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PubMed1997

Normal pediatric testis: comparison of power Doppler and color Doppler US in the detection of blood flow.

PURPOSE: To compare power Doppler and conventional color Doppler ultrasound (US) in the detection of blood flow in the normal pediatric testis and to assess the symmetry of blood flow and the spectral Doppler tracing waveforms in the normal pediatric testis. MATERIALS AND METHODS: Testicular blood flow was assessed prospectively in 68 testes in 34 boys (age range, 6 weeks to 13 years; mean age, 4.6 years) with both conventional color and power Doppler US. Intratesticular blood flow was graded as follows: 0, no intratesticular flow; 1, single intratesticular Doppler signal identified; and 2, multiple intratesticular Doppler signals identified. The symmetry of intratesticular flow was assessed both subjectively and objectively by using the same grading system. Spectral Doppler tracings were obtained in 62 testes in 31 patients. RESULTS: Power Doppler US demonstrated intratesticular blood flow in 66 (97%) testes. Color Doppler US demonstrated intratesticular blood flow in 60 (88%) testes. Combined techniques depicted blood flow in all 68 (100%) testes. Testicular blood flow was judged symmetric in all 34 (100%) patients with power Doppler US and in 31 (91%) patients with color Doppler US. Spectral Doppler tracings demonstrated absence of diastolic flow in 20 (32%) of 62 testes. CONCLUSION: In children, power Doppler US is more sensitive than color Doppler US in the detection of intratesticular blood flow. With power Doppler US, testicular blood flow in healthy children is symmetric, underscoring that the asymptomatic testis can be used as a baseline for assessing flow in the symptomatic testis.

Child, Preschool↗

PubMed1997

Differentiation of hepatocellular adenoma and focal nodular hyperplasia of the liver: comparison of power Doppler imaging and conventional color Doppler sonography.

The aim of our study was to compare the diagnostic efficacy of power Doppler imaging and conventional color Doppler sonography for differentiating between hepatocellular adenoma (HCA) and focal nodular hyperplasia (FNH) of the liver. Thirty-one focal liver lesions (in 29 patients) with histologic proof of HCA (n = 9) or FNH (n = 22) were studied with power and color Doppler sonography according to a standardized examination protocol. The size of the lesions ranged between 1.5 and 14.5 cm (HCA, 3.5-14.5 cm, mean +/- SD 7.3 +/- 3.3 cm; FNH, 1.5-9.1 cm, mean +/- SD 5.1 +/- 2.1 cm). Intratumoral vessels with a venous Doppler spectrum, associated with either pulsatile or continuous peripheral flow, were detected in HCA (eight of nine lesions by power Doppler imaging and six of nine by color Doppler imaging) but not in FNH. In contrast, color signals with an arterial Doppler spectrum, radiating from the center to the periphery of the lesion, were depicted in FNH (20 of 22 cases by power Doppler imaging and 15 of 22 by color Doppler sonography) but not in HCA. Differentiation of HCA and FNH was achieved in 28 of 31 cases (90 %) by power Doppler imaging and in 21 of 31 (68 %) by color Doppler sonography (p < 0.01). Power Doppler imaging is superior to conventional color Doppler sonography in the depiction of the intratumoral flow characteristics of HCA and FNH, and enables a more accurate differential diagnosis than color Doppler sonography.

Adenoma, Liver Cell↗

PubMed1998

Transjugular intrahepatic portosystemic shunts: improved evaluation with echo-enhanced color Doppler sonography, power Doppler sonography, and spectral duplex sonography.

