Phased Array Transducer Research Articles

Ultrasonographic Assessment of Extravascular Lung Water in Hospitalized Patients Requiring Hemodialysis: A Prospective Observational Study

Introduction: Sonographic technologies can estimate extravascular lung water (EVLW) in hemodialysis (HD) patients. This study investigated the suitability of a handheld scanner in contrast to a portable scanner for quantifying EVLW in hospitalized patients requiring HD. Methods: In this prospective study, 54 hospitalized HD patients were enrolled. Bedside lung ultrasound was performed within 30 min before and after dialysis using handheld (phased array transducer, 1.7–3.8 MHz) and portable (curved probe, 5–2 MHz) ultrasound devices. Eight lung zones were scanned for total B-lines number (TBLN). The maximum diameter of inferior vena cava (IVC) was measured. We performed Passing-Bablok regression, Deming regression, Bland-Altman, and logistic regression analysis. Results: The 2 devices did not differ in measuring TBLN and IVC (p > 0.05), showing a high correlation (r = 0.92 and r = 0.51, respectively). Passing-Bablok regression had a slope of 1.11 and an intercept of 0 for TBLN, and the slope of Deming regression was 1.02 within the CI bands of 0.94 and 1.11 in the full cohort. TBLN was logarithmically transformed for Bland-Altman analysis, showing a bias of 0.06 (TBLN = 1.2) between devices. The slope and intercept of the Deming regression in IVC measurements were 0.77 and 0.46, respectively; Bland-Altman plot showed a bias of −0.07. Compared with predialysis, TBLN significantly (p < 0.001) decreased after dialysis, while IVC was unchanged (p = 0.16). Univariate analysis showed that cardiovascular disease (odds ratio [OR] 8.94 [2.13–61.96], p = 0.002), smoking history (OR 5.75 [1.8–20.46], p = 0.003), and right pleural effusion (OR 5.0 [1.2–25.99], p = 0.03) were strong predictors of EVLW indicated by TBLN ≥ 4. Conclusion: The lung and IVC findings obtained from handheld and portable ultrasound scanners are comparable and concordant. Cardiovascular disease and smoking history were strong predictors of EVLW. The use of TBLN to assess EVLW in hospitalized HD patients is feasible. Further studies are needed to determine if TBLN can help guide volume removal in HD patients.

Ultrasound Phase Array Tomography for Biphasic Medium Distribution Imaging Using Synthetic Aperture Beam Scanning

Industrial ultrasonic tomography (UT) possesses unique advantages in visualizing multiphase medium and has received broad attention in the past decades. Facing small bubble distribution imaging, the current independent-transducer-based UT faces bottleneck problems of limited projection number and large projection diameter. To image the cross-sectional bubble distribution, an original concept of ultrasonic phase array tomography (UPAT) is proposed by introducing the ultrasound phase array (UPA) transducers and novel designed sensing strategy into UT. The UPAT emits a wide and directional acoustic beam toward the receivers, on which each element forms a narrow projection to detect small bubbles on its path. Hence, the UPAT forms a novel sensing strategy with shifting and multiangled acoustic beam scanning of the whole cross section, as well as the precise measurement on a high amount of narrow projections. To mathematically model the UPAT, the acoustic field distribution and beam steering algorithm are designed for beam scanning with shifted apertures, while the forward/inverse solutions are proposed for tomographic imaging. In numerical simulations, the eight-transducer UPAT is with much lower imaging error than the state-of-art 32-transducer transmissive/reflective UT with relative error reduced by 65.66% on average. In lab-scale experiments, the reconstructed bubble size, shape, and distribution are with good accuracy, boundary preservation, and image purity.

Phased array probe for the inspection of large steel forgings

Reliable inspection of large steel forgings is a significant problem across multiple industries. When the dimensions of forgings are at least 1000 mm in each direction, ultrasonic phased array inspection becomes difficult because conventional probes are not designed to transmit and focus acoustic energy over such large distances. Using simulations and experiments, this article aims to discuss the possibilities and limitations of phased array imaging of large forged steel ingots. Simulations were used to design a transducer based on the reflected amplitude, as well as the lateral and axial resolutions of defects in a 1000 mm thick block. It was shown that when limiting the aperture to allow easy handling in an industrial inspection setting, the lateral resolution and the reflected amplitude were the main limitations. Increasing the element width maximizes the energy transmitted into the material, but it also moves elements away from each other, thus reducing the lateral resolution. Based on the simulations, an experimental phased array transducer was manufactured with eight elements of 9.25 × 22.5 mm. The probe was used to perform measurements and generate total focusing method images of three different at a depth of 370 mm in a 776 mm forged steel block.

