小覆盖范围CT灌注成像对急性大脑中动脉供血区脑卒中的评价

目的探讨用较小扫描范围的CT灌注成像检查对急性大脑中动脉供血区脑卒中的诊断效能。方法回顾性分析急诊接治的22例连续脑卒中患者,均在发病1～24 h行CT平扫和CT灌注成像检查。应用Z轴80 mm范围灌注参数,得出脑梗死核心区、半暗带的体积。计算半暗带/(半暗带+梗死核心区)比值。根据Z轴长度80 mm的CT灌注结果的治疗方案为基线,将较小覆盖范围获得的结果制定的治疗方案,计算较小范围灌注评价治疗的敏感性与特异性。结果当半暗带/(半暗带+梗死核心区)比值>0.2时,较小覆盖范围应用40 mm范围的CT灌注检查,可以准确评价梗死核心区与半暗带。结论大脑中动脉供血区脑卒中患者,当半暗带/(半暗带+梗死核心区)>0.2时,40 mm的Z轴覆盖范围CT灌注成像能够对病灶的范围与性质做出诊断。     

急性卒中缺血半暗带的CT灌注成像

CT灌注成像能准确和及时地提供卒中后脑组织血流动力学参数,并且与当前公认的脑血流动力学测量手段——氙-CT、功能磁共振成像和正电子发射体层摄影等测得的参数有很好的相关性。因此,CT灌注成像在判断卒中后缺血半暗带研究中的应用日益广泛。     

CT灌注成像在急性脑梗死患者溶栓疗效评价中的应用

目的探讨CT灌注成像在急性脑梗死溶栓疗效评价中的应用价值。方法选择发病6 h内的急性脑梗死患者35例,于溶栓治疗前后行颅脑CT灌注成像检查,观察病变区相对脑血流量(rCBF)、相对脑血容量(rCBV)、相对平均通过时间(rMTT)的变化,于溶栓治疗前后进行神经功能缺损评分。结果急性脑梗死发病6 h内CT灌注成像均发现脑灌注异常的缺血半暗带。溶栓后患者缺血半暗带区rCBF显著增加(P<0.01)、rMTT减小(P<0.01)。溶栓后患者神经功能缺损评分显著降低(P<0.05)。结论急性脑梗死患者溶栓后缺血半暗带区脑灌注异常明显改善,神经功能缺损情况改善。CT灌注成像在急性脑梗死溶栓疗效评价中具有一定的应用价值。     

功能磁共振成像技术在急性缺血性卒中的临床应用进展

功能磁共振成像技术、弥散加权成像和灌注加权成像能超早期明确急性缺血性卒中的诊断、判断缺血半暗带的大小及动态观察病情进展，为临床溶栓治疗提供了直观的影像学依据。     

CT灌注和CT血管成像在缺血性卒中早期诊断中的作用

目的探讨CT灌注和CT血管成像对缺血性卒中患者早期诊断缺血半暗带和缺血部位的作用。方法回顾20例缺血性卒中患者,于发病24h之内均行CT灌注检查,8例行CT血管成像,获取梗死侧与正常侧脑血流量(CBF)、脑血容量(CBV)和平均通过时间(MTT)参数图和脑血管影像,将上述结果进行统计学分析。结果本组急性脑梗死16例,4例TIA患者,经CT灌注检查梗死侧缺血中心区的CBV、CBF为(2.1±0.6)ml/100g、(22.8±26.2)ml.100g-1.min-1,较正常侧明显减少,MTT为(7.6±3.2)s,与正常对照区相比差异有显著性(P<0.01)。15例可见缺血半暗带存在,CT血管成像8例,与CT灌注判断的梗塞血管基本相符。结论CT灌注成像能快速、准确反映缺血半暗带的部位、范围,结合CT血管成像,可以准确判断栓塞血管部位,对早期诊断缺血性卒中和抓住动脉溶栓时机有较好的指导作用。     

缺血半暗带的检测MRI还是PET?

