Doppler Method Research Articles

Insights from the assessment of anatomic valve orifice area after transcatheter aortic valve implantation using transesophageal echocardiography

Abstract Background Although transthoracic echocardiography (TTE) is the gold standard for evaluating effective valve orifice area (EOA) after transcatheter aortic valve implantation (TAVI), the continuous formula is inherently different from anatomic valve orifice area because it implies a minimum jet width through the aortic valve. It has also been reported that the doppler method with TTE overestimates the mean gradient due to pressure recovery and is even less accurate after TAVI. On the other hand, recent technological developments have improved image resolution, making valve morphology possible using transesophageal echocardiography (TEE). Purpose The purpose of this study was to compare transcatheter aortic valve (TAV) area using TEE and TTE to evaluate whether there is a significant difference in each area and to explore factors that influence the difference in area. Methods Patients who underwent TEE-guided TAVI and SAPIEN3 implantation between February 2019 and March 2023 and had aortic valve evaluation with TTE before discharge were included. We retrospectively evaluated the TAV after TAVI using TTE and TEE. Aortic valve orifice area was calculated by two methods: EOA index (doppler-area: DA) calculated by the continuous doppler formula using TTE and t-AVA index (trace-area: TA) derived by the trace method using TEE. TAV tracing was performed in early systole on the short-axis image of the aortic valve. The TAV tracing was performed by physicians specializing in echocardiography, and multiple physicians were blinded to the same case to eliminate inter-rater error. The percentage change between the two groups was calculated from the difference in area by TTE and TEE, and the 75th percentile of the percentage change was defined as the cutoff value for the group with the large difference in TAV area. Results Patients whose TAV was difficult to observe by TEE were excluded, and 464 patients were finally analyzed. TA was significantly larger than DA (1.56±0.28 cm2/m2 vs 1.18±0.26 cm2, p<0.001) and similar for all TAV sizes. However, even though TA expanded as valve size increased, the largest area of DA was observed in the 26mm TAV, and the 29mm TAV was comparable to the 26mm TAV. Only a weak correlation was shown between DA and TA (correlation coefficient: 0.356). There were 43 cases of moderate prosthetic valve-patient mismatch (PPM: EOA-i<0.85cm) in DA, but only 1 case in TA. In multivariate logistic regression analysis, women (OR 2.25, 95% CI 1.17-4.34, p < 0.015) and LV mass index (OR 1.01, 95% CI 1.00-1.02, p < 0.041) were independent factors for the large difference in TAV area. Conclusion After TAVI, the TAV area with TEE was larger than the EOA-i with TTE, and PPM was rarely seen. Depending on valve size, patient background, and cardiac morphology, there are cases of overestimation of postoperative AS in TTE, which may need to be carefully evaluated in women and patients with larger LV mass index.

Detection of Two-Phase Slug Flow Film Thickness by Ultrasonic Reflection

Slug flow is a common phenomenon in closed pipes, occurring in two-phase flow where liquid and gas phases mix, impacting the custody transfer or the efficiency of chemical reactions. This study aims to detect and analyze slug flow film thickness in two-phase flow, providing detailed structural flow information. The ultrasonic or Doppler reflection method is employed to identify slug flow and detect detailed thickness. Additionally, electrical resistance tomography (ERT) is used to image and confirm the presence of slug flow. A high-speed camera records the slug flow's shape in real time, validating its existence. The ultrasonic reflection method offers high accuracy, with a measurement error rate of less than 1% based on experimental results. The study uses a homogeneous block calibration method to measure slug flow thickness. Graphical results reveal clear differences between the slug flow regime, inner pipe wall, and outer pipe wall, with the first echo of slug flow being easily observable. The accuracy of results is attributed to the combination of FPGA (Field-Programmable-Gate-Array) instruments and measurement methods, showcasing the study's novel approach. This research introduces a new perspective or novelty on slug flow in multiphase flow studies, highlighting an innovative method for detecting film thickness.

