彩色多普勒超声对巩膜扣带术后患者眼血流动力学的跟踪观察

目的 观察孔源性视网膜脱离患眼在接受环扎加压术后远期眼部血流动力学的改变.方法 应用Siemens Sequia 512彩色多普勒超声诊断仪分别测定31例患者患眼与对侧眼的眼动脉、视网膜中央动脉、睫状后短动脉的收缩期最大血流速度、舒张末期血流速度、阻力指数,以对侧眼为对照组,分别对术后1～2年及术后3～4年患者的上述指标进行对照分析.结果 术后1～2年组患眼的眼动脉、视网膜中央动脉、睫状后短动脉的各项血流动力学指标与对侧眼相比差异无统计学意义(P>0.05).术后3～4年组患眼的视网膜中央动脉、睫状后短动脉的收缩期最大血流速度及舒张末期血流速度值均显著降低(P<0.05),阻力指数与眼动脉的各项测值患眼与对照组比较差异无统计学意义.术后各眼均未发生眼部缺血症状,视力恢复理想.结论 环扎加压术后1～2年患眼的视网膜与脉络膜血供无明显变化,而在术后3～4年血供有减低趋势.环扎加压术可能会增加患眼远期的亚临床缺血症状.     

Evaluation of Split Renal Function for Children with Kidney Diseases by Renal and Vascular Color Ultrasonography

Renal dynamic imaging and radionuclide renography use radioactivity to evaluate split renal function. We aimed to investigate the use of renal vascular color Doppler ultrasonography for evaluation of split renal function in children. Thirty-five children with unilateral kidney diseases were enrolled. For patients with unilateral renal tumor, peak systolic velocity (V_max?=?113.04 ± 13.59 cm/s) and resistance index (RI?=?0.73 ± 0.02) were higher on abnormal compared with normal sides (V_max?=?86.03 ± 6.49 cm/s, RI = 0.62 ± 0.01), and blood perfusion was good, indicating compensatory enhancement in split renal function. For unilateral renal cyst, V_max (58.20 ± 7.38 cm/s) was lower on the abnormal compared with the normal (87.71 ± 14.83 cm/s) size, and perfusion was poor. For unilateral hydronephrosis and renal atrophy, the parameters were similar to those of renal cyst, suggesting a weakening of renal function. For unilateral renal agenesis, V_max (106.07 ± 13.07 cm/s) and RI (0.71 ± 0.05) were higher, and perfusion was good. Renal vascular color Doppler ultrasonography was superior in the evaluation of split renal function in children, without being invasive or radioactive.     

实时三维超声心动图评价继发孔型房间隔缺损患者的心房容积和功能

目的 应用实时三维超声心动图(RT-3DE)技术评价继发孔型房间隔缺损(S-ASD)患者的心房容积和功能,以及外科修补术对心房容积和功能的影响. 方法 应用RT-3DE技术测量30例S-ASD患者、14例S-ASD外科手术患者和20名正常人的左、右心房的最小容积、最大容积及收缩前容积,并计算左、右心房传导功能和泵血功能.分别比较S-ASD组与正常组,S-ASD组术前与术后结果 . 结果 S-ASD组左、右心房的最大、最小及收缩前容积较正常组增大;左、右心房的主动排空容积较正常组增大,并与分流量(Qp/Qs)呈显著相关(P＜0.05).但其主动排空容积分数与正常组差异无统计学意义,而右心房的被动排空容积分数较正常组减低.外科修补术后,右心房的最大、最小及收缩前容积较术前减低,而左心房最大、最小及收缩前容积较术前增加.左、右心房主动排空容积分数和被动排空容积分数均较术前减低. 结论 RT-3DE能测量并评价S-ASD患者的心房容积和功能.S-ASD患者心房容积增大,右心房传导功能减低,泵血功能未受影响;S-ASD患者外科修补术后右心房容积变小,左心房容积变大,双房的传导功能和泵血功能均减低.     

