破裂与未破裂大脑中动脉瘤容积CT数字减影血管成像对照研究

目的探讨破裂与未破裂大脑中动脉动脉瘤(middle cerebral artery aneurysm,MCAA)在容积CT数字减影血管成像(volume CTdigital subtraction angiograhy,VCTDSA)上的形态学差异。资料与方法回顾性分析2007年9月至2010年1月54例55个MCAA VCTDSA表现,根据颅内有无出血分为破裂组和未破裂组,由两名神经放射学医师采用双盲法评价二者形状、大小、瘤颈、载瘤动脉分叉角度、瘤体纵横比(aspect ratio,AP值),比较二者在形态学上的差异。结果破裂组动脉瘤36个(65.45%),其中椎状或半球状15个(41.6%),囊状12个(33.33%),梭状3个(8.33%),球状1个(2.77%),不规则5个(13.88%);未破裂动脉瘤19个(34.55%),其中锥状或半球状11个(57.89%),囊状4个(21.05%),球状4个(21.05%),二者形状分类上有统计学差异(P<0.05)。破裂组动脉瘤瘤壁伴尖角征12个(33.33%):顶壁8个,侧壁4个;瘤样突起6个(16.67%):顶壁4个,侧壁2个;瘤体上小动脉2个(5.56...     

颅内≤5 mm动脉瘤破裂的危险因素分析

目的 探讨颅内小动脉瘤破裂的危险因素,为颅内未破裂小动脉瘤干预与否提供依据.方法 收集2010-2013年接受介入治疗、有详细影像资料和临床资料的单发性颅内小动脉瘤(≤5 mm)患者180例,其中破裂出血149例,未破裂31例.比较两组患者动脉瘤形态学参数之入射角、动脉瘤瘤体高度与瘤颈长度之比值(AR)、瘤体最大瘤深与近端载瘤动脉直径之比值(SR)、动脉瘤形状、位置和子囊,以及临床危险因素之年龄、性别、高血压、蛛网膜下腔出血史.采用单因素两独立样本t检验(或秩和检验)和卡方检验,以及多变量Logistic回归分析确定两组差异的显著性.结果 单因素分析显示破裂的小动脉瘤多位于前交通动脉(OR=0.166,P=0.023)及基底动脉末端(OR-0.006,P＜0.001),表明前交通部位与基底动脉末端的动脉瘤更易破裂.180例颅内小动脉瘤患者中破裂组与未破裂组动脉瘤部位、子囊、AR值(1.76±0.72对1.35±0.48)、SR值(1.90±0.81对1.31±0.67)、入射夹角(123.9°±23.21°对95.96°±20.2°)均存在明显的统计学差异(P＜0.05),而两组动脉瘤形态、动脉瘤最大直径以及临床危险因素中年龄、性别、高血压、蛛网膜下腔出血史均无统计学意义(P＞0.05).多变量Logistic回归分析显示动脉瘤部位(OR=1.347,P=0.002)、入射夹角(OR=1.057,P＜0.001)、SR值(OR=2.726,P=0.047)为颅内小动脉瘤破裂的独立危险因素.结论 前交通动脉和基底动脉末端部位、SR值＞1.90±0.81、入射角度＞ 123.9°±23.21°为颅内≤5 mm动脉瘤破裂的独立危险因素,可以作为颅内未破裂小动脉瘤干预与否的参考依据.     

基于曲率的破裂腹主动脉瘤计算流体力学研究

目的 分析破裂和未破裂腹主动脉瘤（AAA）曲率和血流动力学参数差异,探讨AAA破裂相关风险。方法 回顾性分析2019年10月至2020年12月在重庆医科大学附属第一医院确诊并接受治疗的35例AAA患者临床资料,其中瘤体破裂13例,未破裂22例。依据患者CTA影像资料,采用计算流体力学（CFD）方法分析比较两组患者解剖学因素和血流动力学参数间差异和相关性。结果 破裂组AAA破裂处壁剪切应力（WSS）显著小于最大血流冲击处WSS[0.025(0.049/0.018) Pa比0.549(0.839/0.492) Pa,P=0.01]。未破裂组瘤体最大血流冲击处WSS显著大于破裂组[（1.378±0.255） Pa比0.549(0.839/0.492) Pa,P<0.01]。破裂组与未破裂组瘤体最大直径[（79.847±10.067） mm比（52.320±14.682） mm,P<0.01]、曲率[（0.139±0.050）比0.080(0.123/0.068),P=0.021]差异均有统计学意义。瘤体最大直径与瘤颈直径呈负相关（r=-0.732,P<0.01）,与曲率呈正...     