Abstract P450: A dual probe ultrasound vector Doppler method for a robust and reliable estimation of blood flow volume and pulse wave velocity on the carotid artery

Background: The arterial pulse wave velocity (PWV) is a strong marker of cardiovascular risk and hypertension. The development of devices enabling a robust and reliable assessment of PWV could play an important role in the early diagnosis and monitoring of those diseases. In this work, we propose an ultrasound technique to estimate blood flow volume (BFV) and PWV by simultaneously using two probes. Methods: Two linear arrays, held by a handle, image two cross-sections of the artery, on two planes intersecting at 40° at the vessel center (A). B-mode and color flow Doppler (CFD) images are reconstructed at high frame rate (HFR): the cross-section HFR CFDs, providing vector-Doppler imaging, avoid any assumptions on flow velocity direction and profile, thus enabling reliable BFV estimates; the HFR B-mode allows tracking the arterial wall, thus enabling robust and time-resolved estimates of the lumen area (B). PWV is estimated as the ratio between the change in flow and cross-sectional area during the early systole (C). The method was preliminary verified by repeating 12 times the BFV and PWV estimation on the carotid artery of 8 healthy volunteers. Results: PWV and BFV measures were in the physiological range of 4.0-6.6 m/s (D) and 4.2-10.8 cm 3 /s, respectively. Measures were repeatable as proved by narrow interquartile ranges and low average standard deviations (1.4 m/s and 1.1 cm 3 /s, for PWV and BFV), which confirm the method's robustness. Conclusions: The proposed technique is suitable for BFV and PWV estimations. Since it is robust to probe repositioning and does not rely on any assumption of flow direction and profile, it could be implemented on wearable cardio-vascular wellness monitoring devices.

ISAR Imaging Analysis of Complex Aerial Targets Based on Deep Learning

Traditional range–instantaneous Doppler (RID) methods for maneuvering target imaging are hindered by issues related to low resolution and inadequate noise suppression. To address this, we propose a novel ISAR imaging method enhanced by deep learning, which incorporates the fundamental architecture of CapsNet along with two additional convolutional layers. Pre-training is conducted through the deep learning network to establish the mapping function for reference. Subsequently, the trained network is integrated into the electromagnetic simulation software, Feko 2019, utilizing a combination of geometric forms such as corner reflectors and Luneberg spheres for analysis. The results indicate that the derived ISAR imaging effectively identifies the ISAR program associated with complex aerial targets. A thorough analysis of the imaging results further corroborates the effectiveness and superiority of this approach. Both simulation and empirical data demonstrate that this method significantly enhances imaging resolution and noise suppression.

Breast multiparametric ultrasound: a single-center experience.

To evaluate the role of multiparametric ultrasound (mpUS) in the characterization of focal breast lesions (FBLs). This prospective study enrolled patients undergoing multiparametric breast ultrasound for FBLs. An experienced breast radiologist evaluated the following ultrasound features: US BI-RADS category, vascularization pattern (internal, vessels in rim and combined) and presence of penetrating vessels with each Doppler method (Color-Doppler, Power-Doppler, Microvascular imaging), strain ratio (SR) and Tsukuba score (TS) with Strain Elastography (SE), Emax, Emean, Emin and Eratio with 2D-shear wave elastography (2D-SWE). Core biopsy for all BI-RADS 4-5 FBLs and 24-month follow-up for all BI-RADS 2-3 FBLs were considered for standard of reference. The diagnostic performance was assessed with the area under curve (AUCs) and cut-off values were determined according to the Youden's index. A total of 139 FBLs were included with 75/139 (53.9%) benign and 64/139 (46.1%) malignant FBLs. Internal vascularization patterns (p < 0.001), penetrating vessels (p < 0.001), TS 4-5 (p < 0.001) and all 2D-SWE parameters (p < 0.001) were significantly different between benign and malignant FBLs. The BI-RADS score provided an AUC of 0.876 (95% CI 0.810-0.926) for the diagnosis of malignant FBLs. Among the 2D-SWE measurements, an excellent diagnostic performance was observed for Emax with an AUC of 0.915 (95% CI 0.856-0.956) and Emean of 0.908 (95% CI 0.847-0.951). Optimal cutoff for the diagnosis of malignant FBLs were US BI-RADS > 3, Strain Ratio > 2.52, Tsukuba Score > 3, Emax > 82.6kPa, Emean > 66.0kPa, Emin > 54.4kPa and Eratio > 330.8. Multiparametric ultrasound, particularly SWE, can improve specificity in the characterization of FBLs.