Quantitative transcutaneous measurements of blood flow in carotid artery by means of pulse and continuous wave Doppler methods.

The authors present results of quantitative measurements of blood in vivo in the carotid artery of man. The Doppler pulse technique was used after being previously verified for steady state flows in tubes and for pulsating flows in a canine aorta where the electromagnetic method was also used for comparison.An ultrasonic probe with two transducers was adapted for determination of the angle of the ultrasonic beam in relation to the vessel allowing the measurement of the vessel diameter which was also determined by means of the ultrasonographic B-mode technique.By means of the Doppler pulse method profiles of the blood velocity in the carotid artery were determined as a function of time.The continous wave Doppler technique together with the zero-crossing system and spectral analysis were also used for making measurements.The flow velocity and the shape of the flow curve with time obtained with the above techniques showed good agreement. The measured flow rate in the carotid artery amounted to Q_M = 1.61/min (maximum instantaneous value) and Q₀ - 0.531/min (mean time value).     

Feasibility of Dual Doppler Velocity Measurements to Estimate Volume Pulsations of an Arterial Segment

If volume flow was measured at each end of an arterial segment with no branches, any instantaneous differences would indicate that volume was increasing or decreasing transiently within the segment. This concept could provide an alternative method to assess the mechanical properties or distensibility of an artery noninvasively using ultrasound. The goal of this study was to determine the feasibility of using Doppler measurements of pulsatile velocity (opposed to flow) at two sites to estimate the volume pulsations of the intervening arterial segment. To test the concept over a wide range of dimensions, we made simultaneous measurements of velocity in a short 5 mm segment of a mouse common carotid artery and in a longer 20 cm segment of a human brachial-radial artery using a two-channel 20 MHz pulsed Doppler and calculated the waveforms and magnitudes of the volume pulsations during the cardiac cycle. We also estimated pulse wave velocity from the velocity upstroke arrival times and measured artery wall motion using tissue Doppler methods for comparison of magnitudes and waveforms. Volume pulsations estimated from Doppler velocity measurements were 16% for the mouse carotid artery and 4% for the human brachial artery. These values are consistent with the measured pulse wave velocities of 4.2 m/s and 10 m/s, respectively, and with the mouse carotid diameter pulsation. In addition, the segmental volume waveforms resemble diameter and pressure waveforms as expected. We conclude that with proper application and further validation, dual Doppler velocity measurements can be used to estimate the magnitude and waveform of volume pulsations of an arterial segment and to provide an alternative noninvasive index of arterial mechanical properties. (E-mail: cjhartley@ieee.org)     

Pulsed Wave Doppler Measurements of Maximum Velocity: Dependence on Sample Volume Size

Pulsed wave (PW) Doppler ultrasound is routinely used in the clinic to assess blood flow. Our annual Doppler quality assurance tests revealed unexpectedly large errors in measurement of maximum velocity, exceeding our tolerance (error >20%), when using certain scanners with small Doppler sample volume dimensions. The aim of this study was to assess the dependence of maximum velocity estimates on PW Doppler sample volume size. A flow phantom with known steady flow was used to acquire maximum velocity estimates (maximum velocities of 24, 39 and 85 cm/s and sample volume range of 0.3–20 mm) with a variety of transducers and scanners in clinical use (51 probes from 4 manufacturers). Selected acoustic outputs were characterized using free-field hydrophone measurements. All maximum velocity estimates were within our tolerance for sample volume sizes ≥1.5 mm, although maximum velocity estimates typically increased with decreasing sample volume size. Errors exceeding our tolerance were commonly found for one manufacturer when using smaller sample volumes, resulting in up to 75% overestimation. Although intrinsic spectral broadening based on transit time considerations may help explain our findings, the sample volume dependence raises potential clinical concerns that users should be aware of and which manufacturers should consider addressing.     

