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1

Tissue typing with ultrasound RF time series: phantom studies  

NASA Astrophysics Data System (ADS)

We report phantom studies on a new approach to ultrasound-based tissue typing. In the proposed approach, we continuously record RF echo signals backscattered from tissue, while the imaging probe and the tissue are fixed in position. The continuously recorded RF data generates a time series of echoes for each spatial sample of the RF signal. We use the spectral and fractal features of ultrasound RF time series averaged over a region of interest, along with support vector machine classifiers, for tissue typing. In this paper, the effects of two properties of tissue on RF time series are investigated: cell size and elasticity. We show that RF time series acquired from agar-gelatin based tissue mimicking phantoms, with difference only in the size of cell-mimicking glass beads, are distinguishable with statistically reliable accuracies up to 82.2%. Similar experiments using phantoms with different elastic properties did not result in consistently high classification accuracies. The results of this study confirm that the evident differences in microstructure of the cancerous versus normal tissue could play a role in the success of the proposed tissue typing method in detection of prostate cancer.

Moradi, Mehdi; Mousavi, Parvin; Rohling, Robert; Abolmaesumi, Purang

2009-02-01

2

Ultrasound-triggered Release of Recombinant Tissue-type Plasminogen Activator from Echogenic Liposomes  

PubMed Central

Echogenic liposomes (ELIP) were developed as ultrasound-triggered targeted drug or gene delivery vehicles (Lanza et al., 1997; Huang et al., 2001). Recombinant tissue-type Plasminogen Activator (rt-PA), a thrombolytic, has been loaded into ELIP (Tiukinhoy-Laing et al., 2007). These vesicles have the potential to be used for ultrasound-enhanced thrombolysis in the treatment of acute ischemic stroke, myocardial infarction, deep vein thrombosis, or pulmonary embolus. A clinical diagnostic ultrasound scanner (Philips HDI 5000) equipped with a linear array transducer (L12-5) was employed for in vitro studies using rt-PA-loaded ELIP (T-ELIP). The goal of this study was to quantify ultrasound-triggered drug release from rt-PA-loaded echogenic liposomes. T-ELIP samples were exposed to 6.9-MHz B-mode pulses at a low pressure amplitude (600 kPa) to track the echogenicity over time under four experimental conditions: 1) flow alone to monitor gas diffusion from the T-ELIP, 2) pulsed 6.0-MHz color Doppler exposure above the acoustically driven threshold (0.8 MPa) to force gas out of the liposome gently, 3) pulsed 6.0-MHz color Doppler above the rapid fragmentation threshold (2.6 MPa), or 4) Triton X-100 to rupture the T-ELIP chemically as a positive control. Release of rt-PA for each ultrasound exposure protocol was assayed spectrophotometrically. T-ELIP were echogenic in the flow model (5 ml/min) for thirty minutes. The thrombolytic drug remained associated with the liposome when exposed to low-amplitude B-mode pulses over 60 min and was released when exposed to color Doppler pulses or Triton X-100. The rt-PA released from the liposomes had similar enzymatic activity as the free drug. These T-ELIP are robust and echogenic during continuous fundamental 6.9-MHz B-mode imaging at a low exposure output level (600 kPa). Furthermore, a therapeutic concentration of rt-PA can be released by fragmenting the T-ELIP with pulsed 6.0-MHz color Doppler ultrasound above the rapid fragmentation threshold (1.59 MPa).

Smith, Denise A.B.; Vaidya, Sampada S.; Kopechek, Jonathan A.; Huang, Shao-Ling; Klegerman, Melvin E.; McPherson, David D.; Holland, Christy K.

2009-01-01

3

How does performance of ultrasound tissue typing affect design of prostate IMRT dose-painting protocols?  

