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。     

基于血流动力学的大脑中动脉分叉处与侧壁动脉瘤破裂风险研究

目的旨在结合血流动力学研究大脑中动脉瘤(MCAA)分叉和侧壁部位对其破裂风险的影响。方法本研究回顾性分析术前行头颅CT血管成像(CTA)并经颅内血管造影或手术确诊的MCAA病人193例,未破裂组24例[(58.5±8.5)岁],破裂组169例[(54.9±10.3)岁],收集病人的临床资料及动脉瘤的形态学参数,同时对2组进行流体力学计算分析,获得壁剪应力、振荡剪切指数(OSICV)等血流动力学参数。采用独立样本t检验、Mann-Whitney U检验或χ2检验、Fisher精确检验比较破裂/未破裂组间各参数差异,采用Logistic回归分析破裂的独立风险因素,并分别比较分叉和侧壁处动脉瘤破裂相关的血流动力学差异。结果破裂和未破裂组间临床资料的差异无统计学意义(P>0.05)。与未破裂组相比,破裂组动脉瘤多分布于大脑中动脉分叉处,血流模式复杂、集中,血流冲击区域小且不稳定,OSICV低(均P<0.05)。Logistic回归分析显示复杂的血流模式、血流冲击面积小及小的OSICV是预测MCAA破裂状态的独立风险因素(均P<0.05)。侧壁动脉瘤破裂组的血流冲击小,而分叉处动脉瘤破裂组则血流更复杂、更集中,血流冲击区域更小,更不稳定(均P<0.05)。结论血流复杂程度、冲击面积和OSICV是MCAA破裂的独立危险因素,MCAA所处部位会影响破裂风险。     

颅内囊状动脉瘤的形态学特征研究

目的 比较颅内动脉瘤破裂与非破裂的形态学,了解破裂动脉瘤的形态学特征.方法 将DSA确诊颅内动脉瘤患者171例分为破裂动脉瘤(指自发性蛛网膜下腔出血)组138例和未破裂动脉瘤组33例,分析两组患者的动脉瘤部位分布、大小及形态.结果 破裂动脉瘤组138例患者共有149枚囊状动脉瘤.115枚(77%)动脉瘤位于前循环,34枚(23%)动脉瘤位于后循环;124枚(83%)为单囊;25枚(17%)远端可见假性动脉瘤形成.未破裂动脉瘤组33例患者,共34枚动脉瘤.29枚(85.3%)动脉瘤位于前循环.5枚(14.7%)动脉瘤位于后循环;32枚(94.1%)动脉瘤为单囊,2枚(5.9%)动脉瘤为不规则形,所有动脉瘤瘤壁均光整,瘤腔内对比剂均匀.结论 破裂动脉瘤常可见典型的表现,包括动脉瘤形态不规则,破13处瘤壁不光整,破口周围易形成假性动脉瘤.     

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.     

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.     

颅内破裂囊状动脉瘤的血管内治疗

目的 探讨颅内破裂囊状动脉瘤的血管内治疗的价值和技术.方法 回顾性分析上海市静安区中心医院和上海华山医院2004年7月-2008年5月.因自发性颅内出血患者就诊,经全脑DSA检查,确诊颅内囊状动脉瘤138例患者,共149枚动脉瘤.(剔除<2mm的微小动脉瘤患者);并行血管内栓塞治疗.结果 本组128枚(86%)囊性动脉瘤完全栓塞;12枚(8%)95%栓塞;9枚(6%)栓塞小于95%,其中4个为宽颈动脉瘤,5个为宽颈大动脉瘤.138例患者中93例(67.4%)患者进行了全脑血管造影随访,DSA随访从6～36个月,平均16.8个月.其中4例(4.3%)复发,但均无再次破裂出血发生.结论 颅内囊性动脉瘤血管内治疗并中期随访提示颅内破裂囊性动脉瘤介入治疗是一种安全、有效的治疗方法;破裂囊性动脉瘤栓塞的重点是栓塞瘤颈和载瘤动脉相邻的真性动脉瘤,远端如形成动脉瘤囊泡或假囊,栓塞时无需栓塞或致密栓塞.长期效果有待进一步随访.     

