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.     

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.     

经颅多普勒对颅内动脉狭窄诊断的临床应用

目的：探讨颅内动脉狭窄经颅多普勒（TCD）检测特点,筛选对于诊断有价值的检测指标。方法：TCD检测86例缺血性脑血管病（ICVD）患者收缩期峰流速（Vp）、舒张末期流速（Vd）、平均血流速度（Vm）、阻力指数（RI）及脉动指数（PI）,着重对血管反应性进行观察。结果：86例患者颅内动脉狭窄为中轻度31例,中度17例,重度12例,大脑中动脉闭塞5例,共计65例为颅内动脉狭窄组（狭窄组）,无动脉狭窄21例为无狭窄组。狭窄组患者大脑中及前动脉血管反应性明显低于非狭窄组（P〈0.05）;轻、中度患者Vp、Vd、Vm、RI及PI与非狭窄组比较无明显改变,重度患者则可见Vp低于非狭窄组（P〈0.01）。结论：TCD是诊断颅内动脉狭窄的有效手段;与MRI及血管造影取长补短,可提高颅内动脉狭窄的诊断率,并可作为ICVD高发人群筛选工具。血管反应性是诊断颅内动脉狭窄的敏感指标,血流速度只能起参考作用,不能作为颅内动脉狭窄的诊断依据及分级标准。     

Patterns of coronary arterial lesion calcification by a novel, cross-sectional CT angiographic assessment

To investigate the patterns and diagnostic implications of coronary arterial lesion calcification by CT angiography (CTA) using a novel, cross-sectional grading method, we studied 371 patients enrolled in the CorE-64 study who underwent CTA and invasive angiography for detecting coronary artery stenoses by quantitative coronary angiography (QCA). The number of quadrants involving calcium on a cross-sectional view for ≥30 and ≥50 % lesions in 4,511 arterial segments was assessed by CTA according to: noncalcified, mild (one-quadrant), moderate (two-quadrant), severe (three-quadrant) and very severe (four-quadrant calcium). Area under the receiver operating characteristic curve (AUC) were used to evaluate CTA diagnostic accuracy and agreement versus. QCA for plaque types. Only 4 % of ≥50 % stenoses by QCA were very severely calcified while 43 % were noncalcified. AUC for CTA to detect ≥50 % stenoses by QCA for non-calcified, mildly, moderately, severely, and very severely calcified plaques were 0.90, 0.88, 0.83, 0.76 and 0.89, respectively (P < 0.05). In 198 lesions with severe calcification, the presence or absence of a visible residual lumen by CTA was associated with ≥50 % stenosis by QCA in 20.3 and 76.9 %, respectively. Kappa was 0.93 for interobserver variability in evaluating plaque calcification. We conclude that calcification of individual coronary artery lesions can be reliably graded using CTA. Most ≥50 % coronary artery stenoses are not or only mildly calcified. If no residual lumen is seen on CTA, calcified lesions are predictive of ≥50 % stenoses and vice versa. CTA diagnostic accuracy for detecting ≥50 % stenoses is reduced in lesions with more than mild calcification due to lower specificity.     

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.     

支架成形术对大脑中动脉狭窄患者短期血液动力学的影响

目的 应用经颅多普勒超声(TCD)观察症状性大脑中动脉(MCA)狭窄患者支架成形术后短期内的血液动力学变化.方法 对标准的抗血小板治疗期间仍有症状发作的29例MCA中重度狭窄患者31条MCA实施支架成形术,应用TCD系统评价术前、术后1 h及3 d内的MCA狭窄段及狭窄下游段的血液动力学变化.结果 血管造影显示支架成形术后MCA的残余狭窄率均＜20%.与术前相比,术后1h及3 d的收缩期峰值血流速度(PSV)明显下降[(162±38)cm/s对(273±77)cm/s,P＜0.01;(168±45)cm/s对(273±77)cm/s,P＜0.01],术后1 h及3 d的PSV差异无统计学意义(P＞0.05).3例患者(3条动脉)术后第3 d TCD发现狭窄段又出现了狭窄样频谱,CT扫描显示2例颅内出血,1例无异常;至少28.6%(8/28)的患者狭窄下游段出现了PSV的成倍增加.对侧MCA支架成形术前后的PSV差异无统计学意义(P＞0.05).结论 支架成形术可明显改善MCA中重度狭窄患者狭窄段及狭窄下游段的血液动力学异常,但存在较高的过度灌注风险.     