SciTech Connect

Purpose: To investigate how the performance characteristics of ultrasound tissue typing (UTT) affect the design of a population-based prostate dose-painting protocol. Methods and Materials: The performance of UTT is evaluated using the receiver operating characteristic curve. As the imager's sensitivity increases, more tumors are detected, but the specificity worsens, causing more false-positive results. The UTT tumor map, obtained with a specific sensitivity and specificity setup, was used with the patient's CT image to guide intensity-modulated radiotherapy (IMRT) planning. The optimal escalation dose to the UTT positive region, as well as the safe dose to the negative background, was obtained by maximizing the uncomplicated control (i.e., a combination of tumor control probability and weighted normal tissue complication probability). For high- and low-risk tumors, IMRT plans guided by conventional ultrasound or UTT with a one-dimensional or two-dimensional spectrum analysis technique were compared with an IMRT plan in which the whole prostate was dose escalated. Results: For all imaging modalities, the specificity of 0.9 was chosen to reduce complications resulting from high false-positive results. If the primary tumors were low risk, the IMRT plans guided by all imaging modalities achieved high tumor control probability and reduced the normal tissue complication probability significantly compared with the plan with whole gland dose escalation. However, if the primary tumors were high risk, the accuracy of the imaging modality was critical to maintain the tumor control probability and normal tissue complication probability at acceptable levels. Conclusion: The performance characteristics of an imager have important implications in dose painting and should be considered in the design of dose-painting protocols.

Zhang Pengpeng [Department of Radiation Oncology, Columbia University, New York, NY (United States)]. E-mail: pz2010@columbia.edu; Osterman, K. Sunshine [Department of Radiation Oncology, Columbia University, New York, NY (United States); Liu Tian [Department of Radiation Oncology, Columbia University, New York, NY (United States); Li Xiang [Department of Radiation Oncology, Columbia University, New York, NY (United States); Kessel, Jack [Department of Radiation Oncology, Columbia University, New York, NY (United States); Wu, Leester [Department of Radiation Oncology, Columbia University, New York, NY (United States); Schiff, Peter [Department of Radiation Oncology, Columbia University, New York, NY (United States); Kutcher, Gerald J. [Department of Radiation Oncology, Columbia University, New York, NY (United States)

2007-02-01

4

Stimulation of Tissue Healing by Ultrasound: Physical Mechanisms of Action  

NASA Astrophysics Data System (ADS)

Even though the use of ultrasound in medicine is better known by its results in diagnostic procedures, the employ of this type of mechanical energy with therapeutic purposes is been used in new and impressive applications. To obtain or to improve tissue healing in many ailments it is used a lot of approaches, from the employ of antibiotics when it is considered by the presence of an infection in the wound, to several types of physical stimulation. One of them is ultrasound. This paper consider some of the most important mechanisms of action of ultrasound in tissue that can be related whit the repair processes and specifies levels of activation of many paths of action. Especial emphasis has received the stimulation of bone repair by ultrasound.

Rodríguez, O.; Chong, J.; Monreal, R.

2004-09-01

5

Challenges in tissue characterization from backscattered intravascular ultrasound signals  

NASA Astrophysics Data System (ADS)

Plaque characterization through backscattered intravascular ultrasound (IVUS) signal analysis has been the subject of extensive study for the past several years. A number of algorithms to analyze IVUS images and underlying RF signals to delineate the composition of atherosclerotic plaque have been reported. In this paper, we present several realistic challenges one faces throughout the process of developing such algorithms to characterize tissue type. The basic tenet of ultrasound tissue characterization is that different tissue types imprint their own "signature" on the backscattered echo returning to the transducer. Tissue characterization is possible to the extent that these echo signals can be received, the signatures read, and uniquely attributed to a tissue type. The principal difficulty in doing tissue characterization is that backscattered RF signals originating as echoes from different groups of cells of the same tissue type exhibit no obvious commonality in appearance in the time domain. This happens even in carefully controlled laboratory experiments. We describe the method of acquisition and digitization of ultrasound radiofrequency (RF) signals from left anterior descending and left circumflex coronary arteries. The challenge of obtaining corresponding histology images to match to specific regions-of-interest on the images is discussed. A tissue characterization technique based on seven features is compared to a full spectrum based approach. The same RF and histology data sets were used to evaluate the performances of these two techniques.

Katouzian, Amin; Sathyanarayana, Shashidhar; Li, Wenguang; Thomas, Tom; Carlier, Stéphane G.