犬颈动脉囊状动脉瘤模型的建立实验研究

目的探讨建立犬颈总动脉囊状动脉瘤模拟人体颅内动脉瘤的可行性。方法采用外科手术方法建立犬颈动脉囊状侧壁动脉瘤模型。结果建立20条健康实验犬颈动脉囊状侧壁动脉瘤模型40枚,血管造影证实动脉瘤与载瘤动脉均通畅者有36枚,4枚动脉瘤腔自发性完全性闭塞,但颈总动脉均保持通畅,模型建立成功率为90.0%。结论犬颈总动脉囊状侧壁动脉瘤是模拟人体颅内动脉瘤的最佳模型之一。     

三维CTA检查预测高危颅内动脉瘤破裂出血的应用价值

目的评价三维CTA(3D-CTA)检查高危颅内动脉瘤破裂出血的应用价值及筛选敏感性指标。方法选择手术确诊颅内动脉瘤患者共60例(80个动脉瘤,破裂出血30个),均采用3D-CTA检查,评估动脉瘤数目、位置、形态、长度、高度、瘤颈宽度、瘤体颈比(AR)、入射夹角、载瘤动脉直径、高度/载瘤动脉直径(SR)、瘤体钙化及血栓,分别采用单因素和多因素Logistic回归分析筛选破裂的高危因素,以受试者工作曲线(ROC)评价动脉瘤破裂的诊断价值。结果单因素分析得出,破裂组患者性别和年龄、动脉瘤数目、位置、高度、载瘤动脉直径、瘤体钙化及血栓与未破裂组比较均无差异(P>0.05);但破裂组动脉瘤形态、长度、瘤颈宽度、AR、入射夹角和SR与未破裂组比较,差异有统计学意义(P<0.05)。多因素Logistic回归分析得出子囊、AR>0.98、入射夹角>105.4°和SR>0.42是动脉瘤破裂的独立危险因素(P<0.05)。ROC分析得出AR诊断动脉瘤破裂的准确性(曲线下面积AUC值)为0.866,临界值1.15;入射夹角诊断准确性为0.845,临界值110°;SR诊断准确性为0.855,临界值0.51。结论3D-CTA检查高危颅内动脉瘤破裂出血有较好的应用价值,子囊、AR、入射夹角和SR值可能是预测破裂的敏感性指标。     

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...     

后交通动脉动脉瘤伴动眼神经麻痹的形态学危险因素分析

【摘要】 目的 从形态学角度分析未破裂后交通动脉（PComA）动脉瘤引起动眼神经麻痹（ONP）的危险因素。方法 回顾性分析2010年1月至2018年10月经脑血管造影确诊的71例单发未破裂PComA动脉瘤患者临床资料。根据临床症状,分为ONP组（n=31）和非ONP组（n=40）。根据动脉瘤形态学特征,采用单因素和多因素logistic回归分析,确定PComA动脉瘤引起ONP的形态学危险因素。结果 单因素分析显示,两组患者动脉瘤瘤颈宽度（P=0.046）、瘤顶指向（P=0.005）、有无子囊（P=0.002）差异均有统计学意义;多因素logistic回归分析显示,瘤颈宽度≤3.8 mm（OR=5.437,P=0.008）、瘤顶指向后外下（OR=5.953,P=0.003）、有子囊（OR=5.356,P=0.014）是ONP发生的独立危险因素。 结论 动脉瘤瘤颈宽度≤3.8 mm、瘤顶指向后外下、存在子囊,可能是PComA动脉瘤引起ONP的形态学危险因素。     

Placement of a Neuroform2 stent into the parent vessel by navigating it along the inner wall of the aneurysm sac

