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At least 271 records · Page 15Linked to original sources

PubMed2001

[Comparison of 3D power doppler ultrasound, color doppler ultrasound and digital subtraction angiography in carotid stenosis].

PURPOSE: To compare easy-to-perform three-dimensional power Doppler ultrasound (3D PDUS) to color Doppler ultrasound (CDUS) and digital subtraction angiography (DSA) in the assessment of internal carotid artery (ICA) stenoses in patients with severe atherosclerosis. METHODS: 26 ICA's (7 without stenosis, 4 low-, 4 middle-, and 11 high-grade stenoses) in 13 patients were examined with DSA, CDUS, and 3D PDUS. CDUS and 3D PDUS were performed with a 7.5 MHz standard transducer and a Sonoline Elegra ultrasound machine. The three methods were performed and interpreted by different persons who were not aware of the diagnoses. RESULTS: Regarding the degree of stenosis correlations between DSA and 3D PDUS were r = 0.98 (p < 0.001), between DSA and CDUS r = 0.97 (p < 0.001), and between CDUS and 3D PDUS r = 0.95 (p < 0.001). Sensitivity and specificity regarding the detection of a high-degree stenosis was 90% and 100% for 3D PDUS, and 100% and 93.3% for CDUS. CONCLUSION: Even in cases with severe atherosclerosis, both sonographic methods reveal similar results comparable to DSA. 3D PDUS does not result in a diagnostic improvement on CDUS, however, it does give the new opportunity for complete data storage, reconstruction, and survey presentations.

Aged↗

PubMed2004

Transcutaneous colour Doppler sonography of lung consolidations: review and pictorial essay. Part 1: pathophysiologic and colour Doppler sonographic basics of pulmonary vascularity.

Anatomically, the lung is characterised by a dual blood supply. The existence of a systemic bronchial arterial supply to the lung in addition to the pulmonary arteries was first described by Galen in the second century. From angiographic studies it is known that pulmonary lesions of different aetiologies are characterised by differences in arterial supply. Colour Doppler sonography makes it possible to classify pulmonary arteries by location, flow direction, and quantitative spectral curve analysis. This article will review pathophysiological and colour Doppler sonographic basics of pulmonary vascularity.

Humans↗

PubMed1993

[Signal processing in ultrasound imaging, Doppler and Doppler imaging].

The main purpose of signal processing in ultrasound imaging is the improvement of the image quality. The basics of three-dimensional, nonlinear image filtering are described in a simple way. For Doppler several million operations are computed per second to obtain the velocity distribution as a function of time. Various methods are described for overcoming the alias problem. For Doppler imaging the necessary computing power increases to several hundred million operations per second. Like other medical imaging methods, diagnostic ultrasound depends on powerful electronic computers.

Blood Flow Velocity↗

PubMed2000

Noninvasive diagnosis by Doppler ultrasonography of fetal anemia due to maternal red-cell alloimmunization. Collaborative Group for Doppler Assessment of the Blood Velocity in Anemic Fetuses.

BACKGROUND: Invasive techniques such as amniocentesis and cordocentesis are used for diagnosis and treatment in fetuses at risk for anemia due to maternal red-cell alloimmunization. The purpose of our study was to determine the value of noninvasive measurements of the velocity of blood flow in the fetal middle cerebral artery for the diagnosis of fetal anemia. METHODS: We measured the hemoglobin concentration in blood obtained by cordocentesis and also the peak velocity of systolic blood flow in the middle cerebral artery in 111 fetuses at risk for anemia due to maternal red-cell alloimmunization. Peak systolic velocity was measured by Doppler velocimetry. To identify the fetuses with anemia, the hemoglobin values of those at risk were compared with the values in 265 normal fetuses. RESULTS: Fetal hemoglobin concentrations increased with increasing gestational age in the 265 normal fetuses. Among the 111 fetuses at risk for anemia, 41 fetuses did not have anemia; 35 had mild anemia; 4 had moderate anemia; and 31, including 12 with hydrops, had severe anemia. The sensitivity of an increased peak velocity of systolic blood flow in the middle cerebral artery for the prediction of moderate or severe anemia was 100 percent either in the presence or in the absence of hydrops (95 percent confidence interval, 86 to 100 percent for the 23 fetuses without hydrops), with a false positive rate of 12 percent. CONCLUSIONS: In fetuses without hydrops that are at risk because of maternal red-cell alloimmunization, moderate and severe anemia can be detected noninvasively by Doppler ultrasonography on the basis of an increase in the peak velocity of systolic blood flow in the middle cerebral artery.

