Doppler System Research Articles

Cerebral emboli detection and autonomous neuromonitoring using robotic transcranial Doppler with artificial intelligence for transcatheter aortic valve replacement with and without embolic protection devices: a pilot study

BackgroundPeriprocedural ischemic stroke remains a serious complication in patients undergoing transcatheter aortic valve replacement (TAVR). We used a novel robotic transcranial Doppler (TCD) system equipped with artificial intelligence (AI) for...

Comparative Approach to Performance Estimation of Pulsed Wave Doppler Equipment Based on Kiviat Diagram

Quality assessment of ultrasound medical systems is a demanding task due to the high number of parameters to quantify their performance: in the present study, a Kiviat diagram-based integrated approach was proposed to effectively combine the contribution of some experimental parameters and quantify the overall performance of pulsed wave Doppler (PWD) systems for clinical applications. Four test parameters were defined and assessed through custom-written measurement methods based on image analysis, implemented in the MATLAB environment, and applied to spectral images of a flow phantom, i.e., average maximum velocity sensitivity (AMVS), velocity measurements accuracy (VeMeA), lowest detectable signal (LDS), and the velocity profile discrepancy index (VPDI). The parameters above were scaled in a standard range to represent the four vertices of a Kiviat plot, whose area was considered the overall quality index of the ultrasound system in PWD mode. Five brand-new ultrasound diagnostic systems, equipped with linear array probes, were tested in two different working conditions using a commercial flow phantom as a reference. The promising results confirm the robustness of AMVS, VeMeA, and LDS parameters while suggesting further investigations on the VPDI.

Right parasternal echocardiographic reference values in the healthy male Iranian Shall sheep.

Among the large animals, the heart of sheep is functionally and structurally very similar to the human heart. In research, sheep are used as an animal model to study the process of cardiac disease pathogenesis and treatment. Therefore, determining the normal values of the heart structures of sheep with echocardiography is of particular emphasis. The purpose of the present research is to define the normal echocardiography values of heart in Iranian Shall breed sheep. In 20 healthy Iranian Shall male sheep weighing 30-35kg and aged 4-6 months, standing echocardiography was done from the right parasternal approach concentrated on the 3rd to 5th intercostal spaces by 2.5-5MHz phased array transducer in the longitudinal and transverse views by B-mode, M-mode and Doppler systems. In M-mode echocardiographic, the parameters of interventricular septal, left ventricular internal diameter, left ventricular free wall, right ventricular free wall and right ventricular internal diameter in diastole and systole as well as end point septal separation, ejection fraction (EF) slope, aortic root diameter, left atrial appendage, left atrial diameter/aortic valve diameter, left ventricular ejection time, fractional shortening, end-diastolic volume, end-systolic volume, EF, stroke volume and cardiac output and in pulsed-wave spectral Doppler echocardiographic, the parameters of mitral valve maximum velocity (Vmax), mitral valve mean velocity (Vmean), mitral valve maximum pressure gradient (PGmax), mitral valve mean pressure gradient (PGmean), mitral valve velocity time integral (VTI), mitral valve E-wave (MV-E), MV-E pressure gradient, mitral valve A-wave (MV-A), MV-A pressure gradient, aortic Vmax, aortic valve Vmean, aortic valve PGmax, aortic valve PGmean, aortic valve VTI, left ventricular outflow tract (LVOT)-Vmax, LVOT-Vmean were measured. All the sheep in this study were healthy and had no signs of heart disease. In this study, the parameters of M-mode and spectral Doppler echocardiographic were assessed and recognized in Iranian Shall sheep. The results demonstrated the parameters of echocardiographic could be dependably determined in Shall sheep which, established normal reference values for these parameters and left ventricular function indices in healthy Shall sheep. These results can be beneficial in appropriate imagination, recognition and measuring cardiac structures. This study can be exerted as a reference for the assessment and diagnosis of heart diseases in sheep medicine and human cardiovascular research in sheep experimental models.

Study on the clinical value of the wearable foetal electrocardiogram monitoring system.