Two-dimensional and M-mode echocardiographic parameters in Ghezel sheep.

Echocardiography is a non-invasive method of cardiac evaluation in most species. Echocardiographic reference parameters are poorly documented in sheep and not documented in Ghezel sheep. The purpose of this study was to determine reference ranges of normal echocardiographic parameters using two-dimensional and M-mode techniques in Ghezel sheep. In 15 healthy female Ghezel sheep aged between 15 and 18 months, echocardiography was performed in standing position from left and right parasternal approach focused at 3rd - 5th intercostal spaces using a 2.50 - 5.00 MHz phased array transducer. The following parameters were measured in two-dimensional echocardiography: left atrial diameter (LAD), mitral valve annulus (MVA), aortic sinus (AoS), aortic valve (AoV), pulmonary sinus (PuS), and pulmonary valve (PuV); and in M-mode echocardiography: interventricular septum (IVS), left ventricular internal diameter (LVID), left ventricular free wall (LVFW), right ventricle free wall (RVFW), right ventricle internal diameter (RVID). Calculated variables included the ratios LAD/Ao and Pu/AoS, and the fractional shortening (FS), end diastolic volume (EDV), end systolic volume (ESV), ejection fraction (EF), stroke volume (SV) and cardiac output (CO) of the left ventricle. In conclusion, echocardiographic parameters could be reliably assessed in Ghezel sheep and our study provided some normal echocardiographic reference ranges that might be useful in proper identification, visualization, and measurements of cardiac structures. Such findings could be useful to assess and to diagnose the specific heart diseases in sheep practice and also for experimental studies in sheep as an animal model used for research purposes in cardiovascular studies of human.

Simultaneous acousto-optic diffractions by two lobes of a shaped phased-array transducer

Simultaneous acousto-optic diffractions by two lobes of a shaped phased-array transducer

Optimal Design of Annular Phased Array Transducers for Material Nonlinearity Determination in Pulse–Echo Ultrasonic Testing

Nonlinear ultrasound has been proven to be a useful nondestructive testing tool for micro-damage inspection of materials and structures operating in harsh environment. When measuring the nonlinear second harmonic wave in a solid specimen in the pulse–echo (PE) testing mode, the stress-free boundary characteristics brings the received second harmonic component close to zero. Therefore, the PE method has never been employed to measure the so-called “nonlinear parameter (β)”, which is used to quantify the degree of micro-damage. When there are stress-free boundaries, a focused beam is known to improve the PE reception of the second harmonic wave, so phased-array (PA) transducers can be used to generate the focused beam. For the practical application of PE nonlinear ultrasonic testing, however, it is necessary to develop a new type of PA transducer that is completely different from conventional ones. In this paper, we propose a new annular PA transducer capable of measuring β with improved second harmonic reception in the PE mode. Basically, the annular PA transducer (APAT) consists of four external ring transmitters and an internal disk receiver at the center. The focused beam properties of the transducers are analyzed using a nonlinear sound beam model which incorporates the effects of beam diffraction, material attenuation, and boundary reflection. The optimal design of the APAT is performed in terms of the maximum second harmonic reception and the total correction close to one, and the results are presented in detail.

Residual Lung Injury in Patients Recovering From COVID-19 Critical Illness: A Prospective Longitudinal Point-of-Care Lung Ultrasound Study.