缺血半暗带概念的提出为缺血性卒中的超早期治疗明确了方向,但在如何迅速准确获得半暗带信息,即如何选择半暗带的测量方法时,是采用弥散加权成像/灌注加权成像不匹配,还是采用正电子发射体层摄影尚存争议。文章就此问题做了回顾。     

超早期成像在缺血性卒中治疗处理中的作用

缺血性卒中始终是残疾或死亡的一个重要原因。目前急性缺血性卒中的治疗选择包括静脉溶栓或血管内治疗,其目的是使近端动脉闭塞再通。迅速确定卒中的可能病因或机制有益于紧急治疗方案的选择。超早期成像在显示卒中病理生理学和制订合理的卒中治疗方案中起着必不可少的作用。缺血性卒中的超早期影像学检查可证实近端血管闭塞、代偿性侧支循环、残存或侧支组织灌注,区别缺血核心区与缺血半暗带。缺血区域,包括核心区和半暗带(多重模式CT或MRI显示的各种不匹配模式)的鉴别有可能优化目前的脑缺血治疗策略。超早期影像学检查的诊断和治疗作用已使之成为缺血性卒中评价和处理的一个关键组成部分。     

医学简讯

超早期CT平扫和灌注CT成像识别半暗带与梗死核心CT平扫(noncontrast CT,NCCT)广泛用于急性卒中的评价,其早期缺血改变(early ischemic change,EIC)的范围与临床转归不良有关,但能否用作静脉溶栓治疗的选择标准仍然存在争议。NCCT最常见的EIC类型是脑实质低密度(parenchymal hypoattenuation,PH),它很可能预示着脑组织严重低灌注和不可逆性缺血性损害;不伴PH的局部脑组织肿胀较为少见,其预后意义不清,但最近有研究提示这种单纯性局部肿胀(isolated focal swelling,IFS)可能代表着缺血半暗带或血流量减少的组织。为了确定PH和IF…     

急性脑梗死患者影像学缺血半暗带的临床评价策略

缺血性卒中再灌注治疗近年来取得了重大进展,治疗前快速精准评估缺血半暗带是临床诊治的紧迫需求.目前,影像学是显示缺血半暗带最直观、有效的方法,该方法通过利用组织窗筛选出能够从再灌注治疗中获益的患者,并预估风险和预后.作者介绍了急性脑梗死影像学缺血半暗带的临床评估模式,并对不同发病时间、拟进行再灌注治疗患者的缺血半暗带评价...     

灌注和弥散加权磁共振成像在超早期脑梗死中的应用

灌注和弥散加权磁共振成像在脑梗死超早期有着潜在的应用价值。近年来的研究认为 ,利用灌注和弥散成像不一致区代表缺血半暗带过于简化 ,而超早期MR灌注参数的改变结合弥散成像可更准确地判断缺血半暗带 ,对超早期指导溶栓治疗和预评价临床预后有重要意义。     

FUNCTIONAL NEUROIMAGING IN ACUTE STROKE

To the present day, the first and most widespread diagnostic approach in the assessment of acute stroke remains CT scan. Its sensitivity is very high (nearly 100%) in detecting intracerebral hemorrhage in the acute period, but its capability of revealing ischemic injury in the very first hours from symptom onset is relatively poor. Since the efficacy of thrombolytic treatment in acute stroke has been suggested by the ECASS and NINDS rt-PA trials, functional neuroimaging able to distinguish potentially salvageable tissue from irreversibly injured areas has acquired primary importance. The possibility to correctly identify the tissue of the ischemic penumbra within the first hours from symptom onset is essential for correct patient selection for thrombolitic treatment. Different imaging strategies are available for the definition of perfusion deficits within the acute time window; among these are positron emission tomography (PET), single photon emission computed tomography (SPECT), Xenon CT (XeCT), dynamic CT perfusion imaging (CTP), diffusion weighted magnetic resonance imaging (DW-MRI), and perfusion weighted magnetic resonance imaging (PW-MRI). Though each technique has its advantages and limitations to present day functional MRI remains the most widespread imaging technique in the assessment of acute stroke being more accessible than both SPECT and PET, and capable of giving information on both perfusion and tissue functional status in a single imaging session.