OBJECTIVE: We assessed the feasibility of contrast-enhanced color Doppler, power Doppler, and spectral duplex sonography for visualization and quantification of flow through transjugular intrahepatic portosystemic shunts (TIPS) in patients in whom the baseline sonographic evaluation was unsatisfactory. SUBJECTS AND METHODS: Thirty-three patients underwent color Doppler, power Doppler, and spectral duplex sonography after TIPS insertion or before TIPS revision (mean time interval +/- SD, 1 +/- 1 day). All sonograms were obtained before and after patients received echo-enhancing contrast material. Sonography was evaluated with regard to presence or absence of flow in the mid portion, portal segment, and hepatic segment of the shunt. The maximal peak velocity was measured in the mid portion of the shunt. For identifying and quantifying stenoses, the percentage of luminal diameter reduction was calculated at the tightest part of the shunt. Shunt angiography and measurements of portosystemic pressure gradients were independently evaluated and compared with the sonographic findings. RESULTS: Flow visualization on unenhanced color Doppler sonography was significantly improved through the use of power Doppler sonography and contrast-enhanced color Doppler and power Doppler sonography (p < .01). Between contrast-enhanced power Doppler and contrast-enhanced color Doppler sonography, a significant difference was found in the portal and hepatic segments (p < .05). All shunt stenoses (n = 8) and occlusions (n = 3) were revealed by power Doppler sonography, whereas color Doppler sonography failed to reveal six of eight stenoses. Compared with unenhanced sonography, the quality of spectral duplex sonography was improved in eight patients after contrast enhancement (p < .05). Maximal peak velocity ranged from 54 to 252 cm/sec (mean +/- SD, 132.7 +/- 52.1 cm/sec) in normal shunts and from 24.5 to 70.0 cm/sec (mean +/- SD, 45.0 +/- 18.9 cm/sec) in stenosed shunts. No correlation was found between maximal peak velocity and portosystemic pressure gradients (r = .28). CONCLUSION: Unenhanced power Doppler and contrast-enhanced color and power Doppler sonography can be helpful in the assessment of TIPS status in patients who previously underwent unsatisfactory sonography. These techniques may allow anatomic evaluation and quantification of shunt stenosis in most patients. Contrast enhancement may also considerably improve the quality of spectral duplex sonography.

Adult↗

PubMed2006

Comparison between color Doppler cineloop- and conventional spectral Doppler-derived maximum velocity and flow in the umbilical vein.

OBJECTIVE: To compare the umbilical venous flow velocity derived from color Doppler cineloop recordings with that derived from conventional spectral Doppler in normal pregnancies. METHOD: In 18 uncomplicated pregnancies between 19 and 39 weeks' gestation, color Doppler was used to find the maximum velocity in the cross-sectional vessel area of a free-floating loop of the umbilical vein. The maximum velocity was determined using the software tool HDI_Lab (Philips Medical Systems) after tracing the vessel area of interest. Conventional spectral Doppler was then used to determine the maximum velocity with the High-Q machine option. The cross-sectional area of the umbilical vein was determined using B-mode imaging and was subsequently used to determine the umbilical volume flow from both Doppler methods. Assuming a parabolic flow profile in the umbilical vein, the mean velocity is equal to half the maximum velocity. The fetal weight was estimated from fetal biometry using the four-parameter Hadlock formula. RESULTS: Maximum velocity was significantly (P = 0.003) higher with color Doppler cineloop (14.3 +/- 2.5 cm/s) compared with spectral Doppler (12.7 +/- 3.2 cm/s). Therefore, using the same cross-sectional area for both methods, the umbilical blood flow was significantly higher (P = 0.001) with color Doppler cineloop (127.9 +/- 59.0 mL/min) than it was with spectral Doppler (112.8 +/- 54.1 mL/min). The umbilical blood flow expressed as volume flow per kg fetal weight was significantly (P = 0.01) higher with color Doppler cineloop (126.0 +/- 57.0 mL/min/kg) than it was with spectral Doppler (115.0 +/- 53.0 mL/min/kg). CONCLUSIONS: Umbilical venous flow velocity derived from color Doppler cineloops is approximately 10% higher than that derived from spectral Doppler-derived velocity. The reduced angle dependence of the color Doppler cineloop technique and the large sampling area of the cross-sectional vessel should allow better determination of the correct maximum velocity in the umbilical vein.

