Doppler Ultrasound Method Research Articles

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.

STUDY AND ANALYSIS OF FETAL HEART RATE MONITORING SYSTEM

Analysis of FHR variability, together with uterine muscle contractions and fetal movement activity, subject to cardiotocographic monitoring, currently play a fundamental role in fetal assessment. The strength of cardiotocography lies in that normal ranges of the results of the FHR signal analysis almost always (>95%) confirm fetal wellbeing. Unfortunately, questionable or abnormal signal features may indicate both fetal distress and its absence. The classic fetal heart rate variability analysis consists in determining the FHR baseline and then in identifying bradycardia/tachycardia, acceleration/deceleration patterns as well as the type and amplitude of oscillations. A more advanced FHR analysis is aimed at evaluating instantaneous FHR variability, especially with beat-to-beat approach, which is very important in fetal condition assessment. The most common technique of recording the FHR signal is the Doppler ultrasound method, which makes it difficult to correctly estimate the instantaneous heart rate variability because the measurements are averaged. On the other hand, instantaneous heart rate variability plays a crucial role in the diagnosis of fetal condition [1]. The increased interest in monitoring the fetal cardiac bioelectrical activity is due to the fact that the analysis of the fetal electrocardiogram ensures high efficiency and accuracy of the heart rate measurement even on a beat-to-beat level. The first fetal electrocardiogram was recorded as early as in the 1960-ies by means of a special spiral electrode enabling direct signal registration from a fetal head. Due to the way the electrode is placed, its use is limited only to the advanced labour stage [1]..

Imaging and Quantification of the Hepatic Vasculature of Mice Using Ultrafast Doppler Ultrasound.

Non-invasive in vivo imaging of the vasculature is a powerful tool for studying disease mechanisms in rodents. To achieve high sensitivity imaging of the microvasculature using Doppler ultrasound methods, imaging modalities employing the concept of ultrafast imaging are preferred. By increasing the frame rate of the ultrasound scanner to thousands of frames per second, it becomes possible to improve the sensitivity of the blood flow down to 2 mm/s and to obtain functional information about the microcirculation in comparison to a sensitivity of around 1 cm/s in conventional Doppler modes. While Ultrafast Doppler ultrasound (UFUS) imaging has become adopted in neuroscience, where it can capture brain activity through neurovascular coupling, it presents greater challenges when imaging the vasculature of abdominal organs due to larger motions linked to breathing. The liver, positioned anatomically under the diaphragm, is particularly susceptible to out-of-plane movement and oscillating respiratory motion. These artifacts not only adversely affect Doppler imaging but also complicate the anatomical analysis of vascular structures and the computation of vascular parameters. Here, we present a qualitative and quantitative imaging analysis of the hepatic vasculature in mice by UFUS. We identify major anatomical vascular structures and provide graphical illustrations of the hepatic macroscopical anatomy, comparing it to an in-depth anatomical assessment of the hepatic vasculature based on Doppler readouts. Additionally, we have developed a quantification protocol for robust measurements of hepatic blood volume of the microvasculature over time. To contemplate further research, qualitative vascular analysis provides a comprehensive overview and suggests a standardized terminology for researchers working with mouse models of liver disease. Furthermore, it offers the opportunity to apply ultrasound as a non-invasive complementary method to inspect hepatic vascular defects in vivo and measure functional microvascular alterations deep within the organ before unraveling blood vessel anomalies at the micron scale levels using ex vivo staining on tissue sections.

