颈内动脉严重狭窄或闭塞的近、远段动脉血流动力学改变

[目的]探讨颈内动脉严重狭窄或闭塞的近、远段动脉的血流动力学改变.[方法]对121例经数字减影血管造影(DSA)或磁共振血管成像(MRI)证实的颈内动脉严重狭窄或闭塞患者(患者组)和80例无颈内动脉病变患者(对照组)行经颅多普勒超声(TCD)检测.[结果]近段的颈总动脉血流波形异常,表现为收缩峰尖窄、舒张期血流速明显减低或消失或舒张早期血流逆转;与对照组比较血流速度减低,搏动指数明显增高(P＜0.01).远段的大脑中动脉血流波形异常,表现为收缩峰圆钝、舒张期血流速增高;血流速度和搏动指数明显低于对照组(P＜0.01).[结论]TCD有助于了解颈内动脉严重狭窄或闭塞的近、远段动脉的血流动力学改变,为临床确定诊断和更深入研究缺血性脑血管病的发病机制提供重要的客观依据.     

Functional assessment of high-grade ICA stenosis with duplex ultrasound and transcranial Doppler

Background: Duplex ultrasound (DUS) has shown a >90% accuracy compared to angiography, concerning the degree of internal carotid artery (ICA) stenosis. However, uncertainty may occur in a severe stenosis, in which peak systolic velocity (PSV) may decrease owing to high flow resistance or high backward pressure. We investigated intracranial collateral flows using transcranial Doppler (TCD) to further evaluate the hemodynamic significance of high‐grade ICA stenosis. Methods: In this retrospective study, 320 consecutive symptomatic patients were examined. The degree of ICA stenosis and collateral capacity in the circle of Willis was investigated by DUS and TCD. In addition, magnetic resonance angiography (MRA) was added in a subgroup of 204 patients. The criterion for hemodynamic significant ICA stenosis was established collateral flow. Results: In 91% of all symptomatic vessels (291 vessels), an ICA stenosis of ≥70% was found. Established collateral flow always indicated precerebral carotid artery disease of ≥70%. Furthermore, in 11% of the whole study material, collateral reserve capacity was found despite high‐grade (≥70%) ICA stenosis. PSV in ICA <2·5 m s^?1 was combined with established collateral flow and MRA stenosis of ≥70% in 9% (19 arterial systems). In 4%, doubt existed concerning the degree of stenosis after DUS. Conclusion: Transcranial Doppler helps to determine whether an ICA stenosis is of hemodynamic significance and to assess collateral patterns. Established collateral blood flow will help to identify patients with ≥70% (ECST) carotid artery disease. TCD might be of value when flow velocity criteria combined with plaque assessment by DUS are inclusive. Other diagnostic methods may also be considered.     

低流量颈动脉海绵窦瘘的TCD特点分析1例 并文献复习

目的:探讨经颅多普勒超声(TCD)在低流量颈动脉海绵窦瘘(CCF)中的诊断意义。方法:通过TCD对1例经DSA确诊的低流量CCF患者的血流动力学进行检测和分析,并结合文献进行回顾性分析,比较其与高流量CCF血流动力学特征的不同,总结其特殊之处。结果:本例低流量CCF患者TCD表现为眼动脉血流速度增高,频谱颅内化。搜索既往报道的关于TCD检测CCF血流动力学特征的病例。高流量CCF的TCD主要表现为:患侧颈内动脉颅外段(瘘口近端)的血流速度明显增高,搏动指数(PI)降低,呈典型的高流低阻表现;患侧大脑中动脉、大脑前动脉流速降低;颈内动脉虹吸段流速明显增高,频谱紊乱,声频嘈杂,同时可出现涡流与紊流,并可探测到相对低平的波动性的静脉血流信号;眶上静脉血流反向,有搏动性且流速增高。低流量CCF的TCD主要表现为:各血流参数无明显差异,颅底各动脉流速、PI值及频谱形态正常且基本对称。结论:TCD对于低流量CCF具有较高的筛查和诊断价值。     