Blood Flow Velocity↗

PubMed1991

Limitations of flow detection by color Doppler: in vitro comparison to conventional Doppler.

There is little awareness of the limitations of flow detection with the commercially available color Doppler flow mapping system. The influence of flow velocity, ultrasound attenuation, and penetration depth on flow detection in color Doppler (Toshiba SSH 65A) were therefore studied in vitro and compared with conventional Doppler. The flow model had physiological flow volumes and laminar flow with parabolic velocity profile in a horizontal tube of Lucite with less than 3 degrees of coincidence. Conventional Doppler flow velocity measurements correlated highly with laser Doppler anemometry results (r = 0.99, SEE = 3 cm/sec). Signal strength of color Doppler and pulsed Doppler was semi-quantitatively graded using a scale from 0 to 5. Scale 1 (sparse signals) was useless for any assessment in color Doppler but just allowed velocity measurement in pulsed Doppler. Using 19-dB attenuation, flow velocities greater than 100 cm/sec had good scores with moderate gain, 60-100 cm/sec needed increasing gain, and velocities less than 40 cm/sec were not detectable with color Doppler but readily so with pulsed Doppler. With increasing attenuation (1-29 dB) and also with increasing penetration depth, flow detection was reduced significantly (P less than 0.001) more in color Doppler than in the pulsed technique (P less than 0.01). In conclusion, low flow velocities, high attenuation, and greater than 8 cm penetration depth may hamper flow detection in color Doppler and, thus, diagnostic accuracy. Conventional Doppler with its superior accuracy and sensitivity should therefore consolidate diagnostic ultrasound assessment.

Blood Flow Velocity↗

PubMed1996

Assessment of tumor vascularity in hepatocellular carcinoma: comparison of power Doppler US and color Doppler US.

PURPOSE: To compare power Doppler ultrasound (US) with conventional color Doppler US for the assessment of tumor vascularity in hepatocellular carcinoma (HCC). MATERIALS AND METHODS: Fifty-one patients with 88 histologically proved HCCs were examined with power and color Doppler US according to a standardized examination protocol. Findings at Doppler studies of each lesion were correlated with findings at digital subtraction angiography. RESULTS: Angiography revealed neovascularization or staining in 75 (85%) of 88 lesions. Intratumoral color signals with an arterial Doppler spectrum were detected in 69 (92%) of 75 angiographically hypervascular tumors at power Doppler US and in 55 (73%) of 75 at color Doppler US (P < .01). Blood flow signals with an arterial Doppler spectrum were not detected at power or color Doppler US in any of the 13 angiographically hypovascular tumors. The small size and the deep location of the lesion significantly reduced (P < .05) the detection rate of blood flow signals at color Doppler US but did not affect the results of power Doppler US. CONCLUSION: Power Doppler US is superior to conventional color Doppler imaging in the depiction of tumor vascularity in HCC.

Aged↗

PubMed1997

Testicular blood flow in boys as assessed at color Doppler and power Doppler sonography.

PURPOSE: To investigate at which age testicular blood flow can be demonstrated consistently by color Doppler sonography and power Doppler sonography. MATERIALS AND METHODS: In this prospective study, 172 normal testes of 86 boys (age range, 4 days to 15 years) were examined with gray-scale ultrasound, color Doppler sonography, and power Doppler sonography. Presence of supratesticular and capsular vessels was determined, testicular volumes were assessed, and intratesticular vessels were quantified by using a semiquantitative score. RESULTS: Supratesticular and capsular vessels were always detectable. Demonstration of intratesticular vessels was inconsistent until 8 years of age at power Doppler sonography and until 12 years of age at color Doppler sonography. Power Doppler sonography depicted more vessels than did color Doppler sonography in 37 (22%) testes (P = .001), and it depicted vessels in 13 (25%) of 51 testes in which color Doppler sonography could not (P = .0002). Correlation between the number of visible intratesticular vessels was slightly closer with age than with testicular volume (r = .59, r = .55 for color Doppler sonography and power Doppler sonography, respectively). CONCLUSION: Intratesticular blood flow can be detected more sensitively and more consistently from a younger age on with power Doppler sonography than with color Doppler sonography.