短暂性脑缺血发作的脑血管造影分析

目的通过全脑血管造影结果,观察短暂性脑缺血发作(transient ischemic attacks,TIA)患者脑动脉狭窄的分布特征及侧支循环情况。方法选择行全脑血管造影检查的120例TIA患者,观察分析其是否存在脑血管狭窄、狭窄程度、狭窄分布特征以及侧支代偿情况。结果造影正常者37例(30.8%),存在脑动脉狭窄或完全闭塞的患者83例(69.2%)。在83例全脑血管造影检查阳性的患者中,前循环受累47例,占56.6%;后循环受累36例,占43.4%。轻中度狭窄的侧支循环发生率(71.4%)和重度狭窄及完全闭塞的侧支循环发生率(41.3%)比较,差异有统计学意义(P<0.05)。侧支循环的代偿主要通过Willis环途径。结论脑血管狭窄是TIA的主要原因之一,侧支循环最常见的途径是Willis环途径,血管狭窄越严重则越可能建立侧支循环。更多还原     

Focal hepatic vein stenoses in diffuse liver disease.

To determine the frequency of focal hepatic vein stenosis in diffuse liver disease and to study the relationship of stenosis to abnormal hepatic venous Doppler waveforms, 92 patients being evaluated for liver transplantation or transjugular intrahepatic portosystemic shunt were prospectively studied with color flow and pulsed Doppler sonography for the presence of focal hepatic vein stenoses and waveform abnormalities. Thirty-six patients had no focal stenoses with normal curves, 26 of 38 patients with Bolondi type I curves had focal stenoses, and 10 of 18 patients with damped type II curves had focal stenoses. Damped hepatic venous velocity curves associated with liver disease probably are caused by increased resistance in the hepatic venous circulation produced by focal stenoses.     

TCD对缺血性脑血管病颅内动脉狭窄的诊断价值

目的：观察经颅多普勒超声（TCD）对颅内血管狭窄诊断的可靠性。方法：对确诊的128例缺血性脑血管病进行TCD与数字减影血管造影（DSA）检查，观察颅内血管的变化情况。结果：128例中共检查血管1112条，TCD发现狭窄血管183条，其中135条与DSA诊断一致，但在TCD检查正常的血管中DSA发现血管狭窄29条，显示TCD诊断血管狭窄的敏感性82．3％，特异性94．9％，阳性预测值73．7％，阴性预测值96．8％，其中对大脑中动脉的价值最大，其后依次为椎动脉、大脑前后动脉。结论：TCD对诊断脑内动脉狭窄具有较高的敏感性和特异性，尤其对大脑中动脉和椎动脉，对大脑前动脉和大脑后动脉诊断须慎重。     

Determination of the hemodynamic factors which influence the carotid Doppler spectral broadening

In the diagnosis of extracranial carotid arterial disease, quantitative measurements from the continuous wave (CW) Doppler spectrum have the potential for detecting stenoses and occlusions. The measurement of maximum peak Doppler frequency at the site of stenosis has been shown to detect severe, but not minor or moderate, stenoses. Diagnosis of minor or moderate stenoses may be possible by assessing the degree of flow disturbance beyond the stenosis. Such flow disturbances cause the Doppler spectrum at peak systole to be broadened, and it has been suggested that the measurement of spectral broadening may be of diagnostic value. This paper describes the results of an in vitro study aimed at determining the hemodynamic factors that influence the severity of the Doppler spectral broadening. The spectral broadening index (SBI) at peak systole, defined as SBI = 1 - Fmean/Fmax, was used to quantify the instantaneous spectrum. In a pulsatile flow in vitro model that produced spectral waveforms virtually identical to those recorded in the human carotid, we observed a direct linear relationship between SBI and the severity of stenosis, at least for those stenoses having greater than 40% cross-sectional area (R = 0.82 to 0.93). The SBI was found to be maximum when recorded immediately beyond the stenosis and returned to normal 4-5 cm downstream from the stenosis. The SBI was higher for nonsymmetrically shaped stenoses than for symmetrical stenoses for lesions greater than 60%, but not for stenoses less than 60%. In this model, the SBI recorded from both normal or abnormal waveforms was not affected by the flow rate.(ABSTRACT TRUNCATED AT 250 WORDS)     