Introduction The Neuroform2 stent has proven to be a very helpful device in the stent-assisted coiling of wide-necked cerebral aneurysms particularly because of its high navigability. We describe the case of a 33-year-old man with a ruptured anterior cerebral artery aneurysm that was successfully embolized and a wide-necked unruptured middle cerebral artery (MCA) aneurysm that required stent-assisted coiling. Methods All attempts to catheterize the parietal branch of the MCA in order to deploy the stent were unsuccessful since various guidewires followed a circular path inside the aneurysm sac. Based on our experience on the flexibility of the Neuroform2 stent, and since the aneurysm was unruptured, we decided to follow the circular path of the wire inside the aneurysm with the stent microcatheter. Results The stent navigated easily into the parietal branch where it was correctly deployed and the aneurysm was uneventfully embolized. Conclusion This maneuver might pose the risk of aneurysm puncture in ruptured aneurysms but might prove helpful in unruptured wide-necked calcified or partially thrombosed aneurysms.     

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.     

Intracranial infective aneurysms presenting with haemorrhage: an analysis of angiographic findings, management and outcome

AIM: This study is an analysis of angiographic findings in 17 patients with infective aneurysms who presented with intracranial haemorrhage and reviews the management and outcome in the context of the existing literature.MATERIALS AND METHODS: A retrospective study of infective aneurysms in 17 patients was carried out. Cranial angiography was performed in all patients. The location, size and outline of aneurysms were analysed. Ten patients were managed conservatively and six patients underwent surgery for the ruptured infective aneurysms and were followed up for a period of 35.8 months and 23 months, respectively.RESULTS: Twenty-two aneurysms were identified (five unruptured) in 17 patients. Twenty aneurysms (90. 9%) were distal in location and two (9.1%) proximal. Sixty percent were in the posterior circulation with 55% in the posterior cerebral artery (PCA) territory, 27.3% in the middle cerebral artery (MCA) territory and 9.1% in the anterior cerebral artery (ACA) territory. Fourteen aneurysms were small (3-5 mm) and eight were medium sized (6-9 mm). 72.7% of aneurysms had irregular outline and 27.3% regular outline. Out of the 10 ruptured aneurysms managed conservatively, eight resolved. One patient died, presumably due to rebleed, and one had infarction due to parent vessel thrombosis. Six aneurysms were surgically managed with good results. Of the five unruptured aneurysms one was surgically managed and the remaining four conservatively managed patients did not bleed during follow-up. CONCLUSION: Patients with ruptured infective aneurysms fared well with medical management and the outcome in this series is better than that reported in literature. Patients on conservative management, however, need closer monitoring with angiographic follow-up. Active management is required with enlarging or persisting aneurysms.     

Endovascular treatment of unruptured intracranial aneurysms

BACKGROUND AND PURPOSE: Intracranial aneurysms are common, with an overall frequency ranging from 0.8% to 10%. Because prognosis after subarachnoid hemorrhage is still very poor, treatment of unruptured aneurysms, either neurosurgically or endovascularly, has been advocated. However, risk of rupture and subsequent subarachnoid hemorrhage needs to be considered against the risks of elective treatment. We analyzed the technical feasibility, safety, and efficacy of endovascular treatment of a consecutive series of unruptured cerebral aneurysms. METHODS: From July 1997 through December 2000, a total of 76 patients with 82 unruptured cerebral aneurysms were treated at our institution. Endovascular treatment was administered to 39 consecutive patients with a total of 42 unruptured cerebral aneurysms. Thirty-six aneurysms were treated with an endovascular technique; in six patients, the parent artery was occluded to eliminate aneurysmal perfusion. Aneurysms were located either in the anterior (n = 31) or posterior (n = 11) circulation. Eight patients had experienced previous subarachnoid hemorrhage from other aneurysms and were treated electively after complete rehabilitation. Ten patients had neurologic symptoms; in 21 patients, the aneurysm was an incidental finding. Eighteen aneurysms were small (0-5 mm), 11 were medium (6-10 mm), nine were large (11-25 mm), and four were giant (> 25 mm). Occlusion rate was categorized as complete (100%), subtotal (95-99%), and incomplete (< 95%) obliteration. RESULTS: Endovascular treatment was technically feasible for 38 of 42 aneurysms. Complete (100%) or nearly complete (95-99%) occlusion was achieved in 34 of 38 aneurysms. In four aneurysms of the internal carotid artery, only incomplete (< 95%) occlusion was achieved. All patients except one with mild neurologic deficits according to the Glasgow Outcome Scale and one with mild memory dysfunction but no focal neurologic deficit achieved good recovery, resulting in a morbidity rate of 4.8% and a mortality rate of 0%. CONCLUSION: Endovascular embolization of unruptured cerebral aneurysms is an effective therapeutic alternative to neurosurgical clipping and is associated with low morbidity and mortality rates. For the management of unruptured aneurysms, endovascular treatment should be considered.     