Adolescent↗

PubMed2003

The Doppler assessment in multiple pregnancy randomised controlled trial of ultrasound biometry versus umbilical artery Doppler ultrasound and biometry in twin pregnancy.

OBJECTIVE: To assess the addition value of umbilical artery Doppler ultrasound added to standard ultrasound biometry measurements in the management of twin pregnancies. DESIGN: A prospective randomised controlled multicentre trial of women with twin pregnancies. SETTING: Tertiary level referral hospitals in Australia, New Zealand and Southeast Asia. POPULATION: Pregnant women with twin pregnancies. METHODS: Women were randomised at 25 weeks of gestation to receive either standard ultrasound biometric assessment or standard assessment plus Doppler ultrasound umbilical artery flow velocity waveform analysis. The studies were repeated at 30 and 35 weeks unless otherwise indicated. Physicians were advised to institute close fetal surveillance in the presence of an abnormal umbilical artery Doppler study or with biometry indicators of fetal compromise. MAIN OUTCOME MEASURES: Standard obstetric (mode of delivery, perinatal mortality, hypertension, antenatal admissions and gestation at delivery) and neonatal (5 minute Apgar scores <5, admissions to neonatal nursery and requirements for ventilation) outcomes and statistical analysis was on intention-to-treat. There were no significant differences between the two groups with respect to demography, antenatal, peripartum and neonatal outcomes. There was no difference in the perinatal mortality rate in the no Doppler group (n = 264), which was 11/1000 live births, and the Doppler group (n = 262), which was 9/1000 live births. There were three unexplained intrauterine deaths in the no Doppler group and none in the Doppler group (OR 0.14, 95% CI 0.01-1.31). Two intrauterine deaths in the Doppler group were due to cord prolapse in labour and a fetomaternal haemorrhage, both very unlikely to be influenced by Doppler surveillance. CONCLUSIONS: In this study, close surveillance in twin pregnancy resulted in a lower than expected fetal mortality from 25 weeks of gestation in both the no Doppler and Doppler groups. The lower rate of unexplained fetal death in the no Doppler group was not significantly different from the Doppler group.

Adult↗

PubMed1997

Visualization of tumor vessels in hepatocellular carcinoma. Power Doppler compared with color Doppler and angiography.

PURPOSE: To assess the visualization of tumor vessels in hepatocellular carcinoma (HCC) by power Doppler sonography. MATERIAL AND METHODS: We examined 40 patients with 47 HCC lesions by means of power Doppler sonography and compared its visualization of tumor vessels with those of color Doppler and angiography. RESULTS: In 38 (81%) of the 47 lesions, power Doppler sonography improved the visualization of tumor vessels compared with color Doppler sonography; in the remaining lesions no significant difference was noted. In lesions located within 7 cm in depth, there was no significant difference between power Doppler sonography and angiography. In 10 (83%) out of 12 small (< or = 2 cm in diameter) lesions and in 11 (85%) out of 13 hypovascular lesions, power Doppler sonography performed considerably better than angiography. In deeper-seated lesions, however, angiography was significantly superior to power Doppler sonography. CONCLUSION: Power Doppler sonography is more sensitive in detecting the fine tumor vessels in most HCCs than color Doppler sonography. In addition, power Doppler sonography can replace angiography in evaluating tumor vascularity in HCCs except in lesions that are deep-seated or located near the heart. In these lesions, angiography can complement power Doppler sonography in demonstrating tumor vessels.

Aged↗

PubMedDate not supplied

Power Doppler imaging: clinical experience and correlation with color Doppler US and other imaging modalities.