应用4D-FLOW MRI血流成像评价颅内囊状动脉瘤血流动力学状态特征

目的 应用四维血流磁共振成像(4D-FLOW MRI)技术,研究颅内囊状动脉瘤及瘤颈周围载瘤动脉内血流动力学变化特征。方法 经头颅CT血管造影(CTA)或磁共振血管造影(MRA)诊断为颅内囊状动脉瘤患者68例;应用4D-FLOW技术扫描并重建后进行血流动力学分析。在载瘤动脉的囊状动脉瘤入口截面处、囊状动脉瘤沿血流方向最大截面处、囊状动脉瘤出口截面处以及对侧动脉的对称位置分别手动勾画血管边缘轮廓,自动获取血流动力学参数。采用配对t检验比较载瘤动脉与对侧动脉之间的血流动力学参数。根据囊状动脉瘤最大径和尺寸比(SR)分组,采用独立样本t检验分析不同分组载瘤动脉血流动力学参数的差异。结果 载瘤动脉与对侧动脉比较,颅内囊状动脉瘤入口截面最大壁剪切应力(WSS)、平均WSS、最大轴向WSS-最大周向WSS小于对侧对称截面;囊状动脉瘤沿血流方向最大截面处最大WSS、平均WSS、平均轴向WSS、平均轴向WSS-平均周向WSS在载瘤动脉中较小,载瘤动脉中的最大能量损失和平均能量损失显著高于对侧动脉,上述差异均具有统计学意义(P<0.05)。在载瘤动脉中最大径>5 mm组的囊状动脉瘤入口截面最...     

基于计算流体力学的腹主动脉瘤破裂风险研究

【摘要】 目的 通过分析真实腹主动脉瘤（AAA）血流动力学参数和血栓指数,探索AAA破裂的风险。 方法 回顾性分析重庆医科大学附属第一医院2016年2月至2018年9月收治的12例破裂AAA（破裂组）和26例未破裂AAA（未破裂组）患者,获取患者CTA图像资料。采用计算流体力学（CFD）方法得到AAA血流动力学参数和血栓指数,并分析两组动脉瘤血流动力学特征。结果 破裂组动脉瘤破裂区域、血流最大冲击区域壁面剪切力分别为（0.031±0.017） Pa、（0.630±0.215） Pa,差异有显著统计学意义（P＜0.001）;未破裂组动脉瘤血流最大冲击区域壁面剪切力为（1.345±0.253） Pa,与破裂组差异有显著统计学意义（P＜0.001）。破裂组腔内血栓指数在瘤体最大直径平面为平均0.551±0.188,在破裂平面为平均0.630±0.190,差异有显著统计学意义（P＜0.002）;未破裂组腔内血栓指数在瘤体最大直径平面为平均0.525±0.188,与破裂组差异无统计学意义（P=0.699）。 结论 血流动力学参数结合腔内血栓指数对预测AAA破裂起到一定作用。     

颅内动脉瘤壁切应力与动脉瘤破裂关系的初步研究——基于患者的三维计算机模拟

目的 通过比较颅内无症状动脉瘤和症状动脉瘤的血流动力学参数,寻找与动脉瘤破裂有关的血流动力学因素.方法 5例患者DSA检查共发现8个颈内动脉动脉瘤,分别位于颈内动脉后交通段及颈眼动脉段.通过旋转DSA,重建动脉瘤三维模型,并使用有限体积法进行血流动力学数值模拟,比较不同组动脉瘤及载瘤动脉的血流动力学参数.两组数据对比时采用独立样本t检验,瘤颈与载瘤动脉比较使用配对t检验.结果 无症状组和症状组动脉瘤瘤颈部平均切应力分别为(5.54±2.89)Pa和(4.78±3.84)Pa,两组间差异无统计学意义(P=0.78);动脉瘤临近载瘤动脉平均切应力分别为(6.6±3.47)Pa和(7.30±3.80)Pa,两组间差异无统计学意义(P=0.80);动脉瘤低切应力区域的大小分别为0.33%和4.72%,两组间差异有统计学意义(P=0.01).结论 动脉瘤壁低切应力区域的大小可能是影响颅内囊状动脉瘤破裂的因素之一.     

