Transmission Of Ultrasound Waves Research Articles

Effects of scattering on ultrasound wave transmission through bioinspired scaffolds

Enhancing tissue growth in scaffolds using ultrasound waves while maintaining the structural integrity of the scaffolds is a challenging problem. Previous studies have primarily focused on the effect of ultrasound waves directly on the tissue, but how the ultrasound wave interacts with the scaffold needs to be further understood, which will have a significant effect on the response of tissue to mechanical stimulation. In this study we investigate how ultrasound wave transmission differs between scaffolds with uniform pore shapes (triangle, square, rectangle, hexagon) and a bioinspired scaffold with higher structural integrity that is inspired from the atomic structure of hydroxyapatite which is a primary component of bone. We use finite element method and ultrasound experiments on 3D-printed scaffolds composed of Acrylonitrile butadiene styrene (ABS) with constant porosity to predict the effect of pore shape and wave signal frequency in the range of 1–20 MHz on acoustic wave scattering and transmission. We find that the pore shape of the scaffold affects the magnitude of ultrasound transmission even when porosity is constant, and that the bioinspired scaffolds can allow as much as 67% more wave transmission compared to scaffolds with rectangular or square pore shapes at 1 MHz frequency. Triangular and hexagonal pores are also found to produce more nonuniform transmitted wavefronts compared to the square and rectangular pores. Peak density is defined as the number of local extrema of the transmitted wave frequency power spectrum and measures the uniformity of the transmitted wave. We find that a higher peak density value for the bioinspired scaffold due to its nonsymmetric structure further produces more nonuniform wave scattering. The results of this study are important for designing bioinspired tissue scaffold geometries to control ultrasound wave penetration and to enhance mechanical stimulation for tissue growth and will also aid in the ultrasonic characterization of porous structures based on changes in pore geometry.

On the question of finding a universal mechanism for the transmission of sound wave energy in iron during heating and deformation

The paper presents a theoretical analysis of the experimental data on the ultrasound speed change in iron during heating and elastic deformation. The mathematical models proposed for assessing the change in the ultrasound speed based on the “adiabatic approximation” method do not explain, using one model, the change in the ultrasound speed in iron during heating and elastic deformation. During theoretical analysis, a new model of ultrasound wave transmission has been proposed, in which the wave energy propagates in the volume of the interatomic bond, namely in the loop, which is formed by the “collectivization” of valence electrons located in the outer orbit of atoms. The new model explains why with an increase in the interatomic distance a, the crystal lattice parameter, and an increase in the natural vibration frequency of atoms Vat during heating and elastic deformation, in one case (heating), the speed of the sound wave decreases, but in the other case (elastic deformation), the speed of the wave increases with a general decrease in the temperature of the rod.

Real time ultrasound assessment of contact progress between food gels and tongue mimicking surfaces during a compression

An in vitro study was conducted to further explore the potential of an emerging ultrasound method for monitoring in real time the progress of the contact between gels with different physical properties and tongue mimicking surfaces (TMSs) during uniaxial compressions. A 1-MHz ultrasound transducer was used to measure the apparent reflection coefficient (R*) of the interface between TMSs (of varied roughness) and gels (agar and/or gelatin). The patterns of R* variations clearly depended on the gels capacity to deform and mold the asperities of the TMSs during compression. Rough TMSs induced a significant decline of R* values, demonstrating an increase of the fraction of the TMSs in direct contact with the gels. Rigidity, fracture properties or adhesion energy of gels influenced the kinetics of contact progress and associated patterns of R* variations. Moreover, the presence of a thick lubrication film between the gels and the TMSs promoted the transmission of ultrasound waves (acting as a coupling agent) and led to decreasing values of R*. Such phenomena were observed both when depositing a water lubrication film of controlled thickness on the TMSs (to mimic salivary film) and when considering gels with high water release capacities. The study confirms the potential of ultrasound methods for exploring physical phenomena related to interactions between food and tongue surface. Such developments could better contribute to unravel the determinants of texture perceptions during food oral processing.

Multi-Angle Liquid Flow Measurement Using Ultrasonic Linear Array Transducer.

Most ultrasonic flowmeters utilize several wedge sensors for transmission and reception. Thus, the location and alignment of the sensors are critical factors that determine the performance of the ultrasonic flowmeter. In this study, we proposed an ultrasound liquid flowmeter utilizing a 128-element linear array transducer with a transmit delay control for varying the incidence angles of ultrasound wave transmission. The performance of the flowmeter was evaluated at flow rates of 0–50 L/min in a specially designed pipe system. Flow estimation was performed with the transit-time method using cross-correlation with phase zero-crossing for sub-sample estimation. While a single plane wave approach performed invasive electromagnetic measurements with only 74% accuracy as a reference, a multiple angular compensation method with 24 angles was proposed to increase the accuracy of measurements up to 93%. This study demonstrated the capability of the non-invasive single-sided ultrasonic flowmeter with a linear array transducer for liquid flow measurements in the metal pipe system.