A spectral Doppler ultrasound method for estimation of skeletal muscle velocity

Skeletal muscle velocity is a key indicator of neuromuscular function, and monitoring its changes plays important role in tracking the progression of musculoskeletal diseases, injuries, and fatigue. However, existing methods for non-invasive estimation of skeletal muscle velocity primarily use B- mode ultrasound, often with processing methods that are time-consuming or computationally expensive, with varying accuracy based on tissue structure. Here, we propose a spectral Doppler envelope estimation method designed for skeletal muscle measurements. When compared to the modified signal noise slope intersection (MSNSI) method, our method reduces the overall mean absolute error by 13.9% and the mean absolute zero error by 82.1%. We validated our method using a portable ultrasound system on a benchtop setup that mimics the acoustic properties, measurement angles, and velocity patterns of skeletal muscles. Ex vivo and in vivo muscle velocity estimates of parallel and pennate muscles will be compared to those obtained using the MSNSI method and manual tracking of B-Mode images. Our proposed method could enable automated estimation of skeletal muscle velocities during dynamic activities in unconstrained environments, providing new insight into neuromuscular function and movement biomechanics, with potential applications in monitoring fatigue, disease progression, or injury recovery. [Work supported by the National Science Foundation.]

A rotary trans-osseous ultrasound blood flow detection method for endoscopic application

Due to the small size and proximity to the spinal cord and vertebral artery, the cervical pedicle screw fixation procedure remains to be challenging in clinical practice. The screw misplacement has a high probability of occurrence of severe complications. How to prevent direct injury to the vertebral artery is a vital study focus in cervical spine surgery. In this work, a trans-osseous ultrasound Doppler method is proposed to explore the possibility of detecting blood flow through thin cortical bone. A miniature single-element prototype probe with a center frequency of 2.5 MHz is prepared. With the classical pulse-echo acquisition, a Spectral Power Index (SPI) algorithm based on Spectral Doppler and sliding window traversal is designed to enhance the Doppler signal intensity. In vitro and in vivo experiments were conducted to investigate the feasibility of this method. The results of in vitro experiments suggest that the anticoagulated bovine blood flowing at a mean velocity of 15 cm/s to 80 cm/s is detectable when the thickness of cortical bone is 0.7 ± 0.1 mm. The in vivo experiment showed that the large blood vessel with a diameter of about 3 mm (radial artery) can be detected through thin cortical bone (thickness of 0.7 ± 0.1 mm). The proposed trans-osseous Doppler method achieves artery detection through thin cortical bone, which has demonstrated the possibility of intraoperative vessel pre-warning. The present study poses a promising strategy to reduce the risk of vertebral artery injury and misalignment rate in the cervical pedicle screw insertion procedure.

Leveraging doppler ultrasound imaging to measure pulse wave velocity changes in a mouse model of arterial stiffening to elucidate molecular pathways underlying cerebral damage

AbstractBackgroundThe highly vascularized brain is particularly vulnerable to changes in pulsatility of blood flow. With age, elastin in arteries breaks down and is replaced by collagen, making arteries less compliant and resulting in arterial stiffening. Stiffening alters pulsatility, which can be measured by pulse wave velocity (PWV), and damages small capillary beds and the neurovascular unit (NVU). The NVU is essential for proper delivery of oxygen and nutrients to the brain. Human studies have demonstrated associations between increased arterial stiffness and biomarkers of Alzheimer’s disease (AD) and neurodegeneration. We adapted a doppler ultrasound imaging method previously only used in rats to measure PWV in a mouse model of arterial stiffening to advance our understanding of the molecular underpinnings of AD and neurodegeneration.Method7‐month‐old, C57BL/6, male and female mice underwent a carotid calcification surgery, where the carotid artery was exposed to 0.3 mol/L CaCl2 (or saline as a control) for 20 minutes. PWV was measured using doppler ultrasound imaging before and after surgery. Two weeks post‐surgery, mice underwent behavioral testing, including locomotor activity, elevated zero maze, Barnes maze, and nest building. Collagen, calcium, and elastin levels in the carotid artery were determined 4 weeks post‐surgery by immunohistochemistry.ResultPreliminary results demonstrate the carotid calcification surgery successfully increased PWV in mice three weeks post‐surgery. Surgery did not inhibit behavioral task performances two weeks post‐operative. Additional data collection is underway applying this method in two transgenic AD mouse models, APP/PSEN1 and P301S, which will include behavioral testing and histological assessment of NVU components, specifically endothelial cells (CD31/PECAM), pericytes (PDGRFb), and astrocytes (GFAP) in the hippocampus.ConclusionElucidating a clear molecular link between increased arterial stiffness and cognition is essential to understanding how age‐related changes in systemic blood flow may influence AD pathology and neurodegeneration. Our preliminary results demonstrate that doppler ultrasound imaging, previously only used in rats, can be applied in mice as a reliable measurement of PWV. We will leverage this model to test the hypothesis that increased PWV is associated with worse spatial learning and memory, impaired functioning of the NVU, and increased AD pathology.