颈内动脉严重狭窄或闭塞后颈总动脉与颈内动脉虹吸段血流频谱的改变

目的：分析颈内动脉严重狭窄或闭塞（ＩＣＡＳＯ）后颈总动脉（ＣＣＡ）和颈内动脉虹吸段（ＳＩＰＨＡ）血流频谱的改变,提高经颅多普勒超声（ＴＣＤ）对ＩＣＡＳＯ的检出率和准确性。方法：ＩＣＡＳＯ患者１２０例,全部经颈部血管彩超检查证实,其中６２例经脑血管造影（ＤＳＡ）进一步确诊双侧病变３３例,单侧病变８７例,共有病变血管１５３条（狭窄９４条,闭塞５９条）。全部行ＴＣＤ检查。结果：（１）狭窄或闭塞侧颈总动脉     

经颅多普勒超声评估颈内动脉严重狭窄或闭塞患者的侧支循环代偿能力

目的探讨经颅多普勒超声（TCD）评估颈内动脉严重狭窄或闭塞患者的侧支循环代偿能力。方法对60例一侧颈内动脉严重狭窄或闭塞患者,根据临床上有无脑缺血和神经功能障碍体征,将患者分为症状性严重狭窄或闭塞组（44例）和无症状性严重狭窄或闭塞组（16例）。TCD柃测Willis环和眼动脉的侧支循环通路。结果TCD显示54例前交通动脉侧支开放,31例后交通动脉侧支开放,15例眼动脉侧支开放。3例症状性严重狭窄或闭塞患者未发现侧支循环。无症状性严重狭窄或闭塞患者的大脑中动脉平均血流速度高于症状性闭塞患者（P〈0．01）。结论TCD有助于了解颈内动脉系统动脉严重狭窄或闭塞患者的侧支循环代偿能力,为评估治疗效果和预后提供重要的客观依据。     

Cardioembolic stroke: Protective effect of a severe internal carotid artery stenosis in a patient with cardiac embolism

Cardioembolic stroke is generally caused by intracranial artery occlusion. Clots may be identified in the intracranial vessels by means of conventional neuroimaging in the acute phase. High‐resolution ultrasonography may show some features suggestive of cardiac emboli when occluding extracranial carotid arteries. We describe a patient with cardioembolic ischemic stroke in the right hemisphere in whom a left internal carotid artery stenosis paradoxically protected the ipsilateral hemisphere from distal intracranial embolism. The patient also presented multiple acute ischemic embolic lesions in the right middle cerebral artery territory and in the right occipital lobe, which was fed by the posterior cerebral artery, anomally originating from the right carotid siphon. Interestingly, the left internal carotid artery—which showed a severe preexisting stenosis—was occluded by the cardiac clot, whereas the right internal carotid artery only presented a moderate stenosis that had probably allowed the clots to pass. Therefore, the severe left internal carotid artery stenosis may have blocked the cardiac embolus, preventing it from reaching the ipsilateral hemisphere. © 2013 Wiley Periodicals, Inc. J Clin Ultrasound 41 :22–27, 2013     

Diagnosing carotid stenosis by Doppler sonography: state of the art.

OBJECTIVE: The goal of this review article is to present the state of the art in the clinical applications and technical performance and interpretation of carotid sonographic examinations. METHODS: Relevant publications regarding color and duplex Doppler sonography (CDDS) of the carotid arteries extracted from a computerized database (MEDLINE) and from references cited in these articles not appearing on the Internet were reviewed. RESULTS: The ability to quickly and efficiently identify stenosis in the carotid artery is an important goal for clinicians and vascular surgeons. Identification of potentially treatable carotid stenosis enables selection of appropriate candidates for endarterectomy or stent implantation. Advances in performance and interpretation of carotid sonographic studies over the last 20 years have been driven by technological improvements in gray scale and CDDS examinations and have made carotid sonography an important means to reach this goal. On the basis of CDDS, intima-media thickness measurements and plaque location and characterization on gray scale imaging, flow disturbance and areas of stenosis on color Doppler sonography, and flow velocities on spectral Doppler sonography are obtained. The degree of the diameter of a stenosis of the internal carotid artery is the main parameter used for therapeutic approaches. Advantages and limitations of the method are included. CONCLUSIONS: Carotid sonography is a unique imaging method for the investigation of carotid abnormalities. Noninvasive, accurate, and cost-effective, it provides morphologic and functional information. It is increasingly becoming the first and often the sole imaging study before endarterectomy, whereas costly and invasive procedures are reserved for special cases.     

