Combined Vector Velocity and Spectral Doppler Imaging for Improved Imaging of Complex Blood Flow in the Carotid Arteries

Color flow imaging and pulsed wave (PW) Doppler are important diagnostic tools in the examination of patients with carotid artery disease. However, measurement of the true peak systolic velocity is dependent on sample volume placement and the operator's ability to provide an educated guess of the flow direction. Using plane wave transmissions and a duplex imaging scheme, we present an all-in-one modality that provides both vector velocity and spectral Doppler imaging from one acquisition, in addition to separate B-mode images of sufficient quality. The vector Doppler information was used to provide automatically calibrated (angle-corrected) PW Doppler spectra at every image point. It was demonstrated that the combined information can be used to generate spatial maps of the peak systolic velocity, highlighting regions of high velocity and the extent of the stenotic region, which could be used to automate work flow as well as improve the accuracy of measurement of true peak systolic velocity. The modality was tested in a small group (N = 12) of patients with carotid artery disease. PW Doppler, vector velocity and B-mode images could successfully be obtained from a single recording for all patients with a body mass index ranging from 21 to 31 and a carotid depth ranging from 16 to 28 mm.     

Common Carotid Artery Flow Measured by 3-D Ultrasonic Vector Flow Imaging and Validated with Magnetic Resonance Imaging

Ultrasound (US) examination of the common carotid artery was compared with a through-plane magnetic resonance imaging (MRI) sequence to validate a recently proposed technique for 3-D US vector flow imaging. Data from the first volunteer examined were used as the training set, before volume flow and peak velocities were calculated for the remaining eight volunteers. Peak systolic velocities (PSVs) and volume flow obtained with 3-D US were, on average, 34% higher and 24% lower than those obtained with MRI, respectively. A high correlation was observed for PSV (r = 0.79), whereas a lower correlation was observed for volume flow (r = 0.43). The overall standard deviations were ±5.7% and ±5.7% for volume flow and PSV with 3-D US, compared with ±2.7% and ±3.2% for MRI. Finally, the data were re-processed with a change in the parameter settings for the echo-canceling filter to investigate its influence on overall performance. PSV was less affected by the re-processing, whereas the difference in volume flow between 3-D vector flow imaging and MRI was reduced to ?9%, and with an improved overall standard deviation of ±4.7%. The results illustrate the feasibility of using 3-D US for precise and angle-independent volume flow and PSV estimation in vivo.     

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     

彩色多普勒超声和磁共振在门静脉系血流测定的应用

目的　进行彩色多普勒超声和磁共振血管造影在门静脉系血流量测定方面的对比。方法　用彩色多普勒超声(CDUS)和二维相位对比磁共振 ( 2D PCMR)测定门静脉高压症者门静脉系统血流量。结果　CDUS与 2D PCMR在门静脉系统血流量的测定无显著差别。结论　CDUS和 2D PCMR都为一种无创检查 ,但CDUS价格低廉 ,可作为门静脉高压症术前首选检查。     

Effect of Velocity Profile Skewing on Blood Velocity and Volume Flow Waveforms Derived From Maximum Doppler Spectral Velocity

Given evidence that fully developed axisymmetric flow may be the exception rather than the rule, even in nominally straight arteries, maximum velocity (V_max) can lie outside the Doppler sample volume (SV). The link between V_max and derived quantities, such as volume flow (Q), may therefore be more complex than commonly thought. We performed idealized virtual Doppler ultrasound on data from image-based computational fluid dynamics (CFD) models of the normal human carotid artery and investigated how velocity profile skewing and choice of sample volume affected V_max waveforms and derived Q variables, considering common assumptions about velocity profile shape (i.e., Poiseuille or Womersley). Severe velocity profile skewing caused substantial errors in V_max waveforms when using a small, centered SV, although peak V_max was reliably detected; errors with a long SV covering the vessel diameter were orientation dependent but lower overall. Cycle-averaged Q calculated from V_max was typically within ±15%, although substantial skewing and use of a small SV caused 10%–25% underestimation. Peak Q derived from Womersley's theory was generally accurate to within ±10%. V_max pulsatility and resistance indexes differed from Q-based values, although the Q-based resistance index could be predicted reliably. Skewing introduced significant error into V_max-derived Q waveforms, particularly during mid-to-late systole. Our findings suggest that errors in the V_max and Q waveforms related to velocity profile skewing and use of a small SV, or orientation-dependent errors for a long SV, could limit their use in wave analysis or for constructing characteristic or patient-specific flow boundary conditions for model studies.     