Power Doppler imaging has recently gained attention as an additional color flow imaging technique that overcomes some of the limitations of conventional color Doppler ultrasound (US). Limitations of conventional color Doppler US include angle dependence, aliasing, and difficulty in separating background noise from true flow in slow-flow states. Owing to its increased sensitivity to flow, power Doppler sonography is valuable in low-flow states and when optimal Doppler angles cannot be obtained. Longer segments of vessels and more individual vessels can be visualized with power Doppler US than with conventional color Doppler sonography. Power Doppler sonography increases diagnostic confidence when verifying or excluding testicular or ovarian torsion and confirming thrombosis or occlusion of vessels. Power Doppler sonography also improves evaluation of parenchymal flow and decreases examination times in technically challenging cases. Power Doppler US is a useful adjunct to mean-frequency color Doppler sonography, especially when color Doppler US cannot adequately obtain or display diagnostic information.

Adolescent↗

PubMed1996

An approach for the use of Doppler ultrasound as a screening tool for hemodynamically significant stenosis (despite heterogeneity of Doppler performance). A multicenter experience. Asymptomatic Carotid Atherosclerosis Study Investigators.

BACKGROUND AND PURPOSE: The Asymptomatic Carotid Atherosclerosis Study (ACAS) Doppler validation study assessed the performance of individual Doppler machines across a spectrum of laboratories. We attempted to establish a threshold specific to individual machines to predict angiographically defined hemodynamic stenosis. The reliability of these Doppler ultrasound criteria was prospectively and independently evaluated among patients screened with ultrasound in the ACAS trial. METHODS: Regression techniques were used to establish the relationship between Doppler velocity and percent stenosis by angiography for 63 specific Doppler machines. This relationship was used to establish a Doppler threshold to provide a 90% positive predictive value (PPV) of a 60% stenosis by angiography. The sensitivity of each Doppler machine to detect a 60% stenosis (at the 90% PPV threshold) was estimated. The efficacy of these Doppler thresholds was then prospectively evaluated by calculating the PPV among ACAS participants eligible by ultrasound. RESULTS: Of the 63 machines, 13 (21%) had an excellent sensitivity (80%+) at 90% PPV. In 32 devices (51%) only a marginal sensitivity (50% to 80%) could be achieved. In 9 devices (14%) the sensitivity was poor (0% to 50%), and in 9 (14%) no threshold could be established. Despite the heterogeneity of Doppler performance, the standardization program worked as designed in the ACAS trial. Of 825 surgical patients, 399 were eligible by Doppler and 395 subsequently underwent angiography. Of these, 32 (8.1%; 95% confidence interval, 5.4% to 10.8%) did not have hemodynamically significant stenosis by arteriography, a proportion nonsignificantly lower than the planned 10% by the PPV. CONCLUSIONS: The performance of Doppler ultrasound was highly variable. This suggests that Doppler performance is likely overstated in the literature, but specific devices may perform satisfactorily to detect individuals with hemodynamically significant stenosis. Because performance differs substantially among devices, local investigators are strongly urged to maintain local standardization series. With such standardization, ultrasound performance is sufficient for admission to clinical trials and as the is sufficient for admission to clinical trials and as the basis for carotid surgery. However, without quality control many ultrasound machines are not adequate to accurately predict the degree of carotid stenosis and should not be the only test to decide whether surgery is warranted.

Angiography↗

PubMedDate not supplied

Evaluation of the intratumoral vasculature of hepatocellular carcinoma by power doppler sonography: advantages and disadvantages versus conventional color doppler sonography.

