IEEE Trans Ultrason Ferroelectr Freq Control
November 2021
Radiation force is a universal phenomenon in any wave motion where the wave energy produces a static or transient force on the propagation medium. The theory of acoustic radiation force (ARF) dates back to the early 19th century. In recent years, there has been an increasing interest in the biomedical applications of ARF.
View Article and Find Full Text PDFWe hypothesize that dissipation of mechanical energy of external impact to absorb mechanical shock is a fundamental function of skeletal muscle in addition to its primary function to convert chemical energy into mechanical energy. In physical systems, the common mechanism for absorbing mechanical shock is achieved with the use of both elastic and viscous elements and we hypothesize that the viscosity of the skeletal muscle is a variable parameter which can be voluntarily controlled by changing the tension of the contracting muscle. We further hypothesize that an ability of muscle to absorb shock has been an important factor in biological evolution, allowing the life to move from the ocean to land, from hydrodynamic to aerodynamic environment with dramatically different loading conditions for musculoskeletal system.
View Article and Find Full Text PDFThe last decade has seen a surge in the development of axial transmission QUS (Quantitative UltraSound) technologies for the assessment of long bones using various modes of acoustic waves. The condition of cortical bones and the development of osteoporosis are determined by numerous mechanical, micro-structural, and geometrical or macro-structural bone properties like hardness, porosity and cortical thickness. Such complex manifestations of osteoporosis require the evaluation of multiple parameters with different sensitivities to the various properties of bone that are affected by the disease.
View Article and Find Full Text PDFThe objective of this study was to evaluate if the Bone UltraSonic Scanner (BUSS) can detect osteoporosis in postmenopausal women. BUSS is an axial transmission multi-frequency ultrasonometer for acquisition of wave propagation profiles along the proximal anterior tibia. We derived 10 diagnostically significant BUSS parameters that were then compared with the DXA spine T-score, which was used in this study as the "gold standard" for the assessment of osteoporosis (T-score<-2.
View Article and Find Full Text PDFTime-reversal acoustics is an effective way of focusing ultrasound deep inside heterogeneous media such as biological tissues. Convection-enhanced delivery is a method of delivering drugs into the brain by infusing them directly into the brain interstitium. These two technologies are combined in a focusing system that uses a "smart needle" to simultaneously infuse fluid into the brain and provide the necessary feedback for focusing ultrasound using time-reversal acoustics.
View Article and Find Full Text PDFUp until about two decades ago acoustic imaging and ultrasound imaging were synonymous. The term ultrasonography, or its abbreviated version sonography, meant an imaging modality based on the use of ultrasonic compressional bulk waves. Beginning in the 1990s, there started to emerge numerous acoustic imaging modalities based on the use of a different mode of acoustic wave: shear waves.
View Article and Find Full Text PDFBackground: Colonoscopy is a frequently performed procedure that requires extensive training and a high skill level.
Objective: Quantification of forces applied to the external portion of the colonoscope insertion tube during the insertion phase of colonoscopy.
Design: Observational cohort study of 7 expert and 9 trainee endoscopists for analysis of colonic segment force application in 49 patients.
Curr Med Imaging Rev
November 2011
From times immemorial manual palpation served as a source of information on the state of soft tissues and allowed detection of various diseases accompanied by changes in tissue elasticity. During the last two decades, the ancient art of palpation gained new life due to numerous emerging elasticity imaging (EI) methods. Areas of applications of EI in medical diagnostics and treatment monitoring are steadily expanding.
View Article and Find Full Text PDFThe velocity of ultrasonic guided waves in long bones is dependent upon two determinants of bone strength: the cortical thickness and the material properties. In this study, six human proximal tibiae in vitro were examined to test the efficacy of an ultrasonic method based on guided waves. Peripheral quantitative computed tomography (pQCT) was used as the comparative reference modality.
View Article and Find Full Text PDFWe describe a drug delivery method that combines Time-Reversal Acoustics (TRA) with Convection-Enhanced Delivery (CED) to improve the delivery of therapeutics to the interstitium of the brain. The Ultrasound-assisted CED approach (UCED) circumvents the blood-brain barrier by infusing compounds through a cannula that is inserted into the brain while simultaneously delivering ultrasound to improve the penetration of pharmaceuticals. CED without ultrasound-assistance has been used to treat a variety of neural disorders, including glioblastoma multiforme, a malignancy that presents a very poor prognosis for patients.
View Article and Find Full Text PDFUltrasound Med Biol
September 2010
Radiation force is a universal phenomenon in any wave motion, electromagnetic or acoustic. Although acoustic and electromagnetic waves are both characterized by time variation of basic quantities, they are also both capable of exerting a steady force called radiation force. In 1902, Lord Rayleigh published his classic work on the radiation force of sound, introducing the concept of acoustic radiation pressure, and some years later, further fundamental contributions to the radiation force phenomenon were made by L.
View Article and Find Full Text PDFChanges in the elasticity of the vaginal walls, connective support tissues, and muscles are thought to be significant factors in the development of pelvic organ prolapse, a highly prevalent condition affecting at least 50% of women in the United States during their lifetimes. It creates two predominant concerns specific to the biomechanical properties of pelvic support tissues: how does tissue elasticity affect the development of pelvic organ prolapse and how can functional elasticity be maintained through reconstructive surgery. We designed a prototype of vaginal tactile imager (VTI) for visualization and assessment of elastic properties of pelvic floor tissues.