Electronic foetal monitoring (EFM), a method to monitor foetal intrauterine conditions and foetal reserve capacity, is the most extensively used intrauterine monitoring technology in obstetrics. This study aims to compare the Thoth wearable foetal electrocardiogram (foetal ECG [FECG]) monitoring system with a traditional Doppler foetal heart monitoring system before labour to investigate their respective values in clinical application. A total of 393 pregnant women admitted to our hospital between 2020 and 2022 participated in this study. They were recruited using the convenience sampling method. We employed a paired design to assess the confusion rate, trend overlap, and foetal heart rate/ECG monitoring consistency, whereas a completely randomised design was used to measure pregnancy outcome indicators. The participants were divided into two groups using a random number table: the Thoth group (n= 196) and the traditional Doppler group (n= 197). Each group was monitored using the corresponding system. The Thoth monitor demonstrated a lower confusion rate compared with the traditional Doppler monitor (0.25% vs 2.04%; χ2= 5.508, P= 0.019). The trend overlap in foetal heart rates was consistently 100%, with 91.2% of readings showing a consistency rate of ⩾ 95%. Additionally, the Thoth monitor recorded a higher cumulative interruption time in the foetal heart rate curve (12.13 ± 2.22 vs 21.02 ± 2.34; t= 18.471, P< 0.001) and more abnormal ECGs (21.21 ± 4.32 vs 18.21 ± 2.91; t= 7.582, P< 0.001) than the traditional Doppler system. The Thoth wearable FECG monitor offers several advantages over the traditional Doppler foetal heart monitoring system. These include a reduced confusion rate, more accurate data collection, a lower rate of clinical misjudgement, reduced workload for medical staff, and enhanced comfort during vaginal delivery. The rates of emergency caesarean sections and neonatal asphyxia in the Thoth group were marginally lower than those in the Doppler group, which may be attributed to issues such as ECG disconnection or interference from the maternal heart rate.

Interaction of macro- and microvascular function underlies brachial artery flow-mediated dilation in humans.

Brachial artery flow-mediated dilation (BAFMD) is induced by hyperemic wall shear rate (WSR) following forearm ischemia. In older adults, there appears to be a reduced brachial hyperemic WSR and altered stimulus-response relationship compared with young adults. However, it is unclear if an altered forearm microvascular response to ischemia influences brachial hyperemic WSR in older adults. We determined associations between brachial hyperemic WSR and forearm skeletal muscle oxygen saturation in young and older adults. Healthy young (n = 17, 29 ± 7 yr) and older (n = 32, 65 ± 4 yr) adults participated in the study. BAFMD by a multigate spectral Doppler system and forearm skeletal muscle oxygen saturation by near-infrared spectroscopy were concurrently measured. When compared with the young, older adults showed reduced oxygen extraction kinetics (OE, 0.15 [0.12-0.17] vs. 0.09 [0.05-0.12]%s-1) and magnitude (So2deficit, 3,810 ± 1,420 vs. 2,723 ± 1,240%s) during ischemia, as well as oxygen resaturation kinetics (So2slope, 2.5 ± 0.7 vs. 1.7 ± 0.7%s-1) upon reperfusion (all P < 0.05). When OE in the young and So2slope in older adults were stratified by their median values, young adults with OE above the median had greater hyperemic WSR parameters compared with those below the median (P < 0.05), but So2slope in older adults did not show clear differences in hyperemic WSR parameters between those above/below the median. This study demonstrates that, in addition to a reduced microvascular response to ischemia, there may be a dissociation between microvascular response to ischemia and brachial hyperemic WSR in older adults, which may result in a further impairment of BAFMD in this cohort.NEW & NOTEWORTHY Microvascular response to ischemia and subsequent reperfusion is diminished in older adults compared with the young. Furthermore, there appears to be a dissociation between the microvascular response to ischemia and brachial hyperemic WSR in older adults, which may further disturb the BAFMD process in this cohort. A reduced BAFMD in older adults may be a result of multiple alterations occurring both at macro- and microcirculation.

Risk factors analysis and the establishment of nomogram prediction model for PICC-related venous thrombosis in patients with lymphoma: a double-center cohort-based case-control study.

