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pulsed wave Doppler ultrasound pulsed Doppler ultrasound [keywords]
- Shunt Flow Evaluation in Congenital Heart Disease Based on Two-Dimensional Speckle Tracking. [JOURNAL ARTICLE]
- Ultrasound Med Biol 2014 Jul 9.
High-frame-rate ultrasound speckle tracking was used for quantification of peak velocity in shunt flows resulting from septal defects in congenital heart disease. In a duplex acquisition scheme implemented on a research scanner, unfocused transmit beams and full parallel receive beamforming were used to achieve a frame rate of 107 frames/s for full field-of-view flow images with high accuracy, while also ensuring high-quality focused B-mode tissue imaging. The setup was evaluated in vivo for neonates with atrial and ventricular septal defects. The shunt position was automatically tracked in B-mode images and further used in blood speckle tracking to obtain calibrated shunt flow velocities throughout the cardiac cycle. Validation toward color flow imaging and pulsed wave Doppler with manual angle correction indicated that blood speckle tracking could provide accurate estimates of shunt flow velocities. The approach was less biased by clutter filtering compared with color flow imaging and was able to provide velocity estimates beyond the Nyquist range. Possible placements of sample volumes (and angle corrections) for conventional Doppler resulted in a peak shunt velocity variations of 0.49-0.56 m/s for the ventricular septal defect of patient 1 and 0.38-0.58 m/s for the atrial septal defect of patient 2. In comparison, the peak velocities found from speckle tracking were 0.77 and 0.33 m/s for patients 1 and 2, respectively. Results indicated that complex intraventricular flow velocity patterns could be quantified using high-frame-rate speckle tracking of both blood and tissue movement. This could potentially help increase diagnostic accuracy and decrease inter-observer variability when measuring peak velocity in shunt flows.
- Prenatal findings in total anomalous pulmonary venous return: a diagnostic road map starts with obstetric screening views. [Journal Article]
- J Ultrasound Med 2014 Jul; 33(7):1193-207.
Optimal perinatal management of total anomalous pulmonary venous return (TAPVR) involves timely identification followed by surgical correction. Antenatal diagnosis, however, has long been a challenge. We aimed to identify consistent prenatal sonographic features in this condition in a large cohort in whom the diagnosis was made antenatally and confirmed postnatally.We conducted a systematic retrospective review of the 2-dimensional and Doppler sonographic features that had helped make the diagnosis of TAPVR at our institution from 2001 to 2012.Twenty-six patients had prenatal diagnosis of TAPVR (mean gestational age, 24.1 weeks). Four of the fetuses with a prenatal diagnosis represented isolated cases of TAPVR; 22 had heterotaxy syndrome, additional cardiac abnormalities, or both. Prenatally diagnosed abnormal pulmonary venous connections were supracardiac (type I) in 18 cases, cardiac (type II) in 1, and infradiaphragmatic (type III) in 7. Lack of a visible connection of the pulmonary veins to the atrium (100%) and the presence of a visible venous confluence on axial 4-chamber views (96%) were the most consistent findings. Cardiac asymmetry and the presence of additional vertical venous channels on 3-vessel or axial abdominal views were also noted but less consistently. Abnormal pulmonary venous spectral Doppler findings were present in 25 of the 26 fetuses.The diagnosis of TAPVR can be suspected on standard axial views included in second-trimester obstetric screening examinations of the fetal heart and confirmed on fetal echocardiography with the use of pulsed wave Doppler imaging. Clues recognizable on obstetric sonographic screening have the potential to contribute to increasing the diagnostic yield for prenatal detection of TAPVR.
- Echocardiography and conventional Doppler examination in clinically healthy adult Cavalier King Charles Spaniels: Effect of body weight, age, and gender, and establishment of reference intervals. [Journal Article]
- J Vet Cardiol 2014 Jun; 16(2):91-100.