速度向量成像技术检测2型糖尿病患者室壁短轴方向运动改变

目的 应用速度向量成像(VVI)技术探讨2型糖尿病(T2DM)患者左室各壁的运动速度、应变和应变率的变化,评价VVI技术检测T2DM患者左室室壁运动改变的价值.方法 T2DM患者44例,根据临床糖尿病微血管病变出现与否分为无微血管病变组(A组)21例、合并微血管病变组(B组)23例,以VVI技术测量左室短轴方向各壁的收缩期最大径向运动速度(Vs)、最大切向应变(Smax)及最大切向应变率(SRmax).结果 与A组比较,B组的心尖部各节段及前、后间隔中部Vs明显减低;B组Smax除侧壁、后壁的基底部无明显差异外,余节段较A组均明显减低;B组心尖各壁、后间隔基底段、后壁中段的SRmax明显减低.结论 VVI技术可用于2型糖尿病患者左室室壁运动的分析,是评价室壁运动的一种有效工具.     

Intraobserver reproducibility and interobserver agreement of ultrasonic flowmetry using the velocity profile color doppler method in the common carotid artery

Application of the velocity profile method is recommended for reliable measurement of flow volume in larger vessels, and ultrasonic flowmetry is a useful clinical tool for this purpose. We used the velocity profile in conjunction with a minor modification in the conventional velocity profile method and examined the reproducibility of flowmetry from color Doppler data. Data of three examiners were allowed to analyze intraobserver reproducibility and interobserver agreement in the common carotid artery, and we measured flow volume in the peripheral vessels of healthy individuals. Estimated flow volumes in five healthy examinees were 350 to 550 ml/min and did not vary significantly between examiners. Interobserver correlation was good (r ₁=0.63), but intraobserver correlations in two sonographers were excellent (r ₁=0.85) in by one who was experienced in this method and poor (r ₁=0.32) in the other. Good interobserver agreement and intraobserver reproducibility of experienced examiners suggests that this method is reliable. Values obtained with normal controls averaged 438±78 (mean±SD) ml/min and 449±64 ml/min, respectively, in the right and left carotid arteries (n=12) and 120±31 ml/min and 83±23 ml/min, respectively, in the right and left vertebral arteries (n=10). Normal values were 542±71 ml/min (n=11) in the right renal artery, 1210±211 ml/min in the abdominal artery (n=10), and 799±182 ml/min in the main portal vein (n=17). Arterial blood flow volume can measure reliably by the velocity profile color Doppler method.     

Quantification of shunt volumes in congenital heart diseases using a breath-hold MR phase contrast technique--comparison with oximetry

Aims: Comparison of breath-hold MR phase contrast technique in the estimation of cardiac shunt volumes with the invasive oximetric technique. Methods and Results: Seventeen patients with various cardiac shunts (10 ASD, 3 VSD, 1 PDA, 3 PFO) and five healthy volunteers were investigated using a 1.5 Tesla system. The mean flow velocity, the mean volume flow and the transverse area in the ascending aorta and the left and right pulmonary artery were measured using the MR phase contrast breath-hold technique (through plane, FLASH 2D-sequence, TR/TE 11/5 ms, phase length 106 ms, VENC 250 cm/s). The ratio of mean flow in the pulmonary (Q _p: sum of mean flows in the left and right pulmonary arteries) and the systemic circulation (Q _s: mean flow in the ascending aorta) was calculated and compared with invasively measured Q _p:Q _s ratios. Oximetry was performed within 24 h of the MR investigation. The non-invasive shunt measurement in the 17 patients showed a mean Q _p:Q _s ratio of 2.00 ± 0.86. Comparing the MR data with the invasively measured Q _p:Q _s showed a correlation coefficient of r = 0.91 (p < 0.001). Conclusion: Cardiac shunt volumes can be measured reliably using a shorter acquisition time with breath-hold MR phase contrast technique.     

