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OBJECTIVES B-lines are a lung ultrasound (LUS) artifact that often indicate pathology. Little is known about the optimal ultrasound machine settings to assess B-lines. We compared settings typically used to evaluate B-lines at our institution with adjusted settings based on recent studies. METHODS In order to determine typical settings for B-line assessment, we retrospectively reviewed LUS images obtained at our institution. We then prospectively performed LUS with both typical and adjusted settings, using curvilinear and phased array probes, in 20 patients presenting to the emergency department with shortness of breath. The prospectively obtained clips were rated for quality and quantity of B-lines by 14 clinicians with experience in LUS, with 1 assigned for typical settings "much greater," 2 for typical settings "slightly greater," 3 for both settings "similar," 4 for adjusted settings "slightly greater," and 5 for adjusted settings "much greater." RESULTS Mean ratings and 95% confidence intervals significantly exceeded the null value of 3 for both B line quality (curvilinear probe: 4.68, 4.50-4.85; phased array probe: 4.02, 3.70-4.35) and B line quantity (curvilinear probe: 4.16, 3.84-4.49; phased array probe: 3.68, 3.41-3.96). CONCLUSIONS B-line quality and quantity were rated higher using adjusted settings based on recently published evidence than when using settings that are typically employed in our institution. Our findings suggest that B-line assessment should be performed with focal zone at the level of the pleura, harmonics off, and gain increased in the far field.

Understanding the basics and nuances of the functionality of ultrasound (US) equipment and of its various knobs and modes will enable the interventional radiologist to acquire higher quality US images. This, in turn will potentially allow US-guided procedures to be performed safely, and with greater operator confidence, and may also allow certain procedures to be performed with US instead of CT or fluoroscopic guidance. In this article, we review the practical aspects of US image optimization for the interventional radiologist, including equipment and transducer selection, depth, focal zone and gain setting adjustment, as well as special considerations for imaging the obese patient. Color Doppler image optimization and recent developments in ultrasound imaging are briefly discussed.

PURPOSE: B-lines on lung ultrasound (US) are the hallmark of pulmonary edema. It is unknown if ultrasound machine settings or probe type matter. METHODS: We created an in-vitro gelatin model. Using lung presets as baseline, five blinded investigators assessed the impact of 32 distinct settings on B-line visibility based on a Likert-Scale (LS) from 0–10 (5 better) separately for two probes. The experiment was then repeated in-vivo in a patient with known pulmonary edema. RESULTS: Based on a multivariable regression LS-ratings were similar when comparing the in-vitro vs. in-vivo experiment (P=0.16; partial R(2)=0.2%) and when using the curvilinear vs. linear probe (P=0.69; partial R(2)=0.02%) but significantly different across machine settings (P

Ultrasound is acoustic waves that can penetrate deeply into tissue in a focused manner with limited adverse effects on cells. As such, ultrasound has been widely used for clinical diagnosis for several decades. Ultrasound induces bioeffects in tissues, providing potential value in therapeutic applications. However, the intrinsic millimeter scale of the ultrasound focal zone represents a challenge with respect to minimizing the illuminated regions to perturb target cells in a precise manner. To control a specific cell population or even single cells, sonogenetic tools that combine ultrasound and genetic methods have been recently developed. With these approaches, several ultrasound-responsive proteins are heterologously introduced into target cells, which enhances the cells' ability to respond to ultrasound stimulation. With optimization of the ultrasound parameters, these tools can specifically manipulate activities in genetically defined cells but not in unmodified cells present in the ultrasound-illuminated regions. These approaches provide new strategies for noninvasive modulation of target cells in various therapeutic applications.

Ultrasound appears to be the most useful imaging tool in the diagnosis and guided treatment of musculoskeletal disorders. However, ultrasonography has been criticized for being user dependent. Therefore, medical professionals should be familiar with the basic principles of ultrasound imaging (e.g., physics and technical skills) to diminish artifacts and avoid misinterpretation. In this review, we focused on the physics of common artifacts, their clinical significance, and the ways to tackle them in daily practice during musculoskeletal imaging. In particular, artifacts pertaining to the focal zone, beam attenuation, path and side lobe of the beam, speed of the sound, and range ambiguity were described.

International audience; The proliferation of photovoltaic (PV) power generation in power distribution grids induces increasing safety and service quality concerns for grid operators. The inherent variability, essentially due to meteorological conditions, of PV power generation affects the power grid reliability. In order to develop efficient monitoring and control schemes for distribution grids, reliable forecasting of the solar resource at several time horizons that are related to regulation, scheduling, dispatching, and unit commitment, is necessary. PV power generation forecasting can result from forecasting global horizontal irradiance (GHI), which is the total amount of shortwave radiation received from above by a surface horizontal to the ground. A comparative study of machine learning methods is given in this paper, with a focus on the most widely used: Gaussian process regression (GPR), support vector regression (SVR), and artificial neural networks (ANN). Two years of GHI data with a time step of 10 min are used to train the models and forecast GHI at varying time horizons, ranging from 10 min to 4 h. Persistence on the clear-sky index, also known as scaled persistence model, is included in this paper as a reference model. Three criteria are used for in-depth performance estimation: normalized root mean square error (nRMSE), dynamic mean absolute error (DMAE) and coverage width-based criterion (CWC). Results confirm that machine learning-based methods outperform the scaled persistence model. The best-performing machine learning-based methods included in this comparative study are the long short-term memory (LSTM) neural network and the GPR model using a rational quadratic kernel with automatic relevance determination.