前交通动脉瘤破裂的临床和放射解剖学危险因素

目的 探讨前交通动脉瘤(ACoAA)破裂的临床和放射解剖学危险因素.方法 从前瞻性建立的脑动脉瘤数据库中收集2008年6月至2013年6月经CTA、MRA和(或)DSA确诊的ACoAA患者.根据动脉瘤状态,入选患者分成ACoAA破裂组和未破裂组.收集动脉瘤破裂可能的临床和放射解剖学危险因素,并作单因素和多变量Logistic回归分析.结果 251例ACoAA患者入选研究,其中131例为ACoAA破裂患者.单因素分析显示破裂组患者年龄明显小于未破裂组(P＜0.01),＜60岁患者和伴有高血压患者比例远高于未破裂组;破裂组动脉瘤平均最大直径大于未破裂组(P＜0.01),最大直径≥3mm比例远高于未破裂组;破裂组大脑前动脉A1段发育不对称(缺如、发育不良)比例远高于未破裂组.多变量Logistic回归分析显示年龄＜60岁、高血压病史、动脉瘤最大直径≥3 mm和大脑前动脉A1段发育不良或缺如是ACoAA破裂独立危险因素.结论 年龄＜60岁、高血压病史、动脉瘤最大直径≥3mm和大脑前动脉A1段发育不良或缺如是ACoAA破裂独立危险因素,可作为未破裂ACoAA是否积极干预的重要参考依据.     

基于CTA形态学及血液炎症指标分析大脑中动脉动脉瘤破裂的风险因素

目的：分析大脑中动脉（MCA）动脉瘤破裂的风险因素,筛选基于动脉瘤形态学和血液炎症细胞的动脉瘤破裂预测指标。方法：回顾性分析2018年1月至2023年4月经过头颅CT血管成像（CTA）确诊的MCA动脉瘤90例,根据CT平扫有无蛛网膜下腔出血和/或脑内血肿,分为未破裂组（53例）和破裂组（37例）,未破裂动脉瘤（UIA）组根据形态分为形态规则组和形态不规则组,比较年龄,性别,入院第一次血常规炎症细胞及计算而得的中性粒细胞与淋巴细胞比值（NLR）、全身性系统炎症反应指数（SIRI）,动脉瘤形态学参数等。通过卡方检验、Student’s t检验或曼-惠特尼U检验分析各组因素,对差异因素进行单因素及多因素逻辑回归分析,最后以ROC曲线对动脉瘤形态学、血液炎症细胞有差异性的因素进行诊断效能评估。结果：MCA动脉瘤形态不规则（OR=8.64,P=0.0063）、SIRI (OR=13.62,P=0.042)、长宽比（OR=25.92,P=0.043）是独立破裂风险因素,其AUC值分别是0.78、0.94、0.75。结论：MCA动脉瘤形态不规则、长宽比和SIRI是动脉瘤破裂的高危险因素,对预测动脉瘤...     

颈动脉分叉部动脉瘤模型的建立

目的探讨建立犬颈动脉分叉部动脉瘤模型的可行性。方法建立18只犬新的颈总动脉(CCA)分叉部动脉瘤模型,随机分为分叉部顶端弹性蛋白酶处理组(实验组,n=9)和生理盐水处理组(对照组,n=9)。术后即刻、12周和24周分别行血管造影观察动脉瘤顶端形态变化,术后12周和24周分别行组织病理学分析。结果血管造影显示实验组中5只模型动脉分叉顶部观察到新生动脉瘤形成,平均直径(3.2±0.4)mm,对照组中所有模型分叉部顶端均未观察到有新生动脉瘤形成。实验组中新生动脉瘤在随访过程中未见到动脉瘤破裂。组织病理学分析显示实验组中分叉部顶端动脉瘤表现为内弹力膜不连续、弹力纤维断裂、肌层变薄、平滑肌细胞减少(与对照组相比,P<0.001)。结论犬重建颈动脉分叉顶端经弹力酶消化所致动脉壁退化可引起新生动脉瘤形成。     