BACKGROUND: To determine whether a difference exists in the relative ability of power Doppler sonography and conventional color Doppler sonography to detect the intratumoral vasculature of hepatocellular carcinoma based on lesion size and location. METHODS: Sixty patients with 88 hepatocellular carcinoma lesions that showed tumor staining on angiography and were enhanced on dynamic computed tomography were evaluated. Power Doppler sonography and color Doppler sonography were used to detect the intratumoral vasculature, and their sensitivity to blood flow was evaluated. RESULTS: Power Doppler sonography showed a superior detection rate for lesions smaller than 2 cm and located 4-8 cm from the abdominal surface in the right hepatic lobe as compared with color Doppler sonography (p < 0.01). Neither power Doppler sonography nor color Doppler sonography depicted the intratumoral vasculature of lesions located more than 8 cm from the abdominal surface (n = 14). Both color Doppler imagings exhibited a low detection rate for lesions in the left hepatic lobe (n = 31, p < 0.01). CONCLUSIONS: Power Doppler sonography should be applied in the evaluation of small or intermediate depth lesions because it is more sensitive to these lesions than color Doppler sonography, but it is not useful for left lobe and deep lesions.

Aged↗

PubMedDate not supplied

Evaluation of breast tumors with color Doppler imaging: a comparison with image-directed Doppler ultrasound.

Doppler ultrasound is an adjunct to other imaging modalities in differentiating benign from malignant breast tumors. Two groups of patients with breast nodules were examined using a 10/4.5 MHz (imaging frequency/pulsed Doppler frequency) image-directed Doppler probe and a 7.0/5.0 MHz color Doppler imaging probe, separately. Whenever flow signals were detected within or at the margin of the breast nodule, the lesion was considered to be malignant. In detecting malignant breast tumors, the sensitivity was 77.3% and 94.5%, specificity 83.3% and 40.1%, accuracy 81% and 63.4% for image directed Doppler and color Doppler imaging, respectively. We found color Doppler to be easier and more efficient in detecting the flow signals of neovascularity in breast tumor. Color Doppler exhibits a higher sensitivity in detecting the malignant breast tumors. However, more false-positive diagnoses were made. Color Doppler ultrasound also expedited the examination, and the whole procedure could be shortened from 35 minutes to 8 minutes compared with our previous examination performed by image-directed Doppler ultrasound. Due to its higher sensitivity and saving in examination time, we use color Doppler imaging as a routine procedure when solid lesions are observed in x-ray mammography or sonography, as a supplement to the diagnosis of breast tumors.

Adolescent↗

PubMed1985

Continuous-wave Doppler echocardiographic assessment of severity of calcific aortic stenosis: a simultaneous Doppler-catheter correlative study in 100 adult patients.

Studies of the correlation of aortic valve gradient determined by continuous-wave Doppler echocardiography and that determined at catheterization have, to date, involved young patients and nonsimultaneous measurements. We therefore obtained simultaneous Doppler echocardiographic and catheter measurements of pressure gradient in 100 consecutive adults (mean age 69, range 50 to 89 years). In 63 patients pressure measurements were obtained with dual-catheter techniques and in 37 they were obtained by withdrawal of the catheter from the left ventricle to the ascending aorta. Forty-six of these patients also underwent an outpatient Doppler study 7 days or less before catheterization. The simultaneous pressure waveforms and Doppler spectral velocity profiles were digitized at 10 msec intervals and maximum, mean, and instantaneous gradients (mm Hg) were derived for each. The correlation between the Doppler-determined gradient and the simultaneously measured maximum catheter gradient was r = .92 (SEE = 15 mm Hg), that between the Doppler-determined and mean catheter gradient was r = .93 (SEE = 10 mm Hg), and that between the Doppler and peak-to-peak catheter gradient was r = .91 (SEE = 14). The correlation between the nonsimultaneously Doppler-determined gradient and the maximum gradient measured by catheter was not as strong (r = .79, SEE = 24). The continuous-wave Doppler echocardiographic velocity profile represents the instantaneous transaortic pressure gradient throughout the cardiac cycle. The best correlation with continuous-wave Doppler-determined gradient was obtained with maximum and mean gradients measured by catheter. Continuous-wave Doppler echocardiography can be used to reliably predict the pressure gradient in adults with calcific aortic stenosis.