颈内动脉严重狭窄或闭塞患者颅内侧支循环的建立--经颅多普勒超声与数字减影血管造影的对照研究

目的:分析颈内动脉严重狭窄或闭塞时,合并或不合并颅内血管狭窄对侧支循环的影响以及经颅多普勒超声(TCD)与数字减影血管造影(DSA)比较的敏感性和特异性.方法:将DSA检查证实的颈内动脉(ICA)严重狭窄或闭塞患者56例分成两组:单纯ICA病变为组Ⅰ29例;合并颅内血管狭窄为组Ⅱ27例.TCD判断侧支循环的标准:(1)、前交通动脉(ACOA)开放:狭窄同侧大脑前动脉(ACA)反向,对侧ACA血流速增快,压对侧颈动脉后狭窄侧大脑中动脉(MCA)血流速度下降;(2)、后交通动脉(PCOA)开放:同侧大脑后动脉(PCA)及椎基底动脉(VBA)血流速增快;(3)、颈外向颈内侧支循环形成:眼动脉或滑车上动脉反向.结果:全部56例患者ACOA和PCOA的发生率(57.14%和60.71%)明显大于OA(25.0%),(P＜0.01).组ⅡACOA的发生率(37.04%)较组Ⅰ(75.86%)明显下降,(P＜0.01).TCD与DSA比较组Ⅰ的敏感性(96.07%),特异性(94.82%);组Ⅱ敏感性(89.47%),特异性(91.22%),两组比较无显著差异(P＞0.05).代偿血管ACA、PCA、BA的平均血流速(cm/s)分别为(101.0±17.36,91.13±27.75和75.86±24.96)均较无代偿同名血管血流速(61.92±16.84,48.80±13.76和43.69±11.01)明显增快,有显著性差异,P＜0.001.结论:颅内侧支循环以Willis环的前交通动脉和后交通开放为主,合并颅内血管狭窄使前交通动脉的开放明显受损;TCD对颈内动脉闭塞患者颅内侧支循环的判断有良好的敏感性和特异性,合并颅内血管狭窄对侧支循环的判断无明显影响.     

彩色多普勒检测主动脉瓣病变患者颈动脉血流变化

为探讨主动脉瓣病变对颈动脉血流动力学变化的影响，对正常组４２例，观察组４７例：其中主动脉瓣关闭不全１３例，主动脉瓣狭窄伴关闭不全３３例，主动脉瓣狭窄１例，进行了彩色多普勒血流检测。正常颈总动脉频谱形态呈三峰形，收缩期两峰Ｖｓ１＞Ｖｓ２；舒张早期可有反向频谱，△Ｔ／Ｔ比值＜１／１０。主动脉瓣狭窄伴关闭不全时，颈总动脉收缩期可出现“Ｍ”形频谱，出现率为７２．２％；１例主动脉瓣狭窄，颈动脉频谱形态呈“圆顶状”状。主动脉瓣关闭不全时，颈总动脉出现“舒张期返流”频谱，即△Ｔ／Ｔ≥１／１０。“舒张期返流”频谱的出现与瓣膜返流程度有关：轻度返流，△Ｔ／Ｔ比值正常或＜１／４，中度返流，在１／４～１／２之间，△Ｔ／Ｔ≥１／２，均为重度返流。６例瓣膜置换术后，４全颈动脉频谱形态恢复正常，２例仍有“舒张期返流”频谱，其主动脉瓣中度关闭不全。结果表明：主动脉瓣狭窄伴关闭不全时，颈总动脉收缩期可出现特征性“Ｍ”形；主动脉瓣关闭不全舒张期可见“舒张期返流”频谱。“舒张期返流”频谱是区分轻与中重度瓣膜关闭不全的简便方法，也可大致区分中与重度关闭不全。比较换瓣前后，颈动脉异常频谱形态变化，可作为间接评价主动脉人工瓣功能的方法之一     