Study on the microscopic characteristics of pentanol/highly active fuel spray based on high-speed droplet tracking velocimetry technology

Pentanol blending with highly reactive fuels for internal combustion engines holds considerable promise. The atomization of sprays closely influences the efficiency and combustion characteristics of the system. Based on Particle Tracking Velocimetry and high-speed shadow imaging technology, we propose a method termed High-speed Droplet Tracking Velocimetry for analyzing spray particle size. Prior to conducting our study, we validated the reliability of High-speed Droplet Tracking Velocimetry through comparisons with the Malvern and Phase Doppler methods. This study utilized long working distance micro high-speed shadow imaging technology in a visualized constant volume combustion chamber to investigate the spray micro-characteristics of pentanol blended with highly reactive fuels, including Fatty Acid Methyl Ester, Hydrogenated Catalytic Biodiesel, and Diesel. The results indicate that under all operating conditions, the droplets of P20H80 (the volume fraction of 20 % n-pentanol mixed with 80 % Hydrogenated Catalytic Biodiesel) are smaller and more uniformly distributed, demonstrating the minimum Sauter Mean Diameter, characteristic diameter, and width of droplet size distribution. The droplet velocities of P20H80 are the lowest, followed by P20Di80 (the volume fraction of 20 % n-pentanol mixed with 80 % Diesel), and P20B80 (the volume fraction of 20 % n-pentanol mixed with 80 % Fatty Acid Methyl Ester) exhibits the highest velocities. These velocity differences among the three fuels generally remain within 10 %-20 % across various injection pressures. P20Di80 shows the highest Reynolds and Weber numbers, followed by P20H80, with P20B80 having the smallest values due to its intermediate physical properties. The gaps between each fuel type range from 20 % to 30 %.

A PLL-Based Doppler Method Using an SDR-Receiver for Investigation of Seismogenic and Man-Made Disturbances in the Ionosphere

The article describes in detail the equipment and method for measuring the Doppler frequency shift (DFS) on an inclined radio path, based on the principle of the phase-locked loop using an SDR receiver for the investigation of seismogenic and man-made disturbances in the ionosphere. During the two M7.8 earthquakes in Nepal (25 April 2015) and Turkey (6 February 2023), a Doppler ionosonde detected co-seismic and pre-seismic effects in the ionosphere, the appearances of which are connected with the various propagation mechanisms of seismogenic disturbance from the lithosphere up to the ionosphere. One day before the earthquake in Nepal and 90 min prior to the main shock, an increase in the intensity of Doppler bursts was detected, which reflected the disturbance of the ionosphere. A channel of geophysical interaction in the system of lithosphere–atmosphere–ionosphere coupling was traced based on the comprehensive monitoring of the DFS of the ionospheric signal, as well as of the flux of gamma rays in subsoil layers of rocks and in the ground-level atmosphere. The concept of lithosphere–atmosphere–ionosphere coupling, where the key role is assigned to ionization of the atmospheric boundary layer, was confirmed by a retrospective analysis of the DFS records of an ionospheric signal made during underground nuclear explosions at the Semipalatinsk test site. A simple formula for reconstructing the velocity profile of the acoustic pulse from a Dopplerogram was obtained, which depends on only two parameters, one of which is the dimension of length and the other the dimension of time. The reconstructed profiles of the acoustic pulses from the two underground nuclear explosions, which reached the height of the reflection point of the sounding radio wave, are presented.

Evaluation of coronary microvascular dysfunction using magnetocardiography: A new application to an old technology

BackgroundIn patients with angina and non-obstructive coronary artery disease (ANOCA), diagnosis of coronary microvascular dysfunction (CMD) remains an unmet need. Magnetocardiography (MCG), is a rest-based, non-invasive scan that can detect weak electrophysiological changes that occur at the early phase of ischemia. ObjectiveThis study assessed the ability of MCG to detect CMD in ANOCA patients as compared to reference standard, invasive coronary flow reserve (CFR). MethodsPatients with ANOCA and invasive coronary physiologic assessment using intracoronary flow measurements with Doppler and thermodilution methods were enrolled. CMD was defined dichotomously as an invasive CFR < 2.0 by Doppler or thermodilution assessment. Noninvasive 36-channel 90-s MCG scan was performed and quantitative assessment of four distinct MCG features was completed. We evaluated the diagnostic performance of 2 or more abnormal MCG features to detect CMD in the overall cohort and performed a subgroup analysis in the subset of patients with Doppler CFR assessment. ResultsAmong 79 ANOCA patients, 25 were CMD positive and 54 patients were CMD negative by CFR. Using invasive CFR as reference, MCG had an ROC AUC of 0.66 with a sensitivity of 68 % and specificity of 65 % for the detection of CMD. In the subgroup with Doppler CFR assessment, MCG had an ROC AUC of 0.76 with a sensitivity of 75 % and specificity of 77 %. ConclusionsIn ANOCA patients, MCG demonstrates the ability to detect CMD using a 90-second non-invasive scan without the need for an intravenous stressor or ionizing radiation. Further investigations are needed to validate an MCG-based diagnostic pathway for CMD.