In this paper, the design process steps of a conventional solar parabolic trough with large rim angle are presented. The various parameters which intervene to obtain the suitable parabolic trough form of the concentrator are applied. Through an experimental characterization, the real focal distance and the focal zone size of the designed concentrator have been determined and compared with those calculated theoretically. Then, its concentration ratio is evaluated and the focused solar flux at the focal zone along the absorber tube is calculated using Soltrace code. It should be noted that the wind speed effect was not taken into account in the experimental tests which are conducted under a solar irradiation of 970 W/m2 and a receiver inclination angle of 36° which corresponds to the experimentation site latitude.

High intensity focused ultrasound (HIFU) has gained clinical interest as a non-invasive local tumour therapy in many organs. In addition, it has been shown that lung cancer can be targeted by HIFU using One-Lung Flooding (OLF). OLF generates a gas free saline-lung compound in one lung wing and therefore acoustic access to central lung tumours. It can be assumed that lung parenchyma is exposed to ultrasound intensities in the pre-focal path and in cases of misguiding. If so, cavitation might be induced in the saline fraction of flooded lung and cause tissue damage. Therefore this study was aimed to determine the thresholds of HIFU induced cavitation and tissue erosion in flooded lung. Resected human lung lobes were flooded ex-vivo. HIFU (1,1 MHz) was targeted under sonographic guidance into flooded lung parenchyma. Cavitation events were counted using subharmonic passive cavitation detection (PCD). B-Mode imaging was used to detect cavitation and erosion sonographically. Tissue samples out of the focal zone were analysed histologically. In flooded lung, a PCD and a sonographic cavitation detection threshold of 625 Wcm − 2(p r = 4, 3 MPa) and 3.600 Wcm − 2(p r = 8, 3 MPa) was found. Cavitation in flooded lung appears as blurred hyperechoic focal region, which enhances echogenity with insonation time. Lung parenchyma erosion was detected at intensities above 7.200 Wcm − 2(p r = 10, 9 MPa). Cavitation occurs in flooded lung parenchyma, which can be detected passively and by B-Mode imaging. Focal intensities required for lung tumour ablation are below levels where erosive events occur. Therefore focal cavitation events can be monitored and potential risk from tissue erosion in flooded lung avoided.

BACKGROUND:\ud \ud A better understanding the mechanisms of cerebral ischemia is important both for diagnosis and treatment.\ud \ud OBJECTIVE:\ud \ud The study aimed to quantify several characteristics of magnetic resonance imaging (MRI) and magnetic resonance spectroscopy (MRS) to indicate the brain tissue changes at different stage of cerebral ischemia in rats.\ud \ud METHODS:\ud \ud In the present study, a rat model of cerebral ischemia was established by middle cerebral artery occlusion (MCAO) in the left hemisphere. MRI and MRS were performed on 15 Sprague Dawley rats 4 H, 24 H, and 1 W after MCAO. Apparent diffusion coefficient (ADC), relative ADC including FNR, PNR, PNF, and metabolite ratio NCC were proposed to reflect the changes of water diffusion and metabolism in brain tissue.\ud \ud RESULTS:\ud \ud ADCs of focal zone and penumbra zone from 1 W group were significantly larger than those from 4H group, respectively (both p

We evaluated the influence of settings on an ultrasound machine on the configuration of a single B-line in a healthy model and analyzed the frequency spectrum. We also devised simple experimental models that generated B-line-like artifacts and evaluated the influence of the machine settings on the configuration. Visualization of B-lines was affected by the spatial compound imaging, the focal zone and the frequency. The spectra of both the B-line and non-B-line region at the same depth had the same center frequency and bandwidth. B-line-like artifact was generated by a spindle-shaped juice sac of a mandarin orange, an edible string-shaped glucomannan gel, glass beads and glass plates. Visualization of B-line-like artifacts was also affected by these machine settings. Our study indicated that the physical basis of some B-lines is multiple reverberations. B-line-like artifacts provide clues for solving key issues, such as the physical basis of B-lines, the sonographic-pathologic correlation in B-lines and the effects of machine settings.

Histotripsy is a tissue ablation method that utilizes focused, high-amplitude ultrasound to generate a cavitation bubble cloud that mechanically fractionates tissue. Effective histotripsy depends on the initiation, control, and maintenance of cavitation bubble clouds in the targeted area. In this study, we hypothesized that a low-pressure acoustic pulse sequence applied before and/or during histotripsy therapy would increase the cavitation initiation pressure threshold and the growth of cavitation bubble clouds. This technique could shrink or “sharpen” the focal zone during histotripsy to produce more precise and well-defined lesions with minimal collateral damage. It may also be a way to actively protect the soft tissue from cavitation damage during lithotripsy by increasing the pressure threshold for bubble cloud initiation. We applied these low-amplitude acoustic pulse sequences before and during histotripsy treatments with the pulse repetition frequency of 1 and 100 Hz, in three different mediums: water, tissue phantom agarose gel, and bovine liver in vitro . Acoustic backscatter signals and optical imaging were used to detect and monitor the initiation, maintenance, and growth of the resulting cavitation bubble cloud. The results demonstrated that the use of low-amplitude acoustic pulse sequences could increase the cavitation pressure amplitude threshold by 20% in the targeted area.