Carotid sonography and transesophageal echocardiography in patients with ischemic stroke or transient ischemic attack in the territory of the carotid artery

PURPOSE: To assess the benefit of combining carotid sonography and transesophageal echocardiography (TEE) for the evaluation of patients with stroke or transient ischemic attack (TIA) in the territory of the carotid artery. METHODS: During a 2-year period in Turku University Hospital, consecutive in patients with stroke or TIA who were candidates for carotid endarterectomy and for oral anticoagulation were evaluated with carotid sonography for symptomatic moderate (50-69%) or severe (>or=70%) internal carotid artery (ICA) stenosis, and with TEE for potential cardiac sources of embolism. RESULTS: In 20% (40/197) of patients, a severe symptomatic ICA stenosis and/or a major risk factor for a cardiac source of embolism were found. In 56% (110/197) of patients, a moderate or severe symptomatic ICA stenosis and/or a potential cardiac source of embolism were found, whereas 11% (21/197) of patients had both a moderate or severe symptomatic ICA stenosis and a potential cardiac source of embolism. CONCLUSIONS: This study suggests that the presence of a moderate or severe symptomatic ICA stenosis does not exclude the presence of a potential cardiac source of embolism and vice versa. Carotid sonography and TEE complement each other and are valuable diagnostic tools that should be recommended in patients with ischemic stroke or TIA in the territory of the carotid artery when they are candidates for carotid endarterectomy and for oral anticoagulation.     

Detection of stenoses in the anterior circulation using frequency-based transcranial color-coded sonography

Atherosclerotic stenoses of the intracranial vessels are less frequent than those of the extracranial vessels, but they are associated with a considerable annual stroke rate. The aim of the present study was to investigate the usefulness of frequency-based transcranial color-coded sonography (TCCS), transcranial Doppler sonography (TCD) and digital subtraction angiography (DSA) in patients with middle cerebral artery (MCA) and intracranial internal carotid artery (ICA) stenosis. Forty patients presenting with 48 intracranial stenoses of the anterior circulation were involved in the study. The stenoses were detected in the neurovascular laboratory during routine TCD examinations. All patients underwent an additional frequency-based TCCS examination. Both the axial and coronal planes were obtained to allow the exact localization of MCA stenosis and differentiation from intracranial ICA stenosis. Angle-corrected flow velocity measurements were performed if straight vessel compartments were 20 mm or more in length. A total of 18 stenoses (44%) were investigated additionally with DSA. According to the investigation with TCD, 20 (42%) stenoses were low-grade, 12 (25%) were moderate, and the remaining 16 (33%) were severe. Angle-corrected flow velocity measurements obtained with the integrated pulse-wave Doppler device of the TCCS machine were highly correlated (0.912, p < 0.001) with those obtained with TCD. TCCS achieved a reliable differentiation of MCA main stem stenosis vs. intracranial ICA stenosis in 7 patients and vs. MCA branch stenosis in 4 patients, but TCD failed in these two subgroups. The agreement between DSA and TCCS to evaluate semiquantitatively 18 intracranial stenoses resulted in a weighted-kappa value of 0.764. The major clinically relevant advantages of TCCS over TCD in MCA stenosis are its ability to differentiate MCA trunk stenosis from terminal ICA or MCA branch stenosis reliably and to perform angle-corrected flow velocity measurements.     

Role of sonography in the evaluation of carotid artery stents

PURPOSE: To study the ability and accuracy of sonography to visualize carotid artery stents and assess criteria for carotid artery stent stenosis. METHODS: Duplex Doppler sonographic examinations were performed on 143 patients in whom 158 carotid artery stents were placed. Follow-up sonography to evaluate 24 of these stents within 24 h of stent placement was compared with post-procedure angiography. Another 23 stents were evaluated with sonography and with follow-up angiography more than 24 h after the procedure. The remainder of the 111 stents were evaluated exclusively with sonography after stent placement. Sonography was used to evaluate stent visibility, stent-media separation, and degree of stent stenosis. RESULTS: Wallstents were the best-visualized stents and Acculink the worst, but the differences were not statistically significant. Of 4 patients with stent-media separation >3 mm, 2 (50%) developed stenosis (40%-59%) at 6 and 12 months from stent placement. The other 2 stents with stent-media separation had not developed stenosis at 6 months' follow-up. A comparison of angiography and sonography performed on the date of stent placement revealed 19 true-negative sonography studies, 4 false-positive studies, 1 true-positive study, and no false-negative studies. A comparison of follow-up angiograms performed more than 24 h after the procedure with follow-up sonography revealed 17 true-negative studies, 1 false-positive study, 5 true-positive studies, and no false-negative studies. CONCLUSIONS: Sonography allows accurate evaluation of stent placement within the vessel and visualization of stent-media distance. Stent-media separation may be an early detection sign for stent stenosis development. Velocity criteria developed for non-stented vessels, when applied to stented vessels, correlate well with angiographic findings. Doppler velocity measurements when compared with visible stent assessment may reduce false-positives.     