儿童肾动脉多普勒超声正常参考值及其临床意义

目的 探讨多普勒超声测量正常儿童肾动脉血流参数的正常参考值及其临床意义。方法 随机选取319名1天~16岁正常儿童,男192名,女127名,以多普勒超声测量双侧肾脏的肾动脉血流参数,包括收缩期峰值流速(V_s)、舒张末期峰值流速(V_d)、平均血流速度(V_m)、收缩期峰值流速与舒张末期峰值流速比值(S/D)、搏动指数(PI)、阻力指数(RI)和收缩期血流加速时间(AT);分析各参数随年龄、体表面积(BSA)的变化趋势。结果 男性与女性儿童及左侧与右侧肾动脉各项血流参数差异均无统计学意义(P均>0.05);正常儿童BSA与年龄呈正相关(r=0.96,P<0.01),与肾动脉血流速度及RI分别呈正相关与负相关(P均<0.05);除AT外,肾动脉血流速度和RI以肾主动脉、段动脉、叶间动脉依次递减(P<0.05)。结论 正常儿童肾动脉多普勒超声血流参数与BSA相关,可作为儿童肾脏疾病诊断的正常参考值。     

In Vivo Lateral Blood Flow Velocity Measurement Using Speckle Size Estimation

In previous studies, we proposed blood measurement using speckle size estimation, which estimates the lateral component of blood flow within a single image frame based on the observation that the speckle pattern corresponding to blood reflectors (typically red blood cells) stretches (i.e., is “smeared”) if blood flow is in the same direction as the electronically controlled transducer line selection in a 2-D image. In this observational study, the clinical viability of ultrasound blood flow velocity measurement using speckle size estimation was investigated and compared with that of conventional spectral Doppler of carotid artery blood flow data collected from human patients in vivo. Ten patients (six male, four female) were recruited. Right carotid artery blood flow data were collected in an interleaved fashion (alternating Doppler and B-mode A-lines) with an Antares Ultrasound Imaging System and transferred to a PC via the Axius Ultrasound Research Interface. The scanning velocity was 77 cm/s, and a 4-s interval of flow data were collected from each subject to cover three to five complete cardiac cycles. Conventional spectral Doppler data were collected simultaneously to compare with estimates made by speckle size estimation. The results indicate that the peak systolic velocities measured with the two methods are comparable (within ±10%) if the scan velocity is greater than or equal to the flow velocity. When scan velocity is slower than peak systolic velocity, the speckle stretch method asymptotes to the scan velocity. Thus, the speckle stretch method is able to accurately measure pure lateral flow, which conventional Doppler cannot do. In addition, an initial comparison of the speckle size estimation and color Doppler methods with respect to computational complexity and data acquisition time indicated potential time savings in blood flow velocity estimation using speckle size estimation. Further studies are needed for calculation of the speckle stretch method across a field of view and combination with an appropriate axial flow estimator.     

An integrated approach to determine left atrial volume, mass and function in hypertrophic cardiomyopathy by two-dimensional echocardiography

Methods

The study included 25 hypertrophic cardiomyopathy (HCM) patients (15 non-obstructive and 10 obstructive) and 25 controls for assessment of left atrial (LA) volume, mass and function by two-dimensional echocardiography. Measurement included mean LA diameter (LAD), LA mass = {(mean LAD + anterior LA wall + posterior LA wall)³ ? mean LAD³} × 0.8 + 0.6, LA volume = [(8/3 π L · A1 · A2), where L is LA length, A1 and A2 are LA area in 4-chambers and 2-chambers, respectively] including maximum (V _max), minimum (V _min), and pre-atrial contraction (V _pre-A), total atrial stroke volume (TA-SV), TA emptying fraction (TA-EF), active atrial SV (AA-SV), AA-EF, passive atrial SV (PA-SV), PA-EF, atrial expansion index (AEI), and LA kinetic energy (LA-KE) = ½ × AA-SV × P × V².