基于容积CT数字减影血管成像对颈内虹吸部动脉瘤破裂风险的研究北大核心CSCD

目的:比较破裂与未破裂虹吸部动脉瘤的形态学特征,为未破裂动脉瘤的风险评估提供参考依据。方法:回顾性分析经容积CT数字减影血管造影(VCTDSA)检查后被诊断为虹吸部动脉瘤的患者151例,其中未破裂组104例(共117个动脉瘤),破裂组47例(共49个动脉瘤),比较破裂组与未破裂组动脉瘤的形状、夹角等共21个指标,对上述指标行单因素分析,然后使用ROC曲线判断指标的灵敏度、特异度以确定最大临界值,最后用多因素logistic回归分析。结果:单因素分析中未破裂组与破裂组虹吸部动脉瘤在形状、部位、宽、高、瘤颈、大小、子母角、倾角、流入角、AR(瘤体长径/瘤颈宽)、SR(最大瘤径/载瘤动脉平均直径)、S1/S2(面积比)、最大径、瘤宽/瘤颈、年龄、多发上差异具有统计学意义。多因素分析显示瘤大小(OR=12.607,95%CI=4.400~36.124,P<0.001)、倾角(OR=4.062,95%CI=1.570~10.513,P=0.004)、是否为多发动脉瘤(OR=4.274,95%CI=1.620~11.272,P=0.003)为虹吸部动脉瘤破裂的独立危险因素。结论:颈内动脉虹吸部动脉瘤的瘤大小、倾角、是否为多发是形态学预测破裂的危险因素,其用于预测动脉瘤破裂的风险具有一定意义。     

Characterization of cerebral aneurysms for assessing risk of rupture by using patient-specific computational hemodynamics models

BACKGROUND AND PURPOSE: Hemodynamic factors are thought to play an important role in the initiation, growth, and rupture of cerebral aneurysms. This report describes a pilot clinical study of the association between intra-aneurysmal hemodynamic characteristics from computational fluid dynamic models and the rupture of cerebral aneurysms. METHODS: A total of 62 patient-specific models of cerebral aneurysms were constructed from 3D angiography images. Computational fluid dynamics simulations were performed under pulsatile flow conditions measured on a normal subject. The aneurysms were classified into different categories, depending on the complexity and stability of the flow pattern, the location and size of the flow impingement region, and the size of the inflow jet. The 62 models consisted of 25 ruptured and 34 unruptured aneurysms and 3 cases with unknown histories of hemorrhage. The hemodynamic features were analyzed for associations with history of rupture. RESULTS: A large variety of flow patterns was observed: 72% of ruptured aneurysms had complex or unstable flow patterns, 80% had small impingement regions, and 76% had small jet sizes. By contrast, unruptured aneurysms accounted for 73%, 82%, and 75% of aneurysms with simple stable flow patterns, large impingement regions, and large jet sizes, respectively. Aneurysms with small impingement sizes were 6.3 times more likely to have experienced rupture than those with large impingement sizes (P = .01). CONCLUSIONS: Image-based patient-specific numeric models can be constructed in an efficient manner that allows clinical studies of intra-aneurysmal hemodynamics. A simple flow characterization system was proposed, and interesting trends in the association between hemodynamic features and aneurysmal rupture were found. Simple stable patterns, large impingement regions, and jet sizes were more commonly seen with unruptured aneurysms. By contrast, ruptured aneurysms were more likely to have disturbed flow patterns, small impingement regions, and narrow jets.     

MR angiography and surgery for unruptured familial intracranial aneurysms in persons with a family history of cerebral aneurysms.