The objective of this study is to examine the risk factors associated with the occurrence of PICC-Related Venous Thrombosis (PICC-RVTE) in individuals diagnosed with lymphoma, as well as to develop a predictive risk nomogram model. A total of 215 patients with lymphoma treated at Yunnan Provincial Tumor Hospital from January 2017 to December 2020 were retrospectively evaluated as the training cohort; 90 patients with lymphoma treated at the Department of Oncology of the First People's Hospital of Anning, Affiliated to Kunming University of Science and Technology during the January 2021 to September 2023 were evaluated as the validation cohort. Independent influencing factors were analyzed by logistic regression, a nomogram was developed and validated, and the model was evaluated using internal and external data cohorts for validation. A total of 305 lymphoma patients were selected and 35 (11.48%) PICC-RVTE occurred, the median time was 13 days. The incidence within 1-2week was 65.71%. Multivariate analysis suggested that the activity amount, thrombosis history(within the last 12 months), ATIII, Total cholesterol and D-dimer levels were independently associated with PICC-RVTE, and a nomogram was constructed based on the multivariate analysis. ROC analysis indicated good discrimination in the training set (area under the curve [AUC] = 0.907, 95%CI:0.850-0.964) and the testing set (AUC = 0.896, 95%CI: 0.782-1.000) for the PICC-RVTE nomogram. The calibration curves showed good calibration abilities, and the decision curves indicated the clinical usefulness of the prediction nomograms. Patients should be advised to undergo color Doppler ultrasound system testing within two week after the implantation of a PICC catheter to detect PICC-RVTE at an early stage. The validated nomogram can be used to predict the risk of catheter-related thrombosis (CRT) in patients with lymphoma who received at least one chemotherapy after PICC catheterization, no bleeding tendency, no recent history of anticoagulant exposure and no severe heart, lung, renal insufficiency. This model has the potential to assist clinicians in formulating individualized treatment strategies for each patient.

High-speed target tracking control system based on short-time rotational reflection imaging.

High-speed tracking technology has wide applications in the military and aerospace industry. However, existing approaches, such as camera arrays or Doppler radar systems, suffer from high cost and inconvenience. This paper reports a high-speed target tracking control system based on short-time rotational reflection imaging, specifically aimed at overcoming certain limitations. In the system we designed, a high-speed camera coupled with a rotating reflector is used to achieve reliable high-speed target tracking. This paper first introduces the working principle and mathematical model of the system, then analyzes the key technologies, including motor response delay time and rotational speed curve fitting, and, finally, verifies the feasibility of the system and the correctness of the theory based on a series of experiments. Experimental results demonstrated that our work is efficient and accurate in target tracking and image clarity. The developed system demonstrates significant potential for widespread use across military and aerospace sectors. Furthermore, the insights gained from our investigation into key technologies could act as a reference point for fellow researchers in related scientific areas.

Mispointing characterization and Doppler velocity correction for the conically scanning WIVERN Doppler radar

Abstract. Global measurements of horizontal winds in cloud and precipitation systems represent a gap in the global observation system. The Wind Velocity Radar Nephoscope (WIVERN) mission, one of the two candidates to be the ESA's Earth Explorer 11 mission, aims at filling this gap based on a conically scanning W-band Doppler radar instrument. The determination of the antenna boresight mispointing angles and the impact of their uncertainty on the line of sight Doppler velocities is critical to achieve the mission requirements. While substantial industrial efforts are on their way to achieving accurate determination of the pointing, alternative (external) calibration approaches are currently under scrutiny. The correction of the line of sight Doppler velocity error introduced by the mispointing only needs knowledge of such mispointing angles and does not need the correction of the mispointing itself. Thus, this work discusses four methods applicable to the WIVERN radar that can be used at different timescales to characterize the antenna mispointing both in the azimuthal and in the elevation directions and to correct the error in the Doppler velocity induced by such mispointing. Results show that elevation mispointing is well corrected at very short timescales by monitoring the range at which the surface peak occurs. Azimuthal mispointing is harder but can be tackled by using the expected profiles of the non-moving surface Doppler velocity. Biases in pointing at longer timescales can be monitored by using a well-established reference database (e.g. ECMWF reanalysis) or ad-hoc ground-based calibrators. Although tailored to the WIVERN mission, the proposed methodologies can be extended to other Doppler concepts featuring conically scanning or slant viewing Doppler systems.