Results

LAD, LA mass, V _max, V _min, and V _pre-A were significantly higher in HCM than controls. TA-SV and TA-EF were comparable in both HCM subgroups and controls. AA-SV and LA-KE were significantly higher in both HCM subgroups than controls. LA-KE was significantly higher in obstructive HCM than non-obstructive (P < 0.001). PA-EF and AEI were significantly lower in obstructive HCM than controls (P < 0.05).

Conclusion

HCM is associated with increased LA size and augmented LA pump function especially obstructive type. LA conduit and reservoir functions are impaired in obstructive HCM.     

速度向量成像技术对2型糖尿病患者足背动脉管壁运动的初步评价

目的应用速度向量成像技术（VVI）探讨2型糖尿病（T2DM）患者足背动脉的管壁长轴方向运动速度、应变及应变率的特点。方法使用西门子公司ACUSON Sequoia 512彩色多普勒超声诊断系统,结合同步心电图描记,声学采集条件下分别获取2型糖尿病足背动脉无形态学改变患者20例（T2DM1组）、糖尿病足背动脉有形态学改变患者26例（T2DM2组）和20例无糖尿病健康人（正常对照组）足背动脉的长轴二维图像,并进行动态存储。测量足背动脉平均内中膜厚度（IMT）,收缩末内径（Ds）,收缩期峰值流速（PSV）;并运用VVI软件进行脱机分析,测量足背动脉管壁长轴方向上的最大纵向运动速度（Vmax）、最大应变（Smax）及最大应变率（SRmax）,并进行比较。结果T2DM1组患者足背动脉IMT、Ds和PSV测值与正常人相比差异均无显著性意义（P〉0.05）,而Vmax、Smax、SRmax测值与正常人相比显著减低（P〈0.05或0.01）。T2DM2组患者足背动脉IMT、Ds、PSV测值和Vmax、Smax、SRmax测值与T2DM1组及正常对照组各测值相比差异均有显著性意义（P〈0.05或0.01）。结论VVI技术可用于T2DM足背动脉病变的分析,尤其对于临床未发现血管病变的糖尿病患者的内皮功能障碍可较早地进行检测。     

Augmented Velocity Index: A New Doppler Index Associated with Arterial Stiffness

Augmented Velocity Index (Avi) is a new Doppler index developed to quantify velocity changes at the late systolic peak. We examined its reliability, association with arterial stiffness and cardiovascular risk factors. The Avi is calculated as (late systolic peak velocity − early systolic peak velocity)/(highest peak systolic velocity − end-diastolic velocity). Fifty volunteers (mean age ± standard deviation: 43.5 ± 14.2 y, men: 52%) without known medical illnesses or drug use were recruited. Carotid Doppler waveforms with measurements of Avi were recorded. Carotid pressure waveforms were obtained by applanation tonometry for measurement of the Augmentation Index (AI). Clinical measurements including body mass index (BMI) and blood pressure (BP) were assessed, and fasting blood was taken for measurement of glycemia and lipid profile. Another 15 volunteers (age range: 22–60 y, men: 33.3%) were recruited to study the reliability of Avi measurement. The results revealed that carotid Avi closely correlated with the index of arterial stiffness, AI (r = 0.76, p < 0.001) on Pearson correlation. On multiple linear regression analysis, Avi remained a significant independent determinant of AI after adjustments for clinical variables. The Avi had significant associations with cardiovascular risk factors (age, BMI, total cholesterol, low-density lipoprotein cholesterol, systolic and diastolic BP). The intra-class correlation coefficients for inter-observer and intra-observer reliability of Avi measurements were 0.93 (95% confidence interval [CI]: 0.8–0.98) and 0.97 (95% CI: 0.92–0.99) respectively. In conclusion, the Avi is a reproducible new Doppler index, independently associated with arterial stiffness in terms of the AI, which initially correlated with cardiovascular risk factors.     

