Intracranial blood flow: quantification with duplex Doppler and color Doppler flow US

The authors compared changes in cerebral blood flow (CBF), determined by means of injection of radiolabeled microspheres, with Doppler blood flow measurements obtained simultaneously in the middle (n = 9) and anterior cerebral arteries (n = 3) in 12 newborn lambs. Doppler estimates of blood flow and mean blood flow velocity correlated well with changes in CBF. However, with changes in mean blood flow velocity, the degree of change in CBF tended to be underestimated. The resistive index correlated well with perfusion pressure but correlated weakly with cerebrovascular resistance and poorly with changes in CBF. Doppler blood flow estimates and mean blood flow velocities correlate well with changes in CBF and allow significant improvement in accuracy over instantaneous velocity or pulsatility measurements alone. Determination of absolute blood flow remains difficult due to systolic and diastolic differences in vessel diameter and intrinsic error in true diameter measurement with currently available color flow technology.     

Cannula-induced vertebral steal in neonates during extracorporeal membrane oxygenation: detection with color Doppler US.

To determine whether flow through the subclavian artery might be affected during extracorporeal membrane oxygenation (ECMO), 40 neonates were examined with color Doppler ultrasound during and after ECMO. Retrograde flow in the right vertebral artery, noted in 12 of the 40 neonates (30%), was consistent with vertebral steal. Brachial systolic velocity was significantly less (P less than .01) on the right than on the left side in neonates both with and without vertebral steal. When the arterial cannula was removed after ECMO, vertebral artery flow became antegrade with symmetric velocity. Brachial velocities became symmetric in infants without vertebral steal, but mild asymmetry persisted in neonates who had had vertebral steal. Only one neonate had clinical signs of arm ischemia, which resolved promptly after removal of the cannula. No surviving neonates (n = 11) had neurologic findings related to the vertebrobasilar insufficiency over a 12-22-month period of observation. Vertebral steal appears to be common during ECMO and is resolved after removal of the cannula.     

Quantified power Doppler US of tumor blood flow correlates with microscopic quantification of tumor blood vessels

P:URPOSE: To evaluate the ability of a quantified power Doppler ultrasonography (US) system to help quantitate differences in tumor vascularity after radiation therapy and administration of tumor necrosis factor (TNF). MATERIALS AND METHODS: Murine glioblastoma tumors were grown in the thighs of two sets of 25 mice each. Each mouse was assigned to one of four treatment groups: control (no treatment), radiation therapy, TNF therapy, or combination therapy (both radiation and TNF therapies). Mice were then evaluated with quantified power Doppler US, and a vascularity index (color area) was calculated for different tumor regions in each group. The tumors were then excised, and histologic evaluation was performed by using an immunofluorescence-tagged monoclonal antibody against blood vessel endothelium. The number of stained blood vessels per high-power field was correlated with the sonographically determined vascularity index. RESULTS: The color area of the total tumor decreased to 37% of that in the control group in mice treated with radiation therapy alone (P: =.02), 26% of that in the control group in mice treated with TNF alone (P: =.05), and 8% of that in the control group in those treated with both TNF and radiation (P: =.006). These results correlated well with the quantified results from immunofluorescent staining (r = 0.98). CONCLUSION: Quantified power Doppler US is a noninvasive method for the evaluation of tumor vascularity and blood flow.     

Intratumoral blood flow: evaluation with color Doppler echography

Blood flow in several types of tumors (two hepatomas, two hemangiomas, two renal cell carcinomas, one hydatidiform mole, and five invasive moles) was assessed with real-time two-dimensional color Doppler echography (ultrasound). In one of the hepatomas and all five of the invasive moles (but not in the hydatidiform mole or in either of the hemangiomas), the intratumoral flow was demonstrated with color Doppler echography, correlating well with the angiographic or dynamic computed tomographic findings. In the invasive moles, rapid blood flow was seen within the hypoechoic zone of the tumor. On follow-up study of four of the invasive moles, disappearance of the hypoechoic area due to blood flow was observed when chemotherapy was successful. Trophoblastic disease is considered to be the best application for color Doppler echography because it provides accurate evaluation of residual tumor after chemotherapy.     

Renal masses: characterization with Doppler US.

The vascularity of indeterminate renal masses in 70 patients was investigated prospectively with duplex ultrasound. The peak-systolic Doppler shift frequency obtained from the renal mass was utilized to attempt distinction between benign and malignant lesions. With use of the criterion of a peak-systolic Doppler shift frequency of 2.5 kHz or greater as evidence of neovascularity, 26 of 37 malignant lesions demonstrated tumor signals (70% sensitivity). Thirty-one of 33 benign lesions lacked tumor signals (94% specificity). Both of the false-positive lesions were infections with inflammatory masses, with peak frequencies of 3.0 and 3.7 kHz. Tumor vascularity in most malignant renal mass lesions gives rise to abnormal, high-frequency, Doppler-shifted signals that can aid the differential diagnosis of renal masses.     