We performed a prospective analysis of point-of-care ultrasound (POCUS) findings in critically ill COVID-19 patients during and after hospitalization. We enrolled 171 COVID-19 intensive care unit patients. POCUS of the lungs was performed with phased array (2-4 MHz), convex (2-6 MHz) and linear (10-15 MHz) transducers, scanning 12 lung areas. Chest computed tomography angiography was performed to exclude suspected pulmonary embolism. Survivors were clinically and sonographically evaluated during a 4 month period for evidence of residual lung injury. Chest computed tomography angiography and echocardiography were used to exclude pulmonary hypertension (PH) and chest high-resolution-computed-tomography to exclude interstitial lung disease (ILD) in symptomatic survivors. Cox regression analysis showed that lymphocytopenia (hazard ratio [HR]: 0.88, 95% confidence intervals [CI]: 0.68-0.96, p=.048), increased lactate (HR: 1.17, 95% CI: 0.94-1.46, p=0.049), and D-dimers (HR: 1.21, 95% CI: 1.03-1.44, p=.03) were mortality predictors. Non-survivors had increased incidence of pulmonary abnormalities (B-lines, pleural line irregularities, and consolidations) compared to survivors (p < .05). During follow-up, POCUS with clinical and laboratory parameters integrated in the semi-quantitative Riyadh-Residual-Lung-Injury scale had sensitivity of 0.82 (95% CI: 0.76-0.89) and specificity of 0.91 (95% CI: 0.94-0.95) in predicting ILD. The prevalence of PH and ILD (non-specific-interstitial-pneumonia) was 7% and 11.8%, respectively. POCUS showed ability to monitor the evolution of severe COVID-19 pneumonia after hospital discharge, supporting its integration in clinical predictive models of residual lung injury.

Shear wave elastography by high frame rate echocardiography can detect diffuse myocardial fibrosis after heart transplantation

Abstract Background Myocardial fibrosis is fundamental in the development of cardiac failure, regardless of ethiology. In both animal models and humans it has been shown that diffuse myocardial fibrosis (DMF) contributes to functional impairment, especially to increased passive myocardial stiffness, which is an important pathophysiological determinant of left ventricular diastolic dysfunction. Histological examination is the gold standard for myocardial fibrosis quantification, however, it requires endomyocardial biopsies which are invasive and not without risk. Echocardiographic shear wave (SW) elastography, based on high frame rate imaging, is an emerging approach for measuring myocardial stiffness in vivo. Natural SWs occur after mechanical excitation of the myocardium, e.g. after mitral valve closure (MVC) and their propagation velocity is directly related to myocardial stiffness, thus providing an opportunity to assess myocardial stiffness at end-diastole. Purpose The aim was to investigate if propagation velocities of natural SWs can be used to detect diffuse myocardial fibrosis in a cohort of heart transplant recipients. Methods We prospectively enrolled 22 patients (10.3±6.3 years after HTx) that underwent CMR during their annual check-up. We performed SW elastography in parasternal long axis views of the left ventricle using a fully programmable experimental scanner (HD-PULSE) equipped with a clinical phased array transducer (Samsung Medison P2–5AC) at 1100±250 frames per second. The SW propagation velocities at MVC were measured in the basal LV septum. Native T1 and extracellular volume (ECV) were measured at the same segment to evaluate DMF. A cut-off value for native T1 of 1040 ms and for ECV of 29% was used to define DMF in our cohort. Results We found good correlations between SW velocities and both myocardial T1 (r=0.80, p&amp;lt;0.0001, Figure A) and ECV (r=0.64, p=0.003, Figure B) measured with CMR. Further, we derived reference thresholds of natural SW velocities to identify DMF in HTx patients. The optimal cut-off value of SW velocity to identify patients with nativT1&amp;gt;1040 ms was 4.84 m/s (AUC 0.81, sensitivity 82%, specificity 82%, Figure C). To identify patients with ECV&amp;gt;0.29 the cut-off value of SW velocity was 4.74 m/s (AUC 0.74, sensitivity 73%, specificity 78%, Figure D). Conclusions End-diastolic shear wave propagation velocities, as measure of myocardial stiffness, showed a good correlation with CMR defined diffuse myocardial injury. Values higher than 4.74 m/s could identify diffuse myocardial injury in HTX patients with a good sensitivity and good specificity. These findings thus suggest that shear wave elastography has the potential to become a valuable non-invasive method for the detection of diffuse myocardial fibrosis. Funding Acknowledgement Type of funding source: None