2007-03-01

6

Effects of ultrasound and ultrasound contrast agent on vascular tissue  

PubMed Central

Background Ultrasound (US) imaging can be enhanced using gas-filled microbubble contrast agents. Strong echo signals are induced at the tissue-gas interface following microbubble collapse. Applications include assessment of ventricular function and virtual histology. Aim While ultrasound and US contrast agents are widely used, their impact on the physiological response of vascular tissue to vasoactive agents has not been investigated in detail. Methods and results In the present study, rat dorsal aortas were treated with US via a clinical imaging transducer in the presence or absence of the US contrast agent, Optison. Aortas treated with both US and Optison were unable to contract in response to phenylephrine or to relax in the presence of acetylcholine. Histology of the arteries was unremarkable. When the treated aortas were stained for endothelial markers, a distinct loss of endothelium was observed. Importantly, terminal deoxynucleotidyl transferase mediated dUTP nick-end-labeling (TUNEL) staining of treated aortas demonstrated incipient apoptosis in the endothelium. Conclusions Taken together, these ex vivo results suggest that the combination of US and Optison may alter arterial integrity and promote vascular injury; however, the in vivo interaction of Optison and ultrasound remains an open question.

2012-01-01

7

Ultrasound-targeted transfection of tissue-type plasminogen activator gene carried by albumin nanoparticles to dog myocardium to prevent thrombosis after heart mechanical valve replacement  

PubMed Central

Background There are more than 300,000 prosthetic heart valve replacements each year worldwide. These patients are faced with a higher risk of thromboembolic events after heart valve surgery and long-term or even life-long anticoagulative and antiplatelet therapies are necessary. Some severe complications such as hemorrhaging or rebound thrombosis can occur when the therapy ceases. Tissue-type plasminogen activator (t-PA) is a thrombolytic agent. One of the best strategies is gene therapy, which offers a local high expression of t-PA over a prolonged time period to avoid both systemic hemorrhaging and local rebound thrombosis. There are some issues with t-PA that need to be addressed: currently, there is no up-to-date report on how the t-PA gene targets the heart in vivo and the gene vector for t-PA needs to be determined. Aims To fabricate an albumin nano-t-PA gene ultrasound-targeted agent and investigate its targeting effect on prevention of thrombosis after heart mechanic valve replacement under therapeutic ultrasound. Methods A dog model of mechanical tricuspid valve replacement was constructed. A highly expressive t-PA gene plasmid was constructed and packaged by nanoparticles prepared with bovine serum albumin. This nanopackaged t-PA gene plasmid was further cross-linked to ultrasonic microbubbles prepared with sucrose and bovine serum albumin to form the ultrasonic-targeted agent for t-PA gene transfection. The agent was given intravenously followed by a therapeutic ultrasound treatment (1 MHz, 1.5 w/cm2, 10 minutes) of the heart soon after valve replacement had been performed. The expression of t-PA in myocardium was detected with multiclonal antibodies to t-PA by the indirect immunohistochemical method. Venous blood t-PA and D-dimer contents were tested before and 1, 2, 4, and 8 weeks after the operation. Results The high expression of t-PA could be seen in myocardium with increases in blood t-PA and D-dimer contents and thrombosis was prevented 8 weeks after operation. Conclusion We successfully fabricated an albumin nano-t-PA gene ultrasound-targeted agent that could prevent dog thrombosis after mechanical heart valve replacement. Our study provides an experimental basis for prevention of human thrombosis-related diseases.

Ji, Jun; Ji, Shang-Yi; Yang, Jian-An; He, Xia; Yang, Xiao-Han; Ling, Wen-Ping; Chen, Xiao-Ling

2012-01-01

8

Fuzzy similarity measures for ultrasound tissue characterization  

NASA Astrophysics Data System (ADS)

