Small Unruptured Intracranial Aneurysms Research Articles

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.

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

BackgroundAccumulating small unruptured intracranial aneurysms are detected due to the improved quality and higher frequency of cranial imaging, but treatment remains controversial. While surgery or endovascular treatment is effective for small aneurysms with a high risk of rupture, such interventions are unnecessary for aneurysms with a low risk of rupture. Consequently, it is imperative to accurately identify small aneurysms with a low risk of rupture. The purpose of this study was to develop a clinically practical model to predict small aneurysm ruptures based on a radiomics signature and clinical risk factors. MethodsA total of 293 patients having an aneurysm with a diameter of less than 5 mm, including 199 patients (67.9 %) with a ruptured aneurysm and 94 patients (32.1 %) without a ruptured aneurysm, were included in this study. Digital subtraction angiography or surgical treatment was required in all cases. Data on the clinical risk factors and the features on computed tomography angiography images associated with the aneurysm rupture status were collected simultaneously. We developed a clinical–radiomics model to predict aneurysm rupture status using multivariate logistic regression analysis. The combined clinical–radiomics model was constructed by nomogram analysis. The diagnostic performance, clinical utility, and model calibration were evaluated by operating characteristic curve analysis, decision curve analysis, and calibration analysis. ResultsA combined clinical–radiomics model (Area Under Curve [AUC], 0.85; 95 % confidence interval [CI], 0.757–0.947) showed effective performance in the operating characteristic curve analysis. In the validation cohort, the performance of the combined model was better than that of the radiomics model (AUC, 0.75; 95 % CI, 0.645–0.865; Delong's test p-value = 0.01) and the clinical model (AUC, 0.74; 95 % CI, 0.625–0.851; Delong's test p-value <0.01) alone. The results of the decision curve, nomogram, and calibration analyses demonstrated the clinical utility and good fitness of the combined model. ConclusionOur study demonstrated the effectiveness of a clinical–radiomics model for predicting rupture status in small aneurysms.

Neutrophil-to-lymphocyte ratio associated with symptomatic saccular unruptured intracranial aneurysm

Background and purposeWhether symptomatic unruptured intracranial aneurysms (UIAs) lead to change in circulating inflammation remains unclear. This study aims to evaluate the role of hematological inflammatory indicators in predicting symptomatic UIA.MethodsAdult patients diagnosed with saccular intracranial aneurysm from March 2019 to September 2023 were recruited retrospectively. Clinical and laboratory data, including the white blood cells (WBC), neutral counts (NEUT), lymphocyte counts (LYM), and monocyte counts (MONO) of each patient, were collected. The neutrophil-to-lymphocyte ratio (NLR) and lymphocyte-to-monocyte ratio (LMR) were calculated as NLR = NEUT/LYM, LMR = LYM/MONO, SII = PLT*NEUT/LYM. The hematological inflammatory indicators were compared in symptomatic saccular and asymptomatic UIA patients. Multivariable logistic regression analyses were performed to explore the factors predicting symptomatic UIA.ResultsOne hundred and fifty UIA patients with a mean age of 58.5 ± 12.4 were included, of which 68% were females. The NLR and LMR were significantly associated with symptomatic UIA, and the association remained in small UIAs (< 7 mm). The multiple logistic regression analysis showed that NLR was independently associated with symptomatic UIA. On ROC curve analysis, the optimal cutoff value of NLR to differentiate symptomatic from asymptomatic was 2.38. In addition, LMR was significantly associated with symptomatic UIA smaller than 7 mm.ConclusionThere was a significant correlation between NLR and symptomatic UIA. The NLR was independently associated with symptomatic UIA.

Glypican-1 may be a plasma biomarker for predicting the rupture of small intracranial aneurysms.