Increasing the stability of the synchronization mode of the PLL system

Nowadays, the extremely rapid development of the global telecommunications network is accompanied by the search for new and the improvement of already existing radio- and other technologies, which are intended to further advance existing systems towards the construction of even more productive global transport networks, as well as networks of wireless broadband access, including 6G mobile communication networks and networks of subsequent generations. Among the important and widely used systems, it is worth highlighting the radio engineering system such as the Phase-Locked Loop (PLL) system, the capabilities for further improvement of which are far from exhausted. In particular, articles on various research issues and the use of the PLL systems for various applications are regularly published in world scientific and engineering publications. The use of PLL covers the issues of stabilizing the frequency of high-frequency generators, building high-precision frequency synthesizers and narrowband tracking filters, signal extraction against the background of noise in Doppler systems, demodulation of signals with frequency and phase modulation, the operation of magnetic recording playback devices, etc. This article analyzes the operating modes of the PLL system, in particular search, capture and hold, and it is found that when searching for the frequency of the reference generator, the system does not provide tuning of the frequency of the voltage-controlled generator as close as possible to this frequency. This, in turn, leads to the fact that after the frequency of the reference generator enters the capture range, the PLL system is instantly activated, which compensates for the current value of the frequency difference between the two generators, using part of the useful capability of the phase detector to process the frequency changes of both generators within the linear section of its discrimination characteristic. This situation is equivalent to not finding the frequencies of the reference and controlled generators, when their frequencies are equal, in the middle of the retention area, which negatively affects the stability of the PLL system as a whole. Based on the conducted analysis and the obtained conclusions, the paper proposes the principle of adjusting the PLL system as close as possible to the middle of the synchronization (holding) area, which ensures increased stability of the system against the influence of external factors, and also positively affects the reduction of the frequency noise level of this system. According to this principle of tuning, a corresponding block diagram of the PLL system was developed and an explanation of the operation of such a scheme was provided.

Achilles tendon thickness and serum asprosin level significantly increases in patients with polycystic ovary syndrome.

In our study, we aimed to investigate the Achilles tendon thickness (ATT) and asprosin levels in patients with polycystic ovary syndrome (PCOS) and to evaluate the relationship of these parameters, which may be related to cardio-metabolic diseases. In our prospective cross-sectional study, 45 female patients with PCOS and 30 female healthy individuals similar in age were included. Serum dehydroepiandrosterone sulfate (DHEAS), total testosterone, anti-Müllerian hormone (AMH) and asprosin levels were measured using appropriate kits and homeostatic model assessment of insulin resistance (HOMA-IR), luteinizing hormone (LH) to follicle-stimulating hormone (FSH) ratio was calculated. ATT measurements were performed by two radiologists using a high-resolution ultrasound doppler system. Serum DHEAS, total testosterone, AMH and asprosin levels, HOMA-IR value, LF/FSH ratio, and ATT values were higher in patients with PCOS compared to healthy controls. Correlation analysis was performed between ATT and other parameters in patients with PCOS. In univariate analysis, parameters associated with ATT were detected as asprosin, DHEAS and AMH. In the linear regression analysis performed with significant parameters, asprosin and DHEAS levels were found to be associated with ATT. ATT values and serum asprosin levels were found to be significantly increased in patients with PCOS, and there is a very close positive relationship between ATT and serum asprosin levels. For this reason, it was thought that ATT measurement could be a cheap, simple and non-invasive monitoring parameter that can be used in the routine cardiometabolic follow-up of patients with PCOS.

Intratesticular Vascular Architecture Seen by Ultrasound Microvascular Imaging (MicroV). Illustration of the Testis Vascular Anatomy.