Transcranial Doppler ultrasound (TCD) is a non-invasive ultrasound method used to examine blood circulation within the brain. During TCD, ultrasound waves are transmitted through the tissues including skull. These sound waves reflect off blood cells moving within the blood vessels, allowing the radiologist to interpret their speed and direction. In this paper, an auto TCD probe is developed to control the 2D deflection angles of the probe. The techniques of Magnetic Resonance Angiography (MRA) and Magnetic Resource Imagine (MRI) have been used to build the 3D human head model and generate the structure of cerebral arteries. The K-Nearest Neighbors (KNN) algorithm as a non-parametric method has been used for signal classification and regression of corresponding arteries. Finally, a global search and local search algorithms are used to locate the ultrasound focal zone and obtain a stronger signal efficient and more accurate result.

// Xiang Zhang 1, 2 , Jiangang Hu 1, 2 , Guanjian Zhao 1, 2 , Ning Huang 1 , Ying Tan 1 , Li Pi 1 , Qing Huang 1 , Feng Wang 1 , Zhigang Wang 2 , Zhibiao Wang 3 , Yuan Cheng 1 1 Department of Neurosurgery, The Second Affiliated Hospital of Chongqing Medical University, Chongqing, 400010, China 2 Chongqing Key Laboratory of Ultrasound Molecular Imaging, Institute of Ultrasound Imaging of Chongqing Medical University, Chongqing, 400016, China 3 Chongqing Key Laboratory of Biomedical Engineering, College of Biomedical Engineering of Chongqing Medical University, Chongqing, 400016, China Correspondence to: Yuan Cheng, email: chengyuan023@aliyun.com Keywords: blood brain barrier, focused ultrasound, acoustic droplet vaporization, perfluoropentane, PLGA Received: January 17, 2017 Accepted: April 05, 2017 Published: April 17, 2017 ABSTRACT Previous studies have shown that focused ultrasound (FUS) combined with systematic administration of microbubbles (MBs) can open the blood brain barrier (BBB) locally, transiently and reversibly. However, because of the micro size diameters, MBs are restricted in the intravascular space and cannot extravasate into diseased sites through the opened BBB. In this study, we fabricated one kind of nanoscale droplets which consisted of encapsulated liquid perfluoropentane cores and poly (ethyleneglycol) - poly (lactide-co-glycolic acid) shells. The nanodroplets had the capacity to realize liquid to gas phase shift under FUS. Significant extravasation of Evan’s blue appeared when acoustic pressure reached 1.0 MPa. Intracerebral hemorrhages and erythrocyte extravasations were observed when the pressure was increased to 1.5 MPa. Prolonged sonication duration could enhance the level of BBB opening and broaden the time window simultaneously. Furthermore, compared with MBs, the distribution of EB extravasation was firmly confined within narrow region in the center of focal zone, suggesting the site of FUS induced BBB opening could be controlled with high precision by this procedure. Our results show the feasibility of serving PEGylated PLGA-based phase shift nanodroplet as an effective alternative mediating agent for FUS induced BBB opening.

The question of the formation of pulses with different duration and capacity in the focal zone of paraboloid mirror concentrating systems (PMC) is considered. The analysis of different types of regulators (shutters) is performed. Curtain and rotary shutters are developed and proposed, which provide the obtaining of light pulses with different shapes and power with a duration of one second and more.

Conduct a laboratory evaluation of a novel low-pressure, broad focal zone electrohydraulic lithotripter (TRT LG-380).Mapping of the acoustic field of the LG-380, along with a Dornier HM3, a Storz Modulith SLX, and a XiXin CS2012 (XX-ES) lithotripter was performed using a fiberoptic hydrophone. A pig model was used to assess renal response to 3000 shockwaves (SW) administered by a multistep power ramping protocol at 60 SW/min, and when animals were treated at the maximum power setting at 120 SW/min. Injury to the kidney was assessed by quantitation of lesion size and routine measures of renal function.SW amplitudes for the LG-380 ranged from (P(+)/P(-)) 7/-1.8 MPa at PL-1 to 21/-4 MPa at PL-11 while focal width measured ~20 mm, wider than the HM3 (8 mm), SLX (2.6 mm), or XX-ES (18 mm). For the LG-380, there was gradual narrowing of the focal width to ~10 mm after 5000 SWs, but this had negligible effect on breakage of model stones, because stones positioned at the periphery of the focal volume (10 mm off-axis) broke nearly as well as stones at the target point. Kidney injury measured less than 0.1% FRV (functional renal volume) for pigs treated using a gradual power ramping protocol at 60 SW/min and when SWs were delivered at maximum power at 120 SW/min.The LG-380 exhibits the acoustic characteristics of a low-pressure, wide focal zone lithotripter and has the broadest focal width of any lithotripter yet reported. Although there was a gradual narrowing of focal width as the electrode aged, the efficiency of stone breakage was not affected. Because injury to the kidney was minimal when treatment followed either the recommended slow SW-rate multistep ramping protocol or when all SWs were delivered at fast SW-rate using maximum power, this appears to be a relatively safe lithotripter.

Laser filamentation is responsible for the deposition of a significant part of the laser pulse energy in the propagation medium. We found that using terawatt laser pulses and relatively tight focusing conditions in air, resulting in a bundle of co-propagating multifilaments, more than 60 % of the pulses energy is transferred to the medium, eventually degrading into heat. This results in a strong hydrodynamic reaction of air with the generation of shock waves and associated underdense channels for each short-scale filament. In the focal zone, where filaments are close to each other, these discrete channels eventually merge to form a single cylindrical low-density tube over a $\sim 1 \mu\mathrm{s}$ timescale. We measured the maximum lineic deposited energy to be more than 1 J/m., Comment: 7 pages, 7 figures

A new ultrasonic testing technique and a new test system using a transducer array have been developed. The test system works as follows: (1) Ultrasonic waves are transmitted from all the ultrasonic transducer elements in the array at the same time; and (2) By additively synthesizing time-converted ultrasound signals transformed from echo signals received by all the ultrasonic transducer elements in the array at the same time, lines of continuously focused receiving beam (receiving needle beam) are closely formed under the transducer array (parallel receiving needle beam). Also, internal flaws in a cross-section are detected at once using the parallel receiving needle beam. The results of experiments using a 50-MHz transducer array and the developed system have proven that ultra-minute internal flaws 20 mm in diameter can be detected at a scan speed of 1000 mm/s. In addition, the focal zone formed is very long as compared with conventional point-focused beam forming. It is concluded that the system is suitable for simultaneous testing of a cross-section of a test object at high scanning speed.

