term microischemia after surgical intervention of aneurysms (P < 0.05). The receiver operating characteristic (ROC) curves of the patients were constructed on the basis of risk factors determined through multivariate logistic regression analysis. Results indicated that aneurysm size (area under ROC curve (AUC) 0.619, sensitivity 94.7%, specificity 17.1%, P = 0.049), Evans index (AUC 0.670, sensitivity 96.4%, specificity 26.8%, P = 0.004), and number of stents (AUC 0.639, sensitivity 44.6%, specificity 90.2%, P < 0.001) effectively predicted the occurrence of microischemia. The incidence of cognitive dysfunction was higher in the microischemic group than in the control group (P < 0.05), and a greater number of microischemic foci was associated with a higher incidence of cognitive dysfunction. The proportion of microschemia foci in the thalamus and basal ganglia in patients with cognitive dysfunction (60.87%) was significantly higher than that in patients without cognitive dysfunction (34.55%) (P < 0.05). Aneurysm size, Evans index > 0.3, and the quantity of stents were independent risk factors for the occurrence of ultra-long-term microischemia after aneurysm embolization and provided good predictive performance. Cognitive dysfunction was closely associated with microischemia, with its severity increasing with an increase in the number of ischemic foci.

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

IntroductionIntracranial aneurysm (IA) is a common cerebrovascular disease. Considering the risks and benefits of surgery, a significant proportion of patients with unruptured IA (UIA) choose conservative observation. Previous studies suggest...

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

We aimed to analyze the aneurysm wall enhancement (AWE) characteristics of asingle unruptured intracranial aneurysm (UIA) and observe the relationship between the symptoms of asingle UIA and the aneurysm wall. In our hospital, 85patients diagnosed with asingle UIA using computed tomography angiography (CTA) were retrospectively analyzed. The patients were divided into symptomatic and asymptomatic groups, including 46asymptomatic and 39symptomatic 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 asingle UIA between the two groups were compared. An investigation explored the correlation between the symptom status of asingle UIA and AWE. We observed acorrelation between symptom status and maximal size, height, and neck width for asingle 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. Alarger AWE range was an independent risk factor for the onset of symptoms in asingle UIA.

Transition of intracranial aneurysmal wall enhancement from high to low wall shear stress mediation with size increase: A hemodynamic study based on 7T magnetic resonance imaging

BackgroundWall shear stress (WSS) has been proved to be related to the formation, development and rupture of intracranial aneurysms. Aneurysm wall enhancement (AWE) on magnetic resonance imaging (MRI) can be caused by inflammation and have confirmed its relationship with low WSS. High WSS can also result in inflammation but the research of its correlation with AWE is lack because of the focus on large aneurysms limited by 3T MRI in most previous studies.This study aimed to assess the potential association between high or low WSS and AWE in different aneuryms. Especially the relationship between high WSS and AWE in small aneurysm. MethodsForty-three unruptured intracranial aneurysms in 42 patients were prospectively included for analysis. 7.0 T MRI was used for imaging. Aneurysm size was measured on three-dimensional time-of-flight (TOF) images. Aneurysm-to-pituitary stalk contrast ratio (CRstalk) was calculated on post-contrast black-blood T1-weighted fast spin echo sequence images. Hemodynamics were assessed by four-dimensional flow MRI. ResultsThe small aneurysms group had more positive WSS–CRstalk correlation coefficient distribution (dome: 78.6 %, p = 0.009; body: 50.0 %, p = 0.025), and large group had more negative coefficient distribution (dome: 44.8 %, p = 0.001; body: 69.0 %, p = 0.002). Aneurysm size was positively correlated with the significant OSI–CRstalk correlation coefficient at the dome (p = 0.012) and body (p = 0.010) but negatively correlated with the significant WSS–CRstalk correlation coefficient at the dome (p < 0.001) and body (p = 0.017). ConclusionAWE can be mediated by both high and low WSS, and translate from high WSS- to low WSS-mediated pathways as size increase. Additionally, AWE may serve as an indicator of the stage of aneurysm development via different correlations with hemodynamic factors.