INFLUENCE OF EXPLANTATION ON THE HEMOCIRCULATION OF THE TESTICLE IN MEN OF FERTILITY AGE: LONG-TERM RESULTS, PRELIMINARY FINDINGS

Abstract. The introduction of explantation techniques into clinical practice allowed to reduce the percentage of recurrence of inguinal hernias to the level of less than 1%. But there are data indicating a negative effect on the reproductive function of men. On the other hand, a number of researchers deny the negative consequences of explantation.
 The purpose of this study is to evaluate the effect of a polypropylene prosthesis on testicular hemocirculation in men of childbearing age.
 Materials and methods. The peak systolic velocity, end-diastolic velocity and resistive index (RI) in the testicular, capsular, and intratesticular arteries were studied using the Doppler ultrasound method in 30 men aged 20-45 who underwent surgical intervention — herniotomy, Lichtenstein hernioplasty for a unilateral inguinal hernia. The obtained results were compared according to the data of the contralateral side. The study was conducted 6 and 12 months after surgery.
 Results and discussion. None of the applied parameters of testicular hemocirculation in the arteries that were studied during the observation period was statistically significantly different from the control.
 Conclusions. Within 6-12 months after hernioplasty, the synthetic explant does not have a negative effect on the state of testicular hemodynamics.

Analysis for Improvement of Doppler Tomography Imaging of Objects Scattering Continuous Ultrasonic Waves

The paper describes an innovative ultrasound imaging method called Doppler Tomography (DT), otherwise known as Continuous Wave Ultrasonic Tomography (CWUT). Thanks to this method, it is possible to image the tissue cross-section in vivo using a simple two-transducer ultrasonic probe and using the Doppler effect. It should be noted that DT significantly differs from the conventional ultrasound Doppler method of measuring blood flow velocity. The main difference is that when measuring blood flow, we receive information with an image of the velocity distribution in a given blood vessel (Nowicki, 1995), while DT allows us to obtain a cross-sectional image of stationary tissue structure. In the conventional method, the probe remains stationary, while in the DT method, the probe moves and the examined tissue remains stationary. This paper presents a method of image reconstruction using the DT method. First, the basic principle of correlation of generated Doppler frequencies with the location of inclusions from which they originate is explained. Then the exact process and algorithm in this method are presented. Finally, the impact of several key parameters on imaging quality is examined. As a result, the conclusions of the research allow to improve the image reconstruction process using the DT method.

Hyaluronic Acid Filler Injection Guided by Doppler Ultrasound.

Doppler ultrasound can be used to detect almost all arteries of the face before injecting the hyaluronic acid (HA) filler. The relatively more dangerous sites of filler injection are the glabellar wrinkle, forehead, temple, nose, and nasolabial fold area, and it is recommended to map the vasculature of these areas by Doppler ultrasound before performing filler injection. The Doppler ultrasound detection method is included as a video. Internal carotid arterial branches, the supratrochlear, supraorbital, and dorsal nasal arteries, and external carotid arterial branches, the superficial temporal and facial arteries, are very important arteries when injecting HA filler; thus, Doppler ultrasound detection is recommended.