Currently, there are no effective methods for predicting the rupture of asymptomatic small intracranial aneurysms (IA) (<7 mm). In this study the aim was to identify early warning biomarkers in peripheral plasma for predicting IA rupture. Four experimental groups were included: ruptured intracranial aneurysm (RIA), unruptured intracranial aneurysm (UIA), traumatic subarachnoid hemorrhage control (tSAHC), and healthy control (HC) groups. Plasma proteomics of these four groups were detected using iTRAQ combined LC-MS/MS. Differentially expressed proteins (DEPs) were identified in RIA, UIA, tSAHC compared with HC. Target proteins associated with aneurysm rupture were obtained by comparing the DEPs of the RIA and UIA groups after filtering out the DEPs of the tSAHC group. The plasma concentrations of target proteins were validated using enzyme-linked immunosorbent assay (ELISA). The iTRAQ analysis showed a significant increase in plasma GPC1 concentration in the RIA group compared to the UIA group, which was further validated among the IA patients. Logistic regression analysis identified GPC1 as an independent risk factor for predicting aneurysm rupture. The ROC curve indicated that the GPC1 plasma cut-off value for predicting aneurysms rupture was 4.99 ng/ml. GPC1 may be an early warning biomarker for predicting the rupture of small intracranial aneurysms. SignificanceThe current management approach for asymptomatic small intracranial aneurysms (<7 mm) is limited to conservative observation and surgical intervention. However, the decision-making process regarding these options poses a dilemma due to weighing their respective advantages and disadvantages. Currently, there is a lack of effective diagnostic methods to predict the rupture of small aneurysms. Therefore, our aim is to identify early warning biomarkers in peripheral plasma that can serve as quantitative detection markers for predicting intracranial aneurysm rupture. In this study, four experimental populations were established: small ruptured intracranial aneurysm (sRIA) group, small unruptured intracranial aneurysm (sUIA) group, traumatic subarachnoid hemorrhage control (tSAHC) group, and healthy control (HC) group. The tSAH group was the control group of spontaneous subarachnoid hemorrhage caused by ruptured aneurysm. Compared with patients with UIA, aneurysm tissue and plasma GPC1 in patients with RIA is significantly higher, and GPC1 may be an early warning biomarker for predicting the rupture of intracranial small aneurysms.

Unruptured untreated intracranial aneurysms: a retrospective analysis of outcomes of 445 aneurysms managed conservatively

Background Factors predicting the growth or rupture of unruptured intracranial aneurysms (UIAs) remain under debate. Increased availability of neuro-imaging has led to increasing incidental findings, therefore understanding the natural history is vital to make appropriate management and follow-up decisions. We analysed a large dataset of UIAs to better identify patients at increased risk, therefore requiring enhanced monitoring and/or prophylactic intervention. Methods Electronic patient records were reviewed from consecutive patients regarding the following data: baseline demographics; past medical and smoking history; indication for imaging detecting the UIA(s); size, location and morphology of UIA(s), duration of imaging follow-up, detection of growth and rupture. Logistic regression was used to identify risk factors for UIA growth or rupture. Subgroup analysis was performed for ‘small’ aneurysms (<7mm). Results 445 UIAs in 274 patients were analysed. Total imaging follow-up was 2268 aneurysm-years (median 3.8 years/UIA). 27 UIAs grew (1.2% annually), and 15 ruptured (0.46%). 70.1% of UIAs were detected incidentally. Mean aneurysm diameter was 4.1mm. Logistic regression identified age < 50, autosomal dominant polycystic kidney disease (ADPKD), hypertension and diameter > 7mm as significant risk factors for growth/rupture. Additionally, previous smoking compared to current smoking was a protective factor against growth or rupture, but no significant difference was seen when comparing current- with non-smokers. Small aneurysm subgroup analysis identified diameter > 5mm, age < 50, ADPKD, and ongoing smoking as risk factors. No significant difference was observed in risk between those with and without previous SAH. Conclusions This study underlines the need for imaging surveillance of even small UIAs. Smoking is a modifiable risk factor for growth/rupture of pre-existing aneurysms, while ADPKD is a particularly strong risk factor.