229 Quantitative Imaging Biomarkers for Risk Stratification of Intracranial Aneurysms

INTRODUCTION: Aneurysm wall enhancement (AWE) has emerged as a potential imaging biomarker for risk stratification of Intracranial aneurysms (IAs). Herein, the contrast-enhanced MRI (CE-MRI) exhibits markedly higher intensity on the IA sac as compared to the non-enhanced MRI (NE-MRI). However, currently it is assessed subjectively by clinicians which can introduce subjectivity. METHODS: We retrospectively collected 105 IAs with their NE-MRI, CE-MRI and Time-of-flight angiography images. IAs were classified as high or low risk if they had PHASES &gt;5 or ELAPSS &gt;20. We then identified the significantly different RFs and used them to build a logistic regression model for identifying high-risk IAs. We also compared the performance of this model with traditional AWE metrics like CCRatio (Average intensity on the IA sac normalized by the corpus callosum intensity) and CRStalk (Average intensity on the IA sac normalized by the pituitary stalk intensity). RESULTS: We found 35 high-risk IAs in the cohort and identified 183 RFs that were significantly different between them. After eliminating collinear RFs, we used 52 RFs to build our final model. We observed that the RF based model vastly outperformed the conventional metrics. In the testing set, we observed that the LR model had a higher accuracy as compared to conventional metrics. We observed that non-uniformity in pre-contrast MRI, homogeneity in post-contrast MRI and the difference in gray level non-uniformity had the highest odds ratios in the LR model. CONCLUSIONS: RFs from pre- and post-contrast MRI could identify high-risk IAs better than conventional metrics. This model in combination with 3D visualization could aid in better visualization of VWE and better risk stratification of IAs.

Wall Enhancement of Coiled Intracranial Aneurysms Is Associated with Aneurysm Recanalization: A Cross-Sectional Study.

Wall enhancement of untreated intracranial aneurysms on MR imaging is thought to predict aneurysm instability. Wall enhancement or enhancement of the aneurysm cavity in coiled intracranial aneurysms is discussed controversially in the literature regarding potential healing mechanisms or adverse inflammatory reactions. Our aim was to compare the occurrence of aneurysm wall enhancement and cavity enhancement between completely occluded intracranial aneurysms and recanalized aneurysms after initially complete coil embolization. In this single-center cross-sectional study, we evaluated intracranial aneurysms after successful coil embolization for aneurysm recanalization, wall enhancement, and cavity enhancement with 3T MR imaging. We then compared the incidence of wall enhancement and cavity enhancement of completely occluded aneurysms with aneurysms with recanalization using the χ2 test and performed a multivariate linear regression analysis with recanalization size as an independent variable. We evaluated 59 patients (mean age, 54.7 [SD, 12.4] years; 48 women) with 60 intracranial aneurysms and found a significantly higher incidence of wall enhancement in coiled aneurysms with recanalization (n=38) compared with completely occluded aneurysms (n = 22, P = .036). In addition, there was a significantly higher incidence of wall enhancement in aneurysms with recanalization of >3 mm (P = .003). In a multivariate linear regression analysis, wall enhancement (P = .010) and an increase of overall aneurysm size after embolization (P < .001) were significant predictors of recanalization size (corrected R 2= 0.430, CI 95%). The incidence of aneurysm wall enhancement is increased in coiled intracranial aneurysms with recanalization and is associated with recanalization size.

Abstract TP3: Predicting Rupture Risk of Intracranial Aneurysms Through Radiomics Analysis

Background: Intracranial aneurysm rupture is a devastating event. Accurate estimation of their rupture risk can help guide management decisions. However, existing prediction methods remain subjective and have limited accuracy. This study is aimed at using clinical and imaging data to create an accurate predictive clinical tool for identification of aneurysms at a higher risk of rupturing. Methods: A prospectively acquired database of patients scanned with 3T high-resolution MRI between 2018 to 2023 was analyzed. Symptomatic status was defined as aneurysms that caused a cranial nerve neuropathy due to compression, and/or presented with a sentinel headache. Saccular aneurysms were segmented within 3D Slicer using co-registered T1 and T1+Gd 3T images. Morphological and aneurysm wall enhancement (AWE) metrics were obtained from the 3D models. Radiomic features (RFs) were extracted using pyRadiomics extension of 3D Slicer. This database was utilized for training and testing different machine learning prediction models. Finally, a Naïve bayes model was then employed for constructing clinical nomograms (Figure). Results: A total of one hundred and four aneurysms were analyzed. Twenty-nine were symptomatic. There were 87 RFs significantly different between symptomatic and asymptomatic aneurysms. Four machine learning prediction models were created based on clinical, morphological, AWE and RFs data. The best predictive model was based on RFs, achieving an accuracy of 74%. Conclusion: RFs combined with clinical, morphological and AWE metrics could potentially be a valuable clinical tool to predict intracranial aneurysms rupture risk.

Association between intracranial aneurysm wall enhancement and intracranial atherosclerotic plaque: a cross-sectional study using high-resolution vessel wall imaging.