Please Explain the Basic Concept of Ultrasound Elastography, and How Can It Help Differentiate Benign From Malignant Breast Lesions?

the strain source and then visualizes the strain induced in tissue with the use of either an external or internal source. In harmonic elastography, low-frequency acoustic waves are transmitted within the tissue. The phase and amplitude of the propagating waves are visualized using color Doppler imaging [3, 4]. In transient elastography, an ultrasound scanner with a high frame rate (i.e., 10,000 frames per second) is used to generate and then track the propagation of shear waves in tissue [5]. Shear waves are tissue movements perpendicular to the direction of the ultrasound wave transmission. In terms of breast elastography, malignant masses tend to be more irregular, are heterogeneous, and typically appear larger at elastography than at gray-scale imaging [6, 7]. In terms of quantitative analysis, malignant lesions generally also exhibit maximum stiffness greater than 80–100 kPa [7, 8]. Invasive cancers with a high histologic grade, large tumor size, nodal involvement, and vascular invasion have also been shown to be signifi cantly correlated with high mean stiffness at shear-wave elastography. Elastography may be useful in improving the specificity of ultrasound evaluation of BI-RADS categories 3 and 4A lesions, including complicated cysts, by avoiding unnecessary biopsy of BI-RADS category 4A masses (i.e., masses for which suspicion of malignancy was low) without a significant loss in sensitivity. Several classification systems in volving elastography, most of which are based on the color pattern, have been proposed. For example, a bull’s-eye artifact has also been described as a characteristic of benign breast cysts, which may appear as a round or oval lesion with a stiff rim associated with two soft spots, one located centrally and the other posteriorly. Ultrasound elastographic features

Acoustic characterization of a neonate skull using a clinical MR-guided high intensity focused ultrasound system for pediatric neurological disorder treatment planning

Transcranial MR-guided Focused Ultrasound (TcMRgFUS) treatments are now clinically performed on adult patients for brain tumor or essential tremor therapies. However, no application has been proposed for children despite their thinner skull being less of an acoustic barrier and the presence of a fontanelle on neonates, which could constitute a natural acoustic window for the transmission of ultrasound waves. As there is minimal literature data on the attenuation and speed-of-sound of the skull in neonatal patients, the aim of this study was to perform the acoustic characterization of a neonate skull.

Fracture Healing Enhancement With Low Intensity Pulsed Ultrasound at a Critical Application Angle

Low-intensity pulsed ultrasound (LIPUS) was shown to have dose-dependent enhancement effect on the osteogenic activity of human periosteal cells that played an important role in fracture healing. It was hypothesized that the stimulatory effects of LIPUS on the periosteal cells could be optimized by adjusting the ultrasound delivered at its critical angle to the surface of bone. This increased the transmission of ultrasound waves on periosteum. By using a rat femoral fracture model, the stimulatory effects of LIPUS transmitted at 0°, 22°, 35° and 48°, and the sham-treatment control were investigated. Treatment efficacy was assessed using radiography, micro-computed tomography (micro-CT), histomorphometry and torsional test. The results showed that callus mineralization and bridging, biomechanical properties were significantly enhanced in the 35° group over the control and 0° groups after week 8. LIPUS transmitted at 35°, which could be the critical application angle, showed the best enhancement effects among all the other groups. LIPUS transmitted at a critical application angle may have greater enhancement effects in fracture healing.

Velocity of ultrasound wave transmission at the bones for evaluating incipient rickets in infants