The testis is a richly vascularized organ supplied by low-flow thin caliber vessels that are only partially detected by traditional Doppler systems, such as color and power Doppler. However, in the vascular representation, these techniques determine, albeit to different extents, a cut of the weak vessels due to the necessary application of wall filters that cut the disturbing frequencies responsible for artifacts generated by pulsations of the vascular walls and surrounding tissues. These filters cut a specific range of disturbing frequencies, regardless of whether they may be generated by low-flow vessels. Recently, a new technology, called Ultrasound Microvascular Imaging (MicroV) has been developed, which is particularly sensitive to slow flows. This new mode is based on new algorithms capable of better selecting the low frequencies according to the source of origin and cutting only the disturbing ones, saving the frequencies originating from really weak flows. When Ultrasound microvascular imaging is used, the vascular map is more detailed and composed of macro and microvasculature, with more subdivision branches, facilitating the interpretation of the normal and, consequently, the pathological. This review aims to describe the vascular architecture of the testis with Ultrasound Microvascular Imaging (MicroV) in healthy testis, compared to traditional color/power Doppler, related to normal anatomy.

Laser Velocimetry for the In Situ Sensing of Deep-Sea Hydrothermal Flow Velocity.

Laser Doppler velocimetry (LDV) based on a differential laser Doppler system has been widely used in fluid mechanics to measure particle velocity. However, the two outgoing lights must intersect strictly at the measurement position. In cross-interface applications, due to interface effects, two beams of light become easily disjointed. To address the issue, we present a laser velocimeter in a coaxial arrangement consisting of the following components: a single-frequency laser (wavelength λ = 532 nm) and a Twyman-Green interferometer. In contrast to previous LDV systems, a laser velocimeter based on the Twyman-Green interferometer has the advantage of realizing cross-interface measurement. At the same time, the sensitive direction of the instrument can be changed according to the direction of the measured speed. We have developed a 4000 m level laser hydrothermal flow velocity measurement prototype suitable for deep-sea in situ measurement. The system underwent a withstand voltage test at the Qingdao Deep Sea Base, and the signal obtained was normal under a high pressure of 40 MPa. The velocity contrast measurement was carried out at the China Institute of Water Resources and Hydropower Research. The maximum relative error of the measurement was 8.82% when compared with the acoustic Doppler velocimeter at the low-speed range of 0.1-1 m/s. The maximum relative error of the measurement was 1.98% when compared with the nozzle standard velocity system at the high-speed range of 1-7 m/s. Finally, the prototype system was successfully evaluated in the shallow sea in Lingshui, Hainan, with it demonstrating great potential for the in situ measurement of fluid velocity at marine hydrothermal vents.

Dapagliflozin promotes angiogenesis in hindlimb ischemia mice by inducing M2 macrophage polarization.

Critical limb ischemia (CLI) is associated with a higher risk of limb amputation and cardiovascular death. Dapagliflozin has shown great potential in the treatment of cardiovascular disease. However, the effects of dapagliflozin on CLI and the underlying mechanisms have not been fully elucidated. We evaluated the effect of dapagliflozin on recovery from limb ischemia using a mouse model of hindlimb ischemia. The flow of perfusion was evaluated using a laser Doppler system. Tissue response was assessed by analyzing capillary density, arterial density, and the degree of fibrosis in the gastrocnemius muscle. Immunofluorescence and Western blot were used to detect the expression of macrophage polarization markers and inflammatory factors. Our findings demonstrate the significant impact of dapagliflozin on the acceleration of blood flow recovery in a hindlimb ischemia mouse model, concomitant with a notable reduction in limb necrosis. Histological analysis revealed that dapagliflozin administration augmented the expression of key angiogenic markers, specifically CD31 and α-SMA, while concurrently mitigating muscle fibrosis. Furthermore, our investigation unveiled dapagliflozin's ability to induce a phenotypic shift of macrophages from M1 to M2, thereby diminishing the expression of inflammatory factors, including IL-1β, IL-6, and TNF-α. These effects were partially mediated through modulation of the NF-κB signaling pathway. Lastly, we observed that endothelial cell proliferation, migration, and tube-forming function are enhanced in vitro by utilizing a macrophage-conditioned medium derived from dapagliflozin treatment. Taken together, our study provides evidence that dapagliflozin holds potential as an efficacious therapeutic intervention in managing CLI by stimulating angiogenesis, thereby offering a novel option for clinical CLI treatment.