Intracranial aneurysms and intracranial atherosclerosis are prevalent cerebrovascular diseases, and individuals with atherosclerosis have a higher incidence of aneurysms than those without atherosclerosis. However, few studies have conducted combined analyses to investigate the potential association between intracranial aneurysms and intracranial atherosclerosis. This retrospective cross-sectional study aimed to investigate the association between the characteristics of the aneurysm wall and intracranial large arterial plaque using high-resolution vessel wall imaging (HR-VWI). Hospitalized patients diagnosed with anterior circulation unruptured intracranial aneurysms (UIAs), who were diagnosed at Huashan Hospital of Fudan University in Shanghai, China, between March 2016 to February 2018, were consecutively recruited for this study. The patients' pre-treatment HR-VWI images and 3D time-of-flight magnetic resonance angiography (3D-TOF-MRA) images were collected. The patients and UIAs were divided into two groups according to the presence or absence of plaque in the M1 segment of the middle cerebral artery (MCA). Clinical information and aneurysm characteristics were compared between the two groups. Aneurysm wall enhancement (AWE) and M1 plaque were graded on scales of 0 to 2 on HR-VWI. Based on the gradings, the correlation between AWE and the M1 plaques was analyzed. A total of 109 patients with 128 saccular UIAs in the anterior circulation were enrolled in the study. Of the patients, there were 56 patients (with 65 UIAs) in the group with M1 plaque and 53 patients (with 63 UIAs) in the group without plaque. There were significant differences between the two groups in terms of both their clinical information (age and hypertension) and aneurysm characteristics (AWE pattern and AWE degree). The grades of the AWE patterns and the AWE degrees of the UIAs were higher in the group with M1 plaque than in the group without plaque. In the M1 plaque group, the grade of M1 plaque was positively correlated with the grade of AWE pattern (correlation coefficient R=0.41, P=0.001) and the grade of AWE degree (correlation coefficient R=0.50, P<0.001). MCA atherosclerosis plaque was associated with the AWE of saccular aneurysms. When evaluating UIAs, attention should also be paid to the large arterial wall, which may assist in assessing the stability of the aneurysm and enable better decision making.

Wall permeability on magnetic resonance imaging is associated with intracranial aneurysm symptoms and wall enhancement.

Wall remodeling and inflammation accompany symptomatic unruptured intracranial aneurysms (UIAs). The volume transfer constant (Ktrans) of dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI) reflects UIA wall permeability. Aneurysmal wall enhancement (AWE) on vessel wall MRI (VWI) is associated with inflammation. We hypothesized that Ktrans is related to symptomatic UIAs and AWE. Consecutive patients with UIAs were prospectively recruited for 3-T DCE-MRI and VWI from January 2018 to March 2023. UIAs were classified as asymptomatic and symptomatic if associated with sentinel headache or oculomotor nerve palsy. Ktrans and AWE were assessed on DCE-MRI and VWI, respectively. AWE was evaluated using the AWE pattern and wall enhancement index (WEI). Spearman's correlation coefficient and univariate and multivariate analyses were used to assess correlations between parameters. We enrolled 82 patients with 100 UIAs (28 symptomatic and 72 asymptomatic). The median Ktrans (2.1 versus 0.4min-1; p < 0.001) and WEI (1.5 versus 0.4; p < 0.001) were higher for symptomatic aneurysms than for asymptomatic aneurysms. Ktrans (odds ratio [OR]: 1.60, 95% confidence interval [95% CI]: 1.01-2.52; p = 0.04) and WEI (OR: 3.31, 95% CI: 1.05-10.42; p = 0.04) were independent risk factors for symptomatic aneurysms. Ktrans was positively correlated with WEI (Spearman's coefficient of rank correlation (rs) = 0.41, p < 0.001). The combination of Ktrans and WEI achieved an area under the curve of 0.81 for differentiating symptomatic from asymptomatic aneurysms. Ktrans may be correlated with symptomatic aneurysms and AWE. Ktrans and WEI may provide an additional value than the PHASES score for risk stratification of UIAs. The volume transfer constant (Ktrans) from DCE-MRI perfusion is associated with symptomatic aneurysms and provides additional value above the clinical PHASES score for risk stratification of intracranial aneurysms. • The volume transfer constant is correlated with intracranial aneurysm symptoms and aneurysmal wall enhancement. • Dynamic contrast-enhanced and vessel wall MRI facilitates understanding of the pathophysiological characteristics of intracranial aneurysm walls. • The volume transfer constant and wall enhancement index perform better than the traditional PHASES score in differentiating symptomatic aneurysms.

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

ObjectivesIn 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 methodsIn 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.ResultsIn 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.ConclusionsGadolinium enhancement of the aneurysm wall predicts aneurysm growth or rupture during short-term follow-up, but not independent of aneurysm size.Clinical relevance statementGadolinium-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.Graphical abstractKey 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.