Periprocedural morbidity and mortality associated with endovascular treatment of intracranial aneurysms

BACKGROUND AND PURPOSE: Despite experience and technological improvements, endovascular treatment of intracranial aneurysms still has inherent risks. We evaluated cerebral complications associated with this treatment. METHODS: From October 1998 to October 2002, 180 consecutive patients underwent 131 procedures for 118 ruptured aneurysms and 79 procedures for 72 unruptured aneurysms. We retrospectively reviewed their records and images to evaluate their morbidity and mortality. RESULTS: Thirty-seven (17.6%) procedure-related complications occurred: 27 and six with initial embolization of ruptured and unruptured aneurysms, respectively, and four with re-treatment. Complications included 22 cerebral thromboembolisms, nine intraprocedural aneurysm perforations, two coil migrations, two parent vessel injuries, one postprocedural aneurysm rupture, and one cranial nerve palsy. Fourteen complications had no neurologic consequence. Three caused transient neurologic morbidity; 10, persistent neurologic morbidity; and 10, death. Procedure-related neurologic morbidity and mortality rates, respectively, were as follows: overall, 4.8% and 4.8%; ruptured aneurysms, 5.9% and 7.6%; unruptured aneurysms, 1.4% and 1.4%; and re-treated aneurysms, 10% and 0%. Combined procedure-related morbidity and mortality rates for ruptured, unruptured, and re-treated aneurysms were 13.5%, 2.8%, and 10%, respectively. Nonprocedural complications attributable to subarachnoid hemorrhage in 118 patients with ruptured aneurysm were early rebleeding before coil placement (0.9%), symptomatic vasospasm (5.9%), and shunt-dependent hydrocephalus (5.9%); mortality from complications of subarachnoid hemorrhage itself was 11.9%. CONCLUSION: Procedural morbidity and mortality rates were highest in ruptured aneurysms and lowest in unruptured aneurysms. Morbidity rates were highest in re-treated aneurysms and lowest in unruptured aneurysms. No procedural mortality occurred with re-treated aneurysms. The main cause of morbidity and mortality was thromboembolism.     

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.     

Visualization of intraaneurysmal flow patterns with transluminal flow images of 3D MR angiograms in conjunction with aneurysmal configurations