Diagnosis of Small Unruptured Intracranial Aneurysms

PurposeDifferentiating normal anatomical variants such as an infundibulum or a vascular loop from true intracranial aneurysms is crucial for patient management. We hypothesize that high-resolution 7 T magnetic resonance imaging (MRI) improves the detection and characterization of normal anatomical variants that may otherwise be misdiagnosed as small unruptured aneurysms.MethodsThis is a retrospective, single-center study. All patients were scanned on a clinically approved 7 T MRI scanner and on a 3 T scanner. Image analysis was performed independently by three neuroradiologists blinded to clinical information. The presence of an unruptured intracranial aneurysm (UIA) and level of diagnostic certainty were assessed and the interrater agreement was calculated. If an aneurysm was present, the anatomic location and shape were recorded and compared.ResultsIn total, 53 patients with equivocal cerebrovascular findings on 1.5 T or 3 T MRI referred for a 7T MRI examination were included. Aneurysms were suspected in 42 patients examined at 3 T and in 23 patients at 7 T (rate difference 36%, 95% confidence interval, CI, 19–53%, p-value < 0.001). Major disagreement between the field strengths was observed in the A1 segment of anterior cerebral artery/anterior communicating artery (A1/ACOM) complex. The interrater agreement among the readers on the presence of an aneurysm on 7 T MRI was higher than that for 3 T MRI (0.925, 95% CI 0.866–0.983 vs. 0.786, 95% CI 0.700–0.873).ConclusionOur analysis demonstrates a significantly higher interrater agreement and improved diagnostic certainty when small intracranial aneurysms are visualized on 7 T MRI compared to 3 T. In a selected patient cohort, clinical implementation of 7 T MRI may help to establish the definitive diagnosis and thus have a beneficial impact on patient management.

Small intracranial aneurysms of the anterior circulation: A negligible risk?

According to the International Study of Unruptured Intracranial Aneurysms, small (<7 mm) unruptured intracranial aneurysms (IAs) of the anterior circulation (aC) carry a neglectable 5-year rupture risk. In contrast, some studies report frequencies of >20% of all ruptured IAs being small IAs of the aC. This contradiction was addressed in this study by analyzing the rates and risk factors for rupture of small IAs within the aC. Of the institutional observational cohort, 1676 small IAs of the aC were included. Different demographic, clinical, laboratory, and radiographic characteristics were collected. A rupture risk score was established using all independent prognostic factors. The score performance was checked using receiver operating characteristic curve analysis. Of all registered small IAs of the aC, 20.1% were ruptured. The developed small IAs of the aC (SIAAC) score (range = -4 to +13 points) contained five major risk factors: IA location and size, arterial hypertension, alcohol abuse, and chronic renal failure. In addition, three putative protective factors were also included in the score: hypothyroidism, dyslipidemia, and peripheral arterial disease. Increasing rates of ruptured IA with increasing SIAAC scores were observed, from 0% (≤-1 points) through >50% (≥8 points) and up to 100% in patients scoring ≥12 points. The SIAAC score achieved excellent discrimination (area under the curveSIAAC = 0.803) and performed better than the PHASES (Population,Hypertension, Age, Size of the aneurysm, Earlier SAH from another aneurysm, Site of aneurysm) score. Small IAs of the aC carry a considerable rupture risk. After external validation, the proposed rupture risk score might provide a basis for better decision-making regarding the treatment of small unruptured IAs of the aC.

Unruptured intracranial aneurysms: relation between morphology and wall strength.

To determine the morphological features distinguishing small unruptured saccular intracranial aneurysms (sIAs) with high and low wall strength (WS) in post mortem subjects. Subarachnoid haemorrhage caused by sIA rupture is associated with increased mortality and morbidity. Analysis of the morphology and biomechanical properties of sIAs might facilitate the identification of clinically relevant risk factors for sIA rupture. Eight single unruptured sIAs were found among eight subjects during 184 post mortem examinations. After assessment of the dimensions, aspect ratio (AR), size ratio (SR), height/width ratio (HW), bottleneck factor (BNF), and shape, sIAs with adjacent cerebral arteries were subjected to quasi-static increasing pressure until the wall of the cerebral artery or sIA ruptured. In three specimens, the sIA ruptured at a significantly lower average pressure than the other cases, in which the rupture occurred within the wall of the adjacent cerebral artery (769 vs. 1,259 mmHg; p = 0.035). The sIAs with low WS, i.e. sIAs that ruptured during experiments, were characterised by significantly increased dome dimensions compared to sIAs with high WS (p < 0.05). At the same time, no significant differences were observed between high and low WS categories regarding AR, SR, HW, and BNF, or the presence of an irregular dome shape. Dome dimension was the only feature that distinguished unruptured sIAs as having low or high WS, and this supports observations that sIAs with increased dome dimensions are characterised by an increased risk of rupture. Thus, dome dimension may be more useful than other morphometric parameters, such as AR, SR, HW and BNF, in assessing the rupture risk assessment of small unruptured sIAs.