Blood Flow Velocity↗

PubMed2002

The role of Doppler left ventricular filling indexes and Doppler tissue echocardiography in the assessment of cardiac involvement in hereditary hemochromatosis.

Although cardiac dysfunction in hereditary hemochromatosis (HHC) can be evaluated by conventional echocardiography, findings are often not specific. To test the hypothesis that the assessment of (1) conventional Doppler left ventricular filling indexes and (2) intrinsic elastic properties of the myocardium by Doppler tissue echocardiography can both enhance the accuracy of echocardiographic diagnosis of cardiac involvement in HHC, a group of 18 patients with HHC (mean age 50 +/- 17 years) and 22 age-matched healthy subjects were studied. The following indexes were characteristic for HHC: (1) the duration of atrial reversal measured from pulmonary venous flow (ms) was longer (118 +/- 20 vs 90 +/- 16; P <.001); (2) systolic lateral mitral, early-diastolic medial mitral, and early-diastolic lateral tricuspid annular velocities were reduced by 23%, 31%, and 13%, respectively; (3) late-diastolic mean myocardial velocity and myocardial velocity gradient (MVG) were also reduced by 22% and 34%, respectively. Late-isovolumic relaxation (late-IVR) MVG (s(-1)) was positive in HHC as opposed to negative in healthy subjects (1.72 +/- 0.85 vs -0.89 +/- 1.15; P <.001) indicating impaired early-diastolic subepicardial relaxation in HHC. The assessment of atrial reversal flow duration, the difference in duration between A-wave and atrial reversal flow, and the presence of positive late IVR-MVG findings were the most accurate variables to differentiate patients with HHC from healthy subjects (80%, 67%, 94% sensitivity and 90%, 95%, 86% specificity, respectively).

Adult↗

PubMed2002

Acute effects of smoking on diastolic function in healthy participants: studies by conventional doppler echocardiography and doppler tissue imaging.

The acute effects of smoking on left ventricular (LV) function were studied in 36 healthy participants (mean age 38 +/- 10 years). The studies were made before and immediately and 30 minutes after smoking a cigarette. From apical 4- and 2-chamber views, the mitral annular velocities, determined by pulsed wave Doppler tissue imaging, were measured at 4 LV sites corresponding to the septum and the anterior, lateral, and inferior walls. A mean value from the 4 sites was used to assess LV function. The peak systolic, early diastolic, late diastolic, and the ratio of early to late diastolic velocities were recorded. In addition, other conventional Doppler echocardiographic diastolic parameters were also determined. Heart rate was increased immediately after smoking (from 67 +/- 8 to 74 +/- 10 bpm, P <.001). There was no change in systolic mitral annular velocity. Diastolic LV function was changed significantly immediately after smoking. The transmitral A wave increased (0.55 +/- 0.1 vs 0.7 +/- 0.1 m/s, P <.001), the transmitral E/A ratio decreased (1.5 +/- 0.6 vs 1.1 +/- 0.3, P <.001), and the transmitral E-wave deceleration time increased (186 +/- 42 vs 211 +/- 44 ms, P <.05). The diastolic myocardial velocity at the mitral annulus also changed significantly: the early diastolic velocity decreased (16 +/- 3 vs 15 +/- 3 cm/s, P <.001), the late diastolic velocity increased (10.9 +/- 2.2 vs 12 +/- 2.4 cm/s, P <.001), and the ratio of early to late diastolic annular velocities decreased (1.5 +/- 0.5 vs 1.2 +/- 0.4, P <.001). The changes in the transmitral flow velocities remained unaltered even 30 minutes afterward, although the heart rate returned to normal. The results were similar in both smokers and nonsmokers. Acute smoking of a cigarette influences LV diastolic function in healthy participants. The mechanism behind this effect cannot be explained only by changes in the heart rate or loading conditions. The mechanism is probably more complex.

Adult↗

PubMed2004

Audio-Doppler guidance using a small-caliber Doppler probe for internal jugular venous puncture for central venous catheterization in infants and children.