SSOCT/A reveals cerebrovascular activity during ischemic stroke in zebrafish

Using swept-source optical coherence tomography/angiography (SSOCT/A), we present a non-invasive examination of the zebrafish brain to comprehend the vasculature and altering cellular dynamics in the cerebral stroke model. Reduced or blocked blood flow to the brain during an ischemic stroke eventually results in cell death from a lack of oxygen and nutrients. SSOCT is used to examine ischemic stroke's aberrant/anomalous blood flow features using phase variance and the Doppler method. The SSOCT speckle-contrast technique is used to track the ensuing cell demise. Fast acquisition times, reduced motion artefacts, label-free viewing, and non-invasive testing are all features of the SSOCT approach for disease surveillance.

Low Stroke Volume Predicts Deterioration in Intermediate-Risk Pulmonary Embolism: Prospective Study.

Prognosis and management of patients with intermediate-risk pulmonary embolism (PE) is challenging. We investigated whether stroke volume may be used to identify the subset of this population at increased risk of clinical deterioration or PE-related death. Our secondary objective was to compare echocardiographic measurements of patients who received escalated interventions vs anticoagulation monotherapy. We selected patients with intermediate-risk PE, who had comprehensive echocardiography within 18 hours of PE diagnosis and before any escalated interventions, from a PE registry populated by 11 emergency departments. Echocardiographers measured right ventricle (RV) size, tricuspid annular plane systolic excursion (TAPSE), and stroke volume (SV) using velocity time integral (VTI) by left ventricular (LV) outflow tract Doppler or two-dimensional method of discs (MOD). The primary outcome was a composite of PE-related death, cardiac arrest, catecholamine administration for sustained hypotension, or emergency respiratory intervention during the index hospitalization. Secondary outcome was escalated intervention with reperfusion or extracorporeal membrane oxygenation therapy. Of 370 intermediate-risk PE patients (mean age 64.0 ± 15.5years, 38.1% male), 39 (10.5%) had the primary outcome. These 39 patients had lower mean SV regardless of measurement method than those without the primary outcome: SV MOD 36.2 vs 49.9 milliliters (mL), P < 0.001; SV Doppler 41.7 vs 57.2mL, P = 0.003; VTI 13.6 vs 17.9 centimeters [cm], P = 0.003. Patients with primary outcome also had lower mean TAPSE than those without (1.54 vs 1.81cm, P = 0.003). Multivariable models, selecting SV as predictor, had area under the receiver operating curve of 0.8 and Brier score 0.08. The best echocardiographic predictor of our primary outcome was SV MOD (odds ratio 0.72 [0.53, 0.94], P = 0.02). Patients who received escalated interventions had significantly lower SV or surrogate measurements, greater RV dilatation, and lower RV systolic function than patients who received anticoagulation monotherapy. Low stroke volume was a predictor of clinical deterioration and PE-related death. Low SV may be used to identify a subset of intermediate-risk PE patients, who are higher risk (intermediate-high risk), and for whom escalated interventions should be considered.

Comparative study between cuff sizes in the determination of systolic blood pressure, by non-invasive methods in anesthetized dogs

The measurement of systolic blood pressure (SBP) is a variable of paramount importance in clinical routine, obtained and measured according to published guidelines for dogs. The study evaluated the influence of cuff size on the determination of systolic blood pressure (SBP) values in dogs, comparing two non-invasive methods. Eighteen healthy dogs of different breeds and ages were used, clinically evaluated and undergoing elective surgeries. SBP was measured using vascular Doppler and high-definition oscillometric methods during the anesthetic period, using both ideal-sized cuffs and smaller cuffs. The dogs were divided into groups, Group 1 composed of dogs with ideal cuff no. 2, Group 2 dogs with ideal cuff no. 3 and Group 3 ideal cuff no The results showed that smaller cuffs significantly overestimated the mean SBP values compared to the ideal cuff values, regardless of the method used. It was concluded that cuffs with a lower than ideal number overestimate SBP values in anesthetized dogs, regardless of the non-invasive method used.