The objectives of this study were (1) to assess the potential effect of body weight (BW), age, and gender on the most commonly used echocardiographic and conventional Doppler variables in a large population of healthy Cavalier King Charles Spaniels (CKCS), and (2) to establish the corresponding reference intervals (RI).134 healthy adult CKCS.Ultrasound examinations were performed by trained observers in awake dogs. M-mode variables included left ventricular (LV) end-diastolic and end-systolic diameters, LV free wall and interventricular septal thicknesses at end-diastole and end-systole, and LV fractional shortening (FS%). The left atrium (LA) and aortic (Ao) diameters were measured using a 2D method, and the LA/Ao was calculated. Pulsed-wave Doppler variables included peak systolic aortic and pulmonary flow velocities, mitral E and A waves, and E/A ratio. Effects of BW, age, and gender on these 15 variables were tested using a general linear model, and RIs were determined by applying the statistical procedures recommended by the Clinical and Laboratory Standards Institute.A significant BW effect was observed for all variables, except LA/Ao, FS%, and mitral E/A ratio. A significant but negligible effect of gender and age was also observed for 5/15 and 4/15 of the tested variables, respectively. Only the BW effect on M-mode variables was considered as clinically relevant and the corresponding regression-based RIs were calculated.Body weight should be taken into account when interpreting echocardiographic values in CKCS, except for LA/Ao, FS%, and mitral E/A ratio.
- Acoustically Active Injection Catheter Guided by Ultrasound: Navigation Tests in Acutely Ischemic Porcine Hearts. [JOURNAL ARTICLE]
- Ultrasound Med Biol 2014 Apr 27.
Catheters are increasingly used therapeutically and investigatively. With complex usage comes a need for more accurate intracardiac localization than traditional guidance can provide. An injection catheter navigated by ultrasound was designed and then tested in an open-chest model of acute ischemia in eight pigs. The catheter is made "acoustically active" by a piezo-electric crystal near its tip, electronically controlled, vibrating in the audio frequency range and uniquely identifiable using pulsed-wave Doppler. Another "target" crystal was sutured to the epicardium within the ischemic region. Sonomicrometry was used to measure distances between the two crystals and then compared with measurements from 2-D echocardiographic images. Complete data were obtained from seven pigs, and the correlation between sonomicrometry and ultrasound measurements was excellent (p < 0.0001, ρ = 0.9820), as was the intraclass correlation coefficient (0.96) between two observers. These initial experimental results suggest high accuracy of ultrasound navigation of the acoustically active catheter prototype located inside the beating left ventricle.
- Combined Vector Velocity and Spectral Doppler Imaging for Improved Imaging of Complex Blood Flow in the Carotid Arteries. [JOURNAL ARTICLE]
- Ultrasound Med Biol 2014 Apr 27.
Color flow imaging and pulsed wave (PW) Doppler are important diagnostic tools in the examination of patients with carotid artery disease. However, measurement of the true peak systolic velocity is dependent on sample volume placement and the operator's ability to provide an educated guess of the flow direction. Using plane wave transmissions and a duplex imaging scheme, we present an all-in-one modality that provides both vector velocity and spectral Doppler imaging from one acquisition, in addition to separate B-mode images of sufficient quality. The vector Doppler information was used to provide automatically calibrated (angle-corrected) PW Doppler spectra at every image point. It was demonstrated that the combined information can be used to generate spatial maps of the peak systolic velocity, highlighting regions of high velocity and the extent of the stenotic region, which could be used to automate work flow as well as improve the accuracy of measurement of true peak systolic velocity. The modality was tested in a small group (N = 12) of patients with carotid artery disease. PW Doppler, vector velocity and B-mode images could successfully be obtained from a single recording for all patients with a body mass index ranging from 21 to 31 and a carotid depth ranging from 16 to 28 mm.
- Non-invasive cardiac output assessment in critically ill paediatric patients. [Journal Article]
- Acta Cardiol 2014 Apr; 69(2):167-73.