OBJECTIVE: We used MR angiography to determine prevalence of unruptured familial intracranial aneurysms in a prepaid medical care program. We compared surgical outcomes and the cost of treating unruptured versus ruptured aneurysms. We compared the cost of MR angiography with the cost of screening mammography and with the cost of surgically treating a ruptured aneurysm. SUBJECTS AND METHODS: During a 30-month period, we performed MR angiography to show cerebral aneurysms in 63 surgical candidates who had one or more first-degree relatives with an aneurysm. Unruptured aneurysms seen on MR angiography were evaluated by digital subtraction angiography (DSA) and treated surgically. RESULTS: MR angiography showed nine unruptured aneurysms in six patients. Eight aneurysms were seen on MR angiography and nine were seen on DSA. Seven unruptured aneurysms were treated surgically. The mean treatment cost was 50% lower for an unruptured aneurysm than that for a ruptured aneurysm. No patient surgically treated for an unruptured aneurysm required rehabilitation, unlike 25% of patients with ruptured aneurysms. The annual total cost of MR angiography was equivalent to 2.9% of the annual cost of screening mammography. The annual cost of MR angiography equaled half the cost of treating one patient after aneurysm rupture. CONCLUSION: MR angiography showed a 9.5% prevalence of unruptured aneurysms among persons who had one or more first-degree relatives with a cerebral aneurysm. DSA confirmed 88% of aneurysms found on MR angiography. Persons with unruptured aneurysms had better treatment outcomes at lower cost than did patients treated for aneurysm rupture. The annual MR angiography cost was low compared with the cost of screening mammography and with the cost of treating one patient with aneurysm rupture.     

Natural history of the canine vein pouch aneurysm model

BACKGROUND AND PURPOSE: The canine vein pouch aneurysm model is widely used for testing and development of devices directed at the endovascular treatment of aneurysms. Our purpose was to determine the incidence of spontaneous thrombosis and rupture of these aneurysms. MATERIALS AND METHODS: A retrospective review of laboratory records of canine vein pouch aneurysms made during a 6-year period was performed. The aneurysm and parent artery dimensions as well as incidences of spontaneous thrombosis and rupture were noted. RESULTS: During the interval studied, 326 vein patch aneurysms were made in 310 canines. Of these, 102 were sidewall (lateral) and 224 were bifurcation aneurysms. Spontaneous occlusion occurred in 9 of the sidewall aneurysms and in only 1 of the bifurcation aneurysms. None of the aneurysms ruptured. CONCLUSION: Spontaneous occlusion of the sidewall canine vein patch aneurysm occurred less than 10% of the time; in the bifurcation aneurysms, it almost never occurred. These characteristics enhance the value of this model for use in testing of devices intended for the endovascular treatment of aneurysms.     

Quantitative comparison of the dynamic flow waveform changes in 12 ruptured and 29 unruptured ICA–ophthalmic artery aneurysms

Introduction

Studies have reported a correlation between blood flow dynamics in the cardiac cycle and vascular diseases, but research to analyze the dynamic changes of flow in cerebral aneurysms is limited. This quantitative study investigates the temporal changes in flow during a cardiac cycle (flow waveform) in different regions of aneurysms and their association with aneurysm rupture.

Methods

Twelve ruptured and 29 unruptured aneurysms from the internal carotid artery–ophthalmic artery segment were studied. Patient-specific aneurysm data were implemented to simulate blood flow. The temporal flow changes at different regions of the aneurysm were recorded to compare the flow waveforms.

Results

In more than 60 % of the cases, peak flow in the aneurysm sac occurred after peak flow in the artery. Flow rate varied among cases and no correlation with rupture, aneurysm flow rate, and aneurysm size was found. Higher pulsatility within aneurysm sacs was found when comparing with the parent artery (P?<?0.001). Pulsatility was high throughout ruptured aneurysms, but increased from neck to dome in unruptured ones (P?=?0.021). Significant changes between inflow and outflow flow profile were found in unruptured aneurysms (P?=?0.023), but not in ruptured aneurysms.

Conclusion

Quantitative analysis which considers temporal blood flow changes appears to provide additional information which is not apparent from aneurysmal flow at a single time point (i.e., peak of systole). By considering the flow waveform throughout the cardiac cycle, statistically significant differences were found between ruptured and unruptured cases — for flow profile, pulsatility and timing of peak flow.     