Aged↗

PubMed2002

Differential diagnosis of lymphadenopathy: power Doppler vs color Doppler sonography.

Our objective was to compare color and power Doppler sonography of superficial lymph nodes. One hundred ninety-three lymph nodes in 161 patients were assessed by color and power Doppler sonography using standardized settings. We tested which modality displayed more intranodal vessels and checked if these differences would have altered the diagnosis. Additional vessels were seen by color Doppler sonography in 18 nodes and by power Doppler sonography in 58 nodes. Amongst those nodes were 15 nodes which showed no vascularization in color Doppler sonography and 23 nodes with only few intranodal flow signals; however, the better sensitivity of power Doppler sonography had no impact on the diagnosis in 42 of 58 nodes. Diagnostic confidence was increased in 7 nodes which showed normal vessels only in power Doppler sonography, although missing flow signals were defined as a benign finding. Pathological vessels were displayed only by power Doppler sonography in 9 nodes, but 6 of these 9 results proved to be false positive. Power Doppler sonography displays more intranodal flow signals than color Doppler sonography, but the diagnostic impact is low because of an increased risk of false-positive results.

Adult↗

PubMed1996

A new Doppler method for quantification of volumetric flow: in vivo validation using color Doppler.

OBJECTIVES: This study was designed to assess the accuracy of a new Doppler method for quantification of volumetric flow in vivo. BACKGROUND: Noninvasive assessment of volumetric flow through heart valves and the great vessels remains a clinical goal. We present a new method for quantification of volumetric flow based on color Doppler mapping that computes velocity vectors over a surface normal to the point of scanning. This Doppler technique assumes only the incompressibility of the fluid. The method is basically independent of the angle of incidence between the ultrasound beam and the direction of blood flow and includes variations of flow area. METHODS: The color Doppler method was tested in seven anesthetized pigs by measuring pulmonary volumetric flows using multiplane Doppler echocardiography. The results were compared with those obtained by the thermodilution technique. In addition, volumetric flows across the mitral valve were determined in 10 normal volunteers by transthoracic Doppler echocardiography and compared with flows obtained with velocity-encoded magnetic resonance imaging (MRI). RESULTS: The mean value of the differences between the thermodilution technique and color Doppler were -0.16 +/- 0.94 liter/min for pulmonary volumetric flows (mean value of differences for [Thermodilution-Color Doppler] +/- 2 SD of differences). The mean value of the differences between MRI and color Doppler were 0.21 +/- 0.83 liter/min for mitral valvular volumetric flows (mean value of differences for [MRI-Color Doppler] +/- 2 SD of differences). CONCLUSIONS: The method showed close agreement with thermodilution and MRI for assessment of volumetric flow in vivo. It is therefore a noninvasive method with potential applications for cardiac output measurement and for quantification of volumetric flow of valvular insufficiency and restrictive lesions.

Adult↗

PubMed1996

Improved Doppler detection of proximal left anterior descending coronary artery stenosis after intravenous injection of a lung-crossing contrast agent: a transesophageal Doppler echocardiographic study.