In this paper we discuss the role of functional neuroimaging in acute stroke.     

Functional neuroimaging in acute stroke

To the present day, the first and most widespread diagnostic approach in the assessment of acute stroke remains CT scan. Its sensitivity is very high (nearly 100%) in detecting intracerebral hemorrhage in the acute period, but its capability of revealing ischemic injury in the very first hours from symptom onset is relatively poor. Since the efficacy of thrombolytic treatment in acute stroke has been suggested by the ECASS and NINDS rt-PA trials, functional neuroimaging able to distinguish potentially salvageable tissue from irreversibly injured areas has acquired primary importance. The possibility to correctly identify the tissue of the ischemic penumbra within the first hours from symptom onset is essential for correct patient selection for thrombolitic treatment. Different imaging strategies are available for the definition of perfusion deficits within the acute time window; among these are positron emission tomography (PET), single photon emission computed tomography (SPECT), Xenon CT (XeCT), dynamic CT perfusion imaging (CTP), diffusion weighted magnetic resonance imaging (DW-MRI), and perfusion weighted magnetic resonance imaging (PW-MRI). Though each technique has its advantages and limitations to present day functional MRI remains the most widespread imaging technique in the assessment of acute stroke being more accessible than both SPECT and PET, and capable of giving information on both perfusion and tissue functional status in a single imaging session. In this paper we discuss the role of functional neuroimaging in acute stroke.     

Advanced Neuroimaging to Guide Acute Stroke Therapy

Traditionally non-contrast CT has been considered the first choice imaging modality for acute stroke. Acute ischemic stroke patients presenting to the hospital within 3-hours from symptom onset and without any visible hemorrhages or large lesions on CT images are considered optimum reperfusion therapy candidates. However, non-contrast CT alone has been unable to identify best reperfusion therapy candidates outside this window. New advanced imaging techniques are now being used successfully for this purpose. Non-invasive CT or MR angiography images can be obtained during initial imaging evaluation for identification and characterization of vascular lesions, including occlusions, aneurysms, and malformations. Either CT-based perfusion imaging or MRI-based diffusion and perfusion imaging performed immediately upon arrival of a patient to the hospital helps estimate the extent of fixed core and penumbra in ischemic lesions. Patients having occlusive lesions with small fixed cores and large penumbra are preferred reperfusion therapy candidates.     

CT灌注成像在缺血性脑血管病中的临床应用

CT灌注成像(CTperfusion,cIP)为缺血性脑血管病的诊断提供了一种新的方法,评价指标包括脑血流量、脑血容量、达峰时间和平均通过时间等.这些用于评价脑血流灌注的半定量指标对于指导选择最佳治疗方案和观察疗效具有非常重要的意义.CIP在缺血性脑血管病中的主要应用范围包括急性缺血性卒中半睛带和梗死灶的判定,以及与其他手段结合预测出血性转化和选择溶栓候选病例.此外,CIP还用于慢性脑缺血患者脑血管储备功能的评价和蛛网膜下腔出血患者脑血管痉挛的诊断和疗效评价等.     

急性卒中患者的缺血半暗带评价

卒中的发病率、致残率和死亡率均很高.缺血半暗带评价对于指导临床治疗和评估预后具有非常重要的意义.目前,可采用MRI、CT、正电子发射体层摄影和单光子发射计算机体层摄影等影像学技术评价缺血半暗带.     

CT灌注成像在缺血性脑血管病中的临床应用

CT灌注成像(CTperfusion,cIP)为缺血性脑血管病的诊断提供了一种新的方法,评价指标包括脑血流量、脑血容量、达峰时间和平均通过时间等.这些用于评价脑血流灌注的半定量指标对于指导选择最佳治疗方案和观察疗效具有非常重要的意义.CIP在缺血性脑血管病中的主要应用范围包括急性缺血性卒中半睛带和梗死灶的判定,以及与其他手段结合预测出血性转化和选择溶栓候选病例.此外,CIP还用于慢性脑缺血患者脑血管储备功能的评价和蛛网膜下腔出血患者脑血管痉挛的诊断和疗效评价等.     