RESEARCH NEW GENERATION ULTRASOUND TECHNOLOGIES IN BLOOD FLOW MONITORING

Currently, ultrasound machines are widely used in hospitals for the first diagnosis of various pathologies. There is also an ultrasound Doppler method to determine and monitor blood flow. Through this method, it is possible to get information about the general condition of the veins and whether there are any problems during the examination of the veins in the clinic. But, it does not have the ability to continuously monitor the condition of the veins. Continuous monitoring of blood flow rate will facilitate the work of doctors during post-operative monitoring or diagnosis of the patient's condition. At the same time, traditional ultrasound transducers may not be comfortable for post-operative examinations. In this article, a number of difficulties encountered during examinations conducted using a conventional ultrasound machine were investigated. At the same time, as a solution to these difficulties, one of the newest technologies of the modern era, the new generation ultrasound machine “USM patch”, its main features and advantages were discussed. This device, based on the working principle of the Doppler effect, is suitable for continuous monitoring of the absolute speed of blood flow in the arteries of the deep layers. It is lightweight, small in size, and has the potential to increase the accuracy and quality of the examination. Keywords: Blood Flow Sensor, movement of red blood cells, Doppler effect, ultrasound machine, Doppler ultrasound patch, biodegradable sensor, automatic

A power Doppler ultrasound method for improving intraoperative tip localization for visually obstructed needles in interstitial prostate brachytherapy.

High-dose-rate (HDR) interstitial brachytherapy (BT) is a common treatment technique for localized intermediate to high-risk prostate cancer. Transrectal ultrasound (US) imaging is typically used for guiding needle insertion, including localization of the needle tip which is critical for treatment planning. However, image artifacts can limit needle tip visibility in standard brightness (B)-mode US, potentially leading to dose delivery that deviates from the planned dose. To improve intraoperative tip visualization in visually obstructed needles, we propose a power Doppler (PD) US method which utilizes a novel wireless mechanical oscillator, validated in phantom experiments and clinical HDR-BT cases as part of a feasibility clinical trial. Our wireless oscillator contains a DC motor housed in a 3D printed case and is powered by rechargeable battery allowing the device to be operated by one person with no additional equipment required in the operating room. The oscillator end-piece features a cylindrical shape designed for BT applications to fit on top of the commonly used cylindrical needle mandrins. Phantom validation was completed using tissue-equivalent agar phantoms with the clinical US system and both plastic and metal needles. Our PD method was tested using a needle implant pattern matching a standard HDR-BT procedure as well as an implant pattern designed to maximize needle shadowing artifacts. Needle tip localization accuracy was assessed using the clinical method based on ideal reference needles as well as a comparison to computed tomography (CT) as a gold standard. Clinical validation was completed in five patients who underwent standard HDR-BT as part of a feasibility clinical trial. Needle tips positions were identified using B-mode US and PD US with perturbation from our wireless oscillator. Absolute mean±standard deviation tip error for B-mode alone, PD alone, and B-mode combined with PD was respectively: 0.3±0.3mm, 0.6±0.5mm, and 0.4±0.2mm for the mock HDR-BT needle implant; 0.8±1.7mm, 0.4±0.6mm, and 0.3±0.5mm for the explicit shadowing implant with plastic needles; and 0.5±0.2mm, 0.5±0.3mm, and 0.6±0.2mm for the explicit shadowing implant with metal needles. The total mean absolute tip error for all five patients in the feasibility clinical trial was 0.9±0.7mm using B-mode US alone and 0.8±0.5mm when including PD US, with increased benefit observed for needles classified as visually obstructed. Our proposed PD needle tip localization method is easy to implement and requires no modifications or additions to the standard clinical equipment or workflow. We have demonstrated decreased tip localization error and variation for visually obstructed needles in both phantom and clinical cases, including providing the ability to visualize needles previously not visible using B-mode US alone. This method has the potential to improve needle visualization in challenging cases without burdening the clinical workflow, potentially improving treatment accuracy in HDR-BT and more broadly in any minimally invasive needle-based procedure.

Photoacoustic Imaging of COVID-19 Vaccine Site Inflammation of Autoimmune Disease Patients.