OBJECTIVE To determine if the starting voltage in a step-wise ramping protocol for extracorporeal shock wave lithotripsy (SWL) alters the size of the renal lesion caused by the SWs. MATERIALS AND METHODS To address this question, one kidney from 19 juvenile pigs (aged 7–8 weeks) was treated in an unmodified Dornier HM-3 lithotripter (Dornier Medical Systems, Kennesaw, GA, USA) with either 2000 SWs at 24 kV (standard clinical treatment, 120 SWs/min), 100 SWs at 18 kV followed by 2000 SWs at 24 kV or 100 SWs at 24 kV followed by 2000 SWs at 24 kV. The latter protocols included a 3–4 min interval, between the 100 SWs and the 2000 SWs, used to check the targeting of the focal zone. The kidneys were removed at the end of the experiment so that lesion size could be determined by sectioning the entire kidney and quantifying the amount of haemorrhage in each slice. The average parenchymal lesion for each pig was then determined and a group mean was calculated. RESULTS Kidneys that received the standard clinical treatment had a mean (sem) lesion size of 3.93 (1.29)% functional renal volume (FRV). The mean lesion size for the 18 kV ramping group was 0.09 (0.01)% FRV, while lesion size for the 24 kV ramping group was 0.51 (0.14)% FRV. The lesion size for both of these groups was significantly smaller than the lesion size in the standard clinical treatment group. CONCLUSIONS The data suggest that initial voltage in a voltage-ramping protocol does not correlate with renal damage. While voltage ramping does reduce injury when compared with SWL with no voltage ramping, starting at low or high voltage produces lesions of the same approximate size. Our findings also suggest that the interval between the initial shocks and the clinical dose of SWs, in our one-step ramping protocol, is important for protecting the kidney against injury.

A prospective, cross-sectional study was performed to qualitatively and quantitatively compare the echogenicity of the renal cortex relative to the liver in healthy dogs. Twenty-five normal adult dogs were examined ultrasonographically. Three standard B-mode images (8.0 MHz) and three tissue harmonic images of the cranial pole of the right kidney adjacent to the caudate lobe of the liver were obtained. Renal and hepatic echogenicities were qualitatively compared by two observers. Subsequently, regions of interest (ROIs) were drawn in the renal cortex and the adjacent liver parenchyma at equal depths on each image, using two different ROI geometries: deep adjacent half-annular ROIs centered at the focal zone and small superficial adjacent squares placed in the near field. Renal and hepatic mean pixel intensities were quantified and averaged for individual subjects. Qualitatively, the right renal cortex was more commonly hyperechoic to liver. Quantitatively, the renal cortical mean pixel intensity was significantly higher than that of liver using deep half-annular ROIs, but not superficial square ROIs, for both standard (P = 0.0007) and harmonic (P = 0.0107) tissue imaging. These findings suggest that the renal cortex can be slightly hyperechoic to adjacent liver. The framework within which the canine renal cortical parenchyma is routinely evaluated in abdominal ultrasonography should be reconsidered, and mild hyperechogenicity relative to the liver (at 8.0 MHz) interpreted as a normal finding.

Detection of aerosolized biological warfare agents by means of LIBS commonly operate with pulsed lasers running at constant repetition rate, resulting in very low hit rates. In this paper, we present a prototype where the LIBS laser is only fired if a particle is expected in the focal zone. A significantly improved hit rate for detection and classification of mm sized single particles in real-time is achieved. Hit rates of 40% and 70% for NaCl particles of sizes 3 and 7:0 mm, respectively, can be reached in triggered configuration, as compared to 1% and 2% when the laser is un-triggered.

Treatment of angiomyolipoma (AML) of kidney with stone has been challenging for urologists. We present our experience of treating the renal stone in the presence of AML with shockwave lithotripsy (SWL). Position of the patient with respect to the direction of the shockwaves and accurate knowledge of the dimension of the focal zone are critical aspects of SWL. Keeping the AML safely away from the focal zone at all times during the procedure is only possible by usage of real-time ultrasonography in lieu of fluoroscopy.

Background High-frequency catheter probe US provides detailed images when the scanning plane is perpendicular to the area of interest and the latter is within the focal zone. A multibending endoscope has been developed that has two bending sections that can be deflected independently. The aim of this study was to determine whether this new endoscope enhances high-frequency catheter probe US. Methods High-frequency catheter probe US was performed with the multibending endoscope in 33 patients with upper-GI lesions. The endoscope was carefully maneuvered until the scanning plane was perpendicular to the area of interest and the target area was within the focal zone of the probe. The effects of deflecting the second bending section on the image and on the rotating elements in the probe were evaluated. Results For 28 lesions, no improvement was observed with use of both bending sections. However, for 5 lesions, the US image was improved by use of the second bending section. These lesions were located in the stomach on the lesser or greater curve. In no instance did deflection of both bending sections result in uneven rotation of the mechanical elements in the probe. Conclusions For certain lesions, US images obtained with a catheter probe can be improved by using an endoscope with a second bending section.

