急性缺血性脑卒中磁敏感加权成像中低信号血管影的临床应用初探

目的 探讨磁敏感加权成像(SWI)中的低信号血管影在急性缺血性脑卒中(acute ischemic stroke,AIS)诊断中的临床应用价值.资料与方法 选择符合纳入标准的AIS患者11例,发病时间3～48 h,其中男性8例,女性3例,年龄28～85岁,行MRI.序列:T_1WI,T_2WI,T_2液体衰减反转恢复序列(T_2FLAIR),扩散加权成像(DWI),三维时间飞跃法磁共振血管成像(3D TOF MRA),SWI,灌注加权成像(PWI)及T_1WQI增强扫描.由3名有经验的神经放射学医师采用盲法分析MRI结果.结果 11例患者均可见大脑中动脉(MCA)供血区缺血病灶.SWI显示MCA内低信号与MRA显示的颈内动脉(ICA)、MCA血管阻塞有较好的相关性(Spearman等级相关系数ps=0.7698,P=0.0056),其预测ICA、MCA血管阻塞的灵敏性为100%,特异性为66.7%.SWI示11例中4例缺血区内可见异常的静脉血管影,PWI显示病灶体积与缺血区内出现走行僵直的静脉血管影这一征象有较好的相关性(Spearman等级相关系数ps=0.8367,P=0.0013);相对平均通过时间(rMIT)与缺血区内出现走行僵直的静脉血管影这一征象也有较好的相关性(Spearman等级相关系数ps=0.7188,P=0.0127).T_1WI增强扫描示1例可见MCA管壁强化.结论 AIS患者SWI中的低信号血管影与血栓形成及血流速度减慢有关,即其病理机制与去氧血红蛋白浓度增加有关.     

Dynamic CT Perfusion Imaging for the Detection of Crossed Cerebellar Diaschisis in Acute Ischemic Stroke

Objective

Although the detection of crossed cerebellar diaschisis (CCD) by means of different imaging modalities is well described, little is known about its diagnosis by computed tomography perfusion (CTP) imaging. We investigated the detection rate of CCD by CTP imaging and the factors related to CCD on CTP images in patients with acute ischemic stroke.

Materials and Methods

CT perfusion maps of cerebral blood volume (CBV), cerebral blood flow (CBF), mean transit time (MTT), and time-to-peak (TTP) obtained from 81 consecutive patients affected by an acute ischemic stroke were retrospectively reviewed. Whole-brain perfusion maps were obtained with a multichannel CT scanner using the toggling-table technique. The criteria for CCD was a unilateral supratentorial ischemic lesion and an accompanying decrease in perfusion of the contralateral cerebellar hemisphere on the basis of CTP maps by visual inspection without a set threshold. Maps were quantitatively analyzed in CCD positive cases.

Results

The criteria for CCD were fulfilled in 25 of the 81 cases (31%). Detection rates per CTP map were as follows: MTT (31%) > TTP (21%) > CBF (9%) > CBV (6%). Supratentorial ischemic volume, degree of perfusion reduction, and infratentorial asymmetry index correlated strongly (R, 0.555-0.870) and significantly (p < 0.05) with each other in CCD-positive cases.

Conclusion

It is possible to detect CCD on all four of the CTP-based maps. Of these maps, MTT is most sensitive in detecting CCD. Our data indicate that CTP imaging is a valid tool for the diagnosis of CCD in patients affected by an acute hemispheric stroke.     