Objective To explore rules of changes in velocity of ultrasound wave transmission at the tibia and radius by a quantitative bone mineral density ultrasound scanner in examination of early incipient rickets in infants and its significance in clinical diagnosis.Methods One hundred and fifty-seven infants who visited child health-care clinic of the Capital Institute of Pediatrics,Beijing during May 2004 to December 2007 and clinically diagnosed as rickets according to the Criteria of Diagnosis for Rickets in Infants and Young Children formulated in 1986 by the Ministry of Health,as well as 124 normal healthy infants as controls,were enrolled in the study and followed-up for three months.Velocity of ultrasound wave transmission at the tibia and radius in all the infants were measured by a bone mineral density ultrasound scanner (Sunlight Omnisense 7000R made in Israel).Results One hundred and fifty-seven infants were clinically diagnosed as rickets,127 of them undergone with carpal plane roentgenography and 90 of the 127 with positive change in bone x-ray imaging and 37 without it.Velocity of ultrasound wave transmission at the tibia and radius measured by z-score was significantly lower in infants with clinically diagnosed rickets than that in healthy controls (Z-values of-10.411 and-10.399 at the tibia and-5.646 and-5.517 at the radius,respectively,P = 0.000 with Mann-Whitney test).Velocity of ultrasound wave transmission at the tibia and radius measured by z-score was lower in those with positive change in x-my imaging than that in those without it,but not reaching a level of statistically significant difference.Velocity of ultrasound wave transmission and z-score correlated positively with change in bone x-ray imaging,respectively with Spearman coefficients of correlation of 0.581 and 0.677 for tibia,0.316 and 0.467 for radius (P = 0.000).Receiver operating characteristic (ROC) curve was drawn from those with rickets and positive left carpal plane roetgenograph.Area under curve of ROC for z-score of velocity of ultrasound wave transmission at the tibia was 0.812 and 0.799 (95% CI 0.758-0.856 and 0.742-0.855,P =0.000),respectively.Area under ROC curve of z-score of velocity of ultrasound wave transmission at the radius was 0.715 and 0.697 (95% CI 0.650-0.780,0.631-0.764,P =0.000),respectively.Cut-off value of z-score was-205--1.95 at the tibia,according to the largest sensitivity and the least false-positivity,with sensibility of 0.8 to 0.9 and specificity of 0.733 to 0.702.As its sensitivity at the radius was more than 0.7,its specificity was lower than 0.524.Conclusions Quantitative ultrasound scanning can be used to detect insufficient bone mineral density in infants and their early skeletal change by rickets but without change in bone x-ray imaging.Velocity of ultrasound wave transmission at the tibia can be used as an indicator to predict early rickets in infants rather than its severity. Key words: Infant; Rickets; Skeleton; Ultrasonography

Karakteristik Transmisi Gelombang Ultrasonik dan Hubungannya dengan Sifat Fisiko-Kimia Buah Naga

Karakteristik Transmisi Gelombang Ultrasonik dan Hubungannya dengan Sifat Fisiko-Kimia Buah Naga

Device for scanning objects by means of ultrasound echography

A device for scanning objects, notably biological tissues, by means of ultrasound echography, which device includes at least one ultrasound transducer (10) which is connected to a transmitter stage (20) for the repeated transmission of ultrasound waves to the object to be examined, and to a receiver stage for receiving the echoes reflected in the direction of the transducer. The device in accordance with the invention is characterized mainly in that the receiver stage includes: (A) a transformation device (110) for transforming the echographic signal by calculation of the Mellin transform of this signal; (B) an arithmetic device (120) for calculating a correction function by transformation of the attenuation function; (C) a processing device (130) which consists of a series connection of a multiplier circuit (131) for multiplying the respective output signals of the transformation devices (110) and (120) and a circuit (132) for calculating the inverse Mellin transform of the signal thus obtained. (D) a processing device (140) for processing the output signal of the arithmetic circuit (132) for calculating the inverse Mellin transform for the display of images of the region scanned and/or data which are representative of the region scanned.

Early pregnancy detection in the mare with ultrasonography

Ultrasound can be defined as the propagation of energy waves with a frequency greater than the upper limit of the hearing range, approximately 20,000 cycles per second (Hertz, Hz.). In medical diagnostic ultrasound, frequencies much greater than that, in the range of 1 to 10 Megahertz (MHz.), are commonly employed. Energy waves of these frequencies can be produced by a transducer utilizing the piezoelectric property of crystals. When an electric current is applied to these crystals, vibrations of a frequency unique to the physical properties of that crystal are produced, resulting in the propagation of sound waves. When sound waves are passed through soft tissues, a portion of their energy will be reflected back toward the transducer as a reflected wave or echo. The echo can impinge on the face of the crystal causing pressure changes which result in the production of an electrical current of a corresponding frequency.] The magnitude of the reflected energy waves will be directly proportional to the difference in density existing at the interface of two tissues. In general, the greater the difference in tissue such as muscle and bone, the greater the impedance to the propagation of sound waves, and the greater the strength of the echo produced. Water is an excellent medium for the transmission of ultrasound waves and provides little impedance for the production of an echo until the signal encounters an interface of the water with an adjacent tissue of a different density. Air or gas, however, is very poor in propagating ultrasound signals and results in severe attenuation of the energy waves when encountered. For this reason, close contact of the transducer and the tissue to be examined without any air interspersed between the two is essential.] As a rule, higher frequency waves result in better detail or resolution of the tissue being examined. However, more attenuation of the sound waves as they pass through tissues is associated with the higher frequencies. Conversely, lower ultrasound frequencies offer deeper tissue penetration with less attenuation but poorer resolution and detail. The returning echo signal can be electronically processed