Computerized ultrasound tissue characterization has become an objective means for diagnosis of diseases. It is difficult to differentiate diffuse liver diseases, namely cirrhotic and fatty liver from a normal one, by visual inspection from the ultrasound images. The visual criteria for differentiating diffused diseases is rather confusing and highly dependent upon the sonographer's experience. The need for computerized tissue characterization is thus justified to quantitatively assist the sonographer for accurate differentiation and to minimize the degree of risk from erroneous interpretation. In this paper we used the fuzzy similarity measure as an approximate reasoning technique to find the maximum degree of matching between an unknown case defined by a feature vector and a family of prototypes (knowledge base). The feature vector used for the matching process contains 8 quantitative parameters (textural, acoustical, and speckle parameters) extracted from the ultrasound image. The steps done to match an unknown case with the family of prototypes (cirr, fatty, normal) are: Choosing the membership functions for each parameter, then obtaining the fuzzification matrix for the unknown case and the family of prototypes, then by the linguistic evaluation of two fuzzy quantities we obtain the similarity matrix, then by a simple aggregation method and the fuzzy integrals we obtain the degree of similarity. Finally, we find that the similarity measure results are comparable to the neural network classification techniques and it can be used in medical diagnosis to determine the pathology of the liver and to monitor the extent of the disease.

Emara, Salem M.; Badawi, Ahmed M.; Youssef, Abou-Bakr M.

1995-03-01

9

Tissue displacements during acupuncture using ultrasound elastography techniques.  

PubMed

Acupuncture needle manipulation has been previously shown to result in measurable changes in connective tissue architecture in animal experiments. In this study, we used a novel in vivo ultrasound (US)-based technique to quantify tissue displacement during acupuncture manipulation in humans. B-scan ultrasonic imaging was performed on the thighs of 12 human subjects at different stages of needle motion, including varying amounts of rotation, downward and upward movement performed with a computer-controlled acupuncture needling instrument. Tissue displacements, estimated using cross-correlation techniques, provided successful mapping and quantitative analysis of spatial and temporal tissue behavior during acupuncture needle manipulation. Increasing amounts of rotation had a significant linear effect on tissue displacement during downward and upward needle motion, as well as on rebound tissue displacement after downward needle movement. In addition to being a valuable tool for studies of acupuncture's mechanism of action, this technique may have applications to other types of needling including biopsies. PMID:15550321

Langevin, Helene M; Konofagou, Elisa E; Badger, Gary J; Churchill, David L; Fox, James R; Ophir, Jonathan; Garra, Brian S

2004-09-01

10

Ultrasound  

MedlinePLUS

Ultrasound is a type of imaging. It uses high-frequency sound waves to look at organs and ... liver, and other organs. During pregnancy, doctors use ultrasound to view the fetus. Unlike x-rays, ultrasound ...

11

Ultrasound data segmentation based on tissue characterization  

NASA Astrophysics Data System (ADS)

When an ultrasonic examination is performed, a segmentation tool would often be a very useful tool, either for the detection of pathologies, the early diagnosis of cancer, the follow-up of the lesions, ... Such a tool must be both reliable and accurate. However, because of the relatively poor quality of ultrasound images due to the speckled texture, the segmentation of ultrasound data is a difficult task. We have previously proposed to tackle the problem using a multiresolution bayesian region-based algorithm. Such an approach, applied to very noisy images, leads to good segmentation results. For computation time purposes, a multiresolution version has been implemented. In order to improve the quality of the segmentation, we propose to get more information about the properties of the tissues and take it into account during the segmentation process. Some acoustical parameters have thus been computed, either directly from the images or from the Radio-Frequency (RF) signal. The parameters used are the Integrated BackScatter (IBS), the density of scatterers, and the Mean Central Frequency, which is a measurement related to the attenuation of ultrasound waves in the media. To test the influence of the acoustical parameters in the segmentation process, a set of numerical phantoms has been computed using the Field software. Each phantom consists in two regions with different acoustical properties : the density of scatterers and the scattering amplitude. From both the simulated RF signal and images, parameters have been computed and segmentation has been processed for each phantom. The quantification of the segmentation quality is based on the number of correctly classified pixels and it has been computed for all the combinations of acoustical parameters. Segmentation results performed on agar-gelatine phantoms with different inclusions are also presented and illustrate the interest of a multiparametric segmentation approach.

Davignon, Franck; Deprez, Jean-Francois; Basset, Olivier

2005-04-01

12

An easily made, low-cost, tissue-like ultrasound phantom material  

Microsoft Academic Search

Ultrasound phantoms are generally of two types. One mimics the acoustic properties of tissue (with regard to the speed of sound, average attenuation, etc.). The main purpose of the other is to approx- imate the sonographic appearance of tissue. The latter is often used as a biopsy training aid. Those which mimic the acoustic properties of tissue have been constructed

Ronald O. Bude; Ronald S. Adler

1995-01-01

13

Characterizing Tissue with Acoustic Parameters Derived from Ultrasound Data.  