A Case-Control Study of the Carotid Intima Media Thickness as a Good Predictor of Subclinical Atherosclerosis in South Indian Women Diagnosed With Polycystic Ovarian Syndrome in a Tertiary Care Hospital

Background and Objective: Polycystic ovarian syndrome (PCOS) is a diverse condition whose likelihood of heightened cardiovascular disease (CVD) risk in the future is often disregarded. We need to predict the risk sooner due to the intrinsic propensity for CVD in Indians, increased prevalence in South Indians, and PCOS patients. The objectives are: 1. To elicit the presence of CVD risk factor in pcos patients 2. Considering CIMT (Carotid Intima Media Thickness) as a good predictor for CVD risk Methods: A total of 50 cases and 50 age and weight (+/-2 kg) matched controls were included in this study. We assessed the CIMT by the Doppler system with electrical linear transducer midfrequency of 10 MHz. Results: Women with PCOS had a greater CIMT (0.05 ± 0.01 cm in cases vs. 0.03 ± 0 cm in controls; p &lt; 0.001). The CIMT of the cases is increased over their controls by 42.4% (014mm), P ≤0.001. The r value of age and CIMT is more when compared to the r value of weight and CIMT in both cases and controls (Age and CIMT: cases: r= 0.431 &amp; controls: r =0.312) (Weight and CIMT: cases: r = 0.164 &amp; controls: r =0.233). Conclusion: In PCOS , CIMT is a good indicator of CVD risk. When opposed to an individual's weight, age shows a stronger positive correlation with CIMT. Hence, PCOS patients must get an early CIMT scan. CIMT must be a crucial component of PCOS management and CVD risk alleviation.

Effective fall detection and post-fall breath rate tracking using a low-cost CW Doppler radar sensor

Existing low-cost Doppler radar-based fall detection systems encounter challenges due to false alarms and the absence of post-fall health tracking, significantly impacting their accuracy and overall compatibility for fall detection. This paper presents a cost-effective, robust solution for a fall detection system with the post-fall health tracking facility using a 3.18 GHz continuous-wave Doppler radar sensor. The experimental data acquisition is conducted in-house under the guidance of a healthcare expert, involving various activities such as standing, sitting, sleeping, running, walking, falling, sit-to-stand, and stand-to-sit transitions. We propose an algorithm comprising four hierarchical stages, each with specific objectives. Considering the complexity, the model is trained differently for each stage to optimize the classification accuracy. The system architecture is designed to minimize computational costs and power consumption through modular implementation in stages, utilizing low-power equipment and incorporating traditional machine-learning algorithms. Experimental results demonstrate a fall detection accuracy of 93.24% and breath rate measurement error of 2.26%, which is competitive with recent state-of-the-art approaches. Obtained results highlight the effectiveness of the proposed system in addressing the challenges of false alarms and post-fall health tracking while maintaining cost-efficiency and accuracy in fall detection.

Assessment of High Frequency Imaging and Doppler System for the Measurements of the Radial Artery Flow-Mediated Dilation

Objectives: In the article we describe the new, high frequency, 20 MHz scanning/Doppler probe designed to measure the flow mediated dilation (FMD) and shear rate (SR) close to the radial artery wall. Methods: We compare two US scanning systems, standard vascular modality working below 12 MHz and high frequency 20 MHz system designed for FMD and SR measurements. Axial resolutions of both systems were compared by imaging of two closely spaced food plastic foils immersed in water and by measuring systolic/diastolic diameter changes in the radial artery. The sensitivities of Doppler modalities were also determined. The diagnostic potential of a high frequency system in measurements of FMD and SR was studied in vivo, in two groups of subjects, 12 healthy volunteers and 14 patients with stable coronary artery disease (CAD). Results: Over three times better axial resolution was demonstrated for a high frequency system. Also, the sensitivity of the external single transducer 20 MHz pulse Doppler proved to be over 20 dB better (in terms of a signal-to-noise ratio) than the pulse Doppler incorporated into the linear array. Statistically significant differences in FMD and FMD/SR values for healthy volunteers and CAD patients were confirmed, p-values < 0:05. The areas under Receiver Operating Characteristic (ROC) curves for FMD and FMD/SR for the prediction CAD had the values of 0.99 and 0.97, respectively. Conclusions: These results justify the usefulness of the designed high-frequency scanning system to determine the FMD and SR in the radial artery as predictors of coronary arterial disease.