TCD对颞浅动脉—大脑中动脉搭桥术前后脑血流的检测

目的：应用经颅多普勒超声（TCD）动态观察大脑中动脉（MCA）在颞浅动脉－大脑中动脉搭桥术（STA－MCA）前后脑血流的变化。方法：对MCA主干狭窄及颈内动脉（ICA）颅外段闭塞影响MCA远端供血障碍的患者行STA－MCA术。采用TCD对5例成功实施STA－MCA术患者术前、术后MCA血流变化进行检测。结果：术前4例MCA主干狭窄及1例ICA闭塞后MCA0远端血流明显减低,呈低搏动性改变。术后血流明显改变,吻合处血流方向逆转。结论：TCD可有效地检测脑血流变化,动态观察STA－MCA架桥术的治疗效果。     

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。     

螺旋CT血管造影对椎基动脉供血不足的诊断价值

目的：探讨螺旋CT血管造影（CTA）对椎基动脉供血不足的诊断与鉴别诊断价值。方法：80例经颅多普勒超声提示有椎基动脉供血不足的患者行CTA检查。其中20例在CTA检查1周内接受减数血管造影（DSA）检查。结果：（1）CTA对椎动脉狭窄程度的评价与DSA呈高度相关（r=0.837P,0.001),对发育不良,血管扭曲的判断与DSA完全一致,对椎动脉起始端钙化的开口位置的显示优于DSA。（2）80例160条椎动脉中,正常88条（55.0%)。粥样硬化性狭窄29条（18.1%)。发育不良性狭窄20条（12.5%)。非自然扭曲18条（11.3%)。扭曲伴狭窄5条（3.1%)。另见起始端钙化7条。结论：CTA能清晰地显示全程椎基动脉系统,对椎基动脉供血不足的病因诊断,预后估计及治疗方案的选择都有重要的临床意义。     

锁骨下动脉盗血综合征经颅多普勒超声分析

目的 分析锁骨下动脉盗血综合征(SSS)与锁骨下动脉(SUBA)狭窄程度、同侧椎动脉(VA)盗血程度的相关性及盗血途径.方法 回顾分析应用经颅多普勒超声诊断的SSS患者37例临床资料,依据血流速度将SUBA狭窄分为轻中度、重度及闭塞3种情况,依据椎动脉血流方向将盗血程度分为Ⅰ期、Ⅱ期、Ⅲ期.比较SUBA不同狭窄程度与盗血程度的相关性.结果 SBUA轻中度狭窄15例,无盗血及Ⅰ期盗血12例(80%);重度狭窄14例,无盗血及Ⅰ期盗血3例(21%);二者比较差异有统计学意义(P＜0.05).轻中度狭窄组Ⅱ期及Ⅲ期盗血3例(20%),重度狭窄组Ⅱ期及Ⅲ期盗血11例(78%),二者比较差异有统计学意义(P＜0.05).重度狭窄组Ⅲ期盗血2例(14%),闭塞组Ⅲ期盗血7例(87%),二者比较差异有统计学意义(P＜0.05).双侧SUBA狭窄10例,其中双侧盗血1例.4例同时行数字减影血管造影术检查,结果与经颅多普勒超声检查结果完全相符;5例同时行CT血管造影术检查,其中3例与经颅多普勒超声检查结果相符,2例未见异常.盗血途径:椎动脉(VA)-VA28例(75.6%),基底动脉(BA)-VA 9例(24.4%).结论 经颅多普勒超声可早期发现SUBA狭窄,间接判断狭窄程度、盗血程度、盗血途径,可早期指导治疗.SUBA狭窄程度与盗血程度成正相关,VA-VA为常见盗血途径.     