Abstract 008: Morphomechanical Analysis of Saccular Aneurysms

Introduction An irregular morphology is considered a high‐risk feature of unruptured intracranial aneurysms. Some of these aneurysms may have blebs where there is a high likelihood of rupture. The process of aneurysm rupture is dynamic and involves factors such as aneurysm geometry, flow dynamics, and aneurysmal wall enhancement. In our study, we aimed to conduct a comprehensive analysis of brain aneurysms, specifically focusing on irregular and regular aneurysms. This analysis included the examination of aneurysmal wall enhancement (AWE), computational fluid dynamics (CFD), and finite element analysis (FEA). Methods The study focused exclusively on unruptured aneurysms and employed high‐resolution vessel wall imaging using 3T MRI. Aneurysms were classified as irregular if they displayed a bleb or multiple lobes. A 3D segmentation of the aneurysm and vessel was generated using 3D Slicer software. Orthogonal spokes were extended from the segmentation into the vessel wall, enabling the creation of intensity (SI) heatmaps. Aneurysmal wall enhancement (AWE) was calculated based on the post‐contrast SI. Furthermore, wall tension (WT) was determined using FEA, and time‐averaged wall shear stress (TAWSS) was computed through CFD utilizing the 3D segmentation. To identify regions of notable activity within the aneurysm, an analysis was conducted by examining values exceeding the 50th percentile threshold. This approach facilitated the inclusion of areas demonstrating heightened activity within the aneurysm. The study comprised two primary analyses: first, a comparison between regular and irregular aneurysms, and second, a secondary analysis that focused specifically on aneurysms with blebs. During this analysis, the bleb, body, and neck regions were isolated for comparative evaluation among different compartments within the aneurysms. Results The study included a total of forty‐seven unruptured saccular aneurysms, with 38% (18/47) classified as having irregular morphology. Comparing aneurysms with irregular morphology to those with regular morphology, it was observed that irregular aneurysms exhibited higher WT (p=0.05) and lower TAWSS (p=0.04). Among the irregular aneurysms, 61% (11/18) were found to have blebs. Within aneurysms containing blebs, significant differences were observed in terms of WT and AWE between the bleb, neck, and aneurysm body (p&lt;0.001 and p=0.03, respectively). Specifically, the blebs exhibited the highest AWE within the aneurysm, followed by the aneurysm body and the neck. The neck exhibited the highest value of WT, followed by the aneurysm body and the bleb. Finally, the neck also demonstrated the highest value of TAWSS, followed by the aneurysm body and the bleb. Conclusion Irregular aneurysms had a higher WT and lower TAWSS. Furthermore, the morphomechanical characteristics of irregular aneurysms varied between the aneurysm neck and body, indicating distinct properties in these regions. Unstable regions of the aneurysm, such as blebs, exhibited elevated AWE along with low TAWSS and WT.

Association of preoperative aneurysmal wall enhancement with relief of chronic headache after surgical clipping of unruptured intracranial aneurysms.

To investigate the association between chronic headache outcome and aneurysmal wall enhancement (AWE) on high-resolution vessel wall imaging (HR-VWI) in patients with unruptured intracranial aneurysms (UIAs) who underwent microsurgical clipping. Two hundred seventy-four UIA patients were retrospectively analyzed. Patients were grouped according to presence of AWE. AWE was subclassified as focal or uniform. Clinical and imaging data were recorded. Headache was evaluated using the 10-point numerical rating scale and Headache Impact Test-6 before and 6months after surgery. The proportions of patients reporting chronic headache in the no AWE, focal wall enhancement (FWE), and uniform wall enhancement (UWE) groups were 5.7%, 24.8%, and 41.8%, respectively. All patients in the UWE group who reported headache before surgery experienced headache improvement after surgery. Decrease in headache severity was greater in the UWE group than in the FWE group. Multivariate binary logistic regression showed that FWE (odds ratio (OR) 0.490; 95% confidence interval (CI), 0.262-0.917; p = 0.026) and small intraluminal thrombus (OR 0.336; 95% CI, 0.142-0.795; p = 0.013) were independent factors protective against preoperative headache. FWE (OR 0.377; 95% CI, 0.195-0.728; p = 0.004) and small intraluminal thrombus (OR 0.235; 95% CI, 0.088-0.630; p = 0.004) were independent predictors of no headache relief after surgery. AWE on HR-VWI is associated with relief of chronic headache after surgical clipping in patients with UIAs. Incidence of chronic headache was highest in patients exhibiting UWE. These patients also experienced the greatest improvement in headache after surgical clipping. This study revealed that high-resolution vessel wall imaging can demonstrate aneurysmal wall plaque and intraluminal thrombus, which may be prognostic imaging markers for chronic headache in patients with unruptured intracranial aneurysms. • Aneurysmal wall enhancement may be associated with chronic headache. • Incidence of chronic headache was highest in patients with aneurysms exhibiting uniform wall enhancement. • Patients with aneurysms exhibiting uniform wall enhancement experienced the greatest improvement in headache after clipping.