National Technical Information Service (NTIS)

In contrast to standard reflection ultrasound (US), transmission US holds the promise of more thorough tissue characterization by generating quantitative acoustic parameters. We compare results from a conventional US scanner with data acquired using an ex...

P. Littrup N. Duric R. R. Leach S. G. Azevedo J. V. Candy T. Moore D. H. Chambers J. E. Mast S. A. Johnson E. Holsapple

2002-01-01

14

Deriving the effective ultrasound equations for soft tissue interrogation  

Microsoft Academic Search

We are interested in the ultrasound interrogation of soft tissue. As soft tissue is a complicated material, we derive the effective acoustic equations using an averaging method known as homogenization to arrive at suitable constitutive equations. Soft tissue is composed of actin, elastin, collagen, and interstitial fluid. Collagen is packaged in parallel-fibered bundles, or fasciles, in the case of tendon

Xuming Xie; R GILBERT; X XIE

2005-01-01

15

Imaging and estimation of tissue elasticity by ultrasound.  

PubMed

Ultrasound (US) elasticity imaging is an extension of the ancient art of palpation and of earlier US methods for viewing tissue stiffness such as echopalpation. Elasticity images consist of either an image of strain in response to force or an image of estimated elastic modulus. There are 3 main types of US elasticity imaging: elastography that tracks tissue movement during compression to obtain an estimate of strain, sonoelastography that uses color Doppler to generate an image of tissue movement in response to external vibrations, and tracking of shear wave propagation through tissue to obtain the elastic modulus. Other modalities may be used for elasticity imaging, the most powerful being magnetic resonance elastography. With 4 commercial US scanners already offering elastography and more to follow, US-based methods may be the most widely used for the near future. Elasticity imaging is possible for nearly every tissue. Breast mass elastography has potential for enhancing the specificity of US and mammography for cancer detection. Lesions in the thyroid, prostate gland, pancreas, and lymph nodes have been successfully imaged using elastography. Evaluation of diffuse disease including cirrhosis and transplant rejection is also possible using both imaging and nonimaging methods. Vascular imaging including myocardium, blood vessel wall, plaque, and venous thrombi has also shown great potential. Elasticity imaging may also be important in assessing the progress of ablation therapy. Recent work in assessing porous materials using elastography suggests that the technique may be useful in monitoring the severity of lymphedema. PMID:18090836

Garra, Brian Stephen

2007-12-01

16

Drug Delivery to Extravascular Tissue by Ultrasound-activated Microbubbles  

NASA Astrophysics Data System (ADS)

Drugs will be delivered to tissue more efficiently if the vascular endothelial permeability is increased. Although recent studies have established that the permeability of single-cell membranes is increased by ultrasound in combination with contrast agents, it is not known whether this combination can also increase the permeability of an endothelial layer. To investigate endothelial layer permeability, we treated monolayers of human umbilical vein endothelial cells with ultrasound and the contrast agent BR14. Endothelial layer permeability was assessed by measuring the transendothelial electrical resistance (TEER) and the transendothelial transport of fluorescein. Ultrasound in combination with BR14 significantly decreased TEER to 68.0 +/- 3.1% of initial values and temporally increased endothelial permeability for fluorescein by 38.1 +/- 16.4 %. After treatment, no cell loss or damage was observed. In conclusion, ultrasound in combination with BR14 increased the endothelial layer permeability. This feature may be used for future ultrasound-guided drug delivery systems.

Kooiman, Klazina; Harteveld, Miranda; de Jong, Nico; van Wamel, Annemieke

2007-05-01

17

Modeling Heat Transfer in Tissue for Therapeutic Ultrasound  

NASA Astrophysics Data System (ADS)

Hyperthermia treatment planning (HTP) is becoming available for individual patients. The components of a HTP system have been described. As an example for the application of HTP in therapeutic ultrasound the temperature distribution in a bovine tongue, heated with a scanning ultrasound focus, is calculated using the Discrete VAsculature (DIVA) thermal model. This model is capable to describe the individual thermal behavior of the discrete blood vessels. Simulations show the overall temperature heterogeneity and the severe thermal underdosage of the tissue around large passing vessels. This implies that in the application of therapeutic ultrasound for malignant tumors great care must be taken.