Safety of coil embolisation in small (smaller than 5 mm) unruptured intracranial aneurysms: A retrospective multicentre analysis

BackgroundRisk-benefit analysis results for the treatment of unruptured aneurysms smaller than 5 mm are controversial. This study aimed to identify the outcomes and complication associated with treating such unruptured aneurysms. MethodsThis was a retrospective study of 165 consecutive patients who underwent endovascular procedures for unruptured cerebral aneurysms of a maximum diameter 5 mm between January 2018 and March 2021. Patient background, aneurysm characteristics, adjuvant technique, volume embolization rate (VER), symptomatic complications, and modified Rankin Scale (mRS) scores were examined. ResultsSixty patients with sufficient data were included in the study. The mean age was 62.1 ± 14.6 years, and the median follow-up period was 12 months. The mean maximum diameter was 4.16 ± 0.63 mm, the neck diameter was 2.73 ± 0.82 mm, and 90% of patients had anterior circulation. Complete occlusion was achieved in 34 cases (57.6%). Although there were no intraoperative ruptures, complications were observed in four patients (6.7%), and one patient (1.7%) had worsened mRS score. Only one patient (1.7%) required retreatment. The first coil VER was independently associated with complete occlusion after endovascular treatment. Univariate analysis of complications showed an association between hypertension, hyperlipidaemia, and the estimated glomerular filtration rate. ConclusionsNo patient experienced mRS score deterioration, and only one patient developed permanent disability due to ischemic complications; hence, we could safely treat small unruptured aneurysms. Complications are not related to procedural factors such as coiling adjuvant technique. However, lifestyle-related diseases are related to complications, and we suggest that physicians should remain vigilant of the indication for coiling when treating patients with underlying diseases.

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

Unruptured intracranial aneurysms are frequently detected during routine clinical diagnostic processes. A significant portion are small aneurysms less than 5 mm in diameter. While follow-up of patients with small aneurysms has been advocated, the cost-effectiveness of such care and the optimal follow-up interval remain unknown. This study aimed to explore the most cost-effective follow-up interval for small (< 5 mm) unruptured intracranial aneurysms. A decision analysis study was performed using a Markov model with Monte Carlo simulations to simulate patients undergoing follow-up by MRA at different time intervals (1-, 2-, 3-, 5-, and 7-year intervals) for small (< 5 mm) unruptured intracranial aneurysms. Input data for the model were extracted from the current literature, primarily meta-analyses. Probabilistic and deterministic sensitivity analyses were performed to evaluate the robustness of the model. Given the current literature and the model in this study, following up every 2 years with noninvasive imaging is the most cost-effective strategy (cost $126,996, effectiveness 21.9 quality-adjusted life-years), showing the highest net monetary benefit. The conclusion remains robust in probabilistic and deterministic sensitivity analyses. As the annual growth risk of small aneurysms and annual rupture risk of growing aneurysms increase, following up every year is optimal. When the cost for follow-up with MRA is less than $2223, following up every year is cost-effective. The most cost-effective follow-up strategy for small (< 5 mm) unruptured aneurysms using MRA is following up every 2 years. More frequent follow-up strategies or prompt preventive treatment would be more appropriate in patients with higher risk factors for growth and aneurysm rupture.

Psychological and Functional Impact of a Small Unruptured Intracranial Aneurysm Diagnosis: A Mixed‐Methods Evaluation of the Patient Journey