Color Doppler sonography in the diagnosis and monitoring of arterial complications after liver transplantation

PURPOSE: We assessed the usefulness of color Doppler imaging in the diagnosis and monitoring of arterial complications after liver transplantation. METHODS: Subjects were 142 liver transplant recipients who underwent serial color Doppler sonographic evaluations of the hepatic arteries after surgery. Patients with abnormal sonographic findings underwent subsequent angiography. RESULTS: Eighteen subjects experienced 20 hepatic arterial complications (13 thromboses and 7 stenoses). In 7 of the 13 thrombosis incidents, hepatic arterial obstruction occurred within a month of surgery and was evident from the absence of Doppler signals; angiography confirmed the absence of hepatic arterial perfusion in these cases. In the other 6 thrombosis cases, the thrombosis developed 3 or more months after surgery and became apparent from the absence of color Doppler signals at the level of the main arterial trunk and the presence of intraparenchymal "tardus parvus" waveforms. In these cases, angiography showed obstruction of the main arterial trunk and the development of compensatory collateral vessels. In 3 of the 7 cases of stenosis, high flow velocities were recorded at the site of the narrowing, and intrahepatic tardus parvus waveforms were present. In the other 4 stenosis cases, the site of stenosis could not be identified, but intraparenchymal tardus parvus waveforms were recorded. CONCLUSION: The use of color Doppler sonography allows the early diagnosis of hepatic arterial complications after liver transplantation. Tardus parvus waveforms indicated severe impairment of hepatic arterial perfusion, from either thrombosis or severe stenosis. The presence of these waveforms enhanced the accuracy of color Doppler diagnosis (100% positive predictive value), and their detection should prompt angiography.     

颈部血管彩超、经颅多普勒超声与脑血管造影的一致性分析

目的探讨颈部血管彩超、经颅多普勒超声(TCD)对颈动脉狭窄、椎-基底动脉狭窄和动脉粥样硬化斑块的诊断价值,分析其与脑血管造影的一致性。方法选取2019年1月~2020年6月106例动脉粥样硬化性脑梗死患者为观察组,53例无脑梗死的动脉粥样硬化高血压病和(或)高脂血症患者为对照组。比较两组颈部血管彩超和TCD对颈动脉与椎-基底动脉中重度以上狭窄、不稳定型斑块的检出率。以脑血管造影为金标准,分析颈部血管彩超和TCD的诊断一致性。结果观察组颈动脉与椎-基底动脉中度狭窄、重度狭窄、完全闭塞的检出率均高于对照组(P < 0.05)。观察组颈动脉粥样硬化不稳定型斑块的检出率高于对照组(P < 0.05)。颈部血管彩超联合TCD对中重度以上狭窄检出的敏感度为93.75%,特异性为88.46%,准确率为92.45%,一致性较高(Kappa=0.801);对不稳定型斑块检出的敏感度为87.67%,特异性为87.88%,准确率为87.74%,一致性较高(Kappa= 0.725)。结论颈部血管彩超和TCD诊断颈动脉狭窄、椎-基底动脉狭窄和动脉粥样硬化斑块准确、无创、便捷,对脑梗死的预防、诊断、病因分析具有重要的参考意义。      