BACKGROUND AND PURPOSE: How the complex flow phenomena generated within unruptured cerebral aneurysms relate to the corresponding aneurysmal geometry is unknown. To estimate the interaction between flow patterns and morphologic features of unruptured cerebral aneurysms, we developed a method to visualize intraanuerysmal flow patterns with transluminal flow imaging of 3D MR angiograms in conjunction with aneurysmal configurations. METHODS: Transluminal images of the vessel lumen were reconstructed with use of a parallel volume-rendering algorithm by selecting information on the margin of lumina from the volume data sets of 3D time-of-flight MR angiograms. Transluminal flow images were then created by superimposing flow-related intraluminal information onto transluminal images. Intraaneurysmal flow patterns were evaluated in three cases of unruptured cerebral aneurysms, based on the animated display of transluminal flow images with stepwise extracted intraluminal volume data of signal intensity, in conjunction with the corresponding aneurysmal configurations depicted on 3D MR angiograms. RESULTS: Transluminal flow images showed 3D visualization of flow-related signal intensity distribution obtained from volume data of MR angiograms, so that qualitative information regarding intraaneurysmal flow patterns could be estimated with respect to morphologic features of cerebral aneurysms. CONCLUSION: Transluminal flow images of 3D MR angiograms allowed feasible visualization of intraaneurysmal flow patterns that were studied. More work is required to validate the technique and clarify the significance of being able to visualize intraaneurysmal flow patterns.     

Computed angiotomography of unruptured cerebral aneurysms

Twenty-seven unruptured cerebral aneurysms in 25 patients were detected by computed angiotomography. A comparison of the computed angiotomographic features in common aneurysm sites with plain CT and conventional arteriography was carried out. An isodense, round cisternal defect and a calcification or high-density mass in the basal cisterns on plain CT are important findings suggestive of unruptured aneurysms larger than 7 mm in diameter. The identification of the aneurysm, as well as of the afferent and efferent arteries on computed angiotomography is essential for the direct diagnosis of smaller unruptured aneurysms related to the circle of Willis. This is possible in a number of cases when the aneurysms are relatively large. It appears that the aneurysm size must be larger than 3 mm in diameter to permit its recognition on the basis of angiotomography and the avoidance of false-positive findings.     

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.     

Quantitative Assessment of Circumferential Enhancement along the Wall of Cerebral Aneurysms Using MR Imaging

BACKGROUND AND PURPOSE:The incidence of wall enhancement of cerebral aneurysms on vessel wall MR imaging has been described as higher in ruptured intracranial aneurysms than in unruptured intracranial aneurysms, but the difference in the degree of enhancement between ruptured and unruptured aneurysms is unknown. We compared the degree of enhancement between ruptured and unruptured intracranial aneurysms by using quantitative MR imaging measures.MATERIALS AND METHODS:We performed quantitative analyses of circumferential enhancement along the wall of cerebral aneurysms in 28 ruptured and 76 unruptured consecutive cases by using vessel wall MR imaging. A 3D-T1-weighted fast spin-echo sequence was obtained before and after contrast media injection, and the wall enhancement index was calculated. We then compared characteristics between ruptured and unruptured aneurysms.RESULTS:The wall enhancement index was significantly higher in ruptured than in unruptured aneurysms (1.70 ± 1.06 versus 0.89 ± 0.88, respectively; P = .0001). The receiver operating characteristic curve analysis found that the most reliable cutoff value of the wall enhancement index to differentiate ruptured from unruptured aneurysms was 0.53 (sensitivity, 0.96; specificity, 0.47). The wall enhancement index remained significant in the multivariate logistic regression analysis (P < .0001).CONCLUSIONS:Greater circumferential enhancement along the wall of cerebral aneurysms correlates with the ruptured state. A quantitative evaluation of circumferential enhancement by using vessel wall MR imaging could be useful in differentiating ruptured from unruptured intracranial aneurysms.

Vessel wall MR imaging with a 3D-T1-weighted FSE sequence has been increasingly used to study intracranial vascular lesions such as atherosclerosis, vasculitis, and aneurysms.^1–4 Previous reports established a link between ruptured aneurysms and wall enhancement by using qualitative vessel wall MR imaging assessments.^1,5,6 However wall enhancement was also observed in unruptured aneurysms^1,6; thus, we hypothesized that the degree of enhancement is higher in ruptured than in unruptured aneurysms. In this study, we used a quantitative method to compare the degree of enhancement between ruptured and unruptured intracranial aneurysms by using a 3D-T1WI FSE sequence.