Background Following a diagnosis of a small unruptured intracranial aneurysm (sUIA), patients often experience psychological ailments which may be attributable to the neurovascular consultation, referral pathway, or long‐term imaging surveillance. Here, we aim to characterize the early sUIA patient journey and evaluate their psychosocial status. Methods A mixed‐methods analysis of sUIA patients attending a large tertiary neurosciences center was performed. For patients presenting to the neurovascular service in 2020, this included: (i) a thematic analysis of patient perspectives extracted from semistructured telephone interviews, (ii) a quantitative assessment of psychological status using the Hospital Anxiety and Depression Scale and (iii) an evaluation of functional independence using a customized activity of daily living questionnaire. The relationship between service or clinical factors, and Hospital Anxiety and Depression Scale subscale scores was statistically tested. Results The sUIA patient cohort (n=105) had a mean age of 56.8 years (SD=15.8, female=69). Thematic analysis of interview responses (n=33) identified 5 recurrent themes underpinning the sUIA patient experience: referral, diagnosis and information sharing, imaging surveillance, psychological impairment and coping strategies, and activities of daily living, all of which contributed to patient concerns. A total of 53.6% of patients achieved a Hospital Anxiety and Depression Scale score signifying at least mild anxiety and/or depression. Lifestyle changes most frequently affected after diagnosis included avoidance of straining‐intensive exercise, change in patterns of substance use, and work‐related performance. Multivariate analysis revealed no significant service or clinical predictors for anxiety or depression. Conclusion For some patients, an sUIA diagnosis appears to be associated, at least qualitatively, with a psychological burden. This is likely mediated through stressors related to the referral, diagnosis, neurosurgical consultation, and image surveillance. In the absence of evidence‐based guidelines regarding these aspects of the early patient journey, we offer suggestions aimed at improving both the neurovascular service and sUIA patient experience.

Small Unruptured Intracranial Aneurysms Can Be Effectively Treated With Flow-Diverting Devices.

PurposeTo investigate the effect and safety of flow diverters in the management of small (<10 mm in diameter) unruptured intracranial aneurysms.Materials and MethodsOne hundred and ten patients with 145 small intracranial aneurysms treated with flow diverters were retrospectively enrolled. The clinical, endovascular, and follow-up data were analyzed.ResultsOne hundred twenty-one flow diverters were deployed for the treatment of 145 small intracranial aneurysms in 110 patients, and the stenting success rate was 99.1%. In 133 (91.7%) aneurysms, only flow-diverting devices were deployed, and in the rest 12 (8.3%) of aneurysms, coils were used to loosely pack the aneurysm after deployment of a flow-diverting device. Five patients (4.5%) experienced ischemic complications, but no hemorrhagic complications were occurred. All patients had clinical follow-up 6–18 (median 12) after the procedure, with the modified Rankin scale score (mRS) 0 in 101 patients, 1 in four patients, 2 in three patients, 4 in one patient, and 5 in one patient. Digital subtraction angiography was performed at follow-up in 90 (81.8%) patients with 118 (81.4%) aneurysms 6–18 months (median 12) after the procedure, with the Raymond grade I in 90 (76.2%) aneurysms and Raymond grade III in 28 (23.7%). Eighteen patients with 22 partially occluded aneurysms at the first angiographic follow-up experienced the second digital subtraction angiography 12–36 months (median 26) after the procedure, and 21 (95.5%) aneurysms were completely occluded. Two patients had asymptomatic in-stent stenosis.ConclusionTreatment of small unruptured intracranial aneurysms with flow diverters can be performed safely and effectively with satisfactory outcomes.

Neutrophil-to-Lymphocyte Ratio Is Associated With Circumferential Wall Enhancement of Unruptured Intracranial Aneurysm

Background and PurposeNeutrophil-lymphocyte ratio (NLR) predicts clinical outcomes in patients with stroke. Aneurysm wall enhancement (AWE) on high-resolution vessel wall magnetic resonance imaging (HR-VWI) is an inflammation marker for intracranial aneurysm (IA). This study aims to evaluate the association of NLR as a peripheral blood inflammatory marker with circumferential AWE in patients with IA.MethodsWe analyzed data of consecutive patients harboring IAs between September 2017 and December 2021 at our institution. The peripheral blood inflammatory indicators were compared between patients with ruptured and unruptured IAs. The presence of circumferential AWE in unruptured IA was identified and quantitatively measured using the aneurysm-to-pituitary stalk contrast ratio (CRstalk) on HR-VWI. We used the optimal cutoff value of 0.5 for CRstalk to differentiate circumferential AWE in unruptured IAs. We assessed the relationship of clinical, laboratory, and radiological characteristics with circumferential AWE and CRstalk ≥0.5 in unruptured IAs.ResultsThe study group was composed of one hundred and twenty-five patients with 142 IAs. NLR level at admission was significantly higher in patients with ruptured IAs than those with unruptured IAs (7.55 vs. 1.81; P < 0.001). AWE on HR-VWI was present in 30 patients with unruptured IAs (38.5%), including 12 with focal AWE and 18 with circumferential AWE. NLR (odds ratio (OR), 2.168; 95% CI, 1.149–4.088) and size (odds ratio, 1.370; 95% CI, 1.126–1.667) were independently associated with circumferential AWE in unruptured IA. NLR was also independently associated with circumferential AWE in small unruptured IA (<7 mm). Furthermore, NLR level at admission was associated with CRstalk ≥.5 in patients with unruptured IA. The optimal cutoff value of NLR for circumferential AWE was 1.86.ConclusionNLR is a valuable peripheral blood inflammatory marker is more often in the rupture status of IA and was associated with circumferential AWE on HR-VWI in unruptured IA.