Recently, non-invasive methods for cardiac output (CO) assessment have been developed including the ultrasonic cardiac output monitor (USCOM). This technique uses the same concept as Doppler echocardiography but differs in two aspects including continuous wave (CW) Doppler and estimated outflow tract diameter (OTD) used in USCOM compared to pulsed wave Doppler and directed measurement of OTD used in echocardiography. We sought to assess the agreement between CO assessment by USCOM and echocardiography in critically ill paediatric patients.Paired measurements of CO in critically ill paediatric patients were simultaneously and independently obtained by USCOM and echocardiography. Agreement between OTD, velocity time integral (VTI), CO, and cardiac index (CI) were assessed by percentage error and Bland-Altman analysis.Thirty-four children (aged 7.86 +/- 5.78years, 44.1% male) had a mean OTD (1.47 +/- 0.38, 1.41 +/- 0.40), VTI (19.13 +/- 6.06, 23.53 +/- 7.31 cm), CO (3.88 +/- 2.19,4.41 +/- 2.83 l/min) and CI (4.23 +/- 1.19,4.77 +/- 1.43 l/min/m2) by echocardiography and USCOM, respectively. Bias +/- precision and percentage of error of OTD, VTI, CO, and CI were -0.07 +/- 0.20 cm, 27.80%; -4.40 +/- 3.84 cm, 31.99%; -0.53 +/- 1.23 l/min, 54.66%; and 0.54 +/- 1.03 l/min/m2, 42.32%, respectively. The bias +/- precision and percentage error were more important in patients with septic shock (n = 16).USCOM was an unreliable tool for absolute value measurement of CO and CI due to the errors of VTI by CW Doppler.
- The Usefulness of Ultrasound Imaging in Digital and Extradigital Glomus Tumors. [JOURNAL ARTICLE]
- Actas Dermosifiliogr 2014 Apr 26.
Recent years have witnessed an increase in the use of ultrasound imaging of the skin in the field of dermatology, as the technique reveals details of vessels and other structures that cannot be detected on physical examination. Extradigital glomus tumors are rarely seen in clinical practice and can pose a diagnostic challenge for dermatologists. We report on 4 patients with a clinical suspicion of extradigital glomus tumor and on 1 patient with a clinical suspicion of subungual glomus tumor. All 5 patients underwent ultrasound examination in B mode and color and pulsed-wave Doppler prior to surgical excision of the tumor and histologic examination, which confirmed the diagnosis in each case. Ultrasound imaging of the skin, combined with clinical findings, provided a simple, noninvasive way of making a prompt diagnosis and identifying the exact location of the lesion for surgical removal.
- Respirophasic carotid artery peak velocity variation as a predictor of fluid responsiveness in mechanically ventilated patients with coronary artery disease. [JOURNAL ARTICLE]
- Br J Anaesth 2014 Apr 9.
/st>We studied respirophasic variation in carotid artery blood flow peak velocity (ΔVpeak-CA) measured by pulsed wave Doppler ultrasound as a predictor of fluid responsiveness in mechanically ventilated patients with coronary artery disease./st>Forty patients undergoing elective coronary artery bypass surgery were enrolled. Subjects were classified as responders if stroke volume index (SVI) increased ≥15% after volume expansion (6 ml kg(-1)). The ΔVpeak-CA was calculated as the difference between the maximum and minimum values of peak velocity over a single respiratory cycle, divided by the average. Central venous pressure, pulmonary artery occlusion pressure, pulse pressure variation (PPV), and ΔVpeak-CA were recorded before and after volume expansion./st>PPV and ΔVpeak-CA correlated significantly with an increase in SVI after volume expansion. Area under the receiver-operator characteristic curve (AUROC) of PPV and ΔVpeak-CA were 0.75 [95% confidence interval (CI) 0.59-0.90] and 0.85 (95% CI 0.72-0.97). The optimal cut-off values for fluid responsiveness of PPV and ΔVpeak-CA were 13% (sensitivity and specificity of 0.74 and 0.71) and 11% (sensitivity and specificity of 0.85 and 0.82), respectively. In a subgroup analysis of 17 subjects having pulse pressure hypertension (≥ 60 mm Hg), PPV failed to predict fluid responsiveness (AUROC 0.70, P=0.163), whereas the predictability of ΔVpeak-CA remained unchanged (AUROC 0.90, P=0.006)./st>Doppler assessment of respirophasic ΔVpeak-CA seems to be a highly feasible and reliable method to predict fluid responsiveness in mechanically ventilated patients undergoing coronary revascularization.Clinical trial registrationNCT 01836081.