Cost-Effectiveness Study of Initial Imaging Selection in Acute Ischemic Stroke Care

PurposeNational guidelines recommend prompt identification of candidates for acute ischemic stroke (AIS) treatment, requiring timely neuroimaging with CT and/or MRI. CT is often preferred because of its widespread availability and rapid acquisition. Despite higher diagnostic accuracy of MRI, it commonly involves complex workflows that could potentially cause treatment time delays. The purpose of this study was to analyze the impact on outcomes of imaging utilization before treatment decisions at comprehensive stroke centers for patients presenting with suspected AIS in the anterior circulation with last-known-well-to-arrival time 0 to 24 hours.MethodsA decision simulation model based on the American Heart Association’s recommendations for AIS care pathways was developed from a health care perspective to compare initial imaging strategies: (1) stepwise-CT: noncontrast CT (NCCT) at the time of presentation, with CT angiography (CTA) ± CT perfusion (CTP) only in select patients (initial imaging to exclude hemorrhage and extensive ischemia) for mechanical thrombectomy (MT) evaluation; (2) stepwise-hybrid: NCCT at the time of presentation, with MR angiography (MRA) ± MR perfusion (MRP) only for MT evaluation; (3) stepwise-advanced: NCCT + CTA at presentation, with MR diffusion-weighted imaging (MR DWI) + MRP only for MT evaluation; (4) comprehensive-CT: NCCT + CTA + CTP at the time of presentation; and (5) comprehensive-MR: MR DWI + MRA + MRP at the time of presentation. Model parameters were defined using evidence-based data. Cost-effectiveness and sensitivity analyses were performed.ResultsThe cost-effectiveness analyses revealed that comprehensive-CT and comprehensive-MR yield the highest lifetime quality-adjusted life-years (QALYs) (4.81 and 4.82, respectively). However, the incremental cost-effectiveness ratio of comprehensive-MR is $233,000/QALY compared with comprehensive-CT. Stepwise-CT, stepwise-hybrid, and stepwise-advanced strategies are dominated, yielding lower QALYs and higher costs compared with comprehensive-CT.ConclusionsPerforming comprehensive-CT at presentation is the most cost-effective initial imaging strategy at comprehensive stroke centers.     

急性缺血性卒中的CT、常规MRI和DWI影像诊断

目的：研究急性缺血性卒中不同时间段的MRI和CT特点并评价其诊断价值。材料和方法：对64例急性缺血性卒中患者进行CT检查、常规MRI和DWI检查，测量梗死病灶平均ADC值和平均相对ADC（rADC）值，并进行统计学分析。结果：急性缺血性卒中发病1—7d之间的CT、常规MRI和DWI信号特点无明显差异，平均ADC值和平均rADC值下降，但梗死区平均rADC随着时间呈上升趋势，发病7d平均rADC值与发病1d、2d、3d、4d有统计学意义（P〈0．05），与发病5d、6d无统计学意义（P〉0．05）。结论：CT、常规MRI、DWI信号特点结合rADC值随时间的演变规律，有助于判断急性缺血性卒中的病理生理改变，为缺血性卒中分期、指导治疗提供依据。     

替罗非班在急性颅内大血管闭塞血管内治疗中应用的安全性分析

目的探讨颅内大血管闭塞性缺血性脑卒中行血管内再通治疗术中合并使用替罗非班对颅内出血的影响。 方法回顾性分析本中心接受血管内再通治疗的急性颅内大血管闭塞性缺血性卒中患者的临床资料,比较术中使用替罗非班与未使用替罗非班两组患者的一般临床特点、治疗方式以及颅内出血并发症等差异。 结果共计纳入173例患者接受血管内再通治疗,其中替罗非班组87例,非替罗非班组86例,替罗非班组中后循环（39.08% vs 25.58%,P=0.034）、糖尿病（24.14% vs 10.47%,P=0.026）比例显著高于非替罗非班组,非替罗非班组中房颤患者比例显著高于替罗非班组（P<0.001）,两组患者手术再通率及随访90 d预后良好比例相当,围手术期颅内出血并发症未见差异。 结论血管内再通治疗合并使用替罗非班是相对安全的,并未增加出血风险。     

Acute stroke differential diagnosis: Stroke mimics

Stroke mimics (SM) are non-vascular conditions that present with an acute neurological deficit simulating acute ischemic stroke and represent a significant percentage of all acute stroke hospital admissions. The most common clinical SM includes conversion/functional (psychiatric disorder); seizures and postictal paralysis; toxic-metabolic disturbances; brain tumours; infections, and migraine. Imaging is essential for SM recognition, being Diffusion weighted imaging (DWI), perfusion imaging and angiographic studies very useful. There are several disorders that may have imaging features that simulate acute ischemic stroke, mainly presenting with cytotoxic oedema and/or perfusion deficits. The imaging features of the most frequent clinical and imaging stroke mimics are reviewed.     