Nomogram-Based Risk Model of Small (≤5 mm) Intracranial Aneurysm Rupture in an Eastern Asian Study.

Background and PurposeRisk stratification of small unruptured intracranial aneurysms (IAs) (< =5 mm) is important for clinical decision-making and management. The aim of this study was to develop an individualized rupture risk model for small IAs in an eastern Asian population.MethodsThis study retrospectively enrolled 343 patients with ruptured (n = 96) and unruptured (n = 285) small IAs. Clinical data and aneurysmal morphology were taken into consideration, regression analysis was performed to identify significant variables, and these variables were then incorporated into a predictive nomogram. The diagnostic performance of the nomogram was evaluated using the area under the receiver operating characteristic (ROC) curve (AUC) and calibration plot. Clinical effectiveness was validated by decision curve analysis (DCA). The PHASES score calculated for each case was used for comparison.ResultsThe nomogram achieved an AUC of 0.849 (95% CI: 0.805–0.893), with a sensitivity of 86.5%, a specificity of 70.9%, and accuracy of 74.7%, which was superior to PHASES score system (AUC = 0.693, sensitivity = 83.6%, specificity = 48.8%, and accuracy = 57.5%). A good agreement between predicted rupture risk and actual rupture status in the small aneurysms was observed, and DCA illustrated the benefit of using the nomogram when decisions needed to be made clinically.ConclusionsThe nomogram based on clinical and morphological risk factors can be useful in assisting clinicians with individualized assessments and benefit-risk balancing in patients with small IAs (< =5 mm).

Circumferential wall enhancement with contrast ratio measurement in unruptured intracranial aneurysm for aneurysm instability.

BackgroundAneurysm wall enhancement on high‐resolution vessel wall imaging (HR‐VWI) may represent vessel wall inflammation for unruptured intracranial aneurysms (UIAs). Further evidence for the role of circumferential aneurysm wall enhancement (CAWE) in evaluating the instability of UIAs is required, especially in small aneurysms (<7 mm).MethodsWe analyzed patients with saccular UIAs who prospectively underwent HR‐VWI on a 3.0 T MRI scanner in our center from September 2017 to August 2021. The presence of AWE was identified and quantitatively measured using the aneurysm‐to‐pituitary stalk contrast ratio (CRstalk) with maximal signal intensity value. The PHASES and ELAPSS scores were used to assess the risk of aneurysm rupture and growth. We evaluated the association of CAWE and CRstalk value with intracranial aneurysm instability.ResultsOne hundred patients with 109 saccular UIAs were included in this study. Eighty‐three UIAs (76.1%) had a size smaller than 7 mm. PHASES and ELAPSS scores were significantly higher in UIAs with CAWE than in UIAs without CAWE (p < .01). The association of CAWE with PHASES and ELAPSS scores remained in small UIAs (<7 mm). The optimal cutoff value of CRstalk for CAWE was 0.5. PHASES and ELAPSS scores were significantly higher in UIAs with CRstalk ≥0.5 than in UIAs with CRstalk <0.5 (p < .01).ConclusionsCAWE on HR‐VWI is a valuable imaging marker for aneurysm instability in UIAs. CRstalk value ≥0.5 may be associated with a higher risk of intracranial aneurysm rupture and growth.