Vector and Doppler Ultrasound Velocities Evaluated in a Flow Phantom and the Femoropopliteal Vein

Ultrasound is used for evaluating the veins of the lower extremities. Operator and angle dependency limit spectral Doppler ultrasound (SDUS). The aim of the study was to compare peak velocity measurements in a flow phantom and the femoropopliteal vein of 20 volunteers with the angle-independent vector velocity technique vector flow imaging (VFI) and SDUS. In the flow phantom, VFI underestimated velocity (p = 0.01), with a lower accuracy of 5.5% (p = 0.01) and with no difference in precision, that is, error factor, compared with SDUS (VFI: 1.02 vs. SDUS: 1.02, p = 0.58). In vivo, VFI estimated lower velocities (femoral: p = 0.001; popliteal: p = 0.001) with no difference in precision compared with SDUS (femoral: VFI 1.09 vs. SDUS 1.14, p = 0.37; popliteal: VFI 1.13 vs. SDUS 1.06, p = 0.09). In conclusion, the precise VFI technique can be used to characterize venous hemodynamics of the lower extremities despite its underestimation of velocities.     

彩色多普勒检测胎儿颈动脉、颅内动脉与脐动脉对照

本文对96例健康胎儿的颈动脉、颅内动脉行彩色多普勒最大血流信号的频谱分析,计算出各动脉血流的RI、PI、S/D值,并分别与脐动脉进行比较。结果:反应胎儿周围血管阻力的上述各项测值在脐动脉与颈总动脉、颈内动脉、大脑中动脉、大脑前动脉、大脑后动脉之间有着显著性差异(P<0.05～P<0.0001),而且它们之间的各项比值亦有一定的规律性。说明胎儿-胎盘循环与胎儿颅脑循环在血管动力学方面有所不同。     

Novel Flow Quantification of the Carotid Bulb and the Common Carotid Artery with Vector Flow Ultrasound

Abnormal blood flow is usually assessed using spectral Doppler estimation of the peak systolic velocity. The technique, however, only estimates the axial velocity component, and therefore the complexity of blood flow remains hidden in conventional ultrasound examinations. With the vector ultrasound technique transverse oscillation the blood velocities of both the axial and the transverse directions are obtained and the complexity of blood flow can be visualized. The aim of the study was to determine the technical performance and interpretation of vector concentration as a tool for estimation of flow complexity. A secondary aim was to establish accuracy parameters to detect flow changes/patterns in the common carotid artery (CCA) and the carotid bulb (CB). The right carotid bifurcation including the CCA and CB of eight healthy volunteers were scanned in a longitudinal plane with vector flow ultrasound (US) using a commercial vector flow ultrasound scanner (ProFocus, BK Medical, Denmark) with a linear 5 MHz transducer transverse oscillation vector flow software. CCA and CB areas were marked in one cardiac cycle from each volunteer. The complex flow was assessed by medical expert evaluation and by vector concentration calculation. A vortex with complex flow was found in all carotid bulbs, whereas the CCA had mainly laminar flow. The medical experts evaluated the flow to be mainly laminar in the CCA (0.82 ± 0.14) and mainly complex (0.23 ± 0.22) in the CB. Likewise, the estimated vector concentrations in CCA (0.96 ± 0.16) indicated mainly laminar flow and in CB (0.83 ± 0.07) indicated mainly turbulence. Both methods were thus able to clearly distinguish the flow patterns of CCA and CB in systole. Vector concentration from angle-independent vector velocity estimates is a quantitative index, which is simple to calculate and can differentiate between laminar and complex flow.     