BACKGROUND: We evaluated an audio-Doppler with a small-caliber probe as a guide for central venous cannulation (CVC) via the internal jugular vein (IJV) in infants and children. METHODS: The right IJV was located with a small-caliber (2.0 mm in diameter) audio-Doppler probe using 10 MHz ultrasound. The probe was placed on the neck about the level of sixth cervical vertebra and was moved until the crisp pulsatile sound of the carotid artery was identified. Then the probe was moved laterally to identify the low-pitched venous hum of the right IJV. After marking the puncture site on the skin, a sterile cannulation procedure was performed. Ultimate success rate, cannulation time < 10 min, successful cannulation within three punctures, and complications were recorded. RESULTS: Ultimate success rate was 65.6% (42/64) in infants (< 12 m), and 94.7% (72/76) in children (12 m or older). Cannulation time < 10 min was 48.4% in infants, and 85.5% in children. Successful cannulation within three punctures was 45.3% in infants and 82.8% in children. Three carotid arterial punctures occurred. CONCLUSIONS: We were not able to demonstrate absolute superiority of the results utilizing this device over the reported results of traditional landmark techniques for CVC via the right IJV. However, this device may contribute to reducing complications and be of value in teaching residents where to insert a needle for an internal jugular puncture.

Anesthesia, General↗

PubMedDate not supplied

Measuring red blood cell flow dynamics in a glass capillary using Doppler optical coherence tomography and Doppler amplitude optical coherence tomography.

Blood, being a suspension of deformable red cells suspended in plasma, displays flow dynamics considerably more complicated than those of an ideal Newtonian fluid. Flow dynamics in blood capillaries of a few hundred micrometers in diameter are investigated using Doppler optical coherence tomography (DOCT) and Doppler amplitude optical coherence tomography (DAOCT), a novel extension of DOCT. Velocity profiles and concentration distributions of normal and rigidified in vitro red blood cell suspensions are shown to vary as functions of mean flow velocity, cell concentration, and cell rigidity. Deviation from the parabolic velocity profile expected for Pouseille flow is observed for both rigid and normal cells at low flow rates. Axial red cell migration both toward and away from the tube axis is observed for both rigid and normal cells as a function of flow velocity. Good agreement is found between our measurements, and theoretical expectations.

Blood Flow Velocity↗

PubMed2006

Assessment of fetal atrioventricular time intervals by tissue Doppler and pulse Doppler echocardiography: normal values and correlation with fetal electrocardiography.

OBJECTIVE: To establish gestational age-specific reference values of normal fetal atrioventricular (AV) time interval by spectral tissue Doppler imaging (TDI) and pulse-wave Doppler (PD) methods, and to assess their correlation with signal-averaged fetal PR intervals (ECG). DESIGN: Cohort study. SETTING: Tertiary centre for fetal cardiology. PATIENTS AND MEASURES: 131 pregnant women between 14 and 42 weeks' gestation underwent 196 fetal echocardiograms and 158 fetal ECG studies. TDI-derived AV intervals were measured as the intervals from atrial contraction (Aa) to isovolumic contraction (IV) and from Aa to ventricular systole (Sa) at the right ventricular free wall. PD-derived AV intervals were measured from simultaneous left ventricular inflow/outflow (in/out) and superior vena cava/aorta (V/AO) recordings. RESULTS: Measurements were possible by ECG in 61%, by TDI in 100%, by in/out in 100% and by V/AO in 97% of examinations. Aa-IV correlated significantly better with PR intervals (y = 0.67x + 38.29, R(2) = 0.15, p < 0.0001, mean bias 8.0 ms) than did in/out (R(2) = 0.10, p = 0.002, bias 18.7 ms) and V/AO (R(2) = 0.06, p = 0.02, bias 12.4 ms). Gestational age and AV intervals were positively correlated with all imaging modalities (R(2) = 0.19-0.31, p < 0.0001). CONCLUSION: This study showed the feasibility of fetal AV interval measurements by TDI, and established gestational age-specific reference data. TDI-derived Aa-IV intervals track ECG PR intervals more closely than PD-derived AV intervals and thus should be used as the ultrasound method of choice in assessing fetal AV conduction.