大脑中动脉狭窄对颅外段颈内动脉血流动力学的影响

目的研究不同程度的大脑中动脉(MCA)狭窄对颅外段颈内动脉(ICA)血流动力学的影响。方法本研究纳入单侧MCA狭窄或闭塞的患者98例,根据狭窄程度分为对照组(MCA中度狭窄,N=46)与观察组(MCA重度狭窄或闭塞,N=52),使用彩色多普勒超声测量两侧颅外段ICA的收缩期峰值流速(Vp)、舒张末期流速(Vd)、平均流速(Vm)、搏动指数(PI)。结果与对照组相比,观察组患侧ICA的Vp、Vm及Vd较健侧明显降低(41.17cm/s vs48.76cm/s,21.22cm/s vs 28.23cm/s,11.82cm/s vs 17.92cm/s,P均<0.05),而患侧PI值明显高于健侧(1.43vs1.20,P<0.01),PI值差值显著增大(0.28vs 0.06,P<0.05)。结论颅外段颈内动脉血流动力学的改变在一定程度上提示了大脑中动脉狭窄的严重程度,能够有效提高TCD对于大脑中动脉狭窄或闭塞进行诊断的准确性。     

Three-dimensional power Doppler sonography in screening for carotid artery disease

PURPOSE: Color Doppler sonography has gained considerable recognition as a noninvasive method to detect carotid artery disease and to assess the degree of carotid artery stenosis. However, results are highly operator-dependent and cannot be presented as survey images. The purpose of this study was to evaluate real-time 3-dimensional (3D) power Doppler sonography as a method for screening for atherosclerosis in the carotid arteries. METHODS: We prospectively screened 75 patients for carotid artery disease using both conventional color Doppler sonography and 3D power Doppler sonography, and the results from the 2 modalities were compared. A total of 150 common carotid arteries, 150 internal carotid arteries, and 150 external carotid arteries were examined utilizing a 7.5-MHz linear-array transducer combined with tissue harmonic imaging. RESULTS: Color Doppler sonography detected 297 normal or atherosclerotic arteries without stenosis, 57 arteries with mild (1-49%) stenosis, 41 with moderate (50-69%) stenosis, 32 with severe (70-99%) stenosis, and 9 with occlusions. The degree of stenosis determined by color Doppler sonography correlated with that determined by 3D power Doppler sonography (r = 0.982-0.998). Moreover, there was a good correlation between the measurements for both the length of the lesion and its distance from the bulb as determined by the 3D volume surveys and by color Doppler sonography (r = 0.986). The interobserver variability rate was 3.7% +/- 0.5%. Generally, the acquisition and reconstruction of the 3D data took less than 5 minutes. CONCLUSIONS: 3D power Doppler sonography is easy to perform and is an accurate method in screening for atherosclerotic lesions of the carotid arteries. Moreover, it provides excellent 3D volume surveys that may be helpful in the planning of surgical treatment.     