Accuracy and Precision of a Plane Wave Vector Flow Imaging Method in the Healthy Carotid Artery

The objective of the study described here was to investigate the accuracy and precision of a plane wave 2-D vector flow imaging (VFI) method in laminar and complex blood flow conditions in the healthy carotid artery. The approach was to study (i) the accuracy for complex flow by comparing the velocity field from a computational fluid dynamics (CFD) simulation to VFI estimates obtained from the scan of an anthropomorphic flow phantom and from an in vivo scan; (ii) the accuracy for laminar unidirectional flow in vivo by comparing peak systolic velocities from VFI with magnetic resonance angiography (MRA); (iii) the precision of VFI estimation in vivo at several evaluation points in the vessels. The carotid artery at the bifurcation was scanned using both fast plane wave ultrasound and MRA in 10 healthy volunteers. The MRA geometry acquired from one of the volunteers was used to fabricate an anthropomorphic flow phantom, which was also scanned using the fast plane wave sequence. The same geometry was used in a CFD simulation to calculate the velocity field. Results indicated that similar flow patterns and vortices were estimated with CFD and VFI in the phantom for the carotid bifurcation. The root-mean-square difference between CFD and VFI was within 0.12?m/s for velocity estimates in the common carotid artery and the internal branch. The root-mean-square difference was 0.17?m/s in the external branch. For the 10 volunteers, the mean difference between VFI and MRA was ?0.17?m/s for peak systolic velocities of laminar flow in vivo. The precision in vivo was calculated as the mean standard deviation (SD) of estimates aligned to the heart cycle and was highest in the center of the common carotid artery (SD?=?3.6% for velocity magnitudes and 4.5° for angles) and lowest in the external branch and for vortices (SD?=?10.2% for velocity magnitudes and 39° for angles). The results indicate that plane wave VFI measures flow precisely and that estimates are in good agreement with a CFD simulation and MRA.     

超声造影评价颈总动脉内中膜厚度的研究

目的 探讨超声造影在颈总动脉前、后壁内中膜厚度(IMT)测定中的应用价值.方法 在二维和超声造影模式下,观察颈总动脉前、后壁内中膜显示清晰程度,分别测量颈总动脉内径,前、后壁IMT值.结果 造影后颈总动脉前壁内中膜显示满意率有明显提高(P＜0.01);造影前、后颈总动脉后壁内中膜显示满意率没有明显差异(P＞0.05);造影后颈总动脉内径值大于造影前颈总动脉内径值(P＜0.05);造影后前壁IMT值大于造影前前壁IMT值(P＜0.01);造影后后壁IMT值小于造影前后壁IMT值(P＜0.01).结论 超声造影可以明显提高颈总动脉前壁内中膜显示满意率.     

Vector Flow Imaging Compared with Pulse Wave Doppler for Estimation of Peak Velocity in the Portal Vein

The study described here investigated whether angle-independent vector flow imaging (VFI) technique estimates peak velocities in the portal vein comparably to pulsed wave Doppler (PWD). Furthermore, intra- and inter-observer agreement was assessed in a substudy. VFI and PWD peak velocities were estimated with from intercostal and subcostal views for 32 healthy volunteers, and precision analyses were conducted. Blinded to estimates, three physicians rescanned 10 volunteers for intra- and inter-observer agreement analyses. The precision of VFI and PWD was 18% and 28% from an intercostal view and 23% and 77% from a subcostal view, respectively. Bias between VFI and PWD was 0.57?cm/s (p?=?0.38) with an intercostal view and 9.89?cm/s (p?<0.001) with a subcostal view. Intra- and inter-observer agreement was highest for VFI (inter-observer intra-class correlation coefficient: VFI 0.80, PWD 0.3; intra-observer intra-class correlation coefficient: VFI 0.90, PWD 0.69). Regardless of scan view, VFI was more precise than PWD.     