Reflective acoustic holograms for arbitrary pressure patterning and focusing

Monolithic passive holographic lenses (MPHLs) are being proposed as an alternative technology to phased array transducers (PATs) and subwavelength structured metamaterials due to their unprecedented spatial control over the sound field. These new capabilities enable precise focusing of acoustic energy or high resolution elaborate pressure patterning without the limitations associated with the aforementioned techniques. In particular, PATs and metamaterials require either an impractical high number of active elements or face fabrication limitations when operated at ultrasonic frequencies, especially underwater or inside the human body. MPHLs do not have such limitations and are being utilized in a wide range of crucial ultrasonic applications such as medical imaging and therapy, ultrasonic contactless energy transfer and nondestructive testing. In this work, we introduce a 3-D-printed metal reflective acoustic hologram. We will present the modeling and design process of such holograms as well as their capabilities for constructing single and multifocal spatial distributions of acoustic energy in a target plane. The effects of operating frequency, hologram material and propagation distance will also be highlighted. The results are verified using finite element multiphysics simulations in COMSOL as well as experimental investigations. [This work was supported by NSF Grant Nos. ECCS—1711139 and IIP-1738689, which are gratefully acknowledged.]

Effect of non-metallic inclusions (NMI) on crack formation in forged steel

Effect of non-metallic inclusions on crack formation in forged steel components is presented in this work. Ultrasonic phased array system was used to locate and identify the defects in the forged steel samples. X-Ray Computed Tomography (XCT), Scanning Electron Microscopy (SEM), optical metallographic and image analysis, Optical Emission Spectrometry (OES) techniques were used for defect analysis and material characterization. Few subsurface cracks were found in the rejected sample of quench tempered steel acquired after the forging process. Defects were clustered near the core of the specimen. Ultrasonic phased array transducer system and XCT confirmed the presence of approximately 100 µm wide and 10 mm long cracks. Optical and SEM images suggested that the cracks were discontinuous and revealed a predominant presence of MnS and Al2O3 inclusions along with traces of SiO2 and SiC inclusions. Further, alumina inclusions were found to be clustered near the core of specimen, which is the crack zone. Cracks could have been initiated due to quench stress and augmented by the clustered alumina inclusions and propagated through the grain boundaries. Strain analysis using EBSD was performed in a sample near the crack to study the distortion of crystal lattice around the alumina inclusions. Considerable strain distribution could be observed in the matrix containing alumina inclusion, but strain seems to be relieved near the crack. It was presumed that alumina inclusions in the matrix acted as a stress concentration factor and led to the crack initiation mechanism.

An ionizing radiation acoustic imaging (iRAI) technique for real-time dosimetric measurements for FLASH radiotherapy.

FLASH radiotherapy (FLASH-RT) is a novel irradiation modality with ultra-high dose rates (>40Gy/s) that have shown tremendous promise for its ability to enhance normal tissue sparing while maintaining comparable tumor cell eradication toconventional radiotherapy (CONV-RT). Due to its extremely high dose rates, clinical translation of FLASH-RT is hampered by risky delivery and current limitations in dosimetric devices, which cannot accurately measure, in real time, dose at deeper tissue. This work aims to investigate ionizing radiation acoustic imaging (iRAI) as a promising image-guidance modality for real-time deep tissue dose measurements during FLASH-RT. The underlying hypothesis is that iRAI can enable mapping of dose deposition with respect to surrounding tissue with a single linear accelerator (linac) pulse precision in real time. In this work, the relationship between iRAI signal response and deposited dose was investigated as well as the feasibility of using a proof-of-concept dual-modality imaging system of ultrasound and iRAI for treatment beam co-localization with respect to underlying anatomy. Two experimental setups were used to study the feasibility of iRAI for FLASH-RT using 6MeV electrons from a modified Varian Clinac. First, experiments were conducted using a single element focused transducer to take a series of point measurements in a gelatin phantom, which was compared with independent dose measurements using GAFchromic film. Secondly, an ultrasound and iRAI dual-modality imaging system utilizing a phased array transducer was used to take coregistered two-dimensional (2D) iRAI signal amplitude images as well as ultrasound B-mode images, to map the dose deposition with respect to surrounding anatomy in an ex vivo rabbit liver model with a single linac pulse precision. Using a single element transducer, iRAI measurements showed a highly linear relationship between the iRAI signal amplitude and the linac dose per pulse (r2 =0.9998) with a repeatability precision of 1% and a dose resolution error <2.5% in a homogenous phantom when compared to GAFchromic film dose measurements. These phantom results were used to develop a calibration curve between the iRAI signal response and the delivered dose per pulse. Subsequently, a normalized depth dose curve was generated that agreed with film measurements with an RMSE of 0.0243, using correction factors to account for deviations in measurement conditions with respect to calibration. Experiments on the ex-vivo rabbit liver model demonstrated that a 2D iRAI image could be generated successfully from a single linac pulse, which was fused with the B-mode ultrasound image to provide information about the beam position with respect to surrounding anatomy in real time. This work demonstrates the potential of using iRAI for real-time deep tissue dosimetry in FLASH-RT. Our results show that iRAI signals are linear with dose and can accurately map the delivered radiation dose with respect to soft tissue anatomy. With its ability to measure dose for individual linac pulses at any location within surrounding soft tissue while identifying where that dose is being delivered anatomically in real time, iRAI can be an indispensable tool to enable safe and efficient clinical translation of FLASH-RT.