Atrial Function↗

PubMed2000

Randomized comparison of elective stent implantation and coronary balloon angioplasty guided by online quantitative angiography and intracoronary Doppler. DESTINI Study Group (Doppler Endpoint STenting INternational Investigation).

BACKGROUND: The purpose of this study was to compare long-term outcomes of coronary stenting in all lesions (elective stenting) or only in lesions with inadequate morphological and functional results after balloon angioplasty (guided PTCA). METHODS AND RESULTS: Treatment of multivessel disease, with any lesion length and vessel size, was allowed provided that all lesions were suitable for stent implantation. Patients were randomized to elective stent implantation (n=370) or guided PTCA (n=365). An optimal PTCA result (residual diameter stenosis </=35%, coronary flow reserve measured with a Doppler guidewire >2.0, absence of threatening dissections) was achieved in 166 lesions (43%). The remaining 218 lesions underwent stent implantation (provisional stenting). Final residual diameter stenosis was lower in the elective and provisional stent groups (9.3% and 10.2%) than in the optimal PTCA group (24.8%, P:<0. 00001). On an intention-to-treat analysis, the probability of >/=1 major adverse cardiac event at 12 months was 17.8% in the elective stenting group and 18.9% in the guided PTCA group (20.1% for optimal PTCA and 18.0% for the provisional stenting subgroup, P:=NS). The incidence of repeat target lesion revascularization at 1 year was 14. 9% in the elective stent group and 15.6% in the guided PTCA group (17.6% for optimal PTCA and 14.1% for the provisional stenting subgroup, P:=NS). CONCLUSIONS: When balloon angioplasty is guided by online quantitative angiography and Doppler-derived coronary flow reserve, with provisional stenting reserved for suboptimal results, early and late clinical outcomes are comparable to those achieved by elective stenting of all patients.

Angiography↗

PubMedDate not supplied

Evaluation of cross-circulation through circle of Willis using an ultrasonic Doppler technique. Part II. Comparison between blood flow velocity by ultrasonic Doppler flowmetry and cerebrovascular resistance.

The correlation between the increase in velocity of blood flow in both the internal carotid and vertebral arteries during a carotid compression and the cerebrovascular resistance (CVR) was investigated in 11 patients with chronic ischemic cerebrovascular disease and 4 without organic brain lesions. The velocity of blood flow was measured by an ultrasonic Doppler flowmeter. CVR was calculated from cerebral blood flow and arterial blood pressure. There was no correlation between the increased velocity of blood flow in the internal carotid and vertebral arteries and CVR. The increased velocity of blood flow in patients with low CVR was, however, significantly higher than that of patients with high CVR. The investigation of cross-circulation by ultrasonic Doppler flowmetry is a useful non-invasive method for the detection of changes in cerebral vascular resistance.

Adolescent↗

PubMed1997

Power Doppler imaging of carotid artery stenosis. Comparison with color Doppler flow imaging and angiography.

BACKGROUND AND PURPOSE: Power Doppler imaging (PDI) is a new sonographic technique that has recently been introduced for vascular application. Since the technical principles of PDI may provide increased sensitivity to visualize the continuity of blood flow in arterial stenoses, we investigated the diagnostic significance of PDI and the intermethod relationship for the measurement and classification of internal carotid artery (ICA) stenosis in comparison with both color Doppler flow imaging (CDFI) and angiography. METHODS: One hundred patients with a total of 128 ICA stenoses (50% to 69%, n = 37; 70% to 79%, n = 27; 80% to 99%, n = 64) and 12 ICA occlusions were consecutively investigated by means of PDI, CDFI, and intra-arterial angiography (n = 48). Reduction of the intrastenotic lumen was measured on longitudinal and transverse views of PDI and CDFI for the calculation of the degree of diameter and area stenosis, respectively. Angiographic stenosis was determined with the use of the North American Symptomatic Carotid Endarterectomy Trial (NASCET), European Carotid Surgery Trial (ECST), and common carotid (CC) methods. RESULTS: PDI provided significantly more excellent or good (92% versus 79%; P < .01) displays of the intrastenotic lumen than CDFI, particularly in complicated high-grade stenosis. While linear regression analysis demonstrated a high overall correlation between PDI and CDFI for diameter (r = .88; P < .001) and area stenosis (r = .79; P < .001), categorization of ICA stenosis revealed best agreement for 80% to 99% area stenoses. Since angiography frequently either underclassified (NASCET method) or overclassified (ECST, CC methods) the degree of ICA stenosis in comparison to both PDI and CDFI, the sonographic-angiographic correlation was only moderate (regression coefficients ranged from .62 to .70; P < .001). CONCLUSIONS: PDI further improves the assessment of ICA stenosis by providing better visualization of the stenotic vascular lumen than CDFI. Sonographic imaging of the stenotic plaque on both PDI and CDFI provided a direct measurement of the local degree of stenosis, while the angiographic grade of stenosis essentially depended on the method used for evaluation.