Comparison of B‐Mode Ultrasound, 3‐Dimensional Ultrasound,and Magnetic Resonance Imaging Measurements of Carotid Atherosclerosis

Objective. We compared the intraobserver and interscan variability of carotid atherosclerosis measured using B‐mode ultrasound for quantifying intima media thickness (IMT), 3‐dimensional ultrasound (3DUS) for quantifying vessel wall volume (VWV) and total plaque volume (TPV), and magnetic resonance imaging (MRI) for measuring VWV. We also evaluated the associations of these measurements and sample sizes required to detect specific changes in patients with moderate atherosclerosis. Methods. Ten patients were evaluated with B‐mode ultrasound, MRI, and 3DUS twice within 14 ± 2 days. Measurements of IMT, MRI VWV, 3DUS VWV, and 3DUS TPV were performed by single observers using manual (VWV and TPV) and semiautomated (IMT) segmentation. Results. Intraobserver coefficients of variation were 3.4% (IMT), 4.7% (3DUS VWV), 6.5% (MRI VWV), and 23.9% (3DUS TPV). Interscan coefficients of variation were 8.1% (MRI VWV), 8.9% (IMT), 13.5% (3DUS VWV), and 46.6% (3DUS TPV). Scan‐rescan linear regressions were significant for 3DUS TPV (R² = 0.57), 3DUS VWV (R² = 0.59), and IMT (R² = 0.75) and significantly different (P < .05) for MRI VWV (R² = 0.87). Conclusions. B‐mode ultrasound‐derived IMT provided the highest intraobserver and interscan reproducibility. Three‐dimensional measurements of VWV derived from 3DUS and MRI provided both high sensitivity and high intraobserver and interscan reliability.     

妊高征患者脑血流变化观察

应用经颅多普勒超声（ＴＣＤ）检测３５例妊高征患者（观察组）及３０例正常孕妇（对照组）的大脑中动脉（ＭＣＡ）、大脑前动脉（ＡＣＡ）、大脑后动脉（ＰＣＡ）、椎动脉（ＶＡ）、基底动脉（ＢＡ）收缩期血流速度（Ｖｓ）舒张末期血流速度（Ｖｄ）、平均血流速度（Ｖｍ）及搏动指数（ＰＩ）。结果显示：观察组中的中、重度妊高征患者脑动脉Ｖｓ、Ｖｄ均高于对照组（Ｐ＜０．０１），并随病情加重逐渐升高。观察组各条脑动脉的Ｖｍ均显著高于对照组（Ｐ＜０．０１）。观察组各条动脉ＰＩ值均显著低于对照组（Ｐ＜０．００１）。同时观察３６例妊高征患者眼底，仅３例中度及６例重度妊高征患者眼底血管有痉挛表现。说明：ＴＣＤ能检测妊高征患者脑血管痉挛所致血流速度改变，表现为血流速度加快，脑血管舒缩功能降低。ＴＣＤ能早期提供妊高征患者脑血流动力学资料，避免脑血管病危及孕妇安全。因而可作为妊高征患者预防脑血管并发症的监测手段之一。     

脉冲多普勒超声对29例肝癌合并门脉瘤栓患者肝动脉血流测定

本文应用超声多普勒对36例原发性肝癌，29例原发性肝癌合并门脉瘤栓及20例正常人的肝总动脉内径及最大血流速度进行测定，结果示：肝总动脉内径：正常人0．387±0．07cm，原发性肝癌0．525±0．02cm，合并门脉瘤栓0．706±0．06cm。最大血流速度；正常人91．05±24．89cm/s，原发性肝癌159．25±42cm／s，合并门脉瘤栓者203．66±61．26cm／s。统计学处理，差别显著（P＜0．01）。提示原发性肝癌合并门脉瘤栓时，由于门静脉血流受阻，肝动脉血流量明显代偿性增强。