Prospective Longitudinal Evaluation of Point-of-Care Lung Ultrasound in Critically Ill Patients With Severe COVID-19 Pneumonia.

ObjectivesTo perform a prospective longitudinal analysis of lung ultrasound findings in critically ill patients with coronavirus disease 2019 (COVID‐19).MethodsEighty‐nine intensive care unit (ICU) patients with confirmed COVID‐19 were prospectively enrolled and tracked. Point‐of‐care ultrasound (POCUS) examinations were performed with phased array, convex, and linear transducers using portable machines. The thorax was scanned in 12 lung areas: anterior, lateral, and posterior (superior/inferior) bilaterally. Lower limbs were scanned for deep venous thrombosis and chest computed tomographic angiography was performed to exclude suspected pulmonary embolism (PE). Follow‐up POCUS was performed weekly and before hospital discharge.ResultsPatients were predominantly male (84.2%), with a median age of 43 years. The median duration of mechanical ventilation was 17 (interquartile range, 10–22) days; the ICU length of stay was 22 (interquartile range, 20.2–25.2) days; and the 28‐day mortality rate was 28.1%. On ICU admission, POCUS detected bilateral irregular pleural lines (78.6%) with accompanying confluent and separate B‐lines (100%), variable consolidations (61.7%), and pleural and cardiac effusions (22.4% and 13.4%, respectively). These findings appeared to signify a late stage of COVID‐19 pneumonia. Deep venous thrombosis was identified in 16.8% of patients, whereas chest computed tomographic angiography confirmed PE in 24.7% of patients. Five to six weeks after ICU admission, follow‐up POCUS examinations detected significantly lower rates (P < .05) of lung abnormalities in survivors.ConclusionsPoint‐of‐care ultrasound depicted B‐lines, pleural line irregularities, and variable consolidations. Lung ultrasound findings were significantly decreased by ICU discharge, suggesting persistent but slow resolution of at least some COVID‐19 lung lesions. Although POCUS identified deep venous thrombosis in less than 20% of patients at the bedside, nearly one‐fourth of all patients were found to have computed tomography–proven PE.

Optimizing linear phased array transducers for non-destructive evaluation of thin layers

AbstractIn this work, a numerical method is proposed in order to achieve design optimisation of phased array (PA) probes for the special application of defects detection in thin films. This approach relies on an extended Fourier-based model that was adapted to predict the two-dimensional ultrasonic displacement field taking place in a thin plate under individual excitation of PA probe elements which have arbitrary orientation with respect to the examined part surface. Excitation is applied through a fluid couplant and is operated at scheduled delays that are managed to enable emission of constructive pulses. This gives the possibility to steer sound waves towards a direction and to focalize the beam in a selected point. An optimisation algorithm based on the concept of pattern search that does not require evaluation of a gradient was used to find the best match in the multidimensional analysis space of possibilities including the elements orientation angles, the elements lengths, the inter-elements distances and work frequency. Optimisation was performed with the objective to maximize the displacement amplitude at the focal point while minimizing simultaneously the effect of beam side lobes. The results obtained by this approach reveal that focalisation can be achieved with enhanced features in comparison with previous algorithms assuming linear elements that are parallel to the surface of the plate.