Based on the observations made in rheumatology clinics, autoimmune disease (AD) patients on immunosuppressive (IS) medications have variable vaccine site inflammation responses, whose study may help predict the long-term efficacy of the vaccine in this at-risk population. However, the quantitative assessment of the inflammation of the vaccine site is technically challenging. In this study analyzing AD patients on IS medications and normal control subjects, we imaged the inflammation of the vaccine site 24 h after mRNA COVID-19 vaccinations were administered using both the emerging photoacoustic imaging (PAI) method and the established Doppler ultrasound (US) method. A total of 15 subjects were involved, including 6 AD patients on IS and 9 normal control subjects, and the results from the two groups were compared. Compared to the results obtained from the control subjects, the AD patients on IS medications showed statistically significant reductions in vaccine site inflammation, indicating that immunosuppressed AD patients also experience local inflammation after mRNA vaccination but not in as clinically apparent of a manner when compared to non-immunosuppressed non-AD individuals. Both PAI and Doppler US were able to detect mRNA COVID-19 vaccine-induced local inflammation. PAI, based on the optical absorption contrast, shows better sensitivity in assessing and quantifying the spatially distributed inflammation in soft tissues at the vaccine site.

Nonlinear ultrasound imaging of the microcirculation

Blood flow at and near the tissue level is a physiological parameter of significant experimental and clinical importance, as it reflects the adaptive response of organs to their normal biological environment, to disease, trauma, and the malignant progression of cancer. The use of microbubbles gives ultrasound imaging access to microvascular hemodynamics, which are beyond the ability of Doppler ultrasound methods. However, expanded clinical use of microbubbles has been limited due in part to a lack of quantification and providing only relative differences in microvascular flow. Past and more recent approaches to the quantification of microvascular blood flow will be presented. Past approaches included the use of focused nonlinear pulsing sequences to isolate microbubble from tissue signals followed by analysis of bolus kinetics or flash replenishment dynamics. Although successfull to some extent, their clinical limitations prohibited extended use and the overall application of contrast enhanced ultrasound (CEUS). Newer approaches include higher frame-rate plane wave acquisitions combined with nonlinear pulsing schemes, which enable the tracking of microbubble flow through microvascular networks. Different approaches of these elevated frame-rate acquisitions will be presented, including use of ultrasound localized microscopy.

Fundamental validation of flow volume measurement by ultrasound pulse Doppler method using simulated circuit

Fundamental validation of flow volume measurement by ultrasound pulse Doppler method using simulated circuit

Quantitative Ultrasound: An Emerging Technology for Detecting, Diagnosing, Imaging, Evaluating, and Monitoring Disease.

Ultrasound has been a popular clinical imaging modality for decades. It is a well-established means of displaying the macroscopic anatomy of soft-tissue structures. While conventional ultrasound methods, i.e., B-mode and Doppler methods, are well proven and continue to advance technically in many ways, e.g., by extending into higher frequencies and taking advantage of harmonic phenomena in tissues, fundamentally new so-called quantitative ultrasound (QUS) technologies also are emerging and offer exciting promise for making significant improvements in clinical imaging and characterization of disease. These emerging quantitative methods include spectrum analysis, image statistics, elasticity imaging, contrast-agent methods, and flow-detection and -measurement techniques. Each provides independent information. When used alone, each can provide clinically valuable imaging capabilities; when combined with each other, their capabilities may be more powerful in many applications. Furthermore, all can be used fused with other imaging modalities, such as computed tomography (CT), magnetic-resonance (MR), positron-emission-tomography (PET), or single-photon emission computerized tomography (SPECT) imaging, to offer possibly even greater improvements in detecting, diagnosing, imaging, evaluating, and monitoring disease. This chapter focuses on QUS methods that are based on spectrum analysis and image statistics.