PURPOSE: To determine whether ultrasonography (US) of the breast performed at a wide range of clinical practices conforms to the American College of Radiology (ACR) standards for quality and to assess the interpretations of breast sonograms. MATERIALS AND METHODS: Static images from 152 breast US examinations performed at 86 institutions were evaluated for compliance with ACR guidelines for breast US hardware, technical factors, imaging protocol, and image annotation. Official interpretations submitted by the referring facilities were compared with static images submitted by the facility. Discrepancies were confirmed by two dedicated breast radiologists after repeat imaging, short-interval follow-up imaging, or biopsy. RESULTS: A total of 60.5% of cases did not comply with at least one ACR guideline on breast US and included 9.2% of cases with inadequate equipment, 14.7% of cases with inappropriate focal zone placement, at least 14% of cases with static images in only one imaging plane, and 25% of cases with incomplete patient identifiers. Clinically relevant interpretation errors and interpretation discrepancies were confirmed in 23 (15.1%) of 152 cases. CONCLUSION: The majority of breast US examinations did not comply with at least some of the standards for quality set forth by the ACR. Attention to these basic standards could substantially improve image quality.

The feasibility of estimating urinary flow velocity from the decorrelation of radiofrequency (RF) signals was investigated in soft tissue-mimicking models of obstructed and unobstructed urethras. The decorrelation was studied in the near field, focal zone and far field of the ultrasound beam. Furthermore, the effect of beam width was investigated. The results of this study suggest that it is feasible to estimate flow velocity in models of the urethra by quantifying the decorrelation of RF ultrasound signals. The decorrelation slope increased more rapidly and more linearly with increasing velocity in the focal zone than in the near and far field. A preliminary example of an in vivo measurement in a healthy volunteer illustrated that this method has potential for clinical use in the future. (E-mail: a.muhammad@erasmusmc.nl) (C) 2014 World Federation for Ultrasound in Medicine & Biology.

To the Editor: Fat transplantation is currently a widely-used procedure in plastic and reconstructive surgery. Despite the guidelines and technical principles are well known, it remains a “blind” method with unpredictable and sometimes inconsistent results. On sonograms, the fat in normal breast parenchyma is hypoechoic, fibrous tissue is echogenic, and glandular tissue is intermediate in echogenicity, and give that, theoretically once injected fat will not offer great contrast with the surrounding tissues. We have investigated the feasibility of ultrasound-assisted fat transplantation and high-quality breast sonograms were obtained using 7.5 to 10 MHz linear transducers, imaging the infiltrated area within the transducer focal zone. This technique was used in 2 patients with different clinical situations

The acoustic lens of the Modularis electromagnetic shock wave lithotripter (Siemens, Malvern, Pennsylvania) was modified to produce a pressure waveform and focal zone more closely resembling that of the original HM3 device (Dornier Medtech, Wessling, Germany). We assessed the newly designed acoustic lens in vivo in an animal model.Stone fragmentation and tissue injury produced by the original and modified lenses of the Modularis lithotripter were evaluated in a swine model under equivalent acoustic pulse energy (about 45 mJ) at 1 Hz pulse repetition frequency. Stone fragmentation was determined by the weight percent of stone fragments less than 2 mm. To assess tissue injury, shock wave treated kidneys were perfused, dehydrated, cast in paraffin wax and sectioned. Digital images were captured every 120 μm and processed to determine functional renal volume damage.After 500 shocks, the mean ± SD stone fragmentation efficiency produced by the original and modified lenses was 48% ± 12% and 52% ± 17%, respectively (p = 0.60). However, after 2,000 shocks, the modified lens showed significantly improved stone fragmentation compared to the original lens (mean 86% ± 10% vs 72% ± 12%, p = 0.02). Tissue injury caused by the original and modified lenses was minimal at a mean of 0.57% ± 0.44% and 0.25% ± 0.25%, respectively (p = 0.27).With lens modification the Modularis lithotripter demonstrates significantly improved stone fragmentation with minimal tissue injury at a clinically relevant acoustic pulse energy. This new lens design could potentially be retrofitted to existing lithotripters, improving the effectiveness of electromagnetic lithotripters.

During the past few years there has been an interest in using magnetic resonance imaging (MRI) to guide focused ultrasound beams during noninvasive surgery. MRI offers good soft tissue contrast, allowing the beam to be accurately aimed. Temperature sensitive MRI sequences can be used during low power test pulses to visualize the temperature elevation in the focal zone at temperature levels that do not cause tissue damage. This allows the beam to be aimed, eliminating all potential image or ultrasound propagation distortions. It may even be possible to calibrate the MRI signal to give the temperature elevation and use it as a feedback to modify the power output to assure adequate thermal exposure during every therapy sonication. Finally, MRI allows tissue changes induced by the sonication to be detected. This may be useful after the treatment to establish the boundaries of the thermal damage and is also very useful when experiments are conducted. All of these aspects of MRI guided ultrasound surgery have b...