Additional Value of Intra-Aneurysmal Hemodynamics in Discriminating Ruptured versus Unruptured Intracranial Aneurysms

BACKGROUND AND PURPOSE:Hemodynamics are thought to play an important role in the rupture of intracranial aneurysms. We tested whether hemodynamics, determined from computational fluid dynamics models, have additional value in discriminating ruptured and unruptured aneurysms. Such discriminative power could provide better prediction models for rupture.MATERIALS AND METHODS:A cross-sectional study was performed on patients eligible for endovascular treatment, including 55 ruptured and 62 unruptured aneurysms. Association with rupture status was tested for location, aneurysm type, and 4 geometric and 10 hemodynamic parameters. Patient-specific spatiotemporal velocities measured with phase-contrast MR imaging were used as inflow conditions for computational fluid dynamics. To assess the additional value of hemodynamic parameters, we performed 1 univariate and 2 multivariate analyses: 1 traditional model including only location and geometry and 1 advanced model that included patient-specific hemodynamic parameters.RESULTS:In the univariate analysis, high-risk locations (anterior cerebral arteries, posterior communicating artery, and posterior circulation), daughter sacs, unstable inflow jets, impingements at the aneurysm body, and unstable complex flow patterns were significantly present more often in ruptured aneurysms. In both multivariate analyses, only the high-risk location (OR, 3.92; 95% CI, 1.77–8.68) and the presence of daughter sacs (OR, 2.79; 95% CI, 1.25–6.25) remained as significant independent determinants.CONCLUSIONS:In this study population of patients eligible for endovascular treatment, we found no independent additional value of aneurysmal hemodynamics in discriminating rupture status, despite high univariate associations. Only traditional parameters (high-risk location and the presence of daughter sacs) were independently associated with ruptured aneurysms.

The prevalence of intracranial aneurysms in the general population is approximately 1%–5%.^1,2 Although most aneurysms remain asymptomatic, a minority rupture, and this scenario is associated with high morbidity and case fatality rates.² For unruptured aneurysms, the risk of treatment complications has to be carefully balanced against the future risk of rupture. At present, risk assessment of unruptured intracranial aneurysms and the decision to treat or observe are mainly based on patient age, family history, aneurysm size, and location.^3–5 However, the predictive value of these characteristics is limited. For example, most ruptured aneurysms are smaller than the recommended minimum of 7 mm for treatment.⁶Several researchers have attempted to better stratify rupture risk by assessments of the associations between local hemodynamic features and aneurysm formation, growth, and rupture by using computational fluid dynamics (CFD).^7–10 In general, due to the difficulty of obtaining patient-specific velocity measurements, assumptions are made for the inflow boundary conditions. However, several studies have shown a large interpatient variation of intracranial artery flow.^11,12The purpose of this study was to test whether estimation of local hemodynamics has additional value in discriminating ruptured and unruptured aneurysms. Thus, high-resolution 3D geometry and patient-specific measurements of local flow velocities in the afferent artery as boundary conditions for hemodynamic simulations were used.^13–15     

Hemodynamic Differences in Intracranial Aneurysms before and after Rupture

BACKGROUND AND PURPOSE:Rupture risk of intracranial aneurysms may depend on hemodynamic characteristics. This has been assessed by comparing hemodynamic data of ruptured and unruptured aneurysms. However, aneurysm geometry may change before, during, or just after rupture; this difference causes potential changes in hemodynamics. We assessed changes in hemodynamics in a series of intracranial aneurysms, by using 3D imaging before and after rupture.MATERIALS AND METHODS:For 9 aneurysms in 9 patients, we used MRA, CTA, and 3D rotational angiography before and after rupture to generate geometric models of the aneurysm and perianeurysmal vasculature. Intra-aneurysmal hemodynamics were simulated by using computational fluid dynamics. Two neuroradiologists qualitatively assessed flow complexity, flow stability, inflow concentration, and flow impingement in consensus, by using flow-velocity streamlines and wall shear stress distributions.RESULTS:Hemodynamics changed in 6 of the 9 aneurysms. The median time between imaging before and after rupture was 678 days (range, 14–1461 days) in these 6 cases, compared with 151 days (range, 34–183 days) in the 3 cases with unaltered hemodynamics. Changes were observed for flow complexity (n = 3), flow stability (n = 3), inflow concentration (n = 2), and region of flow impingement (n = 3). These changes were in all instances associated with aneurysm displacement due to rupture-related hematomas, growth, or newly formed lobulations.CONCLUSIONS:Hemodynamic characteristics of intracranial aneurysms can be altered by geometric changes before, during, or just after rupture. Associations of hemodynamic characteristics with aneurysm rupture obtained from case-control studies comparing ruptured with unruptured aneurysms should therefore be interpreted with caution.