Evaluation of causal heart diseases in cardioembolic stroke by cardiac computed tomography

Cardioembolic stroke is a potentially devastating condition and tends to have a poor prognosis compared with other ischemic stroke subtypes. Therefore, it is important for proper therapeutic management to identify a cardiac source of embolism in stroke patients. Cardiac computed tomography(CCT) can detect the detailed visualization of various cardiac pathologies in the cardiac chambers,interatrial and interventricular septum, valves, and myocardium with few motion artifacts and few dead angles. ...     

动脉溶栓治疗急性缺血性脑梗死的长期疗效

目的 :评价动脉溶栓治疗急性缺血性脑梗死的长期疗效及并发症。材料和方法 :对 14例发病在 6h内的急性缺血性脑梗死患者行颈动脉灌注治疗。血管再通程度根据TIMI分类。临床结果评价在溶栓后 3 0d进行 ,根据ModifiedRankScore (MRS)分为好结果 (MRS 0～Ⅲ )、差结果 (MRSⅣ～Ⅵ )两类。结果 :7例患者为TIMI 0～Ⅰ ,溶栓后 6例患者部分 /完全再通 ,1例未再通 ;另 7例患者为TIMIⅡ ,溶栓后除 1例外均完全再通。溶栓后 3 0d ,14患者中 12例为好结果 ,2例死亡 ,其中 1例死于脑出血。经平均 18个月的随访 (0 .5～ 2a) 12例生存患者均为好结果。结论 :动脉溶栓对发病 6h内的急性缺血性脑梗死是可行安全的 ,能明显降低死亡率和改善预后。对溶栓前脑动脉未完全闭塞患者长期效果尤佳。     

Delayed reperfusion therapy for ischemic stroke tandem occlusion with subsequent secondary prophylaxis of cerebral ischemic events: A case report and literature review

Mechanical thrombectomy is currently the gold standard treatment of large vessel occlusions, especially in anterior circulation acute ischemic stroke. At the same time, the problem of tandem occlusions seems especially important since most of the major clinical mechanical thrombectomy studies did not specifically evaluate patients with concomitant extracranial occlusions or critical stenoses.To date, there is no universally accepted optimal treatment strategy for such tandem lesions in acute ischemic stroke: it remains unclear which lesion – intracranial or extracranial – should be treated first. The selected reperfusion method should be based on the patients’ individual characteristics, data from non-invasive radiologic studies, and the stroke team experience.We present a case of successful reperfusion therapy of acute tandem occlusion of the right internal carotid artery, followed by contralateral carotid artery stenting in a patient with stenosing extracranial atherosclerosis.     

Crossing double stent retriever technique for refractory terminal internal carotid artery occlusion

Mechanical thrombectomy is highly effective for the recovery of acute ischemic stroke with large vessel occlusion. However, refractory occlusions are still encountered despite the use of currently available devices. In this article, we present a case of refractory terminal internal carotid artery occlusion treated with the “crossing double stent retriever technique.” Two thrombectomy procedures with the combined technique using a stent retriever and aspiration catheter failed to recanalize the terminal internal carotid artery occlusion that involved the dominant anterior cerebral artery. We then applied the crossing double stent retriever technique as a rescue technique. Two microcatheters were advanced across the occlusion: one to the anterior cerebral artery and the other to the middle cerebral artery. First, a Trevo NXT 4 mm stent retriever was deployed from the anterior cerebral artery. Next, an additional Trevo NXT 4 mm stent retriever was deployed from the middle cerebral artery, and full immediate restoration of flow was achieved on angiography. Intraprocedural radiological images showed that the 2 microcatheters traversed different pathways, and the 2 stent retrievers completely covered the entire vessel with apparent in-stent clot sign. Both stent retrievers were then pulled back together, and a hard clot was retrieved. Subsequent angiography revealed complete recanalization. The crossing double stent retriever technique seems an effective rescue technique for treating refractory terminal internal carotid artery occlusion, especially with the anatomical feature of branching of the dominant anterior cerebral artery. This technique can facilitate the device-clot-vessel interaction by engaging the clot via 2 different device pathways.     