High-Power Phased-Array Transducer Module for the Construction of a System for the Treatment of Deep Vein Thrombosis.

Blood clot can be disintegrated by high-intensity focused ultrasound alone through inertial cavitation. There are limitations in using single-element ultrasound transducers for this purpose such as lack of steerability and control of the focus in terms of shape and location. Phased-array transducers being able to rapidly scan over the clots can alleviate this problem. A full 3-D control of the ultrasound beam can be achieved by 2-D electronically steerable arrays. However, the required high-pressure amplitude has not been possible with such arrays. In this work, a 2-D 64-element fully populated phased-array transducer module was designed and fabricated for the high-pressure amplitude required for deep vein thrombosis (DVT). Lateral coupling was considered for the transducer design to decrease the electrical impedance and eliminate the need for electrical matching circuit. PZT-4 with a thickness of 0.35 mm, an element surface area of [Formula: see text] mm, and a length of 6 mm showed a mean electrical impedance of 60.4 ± 11.5 measured for each transducer element facilitating effective electric power transfer from the driving electronics. No breakdown was observed when the voltage was increased gradually to 180 ± 3 Vpp. Operation at 180 Vpp was found to be safe over 10,000 repetitions without reduction in the power, resulting in the average pressure amplitude of 1.01 ± 0.09 MPa at 2 mm from the element surface. These pressure amplitude values indicate that an array of eight modules (80 [Formula: see text] mm) is required to reach to the pressure amplitude needed for DVT. Such arrays are practical with the current technology.

Simulation and analysis of the PMN-PT based phased array transducer with the high sound velocity matching layer

The finite element modeling (FEM) simulation and comparison of electroacoustic properties of the PMN-PT based phased arrays with high sound velocity (HSV) and low sound velocity (LSV) matching layers were investigated. The simulated keff of HSV layer based phased arrays (2.7 MHz) is higher than that of LSV matching layer based phased arrays, which reveals that the higher energy conversion efficiency is obtained. The vibration modal analysis shows that the average value of displacement ratio Rdisp of HSV matching layer based arrays (2.7 MHz) is 0.850, which is larger than that of LSV layer based arrays, indicating that the transmission efficiency of longitudinal energy can be enhanced with HSV matching layer. The interaction of transverse vibration between the adjacent elements for HSV layer based arrays become much weaker, which reduce the acoustic energy loss and the interference of transverse wave. The simulation results of echo performance illustrate that the relative error of all data is controlled at 2%, which proves that the FEM simulation has excellent accuracy compare to the practical results. The measured -6 dB bandwidth of the HSV layer based arrays (2.7 MHz) is 7.28 % higher than that of the LSV layer based arrays while the relative sensitivity is almost the same. Besides, the simulated results of electroacoustic properties of phased arrays with different center frequencies demonstrate that the -6 dB bandwidth increased by an average of 7.03 % and the crosstalk level decreased by an average of 1.91 dB when using the HSV matching layer. The crosstalk and clutter wave caused by the transverse vibration can be reduced by applying the HSV matching layer and thus a shorter pulse-echo response and enhancement of the bandwidth of the arrays can be obtained.

Clinical investigation of different types of cases of outdoor patients using ultrasonography in Rangpur Medical College Hospital, Bangladesh