- Guidance for accurate and consistent tissue Doppler velocity measurement: comparison of echocardiographic methods using a simple vendor-independent method for local validation. [JOURNAL ARTICLE]
- Eur Heart J Cardiovasc Imaging 2014 Apr 23.
Variability has been described between different echo machines and different modalities when measuring tissue velocities. We assessed the consistency of tissue velocity measurements across different modalities and different manufacturers in an in vitro model and in patients. Furthermore, we present freely available software tools to repeat these evaluations.We constructed a simple setup to generate reproducible motion and used it to compare velocities measured using three echocardiographic modalities: M-mode, speckle tracking, and tissue Doppler, with a straightforward, non-ultrasound, optical gold standard. In the clinical phase, 25 patients underwent M-mode, speckle tracking, and tissue Doppler measurements of s', e', and a' velocities.In vitro, the M-mode and speckle tracking velocities agreed with optical assessment. Of the three possible tissue Doppler measurement conventions (outer, middle, and inner edge) only the middle agreed with optical assessment (discrepancy -0.20 (95% CI -0.44 to 0.03) cm/s, P = 0.11, outer +5.19 (4.65 to 5.73) cm/s, P < 0.0001, inner -6.26 (-6.87 to -5.65) cm/s, P < 0.0001). A similar pattern occurred across all four studied manufacturers. M-mode was therefore chosen as the in vivo gold standard.Clinical measurements of s' velocities by speckle tracking and the middle line of the tissue Doppler showed concordance with M-mode, while the outer line overestimated significantly (+1.27(0.96 to 1.59) cm/s, P < 0.0001) and the inner line underestimated (-1.82 (-2.11 to -1.52) cm/s, P < 0.0001).Echocardiographic velocity measurements can be more consistent than previously suspected. The statistically modal velocity, found at the centre of the spectral pulsed wave tissue Doppler envelope, most closely represents true tissue velocity. This article includes downloadable, vendor-independent software enabling calibration of echocardiographic machines using a simple, inexpensive in vitro setup.
- Ultrafast Doppler reveals the mapping of cerebral vascular resistivity in neonates. [Clinical Trial, Journal Article, Research Support, Non-U.S. Gov't]
- J Cereb Blood Flow Metab 2014 Jun; 34(6):1009-17.
In vivo mapping of the full vasculature dynamics based on Ultrafast Doppler is showed noninvasively in the challenging case of the neonatal brain. Contrary to conventional pulsed-wave (PW) Doppler Ultrasound limited for >40 years to the estimation of vascular indices at a single location, the ultrafast frame rate (5,000 Hz) obtained using plane-wave transmissions leads to simultaneous estimation of full Doppler spectra in all pixels of wide field-of-view images within a single cardiac cycle and high sensitivity Doppler imaging. Consequently, 2D quantitative maps of the cerebro-vascular resistivity index (RI) are processed and found in agreement with local measurements obtained on large arteries of healthy neonates using conventional PW Doppler. Changes in 2D resistivity maps are monitored during recovery after therapeutic whole-body cooling of full-term neonates treated for hypoxic ischemic encephalopathy. Arterial and venous vessels are unambiguously differentiated on the basis of their distinct hemodynamics. The high spatial (250 × 250 μm(2)) and temporal resolution (<1 ms) of Ultrafast Doppler imaging combined with deep tissue penetration enable precise quantitative mapping of deep brain vascular dynamics and RI, which is far beyond the capabilities of any other imaging modality.