Adult↗

PubMed2005

Tissue Doppler imaging and strain Doppler imaging as modalities for predicting clinical improvement in patients receiving biventricular pacing.

BACKGROUND: The purpose of this study was to determine the utility and efficacy of tissue Doppler imaging (TDI) and strain Doppler imaging (SDI) for evaluating ventricular synchrony and function, and for predicting the long-term clinical improvement in patients undergoing biventricular pacing (BVP). METHODS AND RESULTS: TDI and SDI were performed before and <1 month after initiating BVP in 17 patients with advanced heart failure. An intraventricular conduction delay between the left ventricular (LV) septal and lateral walls was measured by TDI. The average LV strain (LV-strain) was calculated from data obtained at the center of 6 regions of the LV (base and mid-point between the basal and apical portions, and the mid-point between these 2 points on the septal and lateral walls). During a 23+/-7 month follow-up period, 12 patients improved clinically and did not require re-hospitalization for heart failure (responder group), but the remaining 5 did not improve (nonresponder group). Before BVP, the intraventricular conduction delay was greater in the responder group than in the nonresponder group (p<0.01), but after BVP, it did not differ between the 2 groups. LV-strain improved after BVP in the responder group but not in the nonresponder group (p<0.05). CONCLUSION: A high intraventricular conduction delay before BVP and decreased strain shortly after BVP may predict long-term clinical improvement in patients undergoing this treatment.

Aged↗

PubMed2001

Effect of cilnidipine on left ventricular diastolic function in hypertensive patients as assessed by pulsed Doppler echocardiography and pulsed tissue Doppler imaging.

The purpose of the present study was to examine the mechanisms of improvement in left ventricular (LV) diastolic function in hypertensive patients treated with cilnidipine, a new and unique calcium antagonist that has both L-type and N-type voltage-dependent calcium channel blocking actions, using pulsed Doppler echocardiography and pulsed tissue Doppler imaging. The study comprised 35 untreated patients with essential hypertension (19 men and 16 women; mean age 65+/-10 years). The peak early diastolic and atrial systolic transmitral flow velocities (E and A, respectively) and their ratio (E/A), and the peak early diastolic and atrial systolic motion velocities (Ew and Aw, respectively) of the LV posterior wall and their ratio (Ew/Aw) were determined in all patients before and after 1, 3 and 6 months on cilnidipine (10 mg/day). One month: Systolic and diastolic blood pressures were significantly decreased. E and E/A were significantly increased, whereas there were no significant changes in Ew and Ew/Aw. Three months: Ew and Ew/Aw were significantly increased compared to those before and 1 month after cilnidipine. Six months: E and E/A were significantly increased compared with before and 3 months after cilnidipine, and Ew and Ew/Aw were significantly increased compared with before cilnidipine. Moreover, the LV mass index was significantly decreased compared to that before cilnidipine. In summary, changes in LV diastolic performance in patients with essential hypertension following cilnidipine treatment were biphasic with an initial increase in early diastolic transmitral flow velocity and a later increase in early diastolic LV wall motion velocity. The initial and later changes can be related to an acute change in afterload and a later improvement in LV relaxation.

Aged↗

PubMed2003

Vascularity of hepatic VX2 tumors of rabbits: assessment with conventional power Doppler US and contrast enhanced harmonic power Doppler US.