View Article and Find Full Text PDFIEEE Trans Ultrason Ferroelectr Freq Control
April 2010
This paper compares the performance of two different systems for dynamic focusing of ultrasonic waves: conventional 2-D phased arrays (PA) and a focusing system based on the principles of time-reversed acoustics (TRA). Focused ultrasound fields obtained in the experiments with the TRA focusing system (TRA FS), which employs a liquid-filled reverberator with 4 piezotransducers attached to its wall, are compared with the focused fields obtained by mathematical simulation of PAs comprised from several tens to several hundreds of elements distributed randomly on the array surface. The experimental and simulated focusing systems had the same aperture and operated at a frequency centered about 600 kHz.
View Article and Find Full Text PDFMechanical Imaging (MI), a.k.a.
View Article and Find Full Text PDFBackground: To perform a colonoscopy, the endoscopist maneuvers the colonoscope through a series of loops by applying force to the insertion tube. Colonoscopy insertion techniques are operator dependent but have never been comprehensively quantified.
Objective: To determine whether the Colonoscopy Force Monitor (CFM), a device that continually measures force applied to the insertion tube, can identify different force application patterns among experienced endoscopists.
The ability to deliver configurable myocardial lesions was noted as a critical factor to the success of atrial fibrillation (AF) treatment. This article considers the implementation of time reversal acoustics (TRA) principles for ultrasound focusing using an AF cardiac catheter developed for pulmonary vein isolation. Experiments conducted with a single transmitting channel demonstrated that a catheter balloon could be used as an acoustic reverberator to enable focusing and steering of ultrasound short pulses in the TRA mode.
View Article and Find Full Text PDFThis manuscript is a summary of the paper presented at the ICU'2009 on biomedical applications of acoustic radiation force with emphasis on emerging applications in microfluidics, biotechnology, biosensors and assessment of the skeletal system. In this brief overview of current and projected applications of radiation force, no detailed description of the experiments illustrating particular applications are given as this would result in a far different and longer paper. Various mechanisms of acoustic radiation force generations and their biomedical applications are considered.
View Article and Find Full Text PDFThe possibility of using acoustic radiation force in standing waves for stirring and mixing small volumes of liquids is theoretically analyzed. The principle of stirring considered in this paper is based on moving the microparticles suspended in a standing acoustic wave by changing the frequency so that one standing wave mode is replaced by the other, with differently positioned minima of potential energy. The period-average transient dynamics of solid microparticles and gas microbubbles is considered, and simple analytical solutions are obtained for the case of standing waves of variable amplitude.
View Article and Find Full Text PDFAcoustic and seismic waves provide a method to localize compliant mines by vibrating the top plate and a thin soil layer above the mine. This vibration is mostly linear, but also includes a small nonlinear deviation. The main goal of this paper is to introduce a method of processing that uses phase-inversion to observe nonlinear effects in a wide frequency band.
View Article and Find Full Text PDFBreast Cancer Res Treat
November 2009
Mechanical imaging yields tissue elasticity map and provides quantitative characterization of a detected pathology. The changes in the surface stress patterns as a function of applied load provide information about the elastic composition and geometry of the underlying tissue structures. The objective of this study is the clinical evaluation of breast mechanical imager for breast lesion characterization and differentiation between benign and malignant lesions.
View Article and Find Full Text PDFThe paper presents results of a clinical validation study of Bone UltraSonic Scanner (BUSS), a novel dual-frequency axial transmission ultrasonometer, developed by Artann Laboratories. Assessment of bone conditions is based on evaluating relative changes of the axial profiles of ultrasonic characteristics in long bones and utilizes bulk and guided acoustic waves. The objective of this study was to determine the ability of BUSS to discriminate osteoporosis development stages.
View Article and Find Full Text PDFIn this paper, we analyze the physical basis for elasticity imaging of the breast by measuring breast skin stress patterns that result from a force sensor array pressed against the breast tissue. Temporal and spatial changes in the stress pattern allow detection of internal structures with different elastic properties and assessment of geometrical and mechanical parameters of these structures. The method entitled mechanical imaging is implemented in the breast mechanical imager (BMI), a compact device consisting of a hand held probe equipped with a pressure sensor array, a compact electronic unit, and a touchscreen laptop computer.
View Article and Find Full Text PDFIEEE Trans Ultrason Ferroelectr Freq Control
September 2008
The article presents a retrospective view on the assessment of long bones condition using topographical patterns of the acoustic properties. The application of ultrasonic point-contact transducers with exponential waveguides on a short acoustic base for detailed measurements in human long bones by the surface transmission was initiated during the 1980s in Latvia. The guided wave velocity was mapped on the surface of the long bones and the topographical patterns reflected the biomechanical peculiarities.
View Article and Find Full Text PDFObjectives: To evaluate the ability of prostate mechanical imaging (PMI) technology to provide an objective and reproducible image and to assess the prostate nodularity.
Methods: We evaluated the PMI device developed by Artann Laboratories in a pilot clinical study. For the 168 patients (ages 44 to 94) who presented to an urologist for prostate evaluation, PMI-produced images and assessment of prostate size, shape, consistency/hardness, mobility, and nodularity were compared with digital rectal examination (DRE) findings.