Updated Trends,Disparities, and Clinical Impact of Neuroimaging Utilization in Ischemic Stroke in the Medicare Population: 2012 to 2019

ObjectiveThe purpose of this study was to update trends, investigate sociodemographic disparities, and evaluate the impact on mortality of stroke neuroimaging across the United States from 2012 to 2019.MethodsRetrospective cohort study using CMS Medicare 5% Research Identifiable Files, representing consecutive ischemic stroke emergency department or hospitalized patients aged ≥65 years. A total of 85,547 stroke episodes with demographic and clinical information were analyzed using Cochran-Mantel-Haenszel tests and logistic regression. Outcome measures were neuroimaging (CT angiography [CTA], CT perfusion [CTP], MRI, MR angiography [MRA]) utilization, acute treatment (endovascular thrombectomy [EVT] and intravenous thrombolysis [IVT]), and mortality while in the hospital and at 30 days and 1 year post discharge.ResultsSignificantly increasing utilization trends for CTA (250%), CTP (428%) and MRI (18%), and a decreasing trend for MRA (?33%) were observed from 2012 to 2019 (P < .0001). Controlling for covariates in the logistic regression models, CTA and CTP were significantly associated with higher EVT and IVT utilization. Although CTA, MRI, and MRA were associated with lower mortality, CTP was associated with higher mortality post discharge. Less neuroimaging was performed in rural patients; older patients (≥80 years) had lower utilization of CTA, MRI, and MRA; female patients had lower rates of CTA; and Black patients had lower utilization of CTA and CTP.ConclusionsCTA and CTP utilization increased in the Medicare ischemic stroke population from 2012 to 2019 and both were associated with greater EVT and IVT use. However, disparities exist in neuroimaging utilization across all demographic groups, and further understanding of the root causes of these disparities will be crucial to achieving equity in stroke care.     

Endovascular Mechanical Thrombectomy of an Occluded Superior Division Branch of the Left MCA for Acute Cardioembolic Stroke

Cardiac embolism accounts for a large proportion of ischemic stroke. Revascularization using systemic or intra-arterial thrombolysis is associated with increasing risks of cerebral hemorrhage as time passes from stroke onset. We report successful mechanical thrombectomy from a distal branch of the middle cerebral artery (MCA) using a novel technique. A 72-year old man suffered an acute ischemic stroke from an echocardiographically proven ventricular thrombus due to a recent myocardial infarction. Intra-arterial administration of 4 mg rt-PA initiated at 5.7 hours post-ictus failed to recanalize an occluded superior division branch of the left MCA. At 6 hours, symptomatic embolic occlusion persisted. Mechanical extraction of the clot using an Attracter-18 device (Target Therapeutics, Freemont, CA) resulted in immediate recanalization of the MCA branch. Attracter-18 for acute occlusion of MCA branches may be considered in selected patients who fail conventional thrombolysis or are nearing closure of the therapeutic window for use of thrombolytic agents.     

Imaging of the Ischemic Penumbra in Acute Stroke

One of the main reasons for the soaring interest in acute ischemic stroke among radiologists is the advent of new magnetic resonance techniques such as diffusion-weighted imaging. This new modality has prompted us to seek a better understanding of the pathophysiologic mechanisms of cerebral ischemia/infarction. The ischemic penumbra is an important concept and tissue region because this is the target of various recanalization treatments during the acute phase of stroke. In this context, it is high time for a thorough review of the concept, especially from the imaging point of view.     