This study evaluated the HIFU treatment time reductions attainable for several scan paths when optimising the heating approach used (single, discrete pulses versus volumetric scanning) and the paths' focal zone heating locations'; number (N(FZL)), spacings, sequencing order, number of heating cycles (N(CYCLES)), and heating times. Also evaluated were the effects of focal zone size, increased tissue absorptivity due to heating, and optimisation technique.Treatments of homogeneous constant property tumours were simulated for several simple generic tumour shapes and sizes. The concentrated heating approach (which delivered the desired thermal dose to each location in one discrete heating pulse (N(CYCLES) = 1)) was compared to the fractionated heating approach (which dosed the tumour using multiple, shorter pulses repeatedly scanned around the heating path (i.e. 'volumetric scanning' with N(CYCLES) 1)). Treatment times were minimised using both simultaneous, collective pulse optimisation (which used full a priori knowledge of the interacting effects of all pulses) and sequential, single pulse optimisation (which used only the information from previous pulses and cooling of the current pulse).Optimised concentrated heating always had shorter treatment times than optimised fractionated heating, and concentrated heating resulted in less normal tissue heating. When large, rapid tissue absorptivity changes were present (doubled or quadrupled immediately after heating) the optimal ordering of the scan path's sequence of focal zone locations changed.Concentrated heating yields significant treatment time reductions and less normal tissue heating when compared to all fractionated scanning approaches, e.g. volumetric scanning.

International audience; We report on the subwavelength focusing of Rayleigh waves using gradient-index (GRIN) phononic crystals (PCs) made of air holes scatters in a thick silicon substrate. The subwavelength focusing is demonstrated both in the inner and in the silicon substrate behind the GRIN PCs by using a non-contact experimental technique. In both situations, the focal zone was observed at the position, which is in very good agreement with our theoretical predictions, at a frequency in the sound cone free of radiation into the substrate.

An incorporate ultrasonic coupling device for extended focal zone focused photoacoustic imaging was designed. Phantom experimental imaging was carried out. The results show that, with the incorporate ultrasonic coupling device,accurate imaging position of absorber in the sample can be achieved. And it is worth mentioning that without the large water tank,the photoacoustic imaging experimental system become simple. Our work has a potential application in the noninvasive photoacoustic imaging of bio-tissue.

Given changing dietary habits and increased consumption of high-calorie foods, colorectal cancer has become a widespread disease. When colorectal cancer symptoms are ignored, a carcinoma can develop. Therefore, physicians must diagnose colorectal cancer in a timely manner. Unlike endoscopic colonoscopy, narrow-band imaging improves identification of non-neoplastic and neoplastic colonic polyps by recognizing the shapes and patterns of blood vessels. This work identifies different colonic polyp types via narrow-band imaging based on focal zone features of vascular shapes and patterns. The proposed system can identify different polyp types via selection of focal zone images, feature extraction of vessels, and a decision model.

Management of urinary calculi has changed from open pyelolithotomy and ureterolithotomy to predominantly non-invasive procedures such as extracorporeal shockwave lithotripsy (ESWL) as well as endourological such as ureterorenoscopy (URS) and percutaneous nephrolithotripsy (PCNL). Technology has advanced rapidly allowing stone disease to be treated with minimally invasive techniques that have lower morbidity than the open operations of the past. Newer semi-rigid ureteroscopes of size 7 to 9 F allow visualisation of the ureter without traumatic dilatation. There is the flexible ureteroscope developed with smaller fibre optics, the addition of the working channel that allows the use of laser fibres for stone fragmentation and a greater deflection of the tip that enables all parts of the pelvicalyceal system to be inspected for stones. New generation lithotripters for ESWL deliver shockwave to a smaller focal zone so as to minimise damage to surrounding soft tissue but as a result, there are higher failure rates. PCNL, though more invasive than ESWL and URS, is the procedure of choice for large renal stones. It is highly efficient in such situations as newer equipment to disintegrate stone and newer techniques for percutaneous access has been developed. In addition to all these minimally invasive surgical techniques, there is medical therapy available to allow the expulsion of distal ureteric stones as well as alkalinising agents to dissolve uric acid stones. Metabolic evaluation is necessary for patients with recurrent stones. Dietary adjustments may help prevent recurrent stone formation in selected patients depending on the results. With all these techniques currently available, management of urinary calculi has to be tailored according to the size, location of stone as well as patient preference.

The purpose of this chapter is to outline the history of the development of shock wave lithotripsy (SWL) of renal and ureteral stones in China and to present our experiences. The technological aspects and clinical use of Chinese lithotripters are further described. Most lithotripters used for SWL in China are indigenously produced. Lithotripter fabrication began relatively early in China; consequently, our lithotripters have developed distinctive technical characteristics that result in an advantageous cost-benefit ratio, shock waves of lower peak pressure and broader focal zone, and a greater opportunity for anesthesia-/analgesia-free and sedation-free SWL. A single ultrasound is the predominant mode for imaging. Today, SWL has become the first-line modality for renal and ureteral stones across China. Our recommended indications for SWL are similar to the European Association of Urology (EAU) and American Urological Association (AUA) guidelines on urolithiasis. In practice, patients often prefer and select SWL in preference to other modes of treatment due to the aforementioned characteristics. The reported results of SWL in China show comparable or even higher stone-free rates at 3 months; however, there is a higher re-treatment rate compared to Western countries’ reported literature. Auxiliary procedures are less used in SWL in China. In our experiences, the most frequent and commonly seen complication post-SWL was temporary hematuria. Other complications were infrequent, and serious complications were rarely reported. In recent years in China, SWL has also been widely used to treat children with renal and ureteral stones. For such cases, serious complications rarely occurred, and the few long-term studies have yet to show any evidence of negative effects of SWL on children’s renal morphology and function.

All lithotripters have three elements to exert their clinical effect: a shockwave generator which produces and focuses the shock, a means of coupling the shockwave to the patient, and an imaging modality to target the shockwave onto the stone.