Transcranial Doppler evaluation of middle cerebral artery stenosis

Symptomatic stenoses of the middle cerebral artery (MCA) are not uncommon, although Corston observed the occurrence of stroke in 24% of patients with MCA stenoses during a 6-year follow-up study. We tried to use transcranial Doppler (TCD) sonography for the detection and evaluation of MCA stenoses. Intra-arterial angiography demonstrated 16 MCA stenoses of more than 30% diameter reduction in 15 patients (14 atheromatous stenoses, 2 dysplasias). Severe associated lesions were present in 2 cases (more than 75% internal carotid artery stenosis). These 15 patients with MCA stenosis were examined with TCD in a blind study. A Doppler signal from the MCA was obtained through the temporal bone and was recognized on the result of common carotid artery compression test. We ascertained MCA stenosis when TCD demonstrated 1) segmental flow acceleration with peak systolic frequency of more than 3 KHz with or without high energy low frequency direct or reverse components; or 2) segmental increase in systolic peak frequency of more than 20%. Using these criteria, we confirmed through TCD the presence of MCA stenosis in nine out of 12 cases with diameter reduction of at least 50%, and one among four cases with less than 50% diameter reduction. Although our results are consistent with Aaslid and von Reutern's figures, methodological problems and diagnostic criteria have to be improved. Nevertheless, TCD seems to be a useful tool for the detection of stenosis with at least 50% diameter reduction, where it proved to offer a 75% sensitivity. Further studies are necessary to improve sensitivity and specificity.     

经颅多普勒超声量化诊断白兔颈内动脉狭窄的研究

目的探讨血流信号的最大Lyapunov指数在诊断白兔颈内动脉不同程度狭窄中的价值,以期达到利用经颅多普勒超声(TCD)量化诊断血管狭窄的目的.方法通过TCD诊断仪及自行设计的多普勒超声信号采集系统 ,提取白兔颈内动脉正常时及不同程度狭窄时血流信号,并使用小波包分析去噪,得到血流信号的时间序列数据,计算其最大Lyapunov指数,对白兔颈内动脉血流情况的动态活动状态进行对比研究.结果白兔颈内动脉正常时,血流信号的最大Lyapunov指数均为负值,血液流动呈非混沌状态;白兔颈内动脉狭窄时,血流信号的最大Lyapunov指数均为正值,血液流动呈混沌状态,且值越大,狭窄程度越高.结论可利用Lyapunov指数无创诊断白兔颈内动脉狭窄疾病.     

Transcranial Doppler in stroke.

Transcranial Doppler (TCD) has been extensively used in various clinical situations, and in the last two decades has established its role in the management of patients with cerebrovascular disease and stroke. Based on the Doppler principle, it uses ultrasound waves to insonate the blood vessels supplying the brain to obtain hemodynamic information. Anatomic abnormalities of vascular occlusion, stenosis and spasm can be indirectly derived. Intracranial arterial disease is an important cause of ischemic stroke and TCD can detect these with a fair amount of sensitivity and specificity. In hemodynamically significant extracranial internal carotid artery disease, TCD shows significant abnormalities in flow dynamics of the anterior circulation and abnormalities of cerebral vasomotor reactivity. A distinct advantage of TCD is the ability to monitor blood flow in a blood vessel over prolonged periods of time, which has shown microembolic signals in acute ischemic stroke, carotid artery disease, atrial fibrillation and during angiography. In acute ischemic stroke, TCD can be used to elucidate stroke mechanisms, plan and monitor treatment, and determine prognosis. In an era when stroke is increasingly being recognized as an emergency requiring immediate treatment, TCD may be capable of providing rapid information about the hemodynamic status of the cerebral circulation, within the time frame of the rather small 'therapeutic window'. TCD predicts vasospasm with a high degree of sensitivity and specificity and because of its non-invasive nature repeated assessments can be performed after subarachnoid hemorrhage.     

Visualization of bilateral carotid cavernous sinus fistulas with duplex sonography

Duplex sonography used as a primary diagnostic tool in the case of a 17-year-old boy with a traumatic head injury revealed bilateral carotid cavernous sinus fistulas, with bilateral dilated venous convolutions next to the carotid siphon and dilated superior ophthalmic veins. A bilateral craniectomy allowed visualization of the entire circle of Willis together with the dilated cavernous sinuses. Doppler spectral analysis of blood flow in the arterialized superior ophthalmic veins revealed an arterialized venous pattern with retrograde and increased blood flow. The same blood flow profile was found in the venous cavernous sinuses. These findings were confirmed by digital subtraction angiography. We planned to perform embolization of the patient's fistulas, but intracranial and subarachnoid hemorrhaging developed, and the patient died the day before the procedure was to have been performed. The entire pathologic state of carotid cavernous sinus fistulas, from their origin beside the carotid siphon to the superior ophthalmic veins, can be visualized with duplex sonography, particularly when patients have undergone craniectomy. We believe that patients with frontal or basilar skull fracture should undergo duplex sonographic examination to detect carotid cavernous sinus fistulas.     