OBJECTIVE: This study was designed to verify the usefulness of transesophageal Doppler recording of blood flow velocity in the proximal left anterior descending coronary artery, after a peripheral injection of a lung-crossing contrast agent (SHU 508A), in detecting and locating a hemodynamically significant stenosis (vessel narrowing > or = 50%) affecting this portion of the vessel. BACKGROUND: Transesophageal Doppler echocardiography has a limited diagnostic impact on the evaluation of proximal left anterior descending coronary artery stenoses. Peripheral injection of SHU 508A, a lung-crossing contrast agent enhancing Doppler signal to noise ratio in coronary arteries, may allow recording of localized disturbed blood flow velocity at the stenosis site even in the absence of a clear B-mode visualization of the vessel. METHODS: Transesophageal Doppler echocardiography, before and after echo contrast injection, was performed in 31 patients who underwent coronary angiography. Using color Doppler as a guide, pulsed wave Doppler recording of blood flow velocity in the left anterior descending coronary artery was attempted to detect a localized increase in blood flow velocity. B-mode evaluation of the vessel was also performed. RESULTS: Angiography showed a significant proximal left anterior descending coronary artery stenosis in 16 patients (group 1) and no stenosis in 15 patients (group 2). In 15 of 16 group 1 patients, Doppler after contrast injection revealed a localized velocity increase of at least 50% of the reference value; mean (+/-SD) percent increase in velocity was 150 +/- 89% (range 367% to 0%). In group 2 Doppler after contrast injection revealed a mild localized increase in velocity in four patients and no increase in velocity in the remaining 11 patients; mean (+/-SD) percent increase in velocity was 5 +/- 7% (range 21% to 0%, p < 0.001 vs. percent increase in group 1). When a percent velocity increase > or = 50% of the reference value was considered a positive criterion for detecting significant stenosis, the sensitivity and specificity were 92% and 100% respectively. The sensitivity of the evaluation before contrast injection or considering B-mode imaging alone was much lower (25% and 19%, respectively, p < 0.001 vs. evaluation after contrast injection). In addition, color Doppler after contrast injection correctly located the stenosis along the vessel, as compared with angiography. CONCLUSIONS: Blood flow evaluation of the proximal left anterior descending coronary artery by transesophageal Doppler echocardiography after contrast injection is a feasible and reliable method for detecting and locating significant stenoses affecting this part of the vessel and is an improvement over the traditional ultrasound approach.

Aged↗

PubMed1997

Doppler assessment of the uterine and uteroplacental circulation in the second trimester in pregnancies at high risk for pre-eclampsia and/or intrauterine growth retardation: comparison and correlation between different Doppler parameters.

During a 20-month period we studied 175 pregnant women at high risk for hypertensive disorders of pregnancy or intrauterine growth retardation, and 172 patients at low risk, in a prospectively designed cross-sectional trial. Using duplex pulsed wave Doppler ultrasound, we recorded blood velocity waveforms from both main uterine arteries, the uteroplacental arteries in the region of placental implantation and the umbilical artery at 21-24 weeks of gestation. Persistent notches in the main stem uterine arteries and elevated resistance indices of > 0.68 in the uterine arteries and > 0.38 in the uteroplacental arteries were defined as abnormal waveforms. The incidence of proteinuric pregnancy-induced hypertension (PPIH) and intrauterine growth retardation (IUGR) were recorded as main outcome measures. Doppler proved to be more efficient at predicting a complicated pregnancy in those patients who were at high risk: a positive medical history alone was associated with a three-fold greater risk of developing PPIH and/or IUGR. In the high-risk group a single pathological Doppler sign accounted for an additional three- to four-fold increased risk, and the combination of all three pathological signs, a seven-fold additional risk for later disease. In this group PPIH and/or IUGR was found in 58.3%, compared to 8.3% if Doppler results were normal. The criterion for the definition of pathological Doppler results, whether persistent notching, the resistance index (RI) of the main stem uterine artery, or the RI in the arteries of the uteroplacental bed, was of minor importance, as all Doppler parameters were strongly correlated. However, the combination of all parameters was superior to a single parameter, and a bilateral notch was superior to a unilateral notch in terms of minimizing false-positive results. However, Doppler was less powerful in the population at low risk. Here PPIH and/or IUGR was seen in 6.1-6.4% in the group with abnormal Doppler findings compared to 5.2% in pregnancies with normal findings. None of the patients showed bilateral notching. In conclusion, pathological Doppler velocimetry of the uterine and uteroplacental circulation was a powerful predictor of PPIH and/or IUGR in high-risk pregnancies, identifying a group in which 58.3% would suffer from disease later in pregnancy. A combination of several Doppler parameters was superior to a single parameter, although the parameters were strongly correlated with each other.

Blood Flow Velocity↗