Ultrasonography is an easy, noninvasive, rapid investigation advised by doctors worldwide. Hence we diagnosed different types of cases through ultrasonography at outdoor patients admitted to Department of Rangpur Medical College Hospital, Rangpur Bangladesh over a period of four months. Our objective was to investigate the prevalence of different types of cases diagnosed and evaluated by ultrasonography in a variety of physical conditions with multiple clinical scenarios. Ultrasonography were performed using GE Logiq V5 Expert ultrasound machine with linear and curved linear phased array transducers. A total 300 cases were diagnosed, where female and male cases were 204 (68%), 96 (32%) respectively. Most ultrasound examinations were abdominal, with the remainder being obstetric, pelvic, breast, and genitourinary examinations. In this study, abdominal ultrasonography represented 118 case (39.33%), Pelvic 54 (18%), KUB 57 (19%), Breast 7 (2.33%) and Obstetrics 64 (21.33%). We found general clinical prevalence of abdominal cases were Cholelithiasis 17 (5.67%), Cholecystitis 3 (1%), Fatty liver 24 (8%), Hepatic Mass 2 (0.67%), Hepatic cyst 1 (0.33%), Acute hepatitis 2 (0.67%), Acute appendicitis 6 (2%), Ascites 2 (0.67%), Hernia 3(1%), Acute pancreatitis 2 (0.67%), Choledocholithiasis 2 (0.67%), Splenomegaly 1 (0.33 %), Abscess 1 (0.33%) and normal cases were 54 (18%). In genitourinary, Stone 20 (6.67%), Cyst 7 (2.33%), RPD 11 (3.67), Cystitis 4 (1.33), Ectopic kidney 1 (0.33%), Enlarged prostate 6 (2%), Hydronephrosis 1 (0.33%), Mass lesion 2 (0.67%) and normal cases were 7 (2.33%). In Pelvic, RPC 11 (3.67%), Ovarian and adnexal cyst 11 (3.67%), Uterine Anomaly 14 (4.67%), Mass lesion 2 (0.67%), Collection 7 (2.33) and normal cases were 5 (1.67%). In Obstetrics, normal pregnancy with no or minor complications, pregnancy with severe complications and abnormal pregnancy were 31(10.33%), 30(10%) and 3(1.0%) respectively. In Breast, dilated duct 1 (0.33%), Abscess 2 (0.67%), Fibroadenoma 2 (0.67%) and normal cases were 2 (0.67%). Here, we found that Fatty liver, stone in genitourinary tract and gall stone were highly prevalent. So, health care providers need to concern and raise awareness to reduce the number of cases.&#x0D; Asian J. Med. Biol. Res. June 2020, 6(2): 294-298

Ultrasound Ablation in Neurosurgery: Current Clinical Applications and Future Perspectives.

The concept of focusing high-intensity ultrasound beams for the purpose of cerebral ablation has interested neurosurgeons for more than 70 yr. However, the need for a craniectomy or a cranial acoustic window hindered the clinical diffusion of this technique. Recent technological advances, including the development of phased-array transducers and magnetic resonance imaging technology, have rekindled the interest in ultrasound for ablative brain surgery and have led to the development of the transcranial magnetic resonance-guided focused ultrasound (MRgFUS) thermal ablation procedure. In the last decade, this method has become increasingly popular, and its clinical applications are broadening. Despite the demonstrated efficacy of MRgFUS, transcranial thermal ablation using ultrasound is limited in that it can target exclusively the central region of the brain where the multiple acoustic beams are most optimally focused. On the contrary, lesioning of the cortex, the superficial subcortical areas, and regions close to the skull base is not possible with the limited treatment envelope of current phased-array transducers. Therefore, new ultrasound ablative techniques, which are not based on thermal mechanisms, have been developed and tested in experimental settings. This review describes the mechanisms by which these novel, nonthermal ablative techniques are based and also presents the current clinical applications of MRgFUS thermal ablation.

Magnetic resonance-guided focused ultrasound for movement disorders: clinical and neuroimaging advances.

To describe the path of technological developments that have led to the actual application of MRI-guided focused ultrasound in multiple neurological disorders and to update the more recent technical advances in the field. An insight into the latest clinical achievements in movement disorders will be provided, together with the neuroimaging advances for the screening, planning, and outcome evaluation. Developments, such as phased array transducers and MRI guidance have allowed the use of focused ultrasound to successfully perform incisionless therapeutic ablation in deep brain structures. Although its indication through a thalamotomy has been approved for essential and parkinsonian tremor, it has also shown preliminary efficacy for other types of tremor, Parkinson's disease motor signs and neuropsychiatric disorders. In parallel, neuroradiological techniques have helped to improve treatment application and provided new evidence in terms of lesion topography, impact on distant structures and understanding of action mechanisms. Neuroimaging developments have helped to increase successful applications of focused ultrasound as a minimally invasive ablative approach and to understand the mechanisms by which ablation of a certain brain region improves neurological disorders. The field is expanding rapidly and in the coming years it will transform functional neurosurgery.