Intracranial aneurysms are found in 1%–5% of the adult population.^1,2 For ruptured intracranial aneurysms, case morbidity and fatality rates are high.^1,3 However, 50%–80% of all intracranial aneurysms do not rupture during an individual''s lifetime.¹ More commonly, unruptured aneurysms are incidentally found due to increasing use of imaging.^4,5 The risk of rupture should be balanced against the risk of treatment when deciding whether an aneurysm should be treated. In clinical practice, the location and size of the aneurysm are the most important parameters for determining the risk of rupture.^1,6 However, these geometric predictors are insufficient for optimal treatment selection. Therefore, the search for better predictors for rupture continues.^7–9 Previous studies have associated intra-aneurysmal flow patterns and wall shear stress (WSS) distributions with aneurysm rupture status.^7,8,10 However, these results are still controversial. For example, both high and low aneurysmal WSS were separately associated with aneurysm growth and rupture.^11,12 In these risk-assessment studies, potential changes in hemodynamics due to the rupture itself were systematically neglected. Recently, 2 studies have shown changes in aneurysm geometry after rupture.^13,14 These rupture-associated geometric changes may result in differences in hemodynamic characteristics as well.In this study, we had the opportunity to use high-quality 3D imaging data of 9 patients with intracranial aneurysms, obtained before and after rupture, to assess potential differences in hemodynamic characteristics associated with rupture.     

Complications of endovascular treatment of cerebral aneurysms

The number of neuroendovascular treatments of both ruptured and unruptured aneurysms has increased substantially in the last two decades. Complications of endovascular treatments of cerebral aneurysms are rare but can potentially lead to acute worsening of the neurological status, to new neurological deficits or death. Some of the possible complications, such as vascular access site complications or systemic side effects associated with contrast medium (e.g. contrast medium allergy, contrast induced nephropathy) can also be encountered in diagnostic angiography. The most common complications of endovascular treatment of cerebral aneurysms are related to acute thromboembolic events and perforation of the aneurysm. Overall, the reported rate of thromboembolic complications ranges between 4.7% and 12.5% while the rate of intraprocedural rupture of cerebral aneurysms is about 0.7% in patients with unruptured aneurysms and about 4.1% in patients with previously ruptured aneurysms.     

The perianeurysmal environment: influence on saccular aneurysm shape and rupture

PURPOSE: The purpose of this study was to evaluate whether interactions between intracranial cerebral saccular aneurysms and the perianeurysmal environment (PAE), in the form of contact constraints, influence aneurysm shape and risk of rupture. METHODS: A total of 190 consecutive aneurysms during a 34-month period were retrospectively analyzed. Of these, 124 were ruptured (group 1) and 66 were unruptured (group 2). Pretreatment high-resolution CT angiography was available for each aneurysm and was the determinant inclusion criterion. Aneurysm size and location, type of hemorrhage, initial Glasgow Coma Scale rating, World Federation of Neurological Societies grade, Fisher grade, and presence of concomitant aneurysms were recorded. Contact constraints between aneurysms and anatomical structures of the PAE were identified for each aneurysm and further subdivided into balanced or unbalanced depending on whether contact constraints occurred symmetrically on the aneurysm wall. Regular or irregular shape was recorded and correlated to contact constraints. RESULTS: Compared with unruptured aneurysms, ruptured aneurysms were found to be larger and more irregular, to develop more contact constraints with the PAE, and to show higher rates of unbalanced contact constraints. Ruptured aneurysms had a tendency to be found in locations of a constraining PAE. Irregular shape was positively correlated with the presence of an unbalanced contact constraint, even in the absence of obvious contour deformations from an imprint of an adjacent structure. CONCLUSION: The existence of contact constraints between intracranial saccular aneurysms and the PAE were shown to influence shape and risk of aneurysm rupture. Modifications of wall shear stress by contact constraints are discussed. Analysis of contact constraints between aneurysm and the PAE could be considered additional parameters in the assessment of risk of aneurysm rupture.     