Cerebral perfusion during human liver transplantation

Summary. During transplantation of the liver cerebral perfusion was monitored by transcranial Doppler determined middle cerebral artery mean flow velocity (V_mean) and pulsatility index (PI) in six fulminant hepatic failure patients and 11 patients with chronic liver disease. In both groups of patients V_mean, PI and central haemodynamic variables were recorded during (1) the last preanhepatic hour; (2) the anhepatic phase; (3) the first 15 min of reperfusion; and (4) for the following 45 min of reperfusion. No significant differences were detected between the two groups of patients with respect to changes of variables with time. The V_mean (40±13 cm s^-1 [mean±SD]), thoracic electrical impedance (TI) (30±7 Ohm), heart rate (97±19 beats min^-1), mean arterial pressure (84±9 mmHg) and arterial carbon dioxide tension (PaCO₂, 4.5±0.4 kPa) remained stable in the anhepatic phase, while cardiac output (CO, 7.6±2.7 to 5.4±1.41 min^-1), stroke volume (SV, 79±26 to 56±15 ml) and PI (1.2±0.3 to 0.9±0.2) decreased (P<0.05). During reperfusion, CO (9.9±4.01 min^-1), SV (105±40 ml), Pa_CO2 (5.5±0.6 kPa), Vmean (57±17 cm s^-1) and PI (1.2±0.2) became elevated. Taken together, during the anhepatic phase of the liver transplantation a maintained central blood volume as indicated by the constant TI served for a stable blood pressure and in turn cerebral perfusion, whereas revascularization of the graft increased cerebral perfusion concomitant with an elevated carbon dioxide tension.     

肝硬化胆囊壁的高频超声分型与门静脉主干及右支血流动力学的关系

目的 探讨肝硬化胆囊壁的不同分型与门静脉主干及右支血流动力学变化的关系.方法 采用高频超声联合二维及彩色超声观察肝硬化组(69例)和对照组(30名)的胆囊壁分型、厚度、门静脉主干内径(D_(pv))、门静脉主干血流速度(V_(pv))、门静脉主干血流量(Q_(pv))、门静脉右支内径(D_(rpv))、门静脉右支血流速度(V_(rpv))、门静脉右支血流量(Q_(rpv)).同时根据胆囊壁的不同分型将69例肝硬化患者分为胆囊壁不厚亚组、单纯增厚亚组和双边亚组,对比肝硬化各组与对照组以上检测指标的差异.结果 各组间胆囊壁厚度均存在差异(P<0.05);D_(pv)除胆囊壁不厚亚组与单纯增厚亚组间差异无统计学意义外,其余各组间差异均有统计学意义(P<0.01);V_(pv)仅单纯增厚亚组与对照组、双边亚组与对照组间差异有统计学意义(P<0.01);Q_(pv)在双边亚组与其余各组间差异有统计学意义(P<0.05).D_(rpv)、Q_(rpv)各组间差异均无统计学意义;V_(rpv)对照组分别与单纯增厚亚组及双边亚组间差异有统计学意义(P<0.05).肝硬化组与对照组Q_(rpv)/Q_(pv)比值差异无统计学意义(P>0.05).胆囊壁厚度与D_(pv)呈正相关(r=0.886,P<0.01).结论 肝硬化时高频超声下胆囊壁的不同分型与门静脉主干血流动力学变化关系密切,而与门静脉右支血流动力学变化无相关性;胆囊静脉回流受阻并非肝硬化门静脉高压胆囊壁变化主要的血流动力学原因,其发生可能有更内在的机制.     

Color Doppler velocity profile assessment of portal hemodynamics in cirrhotic patients with portal hypertension: correlation with esophageal variceal bleeding