彩色多普勒超声与经颅多普勒超声联合应用对颈内动脉狭窄的诊断价值

目的 探讨彩色多普勒超声与经颅多普勒超声(TCD)联合应用在诊断颈内动脉(ICA)狭窄(狭窄＞50%)的临床价值.方法 对273例缺血性脑血管病患者行CDFI和TCD常规检查,其中32例经脑血管造影(DSA)确定为ICA单、双侧狭窄或闭塞.以DSA为标准,计算CDFI、TCD 及二者联合检查结果的符合率.结果 CDFI诊断符合率为83%(53/64),TCD为78%(50/64),二者联合应用符合率为94%(60/64).结论 CDFI与TCD的联合应用能明显提高对I CA狭窄诊断的准确性.     

Color duplex sonography of occlusion of the common carotid artery with reversed flow in the extracranial internal carotid artery

In a small percentage of cases with an occluded common carotid artery (CCA), the patency of the arteries beyond the carotid bulb is preserved. Color duplex sonography is useful for assessing blood flow in these vessels. We present a case of retrograde flow in an internal carotid artery (ICA) with an occluded ipsilateral CCA identified using color duplex sonography in a 70-year-old man with diabetes and known atherosclerotic disease. Color duplex sonography revealed that the right CCA was totally occluded near its origin and that flow was re-established at the bulb. Flow in the right ICA was directed cephalad, with a low-frequency, damped waveform; flow in the right external carotid artery (ECA) was bidirectional, with increased reversed diastolic flow. Extensive atherosclerotic lesions were also found in the left side. Endarterectomy of the left carotid bifurcation was performed. Follow-up color duplex sonography 3 months later revealed a small increase of stenosis in the left CCA and mild stenosis in the left ICA. The right CCA remained occluded, but reversed flow with a high-resistance flow pattern was seen in the ipsilateral ICA that supplied the ECA, which had cephalad-directed flow.     

颈内动脉狭窄或闭塞经颅多普勒超声、脑血流灌注及磁共振血管造影对比研究

目的 应用经颅多普勒超声（TCD）、脑血流灌注（SPECT）及磁共振血管造影（MRA）检查，探讨对颈内动脉（ICA）狭窄或闭塞的早期诊断价值。方法42例ICA狭窄或闭塞患者经TCD、SPECT及MRA检查，与DSA进行对比分析。结果TCD、MRA对ICA狭窄或闭塞检测结果与DSA比较，符合率分别为90、8％、80．5％，对侧枝循环开放判断，符合率分别为92．2％、47、6%。TCD检测患侧和健侧MCA的Vs、PI值存在显著性差异（P〈0.001）。SPECT阳性区与MCA的Vm、PI相关系数分别为-0、672，-0．658，有良好的相关性。结论TCD、SPECT及MRA检查联合应用，从不同角度为ICA狭窄或闭塞的早期诊断提供了较全面的客观依据，是可靠的综合性检查方法。     

TCD在诊断一侧颈内动脉闭塞或不全闭塞中的应用

本文报告５例由经颅多普勒（ＴＣＤ）诊断为一侧颈内动脉（ＩＣＡ）闭塞或不全闭塞，其中１例为病，４例经ＭＲＩ血管造影（ＭＲＡ）证实，另一例经高频双功Ｂ超证实，结合文献探讨了ＴＣＤ诊断一侧ＩＣＡ闭塞的要点，即病变侧大脑中动脉（ＭＣＡ）的收缩峰流速减低，波形减弱，ＰＩ及ＰＴＩ值的减低是诊断本病的敏感指标，而侧枝循环的形成是诊断的重要条件，压颈总动脉（ＣＣＡ）试验则对于鉴别闭塞或不全闭塞、代偿血流来源以及ＩＣＡ病变部位的粗略判断都是有益的。作者还依据侧枝循环出现的类型，将本病的ＴＣＤ诊断分为４型：前交通动脉型、后交通动脉型、眼动脉反流型及混合型，文章最后认为ＴＣＤ是诊断本病的一种准确性高、经济易行的无创伤性检查。