Wall shear stress on ruptured and unruptured intracranial aneurysms at the internal carotid artery

BACKGROUND AND PURPOSE: Hemodynamics is often recognized as one of the major factors in aneurysm rupture. Flow impingement, greater pressure, and abnormal wall shear stress are all indications for aneurysm rupture. Characterizing wall shear stress for intracranial aneurysms at similar anatomic locations may help in understanding its role.MATERIALS AND METHODS: Twenty-six intracranial aneurysms at the paraclinoid and superclinoid segments of the internal carotid artery from 25 patients between July 2006 and July 2007 were studied retrospectively. Among them, 8 aneurysms were ruptured and 18 were unruptured. Computational fluid dynamics was used to determine the wall shear distribution. Morphologic and hemodynamic variables was analyzed by using the Mann-Whitney rank sum test.RESULTS: Wall shear stress was qualitatively the same throughout the cardiac cycle; thus, only wall shear stress at the end of diastole was compared. Both ruptured and unruptured aneurysms have similar maximal wall shear stress (26 versus 23 N/m²), and mean wall shear stress is shown to be a function of the aneurysm area. Ruptured aneurysms also have a greater portion of aneurysm under low wall shear stress (27% versus 11% for unruptured aneurysms, P = .03).CONCLUSION: For intracranial aneurysms at the internal carotid artery, an area of low wall shear is associated with aneurysm rupture.

Hemodynamics is recognized as one of the many factors responsible for aneurysm rupture.¹ Many hemodynamic variables, including flow pattern and wall shear stress, are hypothesized to be the causes.^2,3 Intra-aneurysmal flow results in complex flow structure and different flow impinging sites, some at the ostium and some at the dome.^3,4 This complex flow yields a variable wall shear stress distribution on the aneurysm wall. Because wall shear stress regulates endothelial functions,^5,6 understanding of wall shear distribution on the aneurysm wall becomes very important.Recent development of numerical tools has enabled us to study hemodynamics in realistic patient aneurysm geometries.^3,7 Studies based on patient-specific aneurysm models are benefited greatly by advanced 3D angiography because 3D images capture detailed anatomic features that are often neglected in idealized geometry.^7-9 Fine anatomic details render a different flow structure, and these studies have improved our knowledge of the influence of aneurysm morphology on intra-aneurysmal flow.¹⁰ Studying aneurysms at similar anatomic locations allows us to focus on intra-aneurysmal flow, wall shear stress, and aneurysm behaviors. Therefore, we studied the wall shear stress distribution on 26 intracranial aneurysms at the paraclinoid and superclinoid segments of the internal carotid artery and examined the role of hemodynamic variables.     

破裂的颅内动脉瘤大小及其相关因素分析

目的：探讨颅内破裂动脉瘤的临床及影像学特点与瘤大小之间的关系。方法：回顾性分析2005年1月～2006年12月在我科行全脑血管造影并经手术证实有动脉瘤的患者264例,分别研究〈5nm和≥5mm的破裂动脉瘤的临床及影像学特点,分析动脉瘤的位置、患者的血压、年龄、性别、血糖以及瘤体长径／宽径比值与瘤体大小之间的关系。结果：264例患者共发生动脉瘤302个,其中破裂动脉瘤273个,未破裂动脉瘤29个,9例患者同时患有2个破裂动脉瘤,〈5mm的动脉瘤87个,≥5mm的动脉瘤186个。动脉瘤的部位、患者的血压、年龄、性别以及血糖与破裂动脉瘤的大小无明显关系（P〉0．05）。瘤体长径／宽径比值与动脉瘤大小之间有明显的统计学差异（P=0．002）。位于前交通动脉、后交通动脉起始处以及50～60岁年龄段的患者,其破裂的颅内小动脉瘤分别为33个（37．93％）、27个（31．03％）和38个（43．68％）,要多于其它部位及其它年龄段。结论：动脉瘤的部位、患者的血压、年龄、性别以及血糖对动脉瘤的大小无明显影响;最大径〈5mm的颅内动脉瘤也有一定的破裂风险,其数目也达到一定的比例;瘤体长径与宽径比值或许可用来预测颅内不同大小动脉瘤的破裂风险。