Emergency Management of Acute Ischemic Stroke

With the advent of new therapeutic options for acute ischemic stroke, expeditious evaluation of patients with suspected stroke has become imperative. Goals of the initial evaluation are to determine the time of symptom onset, severity of the neurologic deficit, and to exclude intracranial hemorrhage and other mimics of acute ischemic stroke. CT and MRI perfusion studies may demonstrate the presence of an ischemic penumbra and aid in identification of patients who may benefit from thrombolysis. Intravenous recombinant tissue plasminogen activator (IV rtPA) remains the gold standard for acute ischemic stroke treatment, and the therapeutic time window recently has been extended to 4.5 h in certain patients. Catheter-based intra-arterial thrombolysis is being used increasingly as “rescue therapy” after IV rtPA and as primary therapy in select patients who are ineligible for intravenous therapy. Trials investigating the efficacy and safety of intra-arterial therapy are ongoing.     

急诊多参数CT用于预测急性脑梗死的最终梗死体积

目的探讨常规CT、CT血管造影(CTA)和CT灌注(PCT)等多参数CT预测急性脑梗死患者最终脑梗死体积的价值。方法回顾性分析107例急性前循环脑梗死患者的临床资料。利用多参数CT评估脑梗死体积、缺血半暗带体积及血管再通情况,测量3⁶个月的最终脑梗死体积。进行3次多因素线性回归分析,判定影像参数与临床预后的相关性。结果 107例患者中,常规CT提示大脑中动脉高密度征阳性71例,早期脑卒中CT评分(8.0±1.7)分;CT血管造影显示平均颈动脉狭窄程度(36.3±43.8)%,PCT计算脑梗死体积(36.3±43.8)ml,半暗带体积(40.5±26.2)ml,总缺血体积为(69.2±26.1)ml。3次多因素线性回归模型能预测最终脑梗死体积(R1=0.542,P1=0.009;R2=0.494,P2=0.004;R3=0.494,P3=0.004)。血管再通时PCT中脑梗死和缺血半暗带、颈内动脉狭窄程度和侧支循环评分是最终脑梗死体积的独立预测因素(P=0.000,P=0.000,P=0.004)。结论脑卒中超早期的影像评估应包括有灌注信息的多参数CT,以尽早获取血管再通及半暗带体积,指导临床治疗。     

ISCHAEMIC PENUMBRA: HIGHLIGHTS

The ischaemic penumbra was described for the first time in the late 1970s as a ring of hypoperfused zone surrounding the region of complete infarction. The penumbral zone is a functionally silent tissue which is able to regain its function if promptly reperfused. This implies that the ischaemic penumbra is not a static but a “dynamic” and “time-dependent” concept. In this paper we describe the role of neuroimmaging tecniques such as single photon emission tomography (SPET), positron emission tomography (PET), and diffusion-weighted and perfusion-weighted magnetic resonance imaging (DWI and PWI) in the study of ischaemic penumbra. These functional imaging techniques have the advantage of giving “in vivo” quantitative estimate of cerebral blood flow (CBF) as well as information on how the ischaemic tissue metabolic changes develop. It follows that, as therapeutic options for treating acute stroke evolve, neuroimaging strategies are assuming an increasingly important role in the initial evaluation and management of the acute ischaemic patient. In this regard, a wide range of therapeutic approaches have been investigated for either ameliorating the perfusion, or interfering with the pathobiochemical cascade leading to ischaemic neuronal damage, or improving endogenous neuroprotection pathways

The “time windows” required for these treatments to be effective varies being rather short for reperfusion and longer for neuroprotection. Salvaging more penumbra would enhance recovery and thereby allow the most appropriate candidate for therapeutic trials to be selected.