一站式CT血管造影+CT脑灌注成像可评估脑血管狭窄程度及侧支循环的开放程度

  目的  探究一站式CT血管造影术（CTA）+CT脑灌注成像（CTP）检查在急性脑梗死合并脑血管狭窄或闭塞诊断及脑血流灌注评估中的应用价值。  方法  选择2021年1月~2022年5月共86例急性脑梗死患者作为研究对象,均给予CTA+CTP检查。根据脑血管狭窄程度将其分为轻中度组（中度狭窄、轻度狭窄,n=60）及重度组（脑血管闭塞、重度狭窄,n=26）,分析脑血流灌注指标[脑血流量（CBF）、局部血容量（CBV）、平均通过时间（MTT）、达峰时间（TTP）]对脑血管狭窄程度的评估价值;根据侧支循环开放程度将患者分为侧支循环较好组（n=36）及侧支循环不良组（n=21）,分析脑血管灌注指标对侧支循环开放程度的评估价值。  结果  86例脑梗死患者脑血管闭塞、重度狭窄、中度狭窄及轻度狭窄发生率分别为10.47%（9/86）、19.77%（17/86）、36.05%（31/86）、33.72%（29/86）;轻中度组及重度组患者患侧CBV及CBF均小于健康侧,TTP、MTT长于健康侧（P < 0.05）;重度组健康侧的CBV、CBF小于轻中度组（P < 0.05）;重度组患侧相比于健康侧CBV、CBF下降值及TTP、MTT增大值大于轻中度组（P < 0.05）;CTP指标联合检测评估脑血管狭窄程度的AUC大于CBV、CBF等指标单独检测（P < 0.05）。侧支循环不良组的CBF高于侧支循环较好组,CBV低于侧支循环较好组,MTT、TTP短于侧支循环较好组（P < 0.05）;CTP指标联合检测评估侧支循环开放程度的AUC值大于各指标单独检测（P < 0.05）。  结论  CTA+CTP检查可急性脑梗死患者脑部血流灌注情况,可用于评估脑血管狭窄程度及侧支循环开放程度。      

颅内动脉狭窄与大脑中动脉供血区梗死形态关系的研究

目的:探讨大脑中动脉(MCA)供血区的梗死形态与颅内动脉狭窄之间的关系。方法:回顾性分析78例连续的急性MCA区域梗死且颅内动脉狭窄患者的临床资料。结果:重度ICA病变更多表现为穿支动脉伴皮质支梗死(5/16,P<0.05),而重度MCA病变则好发穿支动脉伴分水岭(4/30,P<0.05)及穿支动脉伴皮质支和分水岭的梗死(6/30,P<0.05)。结论:颅内动脉狭窄的程度与梗死形态亦存在一定关联,可能与多种机制有关,其中分水岭梗死可能提示灌注不足。     

TCD评估大脑中动脉区脑梗死患者的血流动力学变化

目的采用TCD评估大脑中动脉(MCA)区脑梗死后的血流动力学变化。方法对35例经头颅磁共振证实的MCA区急性脑梗死患者(病例组)和30例健康对照组行TCD检查。结果病例组患侧MCA流速低于健侧,两侧MCA流速比值低于对照组,两组间有显著性差异;病例组患侧与健侧大脑前动脉(ACA)流速比值高于对照组,两组间有显著性差异;病例组双侧大脑后动脉(PCA)流速比值跟对照组相比无显著性差异;所有病例组患侧MCA脉动指数减低(P<0.001)。结论TCD提供的血流动力学参数可以部分反映MCA病变后的侧支循环情况,MCA区脑梗死后侧支循环代偿以ACA为主。     

椎动脉颅内段血流速度及频谱波形异常的分析与诊断

目的探讨椎动脉颅内段血流异常的类型、病变部位及产生原因。方法对299例经磁共振血管成像和/或数字减影血管造影证实的颅内外动脉严重狭窄或闭塞患者,采用经颅多普勒超声(TCD)和颈动脉连续波多普勒超声(CWD)评估椎动脉颅内段血流异常。结果299例患者共检测598支椎动脉颅内段,其中508支血流异常:狭窄血流(32支)、无血流(17支)、低流速低阻力(58支)、低流速高阻力(42支)、代偿血流(287支)和窃血频谱(72支)。狭窄血流或无血流均在病变部位直接检出,其他4种类型血流异常则是病变部位近端或远端动脉的间接血流改变。结论采用TCD和CWD评估椎动脉颅内段血流异常可为临床寻找后循环缺血的原因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。