Agreement between multiparametric MRI (PIVOT), Doppler ultrasound, and near-infrared spectroscopy-based assessments of skeletal muscle oxygenation and perfusion

Skeletal muscle perfusion and oxygenation are commonly evaluated using Doppler ultrasound and near-infrared spectroscopy (NIRS) techniques. However, a recently developed magnetic resonance imaging (MRI) sequence, termed PIVOT, permits the simultaneous collection of skeletal muscle perfusion and T2* (an index of skeletal muscle oxygenation). PurposeTo determine the level of agreement between PIVOT, Doppler ultrasound, and NIRS-based assessments of skeletal muscle perfusion and oxygenation. MethodsTwelve healthy volunteers (8 females, 25 ± 3 years, 170 ± 11 cm, 71.5 ± 8.0 kg) performed six total reactive hyperemia protocols. During three of these reactive hyperemia protocols, Tissue Saturation Index (TSI) and oxygenated hemoglobin (O2Hb) were recorded from the medial gastrocnemius (MG) and tibialis anterior (TA), and blood flow velocity was recorded from the popliteal artery (BFvpop) via Doppler Ultrasound. The other three trials were performed inside the bore of a 3 T MRI scanner, and the PIVOT sequence was used to assess perfusion (PIVOTperf) and oxygenation (T2*) of the medial gastrocnemius and tibialis anterior muscles. Positive incremental areas under the curve (iAUC) and times to peak (TTP) were calculated for each variable, and the level of agreement between collection methods was evaluated via Bland-Altman analyses and Spearman's Rho correlation analyses. ResultsThe only significant bivariate relationships observed were between the T2* vs. TSI iAUC and PIVOTperf vs. BFvpop values recorded from the MG. Significant mean differences were observed for all comparisons (all P ≤ 0.038), and significant proportional biases were observed for the PIVOTperf vs. tHb TTP (R2 = 0.848, P < 0.001) and T2* vs. TSI TTP comparisons in the TA (R2 = 0.488, P = 0.011), and the PIVOTperf vs. BFvpop iAUC (R2 = 0.477, P = 0.013) and time to peak (R2 = 0.851, P < 0.001) comparisons in the MG. ConclusionsOur findings suggest that the PIVOT technique has, at best, a moderate level of agreement with Doppler ultrasound and NIRS assessment methods and is subject to significant proportional bias. These findings do not challenge the accuracy of either measurement technique but instead reflect differences in the vascular compartments, sampling volumes, and parameters being evaluated.

Behaviors of sliding bubbles in an inclinable turbulent channel flow investigated by optoacoustic measurement

Bubbles sliding in the vicinity of inclined walls are experimentally investigated to understand their fundamental behavior inside a turbulent boundary layer. A qualitative visualization confirms that the bubble shape varies with changes in channel inclination. An optoacoustic measurement technique is adopted to investigate the sliding motion of the bubbles. The diameters and advection velocities of individual bubbles are obtained from particle-tracking-type image processing, while the liquid velocity profiles in the bubbly flow and the maximum distance between the wall and bottom of the bubble are obtained using an ultrasound pulsed Doppler method. The combined measurement confirms that the effect of buoyancy on the slip velocity of the bubble is enhanced by an increase in inclination. Moreover, the drag and buoyancy determine the bubble shape in the inclined condition. The drag coefficient is derived from the measured variables using a force balance equation between drag and buoyancy, and we reveal that the drag coefficient increases with the inclination angle up to 35°. Finally, we propose a modeling equation for the drag coefficient in terms of the Weber number, inclination angle, and ellipticity of the bubble. This equation is applicable to bubbles inside turbulent boundary layers.

Early Diagnosis of Intracranial Internal Carotid Artery Stenosis Using Extracranial Hemodynamic Indices from Carotid Doppler Ultrasound.