Hands-free continuous carotid Doppler ultrasound for detection of the pulse during cardiac arrest in a porcine model

Background/PurposePulse palpation is an unreliable method for diagnosing cardiac arrest. To address this limitation, continuous hemodynamic monitoring may be a viable solution. Therefore, we developed a novel, hands-free Doppler system, RescueDoppler, to detect the pulse continuously in the carotid artery. MethodsIn twelve pigs, we evaluated RescueDoppleŕs potential to measure blood flow velocity in three situations where pulse palpation of the carotid artery was insufficient: (1) systolic blood pressure below 60 mmHg, (2) ventricular fibrillation (VF) and (3) pulseless electrical activity (PEA). (1) Low blood pressure was induced using a Fogarty balloon catheter to occlude the inferior vena cava. (2) An implantable cardioverter-defibrillator induced VF. (3) Myocardial infarction after microembolization of the left coronary artery caused True-PEA. Invasive blood pressure was measured in the contralateral carotid artery. Time-averaged blood flow velocity (TAV) in the carotid artery was related to mean arterial pressure (MAP) in a linear mixed model. ResultsRescueDoppler identified pulsatile blood flow in 41/41 events with systolic blood pressure below 60 mmHg, with lowest blood pressure of 19 mmHg. In addition the absence of spontaneous circulation was identified in 21/21 VF events and true PEA in 2/2 events. The intraclass correlation coefficient within animals for TAV and MAP was 0.94 (95% CI. 0.85–0.98). ConclusionsIn a porcine model, RescueDoppler reliably identified pulsative blood flow with blood pressures below 60 mmHg. During VF and PEA, circulatory arrest was rapidly and accurately demonstrated. RescueDoppler could potentially replace unreliable pulse palpation during cardiac arrest and cardiopulmonary resuscitation.

Ultrasound lmaging-vulnerable plaque diagnostics: Automatic carotid plaque segmentation based on deep learning

PurposeThe purpose of this article is to develop a novel algorithm based on a kind of deep convolutional neural network for the automatic carotid plaque segmentation and stroke risk assessment from the carotid artery plaque using Doppler ultrasound system. This can improve the segmentation accuracy of carotid artery plaque from ultrasound scans which enhance the accuracy of stroke risk assessment caused by carotid plaque, and help researchers and experts to make more accurate quantitative estimates. MethodThis study used the Doppler system, combined with segmentation technique, to identify the nature and structure of plaques, which could be used for risk assessment of people at high risk of clinical suspicion of stroke. The carotid Doppler scan images used in this experiment were mainly from patients in the radiological department of a hospital. A total of 568 carotid ultrasound scanning of carotid Plaque were included. This experiment uses ResNet50, Inception_v3, and RPN for feature extraction of medical images, using RELU as the activation function. The data set after data enhancement is used for training and prediction, and the experimental results are compared. ResultBased on the physiological analysis of method we used and the risk assessment, we achieved results consistent with the result we predicted by doing a series of experiments and comparing different groups. We implemented a deep learning framework to segment Doppler ultrasound images, and achieved the highest accuracy of 92.94% by using fine-tuned and adjusted hyperparameters. ConclusionResults suggested that the ResNet50 and Inception_v3 may be used to classify the types of plaque and the method we used was more accurate than the traditional methods, which indicated that we just found an appropriate way to analyze plaque vulnerability and find the solution in time. It can provide a reliable and flexible method in recent clinical drug interventions.