Optimization of Ultrasound Backscatter Spectroscopy to Assess Neurotoxic Effects of Anesthesia in the Newborn Non-human Primate Brain

Studies in animal models have revealed that long exposures to anesthetics can induce apoptosis in the newborn and young developing brain. These effects have not been confirmed in humans because of the lack of a non-invasive, practical in vivo imaging tool with the ability to detect these changes. Following the successful use of ultrasound backscatter spectroscopy (UBS) to monitor in vivo cell death in breast tumors, we aimed to use UBS to assess the neurotoxicity of the anesthetic sevoflurane (SEVO) in a non-human primate (NHP) model. Sixteen 2- to 7-day-old rhesus macaques were exposed for 5 h to SEVO. Ultrasound scanning was done with a phased array transducer on a clinical ultrasound scanner operated at 10 MHz. Data consisting of 10–15 frames of radiofrequency (RF) echo signals from coronal views of the thalamus were obtained 0.5 and 6.0 h after initiating exposure. The UBS parameter “effective scatterer size" (ESS) was estimated by fitting a scattering form factor (FF) model to the FF measured from RF echo signals. The approach involved analyzing the frequency dependence of the measured FF to characterize scattering sources and selecting the FF model based on a χ2 goodness-of-fit criterion. To assess data quality, a rigorous acceptance criterion based on the analysis of prevalence of diffuse scattering (an assumption in the estimation of ESS) was established. ESS changes after exposure to SEVO were compared with changes in a control group of five primates for which ultrasound data were acquired at 0 and 10 min (no apoptosis expected). Over the entire data set, the average measured FF at 0.5 and 6.0 h monotonically decreased with frequency, justifying fitting a single FF over the analysis bandwidth. χ2 values of a (inhomogeneous continuum) Gaussian FF model were one-fifth those of the discrete fluid sphere model, suggesting that a continuum scatterer model better represents ultrasound scattering in the young rhesus brain. After application of the data quality criterion, only 5 of 16 subjects from the apoptotic group and 5 of 5 subjects from the control group fulfilled the acceptance criteria. All subjects in the apoptotic group that passed the acceptance criterion exhibited a significant ESS reduction at 6.0 h. These changes (–6.4%, 95% Interquartile Range: –14.3% to –3.3%) were larger than those in the control group (–0.8%, 95% Interquartile Range: –2.0% to 1.5%]). Data with a low prevalence of diffuse scattering corresponded to possibly biased results. Thus, ESS has the potential to detect changes in brain microstructure related to anesthesia-induced apoptosis.

An MRI-Guided Ring High-Intensity Focused Ultrasound System for Noninvasive Breast Ablation.

High-intensity focused ultrasound (HIFU) has been used for noninvasive treatment of breast tumors, but the present magnetic resonance imaging (MRI)-guided HIFU (MRI-HIFU) systems encounter skin burn. In this study, a novel MRI-HIFU breast ablation system was developed to improve the above problem. The system consisted of the ring HIFU phased-array transducer, a commercial power amplifier, the mechanical positioner, and the graphical user interface control software. MRI thermometry was also established to monitor the temperature in the HIFU-treated tissue. Ablation of pork and the in vivo rabbit leg were carried out to validate the developed system. Results of fat-surrounding pork ablation showed that the ring HIFU system reached a safe margin of 3 mm without fat burn. Moreover, precision of the positioner moving the HIFU focal zone was within 6% error under MRI circumstances. The representative MRI temperature images show that the peak temperatures among the five ablations ranged between 66 °C and 91 °C, and their thermal doses were over 10000. The system could also ablate the biceps femoris of a rabbit without skin burn to form a lesion of 2.5 mm beneath the skin. With the HIFU dose of 315 W/10 s, the MRI temperature map revealed that the maximum temperature and the thermal dose were 60 °C and 3380, respectively. The MRI-guided ring HIFU system can ablate the target tissue near subcutaneous fat without fat burn. The system prototype is a promising tool for clinical implementation.