Toroidal HIFU transducers have been shown to generate large conical ablations (7 cm3 in 40 seconds). The focal zone is composed of a first ring-shaped focal zone and an overlap of ultrasound beams behind this first focus. A HIFU device has been developed on this principle to treat liver metastases during an open procedure. Although these large lesions contribute to reduce treatment time, it is still needed to juxtapose 4 to 9 single HIFU lesions to treat liver metastasis (2 cm in diameter) with safety margins. In this work, a different toroidal geometry was used. With this transducer, the overlap area is located between the probe and the focal ring. The objective was to use this transducer with electronic focusing in order to create a spherical shape lesion with sufficient volume for the destruction of a metastasis of 2 cm in diameter without any mechanical displacement. The operating frequency of the toroidal transducer was 2.5 MHz. The radius of curvature was 70 mm with a diameter of 67 mm. The focal ri...

Background: Temporal triangular alopecia (TTA; also called "congenital triangular alopecia") is a common disorder that is assumed to be congenital. Little is known about its histologic features. Objective: Our purpose was to describe four new cases, review the literature, and present histologic features based on vertical and transverse sectioning. Methods: The history, clinical features, and histologic findings of four patients with TTA are described and the relevant literature reviewed. Results: Lesions of TTA are seldom congenital, and most are best described as lancet-shaped. The "bald spot" contains normal numbers of hairs, although virtually all are vellus or indeterminate follicles. Conclusion: Most cases of TTA appear to develop during the first few years of life, and the designation "congenital" is a misnomer. The appearance of alopecia can be best explained as a focal zone of hair miniaturization leading to vellus hair formation.

High resolution acoustical imaging involves hard constraints for the ultrasonic probes which are used: a high resonance center frequency, a very wide bandwidth, a good sensitivity and a strong focusing of the beam. The system which is described uses two kinds of focused transducer: a very broad band 17 MHz center frequency transducer (PZT), and a 45 MHz copolymer transducer. The focal distances are respectively 7 mm and 6 mm in water. The movement of the transducer provides a 6 mm wide and 5 mm deep echographic cross-section with at the rate of 15 images/s. The resolution is respectively at 17 MHz and 45 MHz, 80 μm and 60 μm in axial and 250 μm and 60 μm in lateral in the focal zone. The device was tested on fantoms in water and in vivo with applications in Dermatology

Knowledge of appropriate ultrasonographic (US) techniques and the US appearance of the normal breast and specific lesions is essential for successful application of breast US. The highest quality breast sonograms are achieved with 5-10-MHz linear transducers, imaging the lesion within the transducer focal zone, and relatively steep time-gain compensation curves. On sonograms, the fat in normal breast parenchyma is hypoechoic, fibrous tissue is echogenic, and glandular tissue is intermediate in echogenicity. Some normal structures can simulate masses, including the anterior costochondral junction when imaged in cross section and fat lobules outlined by Cooper ligaments when imaged in a perpendicular plane. Cysts have an anechoic interior, sharp margins, and posterior acoustic enhancement. Benign solid lesions are usually hypoechoic but variable in US appearance, which can overlap with that of complicated cysts. The classic US appearance of breast carcinoma is a hypoechoic mass with inhomogeneous internal echoes, irregular margins, and variable acoustic shadowing, although carcinoma can appear well circumscribed or have posterior acoustic shadowing in some cases. The most important function of breast US is differentiating a cyst from a solid lesion. US is also useful for evaluating a palpable mass in either young patients (30 years old) or those with dense breasts and negative mammographic results.

High intensity focused ultrasound (HIFU) technique is regarded as a noninvasive treatment method for benign and malignant tumor with great potential. While ablating a large volume tumor by using scan method, it is difficult to decide the sequence of the foci and focal zone scanning path trajectories. This article proposes a rapid scan strategy for ablating target regions which is available only for phased array transducers since fast change on focus position is needed. According to this new method, a predetermined sequence of treatment spots is applied, which is uniform random-distributed and the heating time on every spot is much shorter than the tradition method. Through numerical simulation, we analyzed the new scan method with different treatment parameters. A symmetric lesion was resulted from the new random scan method. Additionally, through this method, the problem of treatment plan in HIFU could be simplified.

This study evaluates the hypothesis that optimising the path of a high intensity focused ultrasound (HIFU) treatment's N focal zone heating pulses can significantly reduce treatment time, and identifies the underlying bio-thermal principles.Thirty-one scanning paths were investigated using 3D simulations, with a minimum thermal dose delivered to every tumour position. Treatment time was calculated as the sum of the N, individually optimised heating and cooling periods. Tumours were superficial (skin to tumour distance ranging from 1.3 to 2.5 cm), but always deep enough so that the pre-tumour normal tissue was routinely heated to its constraint temperature (range: 42-45°C). Properties were uniform and constant, and a range of blood perfusion and phased array powers were studied.The best paths significantly reduced treatment times, with the largest gains occurring when (1) temperature superposition inside the tumour was maximised by successively heating the focal zone positions located in a 'stack' along the transducer's axis, and (2) the focal zone was moved laterally to an optimised location and another stack was applied. Stacking takes advantage of the focal zone's elongated shape, which produces axial temperature superposition within the tumour. Reduced tumour heating times also reduced energy deposition in the normal tissues, thus reducing or eliminating the need for inter-pulse cooling.HIFU treatment times can be significantly reduced by taking advantage of axial temperature superposition in tumours. Further reductions are obtained by correct choice of the transverse scan path.