Rotational Doppler effect of vortex beam with frequency-shifted laser feedback

We propose and demonstrate a rotational Doppler measurement system based on frequency-shifted laser feedback interferometry. The system utilizes a vortex beam as the probe, which is modulated by the target and then reflected back into the laser cavity. Compared with the conventional rotational Doppler methods, this approach effectively enhances the amplitude of the generated beat signal through intra-cavity interference between the echo signal and local oscillator. Consequently, it improves sensitivity in weak-signal detection and enables measurement with low probe-beam power. A signal to noise (SNR) enhancement of over 15 dB was observed compare to the Mach-Zehnder structure. This system inherits the advantages of rotational Doppler effect, possessing the capacity to get a frequency proportional to the topological charge of vortex. Experimental validation demonstrates accurate measurement of rotational angle and velocity, with the ability to distinguish rotational direction through heterodyne detection. For vortices with topological charge ranging from 18 to 21 and rotational speeds in range of 150 to 600 revolutions per minute (RPM), the measurement error is within ±3 RPM. Overall, the proposed system possesses high sensitivity to echo signal, low photon consumption, and direction information availability, which provides a new approach for optimizing the rotational Doppler effect in practical applications.

Investigation on vector Doppler method for carotid artery wall with focused transmit beams produced from a cross-shaped probe

Conventional methods for estimating 1D or 2D velocities were developed for the dynamic measurement of carotid walls. However, a carotid wall moves in 3D due to a heart pulsation, and the wall motion velocity in the longitudinal-axis cross-section is affected by out-of-plane displacements that cannot be measured with a 1D array probe. To estimate the out-of-plane displacement, we proposed the cross-shaped probe. The cross-shaped probe can estimate 3D velocity vector with 256 transmit-receive channels. Single or multiple focused beams were transmitted by the main array of the cross-shaped probe, and the RF signals received all the elements were used for 3D velocity vector estimation based on the multi-angle Doppler method. Numerical simulations and basic experiments showed that out-of-plane displacements in the longitudinal-axis cross section can be estimated. Furthermore, the in vivo experiments on a human common carotid artery showed that arterial wall motion during a cardiac cycle can be measured.

Геометрический фактор односпутниковой системы определения местоположения абонентских терминалов по оценкам частоты доплеровским методом

The article presents a mathematical description of the doppler method of satellite communication systems user terminals geolocation by a retransmitted signal, as well as an analytical expression of the geometric factor of determining the location of user terminals. The analysis of the geometric factor distribution on the Earth's surface in the radio visibility zone of the repeater satellite is carried out.

Effects of beam steering angle and excitation frequency on blood flow imaging with plane wave imaging

The vector Doppler method was developed to overcome the limitations of conventional methods, which can only estimate axial velocities. Because the vector Doppler method uses steered beams, the excitation frequency is set lower than the resonance frequency of the transducer elements to prevent the generation of grating lobes. Although lowering the steering angle is another solution, a larger steering angle span leads to a more accurate estimation of velocity vectors. We have developed a method for estimating the steering angle from the received echo signals, which might enable an accurate estimation of velocity vectors even with small steering angles. In this study, the effects of steering angle and excitation frequency were investigated by numerical simulation and in vivo measurement of the carotid artery. The results showed that similar accuracies were obtained at high (6.94 MHz) and low (4.8 MHz) frequencies, and that better visualization of weak echoes from blood cells was achieved at 6.94 MHz.

A novel microwave Doppler method for mass estimation of machine-picked seed cotton

Obtaining information on cotton yields and creating a spatial map of cotton production is the starting point for implementing precision agriculture. Microwave technology has been used for yield estimation in China for crops such as corn and soybeans and has shown strong applicability. However, research on cotton yield estimation using microwave technology is weak. Therefore, this paper proposes a method for seed cotton mass estimation based on the microwave Doppler method and designs bench tests to prove the feasibility of the method. First, a seed cotton speed estimation model was established based on the microwave Doppler effect and fast Fourier transform. On this basis, a seed cotton velocity estimation experiment was designed to study the effects of sensor installation angle and position, pipe collision friction, air resistance, and the interaction force between the seed cotton on the seed cotton movement velocity. The power spectral density (PSD) of the acquired microwave data is then estimated using the modified periodogram method. The least squares method was used to establish a linear regression model between seed cotton mass and the corresponding PSD, and finally the free-fall mass experiment and pneumatic conveying mass experiment yielded that the estimation errors of seed cotton mass were 7.30% and 6.17%, respectively. The experimental results show that the estimation error is small when using microwave technology for seed cotton mass estimation, which meets the requirements of actual operation.