Absolute flow measurements using pulsed Doppler US. Work in progress

Quantitative flow measurements were assessed in both laboratory and canine models using pulsed Doppler ultrasonography (US). A hydrodynamic model consisting of a Harvard pulsatile pump, a water bath, tubing, and a variable resistance reservoir was used to obtain absolute volumetric flow measurements. Parameters including angle of incidence, size of tubing, stroke volume, stroke rate, sample volume, and transducer frequency were changed independently. The effect of varying these parameters on the determination of absolute flow was analyzed. Absolute flow measurements using duplex US were performed in the canine aorta and femoral artery with reference to the electromagnetic flow probe. These data are presented, along with methods to reduce error in flow measurements that can be directly applied to quantitative estimates of blood flow in humans.     

Testicular tumors: findings with color Doppler US.

A study of 28 patients with surgically proved testicular tumors was performed to determine the appearance at color Doppler ultrasound (US) scanning. There was a general correlation of tumor size and vascularity. Twenty of 21 (95%) tumors larger than 1.6 cm were hypervascular. Six of seven (86%) tumors smaller than 1.6 cm were hypovascular. One small, 1.1-cm-diameter seminoma was hypervascular, and one 2.8-cm-diameter seminoma was hypovascular. The histologic findings of the tumor did not correlate with the vascularity of the lesion as seen at color Doppler US. Resistive indexes ranged from .476 to 1.0 (mean, 0.70). Peak systolic velocities ranged from 8.4 cm/sec to 64.9 cm/sec (mean, 9.8 cm/sec). Venous flow was detected in eight tumors. The gray-scale findings, as well as history and physical examination findings, correctly suggested a neoplasm in all cases. The findings at color Doppler US were prospectively interpreted as indicative of neoplasm in 27 cases and as indicative of inflammation in one case. The authors conclude that color Doppler US scanning has only a limited role in the evaluation of testicular tumors.     

Superior mesenteric artery blood flow velocity and estimated volume flow: duplex Doppler US study of preterm and term neonates

To obtain information about intestinal hemodynamics of healthy neonates, the authors assessed velocity and volume of blood flow with duplex Doppler sonography in the superior mesenteric artery (SMA) in 91 stable preterm and term neonates. Blood flow velocity in the SMA and estimated volume blood flow increased linearly with gestational age and increasing body weight. The mean estimated volume blood flow (+/- standard deviation) was 43 mL/kg/min +/- 13 and did not depend on differences in body weight. The authors also assessed blood flow velocity in the SMA and volume blood flow in 18 infants with conditions that may affect blood supply to the bowel. Twelve infants who were small for gestational age appeared to have an abnormally low resistance of the vascular bed of the SMA during the 1st days of life, as compared with stable appropriate-for-gestational-age infants matched for gestational age. Three of six term neonates with cardiovascular abnormalities had left ventricular outflow obstruction and an abnormal blood flow velocity waveform of the SMA, suggesting a decrease in blood supply to the bowel. The results of this study may help in evaluations of intestinal perfusion in infants with abnormal conditions.     

Right carotid artery ligation in neonates: classification of collateral flow with color Doppler imaging

Extracorporeal membrane oxygenation (ECMO) is a lifesaving procedure for neonates that involves permanent ligation of the right common carotid artery. To determine the collateral flow patterns that develop after ligation, 58 infants underwent a total of 115 color Doppler imaging studies during (n = 54), within 1 month after (n = 36), or more than 1 month after (n = 25) ECMO. On the basis of the direction of flow in the right internal carotid artery (ICA) proximal and distal to the right posterior communicating artery (PCoA), 85 of the 115 studies were placed in one of three categories: (a) Anterior communicating artery (ACoA) dominance (n = 22), with retrograde flow in the entire right ICA, was most common during ECMO and was never seen more than 1 month after ECMO. (b) PCoA dominance (n = 47), with antegrade right ICA flow distal to the right PCoA but retrograde proximally, was common during all time periods. (c) External carotid artery (ECA) dominance (n = 16), with antegrade flow throughout the right ICA, was noted in 53% of studies more than 1 month after ECMO but in only 9% of earlier studies. Patterns changed from ACoA to PCoA to ECA dominance in 17 infants, but no change in the opposite direction was noted.     

TCD与彩色多普勒超声对椎动脉流速减慢的对比研究

目的:对比分析椎动脉血流速度减慢患者经颅多普勒(TCD)与彩色多普勒超声(CDFI)检测结果,探讨其有无差异。方法:应用TCD和CDFI分别检测82例椎动脉血流速度减慢患者的椎动脉血流动力学指标及二维结构。结果:TCD与CDFI所测椎动脉血流速度和阻力指数(RI)值比较无差异(P0.05)。结论:TCD与CDFI联合检测椎动脉血流速度减慢患者,可证实椎动脉血液循环障碍的客观存在及病变部位所在,揭示了椎动脉血流速度减慢的病理基础。