A study has been conducted of the focal zone "superbooms" associated with tactical maneuvers of military supersonic aircraft. Focal-zone footprints were computed for 21 tactical maneuvers: two for the SR-71 aircraft during acceleration, and 19 for fighters engaged in air combat maneuver (ACM) training. These footprints provide quantitative results which may be used for environmental planning and were the primary objective of this study. A significant observation from these footprints is that focus factors and footprint areas for high-g fighter maneuvers are substantially smaller than those for gentle maneuvers associated with larger aircraft.

Transparent biological tissues can be precisely dissected with ultrafast lasers using optical breakdown in the tight focal zone. Typically, tissues are cut by sequential application of pulses, each of which produces a single cavitation bubble. We investigate the hydrodynamic interactions between simultaneous cavitation bubbles originating from multiple laser foci. Simultaneous expansion and collapse of cavitation bubbles can enhance the cutting efficiency by increasing the resulting deformations in tissue, and the associated rupture zone. An analytical model of the flow induced by the bubbles is presented and experimentally verified. The threshold strain of the material rupture is measured in a model tissue. Using the computational model and the experimental value of the threshold strain one can compute the shape of the rupture zone in tissue resulting from application of multiple bubbles. With the threshold strain of 0.7 two simultaneous bubbles produce a continuous cut when applied at the distance 1.35 times greater than that required in sequential approach. Simultaneous focusing of the laser in multiple spots along the line of intended cut can extend this ratio to 1.7. Counter-propagating jets forming during collapse of two bubbles in materials with low viscosity can further extend the cutting zone - up to a factor of 1.54., 16 pages, 8 figures. Paper is accepted for publication in Physical Review E

After clinical introduction in 1980, extracorporeal shock wave lithotripsy (ESWL) became the primary choice of treatment for most urinary stones within less than 10 years. Stone disintegration and passage of fragments are influenced by technical demands on the lithotripter and clinical prerequisites on behalf of the patient and surgeon. There are no standardized parameters to characterize shock waves physically or to define their optimal configuration. Primarily there is the discussion about the size of focal zone and the energy flux within it. Actually, there is a trend to use smaller focal sizes for ureter stones and larger for renal stones without proof by relevant studies. The shock waves disintegrate the calculi in a sequential process by different mechanisms, for example, spallation, squeezing, cavitation induced by microbubbles, and dynamic fatigue. The propagation of the shock wave from the generator through the patient to the stone has to be ensured by optimal acoustic coupling of the waves. The stones have to be positioned precisely in the focal point imaged by fluoroscopy or sonography. Prospective randomized trials proofed that pulse rate should not exceed 90 pulses/min and shock wave energy should be ramped along ESWL session from low to high level up to the limit of applicable shock wave dose (shot number and energy) to improve stone fragmentation and reduce the risk of kidney trauma. After treatment, including retreatment in some cases, the diagnostic tools of radiology and ultrasound define if the stone is “completely” disintegrated and passage of fragments can be expected. In case of incomplete fragmentation, alternative endoscopic treatments have to be respected. The efficiency of lithotripters can be estimated by calculating quotients including stone-free rate, number of retreatments, auxiliary and alternative treatments. This is a nonstandardized possibility to compare different lithotripters additionally to the possibility of in vitro studies and the rare prospective randomized trials.

Application of ultrasound (US) has been demonstrated as an effective way to realize thrombus dissolution. Cavitation is hypothesized to be an important mechanism of US thrombolysis, but the relationship between quantified cavitation and thrombolysis efficiency has not been studied extensively. The purpose of this work was to study focused US thrombolysis feasibility and the relationship between cavitation dose and thrombolysis efficiency. Porcine clots were cut into small pieces and inserted into small rubber tubes, then placed in the focal zone of a 1.2 MHz source transducer in a water tank. At the same time, a passive cavitation detection method was used to investigate the role of both inertial and stable cavitation during thrombolysis. After thrombolysis, the debris of clots was microscopically observed, and the distribution of particles' sizes was measured by Coulter Counter. The thrombolysis efficiency, inertial cavitation dose (ICD) and stable cavitation dose (SCD) were calculated with varying pulse length and duty cycle for 120 s at ISAL of 4243 W/cm2. The differences of ICD and SCD in focal zone from when US was exposed to clot (thrombolysis) and when US was merely exposed to water (control) were calculated. According to the results, a high efficiency (90.83 plusmn 3.72%) could be achieved at duty cycle of 1:10 and pulse length of 2 ms. The debris diameters were mostly under 8 um (>99.69%). The subharmonic and broadband noise were both present during US thrombolysis. ICD and SCD generated by pulsed US increased significantly with increasing duty cycle, pulse length, which showed almost the same trends with thrombolysis efficiencies. SCD in thrombolysis was more than 9 times higher than that in control during the first recorded 132 ms. The preliminary experimental results indicated that stable cavitation may play a more important role in US thrombolysis.

Cavitation effects during biliary lithotripsy can produce sonographically visible microbubbles. The relationship between microbubble formation and clinical outcome of gallstone lithotripsy performed with a commercial lithotriptor was studied in 50 treatments in 29 patients. Microbubble formation in bile was a useful predictor of successful stone fragmentation in 31 of 34 treatments. Microbubble formation in the liver correlated with transient hepatocellular damage (as indicated by a twofold rise in serum transaminase levels) immediately after seven of 10 treatments. Advancing the focal volume of the lithotroptor deeper into the patient (placing the stone at the proximal point of the focal zone) may be a useful strategy for reducing hepatic cavitation effects, which appear to be responsible for temporary hepatocellular damage.