470 Robotic Transcranial Doppler With Artificial Intelligence for Real-Time Intraoperative Neuromonitoring During Endovascular Carotid Revascularization – A Novel and Autonomous Neuromonitoring Tool

INTRODUCTION: Real-time intraoperative neuromonitoring is crucial to account for cerebral blood flow and embolic protection offered by proximal and distal cerebral protection devices during carotid revascularization procedures. METHODS: All patients diagnosed with high-grade carotid stenosis were prospectively enrolled between October 2021 thru February 2022. The TCD Robot head-brace system was used to secure the patients head, and the robot calibrated to automatically identify ipsilateral MCA or the terminal ICA. Patient demographics and procedural characteristics relevant to the robotic system such as signal strength, time to find signal, intracranial depth of the relevant vessel, cerebral waveform, and emboli count were recorded for the 4 critical phases: i- Access to crossing the lesion, ii- Filter and balloon deployment, iii- Stent placement and implantation, and iv- Removal of delivery system. RESULTS: Eight patients were included in our study (6 males [75%]; mean age 71.5 ± 3.9). Six out of 8 patients were symptomatic with a mean diameter stenosis of 83.5 ± 4.1. Average time taken to find a stable signal was 62 seconds (Range: 10-122). Terminal ICA was the vessel identified in all cases with a mean depth of 64mm (Range: 59-71). Flow arrest was demonstrated in all cases with flow reversal demonstrated in 2. Mean duration for the TCD Robotic surveillance was 23.6 ± 0.9 minutes with an average of 117 distal emboli (Range: 45-143) recorded by the device. Linear regression model identified stent placement and implantation as statistically significant (P = 0.0419) contributor to the final emboli count. CONCLUSIONS: To our knowledge, this is the first case series of real-time comprehensive neuromonitoring using a Robotic Transcranial Doppler system with Artificial Intelligence demonstrating various cerebral blood flow parameters including flow arrest and distal embolic incidence intra-operatively.

Cerebral autoregulation and blood flow distribution in the precerebral arteries for determining indications of extra-intracranial bypass in patients with carotid artery occlusion

Background. Prevention of ischemic stroke in patients with carotid artery occlusion is conventionally associated with performing cerebral revascularization. However, determining the indications for it is still an actual problem. The informative value of noninvasive assessment of cerebral autoregulation and blood flow distribution in the precerebral arteries in patients with carotid artery stenosis is shown. At the same time, in patients with carotid artery occlusion, these indicators have been studied to a lesser extent.Aim. To evaluate the informative value of cerebral autoregulation and blood flow distribution in the precerebral arte ries for determination the indications of extra‑intracranial bypass in patients with carotid occlusion.Materials and methods. 54 patients (aged from 41 to 83 y. o.) with carotid artery occlusion were studied. Blood flow velocity in intracranial arteries was determined with transcranial Doppler (system Multi‑Dop X), whereas flow velocity index in precerebral arteries – with duplex scanning (system Vivid Е). Cerebral autoregulation was assessed based on phase shift between spontaneous oscillations of blood flow velocity in basal cerebral arteries and systemic blood pressure within the range of Mayer’s waves (80–120 mHz).Results. The state of cerebral autoregulation was imparied on both sides in 90 % patients with the symptomatic carotid occlusion (0.3 ± 0.3 rad ipsilateral, 0.7 ± 0.6 rad contralateral). The state of cerebral autoregulation was not impaired in 79 % patients with asymptomatic carotid occlusion (1.0 ± 0.3 rad ipsilateral, 1.1 ± 0.4 rad contralateral). The flow velocity index in the contralateral internal carotid artery (306 ± 109 ml / min) and the ipsilateral vertebral (139 ± 69 ml / min) and external carotid (175 ± 72 ml / min) arteries was increased.Conclusions. Noninvasive preoperative assessment of cerebral autoregulation and blood flow distribution in the precerebral arteries makes to evaluate the state of the cerebrovascular reserve to quantify and can be used to determining indications for cerebral revascularization in patients with carotid occlusion.