Atherosclerotic intracranial internal carotid artery stenosis (IICAS) is a leading cause of strokes. Due to the limitations of major cerebral imaging techniques, the early diagnosis of IICAS remains challenging. Clinical studies have revealed that arterial stenosis may have complicated effects on the blood flow’s velocity from a distance. Therefore, based on a patient-specific one-dimensional hemodynamic model, we quantitatively investigated the effects of IICAS on extracranial internal carotid artery (ICA) flow velocity waveforms to identify sensitive hemodynamic indices for IICAS diagnoses. Classical hemodynamic indices, including the peak systolic velocity (PSV), end-diastolic velocity (EDV), and resistive index (RI), were calculated on the basis of simulations with and without IICAS. In addition, the first harmonic ratio (FHR), which is defined as the ratio between the first harmonic amplitude and the sum of the amplitudes of the 1st–20th order harmonics, was proposed to evaluate flow waveform patterns. To investigate the diagnostic performance of the indices, we included 52 patients with mild-to-moderate IICAS (<70%) in a case–control study and considered 24 patients without stenosis as controls. The simulation analyses revealed that the existence of IICAS dramatically increased the FHR and decreased the PSV and EDV in the same patient. Statistical analyses showed that the average PSV, EDV, and RI were lower in the stenosis group than in the control group; however, there were no significant differences (p > 0.05) between the two groups, except for the PSV of the right ICA (p = 0.011). The FHR was significantly higher in the stenosis group than in the control group (p < 0.001), with superior diagnostic performance. Taken together, the FHR is a promising index for the early diagnosis of IICAS using carotid Doppler ultrasound methods.

Color Doppler and Ankle-brachial Index in the Diagnosis of Peripheral Artery Disease in Type II Diabetic Subject

Objective: To determine the association of color doppler and ankle-brachial index (ABI) in the diagnosis of peripheral artery disease in type ii diabetic subject.&#x0D; Methods: The study was carried out at ultrasound department of Advanced Radiology Clinic (ARC), Karachi, from January 2020 to December 2020. Patients of diagnosed diabetes mellitus for at least 4 years of either gender between 30-70 years of age were included. All patients were instructed to avoid heavy exercise, smoking and caffeinated beverages before the examination for at the minimum of two hours. All the cases underwent Standard Doppler examination of lower limb peripheral arteries performed by radiologist having experience of more than 10 years. Spectral waveform analysis was evaluated and presence of Biphasic flow or monophasic flow on color Doppler was labelled as peripheral artery disease. The ABI was computed for each patient by measuring the systolic blood pressure in supine position starting with the right arm then proceeding towards right leg, left leg, and finally for the left arm. ABI is a ratio obtained from dividing the higher of the ankle blood pressures for each leg by the highest of the right and left arm’s brachial systolic blood pressures. It was labelled as peripheral artery disease if the value was &lt;0.9. This information along with the demographics was entered in the Performa by the researcher. Data was analyzed by using SPSS Version 26.&#x0D; Result: Mean age of enrolled participants was 58.21±6.74 year. There were 78.6% were males and 21.4% were females; mean duration of diabetes was 11.24±5.62 years. Out of all 121 cases were diagnosed color doppler and 118 cases found positive on ABI. Although ankle-brachial index shows almost similar diagnosis like color doppler ultrasound in the assessment of peripheral arterial disease (P-0.649).&#x0D; Conclusion: This study concludes that ankle-brachial index is a feasible, non-invasive technique almost similar to color Doppler ultrasound method for the detection of peripheral arterial disease. The ankle-brachial index technique is most important in periphery areas where color Doppler ultrasound is not available.

Lift coefficient of bubble sliding inside turbulent boundary layers in an inclinable channel flow

The behavior of bubbles traveling in the proximity of a tilted wall is studied experimentally to understand the fundamental sliding motion of bubbles inside turbulent boundary layers along an inclined wall. The qualitative visualization of sliding bubbles confirms the contribution of bubble buoyancy on the sliding motion for negative and positive inclinations of the channel. An opto-acoustic combined measurement technique is adopted to explore the sliding motion. Liquid velocity profiles in the bubbly flow and the distance between the wall and bottom of the bubble are obtained using the ultrasound pulsed Doppler method, while the bubble diameters and velocities are obtained from particle-tracking type image processing. The combined measurements reveal that the velocity of bubbles decreases under the negative slope condition and increases under the positive slope condition due to opposite buoyancy effects. In addition, the distance between the wall and bottom of the bubble increases with an increase in negative inclination. The lift coefficient is derived from the measured variables using a force–balance equation among the buoyancy, lift, and surface tension. Finally, we propose modeling equations for the lift coefficient expressed in terms of the Reynolds, Weber, and Bond numbers, which apply to the bubbles inside boundary layers.