Lagendijk, Jan J. W.; Raaymakers, Bas W.

2006-05-01

18

Pressure and temperature distribution in biological tissues by focused ultrasound  

NASA Astrophysics Data System (ADS)

The interaction between ultrasound and biological tissues has been the subject of a number of investigators for nearly half a century and the number of applications of high intensity, focused ultrasound for therapeutic purposes continues to grow. This paper is motivated by possible medical applications of focused ultrasound in minimally invasive treatment of a variety of musculoskeletal disorders that are responsive to thermal treatment. The mechanical and thermal effects in a subject"s body induced by high-frequency ultrasound are simulated using PZFlex, a finite element based program. The FEM model described in this report is of a transverse section of the body at the level of the second lumbar vertebra (L2) extracted from a CT image. In order to protect the nerves inside the spinal canal as well as to obtain an effective heating result at the focal region within the intervertebral disk, a suitable orientation of axis of the focused ultrasound lens have to be determined in advance. The pressure, energy loss distribution and temperature distribution are investigated in this paper with the different orientations of the axis and different transverse diameter of the spherical ultrasound lens. Since nonlinear effects are expected to be important in the therapeutic application in some literatures, this paper also demonstrates the effects of nonlinearities on the pressure and temperature distribution induced by focused ultrasound in a two dimensional model. Finally, a comparison of the results between linear and nonlinear cases is reported.

Mal, Ajit K.; Feng, Feng; Kabo, Michael; Wang, Jeffrey; Bar-Cohen, Yoseph

2003-07-01

19

Ultrasound  

Cancer.gov

Ultrasound uses sound waves with frequencies above those humans can hear. A transducer sends sound waves traveling into the body which are reflected back from organs and tissues, allowing a picture to be made of the internal organs. Ultrasound can show

20

The thresholds and mechanisms of tissue injury by focused ultrasound  

NASA Astrophysics Data System (ADS)

Therapeutic ultrasound is used in clinics around the world to treat ailments such as uterine fibroids, kidney stones, and plantar fasciitis. While many of the therapeutic effects of ultrasound are elicited by hyperthermia, bubbles can also interact with tissue to produce beneficial effects. For example, bubbles are used in boiling histotripsy to de-bulk tissue and are used in shock wave lithotripsy to break kidney stones. However, the same bubbles that break the kidney stones also damage the kidney, which is why bubble damage is a concern in every ultrasound application including fetal imaging. Whether the aim is to emulsify a tumor or image a fetus, understanding the thresholds and mechanisms of tissue injury by bubbles in an ultrasound field is important for all ultrasound applications and was the goal of this dissertation. One specific application of therapeutic ultrasound, known as boiling histotripsy, uses shock wave heating to explosively expand a millimeter-size boiling bubble at the transducer focus and fractionate bulk tissue. Yet it was unclear how the millimeter-size boiling or vapor bubble broke down the tissue into its submicron components. In this dissertation, we experimentally tested the hypothesis that ultrasonic atomization, or the emission of fine droplets from an acoustically excited liquid film, is the mechanism by which the millimeter-size boiling bubble in boiling histotripsy fractionates tissue into its submicron components. Using high speed photography, we showed that tissue can behave as a liquid such that a miniature acoustic fountain forms and atomization occurs within a millimeter-size cavity that approximates the boiling or vapor bubble produced by boiling histotripsy. The end result of tissue atomization was a hole in the tissue surface. After showing that tissue can be eroded by atomization, a series of experiments were conducted to determine the tissue properties that influence atomization. The results indicated that highly collagenous tissues such as the liver capsule were difficult to atomize; however it was also shown that surface wetting could be used to enhance atomization by changing the focus of the inverted and reflected ultrasound wave. Finally, the role of bubbles in tissue atomization was investigated using a high static pressure chamber, where it was determined that bubbles are necessary for tissue fractionation. While the investigation into the mechanism of boiling histotripsy was the primary focus of this dissertation, we also established thermal and mechanical injury thresholds for renal tissue injury. This work was driven by the need to determine the safety of a specific therapeutic ultrasound application - renal stone repositioning by ultrasonic propulsion - for FDA approval to begin clinical trials. The end result of this dissertation was an increased understanding of how and at what levels bubbles in an ultrasound field can damage tissue, which is important for developing safe and reliable therapies.