PURPOSE: Using the color Doppler velocity profile (CDVP), we investigated portal hemodynamics and their relationship with esophageal variceal bleeding (EVB) in patients with cirrhosis and portal hypertension. METHODS: The hemodynamics of the portal trunk, right anterior portal branch, and splenic vein were evaluated in 69 cirrhotic patients with portal hypertension and 46 healthy volunteers. The CDVP, a recently developed Doppler software, was used to measure blood flow velocity and flow volume; evaluate the spatial distribution of flow velocities in the cross-section of a vessel (velocity profile), as reflected by the profile parameter (n); and assess changes in flow volume over time (flow profile). The congestion index was calculated by dividing the cross-sectional area by the maximum cross-sectional velocity (CSVmax). The hemodynamic features were compared between patients without a history of EVB [EVB(-)] and those with a history of EVB [EVB(+)], and a logistic regression model was employed to identify factors associated with EVB. RESULTS: Compared with the healthy group, the cirrhotic group had a significantly lower mean CSVmax in the portal trunk and right anterior portal branch (both p < 0.01), a significantly elevated mean flow volume in the splenic vein and portal trunk (both p < 0.01), a significantly elevated mean ratio of splenic vein flow volume to portal trunk flow volume (SV/PT) (p < 0.001), and a significantly greater mean congestion index in the portal trunk, right anterior portal branch, and splenic vein (all p < 0.01). In the cirrhotic group, there was a significantly higher incidence of a flat flow pattern in the right anterior portal branch and a phasic flow pattern in the splenic vein than in the healthy group (both p < 0.01). Among cirrhotic patients, the EVB(+) group had a significantly greater mean flow volume in the splenic vein (p < 0.01), greater mean SV/PT (p < 0.01), greater mean spleen size (p < 0.05), and lower mean portal trunk n value (p < 0.05) compared with the EVB(-) group. Logistic regression analysis revealed that the SV/PT and portal trunk n value were independent EVB-related factors. CONCLUSIONS: The results suggest that portal hemodynamics in cirrhotic patients are characterized by passive congestion and increased blood flow. However, these 2 features had different preponderances in different parts of the portal venous system. Increased flow in the splenic vein may be the primary source of increased portal flow and may play a role in the development of EVB. The SV/PT and portal trunk n value may be valuable factors for predicting EVB.     

Accuracy and Reproducibility of a Novel Dual-Beam Vector Doppler Method

Conventional Doppler ultrasound (US) investigations are limited to detect only the axial component of the blood velocity vector. A novel dual-beam method has been recently proposed in which the Doppler angle is estimated through a reference US beam, and the velocity magnitude through a measuring US beam, respectively. In this study, the performance of such a method has been assessed quantitatively through in vitro and in vivo measurements made in different experimental conditions. In vitro, more than 300 acquisitions were completed using seven transducers to insonify a straight tube phantom at different Doppler angles. In steady laminar flow conditions, the velocity magnitude was measured with mean error of –1.9% (95% confidence interval: –2.33% to –1.47%) and standard deviation of 3.4%, with respect to a reference velocity. In pulsatile flow conditions, reproducibility tests of the entire velocity waveforms provided an average coefficient of variation (CV) of 6.9%. For peak velocity measurements made at five Doppler angles and three flow rates, the intrasession and intersession CVs were in the range 0.8–3.7% and 2.9–10.6%, respectively. The peak systolic velocities (PSVs) in the common carotid arteries of 21 volunteers were estimated with 95% limits of agreement of ± 9.6 cm/s (intersession). This analysis shows that the proposed dual-beam method is capable of overcoming the Doppler angle ambiguity by producing reliable velocity measurements over a large set of experimental conditions. (E-mail: piero.tortoli@unifi.it)     

Pulsed Doppler with B-mode imaging for quantitative blood flow measurement.

A technique is described, using the UI Octoson and a frequency-offset pulsed Doppler system, to obtain fully quantitative blood flow measurements in deep-lying vessels. By uniformly insonating the vessel and using a mean frequency Doppler demodulator, average velocity is obtained regardless of the velocity profile. B-scan imaging provides the necessary anatomic information to calculate volume flow from this average velocity. Results of in vitro flow measurement tests indicate accuracies of ± 14% rms error, ± 32% maximum error. The causes of error appear to be well understood, and in a number of cases they can be corrected. Preliminary clinical measurements of fetal umbilical vein flow and adult right branch portal vein flow are also presented.