402 Cost-Effectiveness Analysis on Small (&lt;5 mm) Unruptured Intracranial Aneurysm Follow-up Strategies

INTRODUCTION: Unruptured intracranial aneurysms are frequently detected during routine clinical diagnostic processes. A significant portion is small aneurysms less than 5mm. While follow-up patients with small aneurysms have been advocated, the cost-effectiveness of such care and the optimal follow-up interval remain unknown. METHODS: A decision analysis study was performed utilizing a Markov model with Monte Carlo simulations to simulate patients undergoing follow-up by MRA at different time intervals (1-,2-,3-, 5-and 7-year intervals) for small (&lt;5mm) unruptured intracranial aneurysms. Input data for the model was extracted from the current literature, primarily latest Meta-analysis. Probabilistic sensitivity analysis and deterministic sensitivity analyses were performed to evaluate the robustness of the Model. RESULTS: Given current literature and our model, following-up every 3 years with noninvasive imaging is the most cost-effective strategy (cost = $99611, effectiveness = 19.00 QALYs), showing the highest net monetary benefit. The conclusion remains robust in probabilistic sensitivity analysis and deterministic sensitivity analyses. As the annual rupture risk of small aneurysms exceeds 9.8% (base-case 3.1%), following up every 2 years becomes the optimal strategy. CONCLUSION: The most cost-effectiveness follow-up strategy for small (&lt;5mm) unruptured aneurysms using MRA is follow-up every 3 years. More frequent follow-up strategies or prompt preventive treatment would be more appropriate in patients with a higher rupture risk of growing aneurysms.

Hemodynamic analysis for endovascular treatment in small unruptured intracranial aneurysms: a matched comparison study of flow diverter versus LVIS

BackgroundWe compared the treatment of small unruptured intracranial aneurysms (UIAs) with flow diverter and LVIS-assisted coiling to determine the effects of hemodynamic changes caused by different stent and coil packing in endovascular treatment.MethodsFifty-one UIAs in 51 patients treated with pipeline embolization device (PED) were included in this study and defined as the PED group. We matched controls 1:1 and enrolled 51 UIAs who were treated with LVIS stent, which were defined as the LVIS group. Computational fluid dynamics were performed to assess hemodynamic alterations between PED and LVIS. Clinical analysis was also performed between these two groups after the match.ResultsThere was no difference in procedural complications between the two groups (P = 0.558). At the first angiographic follow-up, the complete occlusion rate was significantly higher in the LVIS group compared with that in the PED group (98.0% vs. 82.4%, P = 0.027). However, during the further angiographic follow-up, the complete occlusion rate in the PED group achieved 100%, which was higher than that in the LVIS group (98.0%). Compared with the LVIS group after treatment, cases in the PED group showed a higher value of velocity in the aneurysm (0.03 ± 0.09 vs. 0.01 ± 0.01, P = 0.037) and WSS on the aneurysm (2.32 ± 5.40 vs. 0.33 ± 0.47, P = 0.011). Consequently, the reduction ratios of these two parameters also showed statistical differences. These parameters in the LVIS group showed much higher reduction ratios. However, the reduction ratio of the velocity on the neck plane was comparable between two groups.ConclusionsBoth LVIS and PED were safe and effective for the treatment of small UIAs. However, LVIS-assisted coiling produced greater hemodynamic alterations in the aneurysm sac compared with PED. The hemodynamics in the aneurysm neck may be a key factor for aneurysm outcome.

Screening of unruptured intracranial aneurysms in 50 to 60-year-old female smokers: a pilot study