AIM: To investigate the characteristics of the vascularity of hepatic metastasis. METHODS: Six New Zealand rabbits, weighing averagely 2.7+/-0.4 kg, were selected and operated to establish hepatic VX2 tumor carrier model. Hepatic VX2 tumors were then imaged with conventional B mode US, second harmonic imaging (SHI), color Doppler flow imaging (CDFI), power Doppler imaging (PDI) and harmonic PDI by a transducer S8 connected to HP-5 500 ultrasound system. A kind of self made echo contrast agent was intravenously injected at a dose of 0.01 mL/kg through ear vein, and then the venous passage was cleaned with sterilized saline. RESULTS: Totally, 6 hypoechoic lesions and 3 hyperechoic lesions were found in the six carrier rabbits with a mean size about 2.1+/-0.4 cm under conventional B mode ultrasound, they were oval or round in shape with a clear outline or a hypoechoic halo at the margin of the lesions. Contrast agent could not change the echogenicity of the lesions under conventional B mode and SHI, however, it could greatly increase the flow sensitivity of the lesions under PDI and harmonic PDI. Nutrient artery of these metastatic lesions might also be well depicted under contrast enhanced PDI and harmonic PDI. CONCLUSION: Our result suggested that contrast enhanced PDI, especially harmonic PDI, was a promised method in the detection of vascularity of hepatic tumor nodules.

Animals↗

PubMed2000

Power Doppler sonography of breast masses: correlation of Doppler spectral parameters with tumor angiogenesis and histologic growth pattern.

The purpose of this study was to examine the relationship between spectral analysis on power Doppler sonography and microvessel density. Power Doppler sonography was performed in 71 patients with breast masses (36 invasive carcinomas and 35 benign lesions). Microvessel density was measured in surgical specimens from all breast carcinomas using anti-factor VIII-related antibody. Invasive carcinomas were divided into two groups according to their growth pattern (solid type, scirrhous type). The pulsatility index and resistive index were high in malignant tumors compared with those in benign lesions (P < 0.001). The maximum velocity had weak statistical significance (P < 0.05). Although the correlation of maximum velocity with microvessel density was strong in solid tumors (P < 0.001), the maximum intensity in scirrhous tumors had no correlation with microvessel density. In conclusion, solid tumors showed a tendency toward correlation of maximum velocity with microvessel density. High maximum velocity with high microvessel density suggests breast carcinoma and could be predictive of a poor prognosis in invasive breast carcinoma.

Adult↗

PubMed2006

Prenatal diagnosis of vasa previa through color Doppler and three-dimensional power Doppler ultrasonography. A case report.

Vasa previa occurs in pregnancy when one of the membrane vessels extends down to the level of the internal cervical os, ahead of the fetal presenting part and unsupported by the placenta tissue or umbilical cord. The rupture of the vessels might happen spontaneously or artificially and frequently results in fetal exsanguination and demise. Ultrasound prenatal diagnosis is highly important as it allows the identification of patients at risk, thus an elective cesarean can be performed before rupture the membranes. We report a case of vasa previa diagnosed through color Doppler mode in the 30th week of gestation, emphasizing the contribution of three-dimensional power Doppler to the adequate mapping of aberrant vessels, which greatly contributed to the success of the perinatal result.

Adult↗

PubMed1991

[Quantification of mitral regurgitation by Doppler color flow mapping: comparison of mitral regurgitant fraction and volume with Doppler measurements].

Color flow imaging of the regurgitant areas has been used to quantitate the severity of valvular regurgitation, however, the exact relationship between color flow areas and regurgitant volumes or fraction has not been clarified. This study was designed to determine whether measurements of jet flow areas and distances using color flow imaging are closely related to the regurgitant volume (MRV:ml/beat) and fraction (MRF: %). Doppler examinations were performed in 29 patients with mitral regurgitation (MR). The MR jet was depicted as the largest clearly definable flow disturbance on the echo images, and the maximal jet area (cm2) and length (cm) were measured. The MRV and MRF were obtained from the Doppler measurements of the transmitral flow (TMF) and the aortic flow (AF) as follows: MRV = TMF-AF, MRF = MRV/TMF x 100. The maximal jet area showed significant correlations with the MRV and MRF (r = 0.75 and 0.75, p < 0.01), and the maximal jet length showed even better correlations with the MRV and MRF (r = 0.82 and 0.80, p < 0.01), irrespective of the etiology of MR. Thus, both the maximal jet area and length obtained from color flow imaging can be simple and useful measurement methods for predicting the MRV and MRF.

Blood Flow Velocity↗