大鼠急性脑缺血再灌注的磁共振灌注扩散成像与病理对照研究

目的探讨急性脑缺血再灌注的磁共振灌注成像(PWI)及扩散成像(DWI)的表现以及其病理改变。方法取70只Wistar大鼠,用线栓法建立右侧大脑中动脉栓塞(MCAO)模型,分为假手术(A组)、栓塞30min及再灌注30min、60min(B、B1、B2组)、栓塞60min及再灌注30min、60min(C、C1、C2组),每组各10只。对各组分别行头部MRI扫描,计算缺血区的DWI异常信号相对面积(rSD)、相对表观扩散系数(rADC)、PWI异常信号相对面积(rSP)、相对平均通过时间(rMTT),将所测值进行比较。对缺血区脑组织进行病理观察。结果实验各组在T1WI、T2WI像上均未见异常信号。A组的DWI和PWI亦未见异常信号。在DWI像上,B、C、B1、B2、C2、C1组在右侧基底节区高信号的范围由小扩大,随后逐渐缩小。在PWI像上,B、C组在右侧基底节区出现明显低灌注信号,在B1、C2组则出现高灌注信号,C1组呈现稍低灌注信号,B2组的信号基本正常。在B、C2组间存在MTT/DWI异常信号不匹配区。病理观察:DWI异常信号区及MTT/DWI异常信号不匹配区均可见细胞器肿胀,提示为半暗带,B1、C1组可见轻度血管源性水肿,B2、C2组未见明显病理改变。结论细胞内水肿是半暗带的病理改变之一,在早期脑梗塞DWI高信号仍提示为半暗带组织,再灌注早期可出现血管源性水肿,再灌注越早脑细胞越容易恢复正常。     

动脉内溶栓治疗椎基底动脉系急性脑梗塞的初步临床应用

目的: 经动脉内溶栓治疗5例椎基底动脉系急性脑梗塞患者,观察其临床疗效.材料和方法: 5例患者发病均在12小时内; 治疗前均行CT检查,CT示没有出血或与神经功能缺损对应的低密度区.经右股动脉入路,全脑血管造影确认病变类型,选择性将微导管送入患侧椎基底动脉内病变处,在30min左右注入50～75万单位尿激酶.治疗1小时后行脑血管造影复查.结果: 5例患者中有4例血管再通.Glasgow评分,治疗前为6.20±1.30分,治疗后24小时9.40±4.56分;3例存活患者治疗前7.0±1.0分,治疗后24小时12.33±3.06分.3个月预后良好者有3例(RS评分0～1分);2例死亡.结论:早期动脉内溶栓治疗急性脑梗塞有助于闭塞血管再通,有益于病情恢复.     

Application of contrast agents in the evaluation of stroke: Conventional MR and echo-planar MR imaging

The availability of new therapeutic interventions, including neuroprotective agents and endovascular thrombolysis, has given new hope to patients suffering an acute stroke. Early intervention remains a key factor in the effectiveness of these new and traditional treatments. More importantly, the capability to assess the viability and reversibility of the ischemic tissue became essential for better delineation and differentiation of infarcted versus ischemic tissue and patient management. Abnormal MR imaging (MRI) findings during acute stroke usually reflect the underlying pathophysiologic changes, which can be classified into three sequential stages: (a) hypoperfusion, (b) cellular dysfunction and (c) breakdown of the blood-brain barrier. The first stage is a kinetic phenomenon (not biologic) and, therefore, can be detected immediately. Contrast agents accentuate the abnormal flow kinetics and facilitate the early diagnosis of ischemia using either conventional MRI or newly developed echo-planar perfusion imaging (EPPI). The demonstration of abnormal arterial or parenchymal enhancement on conventional MRI during acute stroke provides the earliest sign of vascular occlusion/stenosis. EPPI, in contrast, provides information related to microcirculation (< 100 microns) and tissue reserve (cerebral blood volume) that cannot be obtained by conventional angiography and is directly related to the target end-organ. Further information obtained from both contrast MRI and EPPI may have a predictive value in the clinical outcome of acute stroke patients.