The prevalence of unruptured intracranial aneurysms (UIAs) is around 2–3% in the general population. We hypothesized that the prevalence of small UIAs is higher among 50 to 60-year-old female smokers, since the incidence of aneurysmal subarachnoid hemorrhage (aSAH) is exceptionally high in 60 to 70-year-old female smokers. Ethics approval for this pilot study of 50 women was obtained from the hospital ethics committee. In order to minimize recruitment bias, preliminary invitation letters were sent to 50 to 60-year-old women who were known to be active smokers. Those interested in participating were further informed about the study rationale and protocol. Following written consent, participants filled a detailed questionnaire and underwent computed tomography angiography (CTA) analysis. All abnormalities were recorded. Of the 158 preliminary invitation letters, 70 potential participants initially replied. Of these, 50 returned questionnaires and written consents, 43 of which underwent CTA analysis. Most (39; 91%) were postmenopausal, and 9 (21%) were hypertensive. Two reported a family history (≥ 1 first-degree members) of intracranial aneurysms. UIAs (maximum sizes of 2, 2, 3, 3 and 7 mm) were found in five (12%) female smokers. One woman was operated on, and the remaining four were treated with non-invasive preventive actions (smoking cessation and follow-ups). Small UIAs, which may be best suited for non-invasive preventive actions, may be relatively common in 50 to 60-year-old female smokers. Whether this kind of targeted screening leads to improved health in female smokers requires further investigation.

Imaging versus Intervention in Managing Small Unruptured Intracranial Aneurysms: A Cost-Effectiveness Analysis

Objective: Current guidelines recommend active surveillance with serial magnetic resonance angiography (MRA) for management of small, asymptomatic unruptured anterior circulation aneurysms (UIAs). We sought to determine the cost-effectiveness of active surveillance compared to immediate surgery. Methods: We developed a Markov cost-effectiveness model simulating patients with small (<7 mm) UIAs managed by active surveillance via MRA, immediate surgery, or watchful waiting. Inputs for the model were abstracted from the literature and used to construct a comprehensive model following persons from diagnosis to death. Outcomes were quality-adjusted life-years (QALYs), lifetime medical costs (2015 USD), and incremental cost-effectiveness ratios (ICERs). Cost-effectiveness, deterministic, and probabilistic sensitivity analyses were performed. Results: Immediate surgical treatment was the most cost-effective management strategy for small UIAs with ICER of USD 45,772 relative to active surveillance. Sensitivity analysis demonstrated immediate surgery was the preferred strategy, if rupture rate was >0.1%/year and if the diagnosis age was <70 years, while active surveillance was preferred if surgical complication risk was >11%. Probabilistic sensitivity analysis demonstrated that at a willingness-to-pay of USD 100,000/QALY, immediate surgical treatment was the most cost-effective strategy in 64% of iterations. Conclusion: Immediate surgical treatment is a cost-effective strategy for initial management of small UIAs in patients <70 years of age. While more costly than MRA, surgical treatment increased QALY. The cost-effectiveness of immediate surgery is highly sensitive to diagnosis age, rupture rate, and surgical complication risk. Though there are a wide range of rupture rates and complications associated with treatment, this analysis supports the treatment of small, unruptured anterior circulation intracranial aneurysms in patients <70 years of age.

Three-dimensional vortex characterization in small intracranial aneurysms based on four dimensional flow magnetic resonance imaging at 7 Tesla

Effective vectors and approaches are proposed to identify the three-dimensional (3D) vortex motion in small intracranial aneurysms (≤7 mm) based on four dimensional flow magnetic resonance imaging at 7 T. Six subjects with small intracranial aneurysms were scanned. The 3D vortex identification vector Γ2⃗ and scalar Ω are computed with velocity vectors. The high Γ2,magnitude region is defined using region growing based on the threshold value determined by an empirical nonlinear relation between Γ2,magnitude and the scalar Ω inside the aneurysmal sac, while the threshold of Ω = 0.6 is used to define the high Ω region. The spatially averaged vector Γ2⃗ and the vorticity vector ω⃗ over the defined high Γ2,magnitude and Ω regions are found to denote the corresponding vortex motion directions, respectively. With these two vectors, the 3D vector Γ1⃗ is invoked to localize vortex motion centers. Threshold values of region growing for the high Γ2,magnitude region from the nonlinear relation for each subject are in the range of 0.51 and 0.59. The volume of the defined high Γ2,magnitude region is close to that of the defined high Ω region. The angle between the generated two averaged vectors Γ2⃗ and ω⃗ is small for all subjects, with the maximum being 9.17°. The located vortex motion centers from Γ1⃗ based on Γ2⃗ and Ω(ω) are the same for each subject inside the aneurysm. The small angle between the two averaged vectors and the located same vortex center supports the effectiveness of the proposed method to characterize vortices in small unruptured intracranial aneurysms.