Endoscopic Ultrasonography In Diagnostic Endohepatology: The Hepatologist's Swiss Army Knife.

In recent years, significant advances have been made in endoscopic ultrasonography (EUS) processors, transducers, and the instruments used. In parallel with these developments, the importance of EUS in the diagnosis, treatment, and management of chronic liver diseases has increased considerably. One of the most important advantages of EUS is that the ultrasound probe can examine the liver area under examination from a very close distance. Additionally, EUS provides the ability to provide excellent spatial files and realtime images; Doppler, elastography, and contrast methods are also widely used to increase diagnostic accuracy in EUS evaluations. Endoscopic ultrasound-guided procedures are an alternative method used when percutaneous approaches are not feasible. Endoscopic ultrasound-based advanced applications such as EUSguided liver biopsy (LB), EUS-guided ascites assessment, the use of EUS in the evaluation of focal lesions of the liver, and EUS portal pressure gradient (EUS-PPG) measurements are becoming increasingly common and important. As a result of the developments in EUS devices and instruments, it is possible to perform all diagnostic procedures in hepatology with EUS. In other words, EUS can provide all the imaging and interventional procedures that a hepatologist would require for diagnosis in a single session, without the need for any other expertise other than the gastroenterologist (such as a radiologist, interventional radiologist, or surgeon). This is called the single-procedure diagnostic approach, or "all in one" in hepatology. From a hepatologist's perspective, EUS can be thought of as the "hepatologist's Swiss army knife."

Finger flexor rigidity in the healthy population

The involvement of the hand flexors in trigger finger is not clear. This study aimed to examine the rigidity of the flexor tendon in the first pulley territory in the hand by using ultrasound in a healthy population, as well as to create a reference scale of rigidity for the flexor tendons to compare those values in trigger fingers. We tested 35 healthy volunteers using a linear ultrasound transducer and the color Doppler method. Rigidity levels below the first pulley were examined and compared between the different fingers of the hand and the relationship between rigidity and sex and the three different age groups was evaluated. In the healthy population, the rigidity of the flexor tendons of the hand in the territory of the first pulley varied between 233.1 and 962.8 kPa, with an average of 486.42 kPa and standard deviation of 114.85. We showed that the flexors in the dominant hand were more rigid, there was a difference between the rigidity of the flexor tendons of the thumb and the other fingers of the same hand, and the ring finger of the dominant hand had stiffer flexor tendons than the fingers of the other hand in the male population. We created a value scale for the rigidity of the flexor tendons of the fingers. This base scale can be compared between different pathologies, including trigger finger. The study and all experimental protocols were approved by the local ethical committee.

Comparison of Doppler Guided Seldinger Technique Versus Classic Palpatory Seldinger Technique for Radial Artery Cannulation-an Open Label Randomized Controlled Trial

Objective: Radial artery cannulation is commonly performed by the conventional palpatory technique. However, in circumstances where the cannulation is difficult, other methods such as Doppler or ultrasound are used to guide the cannulation. Incorporating the Seldinger technique can further improve the successful cannulation. The aim of the study was to compare the first attempt success rate of radial artery cannulation between conventional palpatory Seldinger technique and Doppler guided Seldinger technique. Methods: Ninety patients undergoing major open abdominal surgeries were divided into two groups -the Classic palpatory and the Doppler guided radial artery cannulation. The Seldinger Technique was used in both the groups. First attempt success rate of radial artery cannulation and time to cannulation were noted by both the techniques. Results: The number of attempts and the time to cannulation were significantly less in the palpatory Seldinger group as compared with the Doppler Seldinger group. Complication rates were similar in both the groups but there were 4 failure in palpatory Seldinger group. Conclusion: The classic palpatory technique along with the Seldinger technique for radial artery cannulation is better in terms of first attempt cannulation rate and duration of cannulation than the Doppler guided Seldinger technique in patients undergoing elective surgeries. However, Doppler method had no failures and can be a useful rescue method in failed cannulation.

A High-Precision Joint Smoothing Method for Inter-Spacecraft Radio Frequency Doppler and Distance Measurements using P-Spline Approximation

A High-Precision Joint Smoothing Method for Inter-Spacecraft Radio Frequency Doppler and Distance Measurements using P-Spline Approximation