Simon, Julianna

21

Therapeutic Ultrasound Enhancement of Drug Delivery to Soft Tissues  

NASA Astrophysics Data System (ADS)

Effects of exposure to 1.58 MHz focused ultrasound on transport of Evans Blue Dye (EBD) in soft tissues are investigated when an external pressure gradient is applied to induce convective flow through the tissue. The magnitude of the external pressure gradient is chosen to simulate conditions in brain parenchyma during convection-enhanced drug delivery (CED) to the brain. EBD uptake and transport are measured in equine brain, avian muscle and agarose brain-mimicking phantoms. Results show that ultrasound enhances EBD uptake and transport, and the greatest enhancement occurs when the external pressure gradient is applied. The results suggest that exposure of the brain parenchyma to ultrasound could enhance penetration of material infused into the brain during CED therapy.

Lewis, George; Olbricht, William

2009-04-01

22

Variations in temperature distribution and tissue lesion formation induced by tissue inhomogeneity for therapeutic ultrasound.  

PubMed

Tissue inhomogeneity might have an important effect on the treatment accuracy of therapeutic ultrasound. Both computer simulation and measurement were performed to study the influence of tissue inhomogeneity on the temperature distribution and tissue lesion formation induced by focused ultrasound. The inhomogeneous tissue is considered a combination of a homogeneous medium and a phase aberration screen in this article. Temperature distributions and lesion dimensions were predicted using the combination of acoustic non-linear and bio-heat transfer equations. To verify the theoretical predictions, polyethylene plates with phase distributions of different correlation lengths and standard deviations were made to mimic inhomogeneous tissues such as human abdominal tissue, and a series of experiments were performed, including acoustic and thermal measurements. The results indicate that the tissue inhomogeneity caused phase aberration of the ultrasound beam. With increasing standard deviation and correlation length of phase aberration, the scattering level of the acoustic field increased, while ultrasound-induced peak temperature and lesion size decreased. This study provides a theoretical and experimental basis for future development of accurate treatment plans for high-intensity focused ultrasound. PMID:24768487

Liu, Zhenbo; Guo, Xiasheng; Tu, Juan; Zhang, Dong

2014-08-01

23

Slow light for deep tissue imaging with ultrasound modulation  

NASA Astrophysics Data System (ADS)

Slow light has been extensively studied for applications ranging from optical delay lines to single photon quantum storage. Here, we show that the time delay of slow-light significantly improves the performance of the narrowband spectral filters needed to optically detect ultrasound from deep inside highly scattering tissue. We demonstrate this capability with a 9 cm thick tissue phantom, having 10 cm-1 reduced scattering coefficient, and achieve an unprecedented background-free signal. Based on the data, we project real time imaging at video rates in even thicker phantoms and possibly deep enough into real tissue for clinical applications like early cancer detection.

Zhang, Huiliang; Sabooni, Mahmood; Rippe, Lars; Kim, Chulhong; Kröll, Stefan; Wang, Lihong V.; Hemmer, Philip R.

2012-03-01

24

Nakagami imaging for detecting thermal lesions induced by high-intensity focused ultrasound in tissue.  

PubMed

High-intensity focused ultrasound induces focalized tissue coagulation by increasing the tissue temperature in a tight focal region. Several methods have been proposed to monitor high-intensity focused ultrasound-induced thermal lesions. Currently, ultrasound imaging techniques that are clinically used for monitoring high-intensity focused ultrasound treatment are standard pulse-echo B-mode ultrasound imaging, ultrasound temperature estimation, and elastography-based methods. On the contrary, the efficacy of two-dimensional Nakagami parametric imaging based on the distribution of the ultrasound backscattered signals to quantify properties of soft tissue has recently been evaluated. In this study, ultrasound radio frequency echo signals from ex vivo tissue samples were acquired before and after high-intensity focused ultrasound exposures and then their Nakagami parameter and scaling parameter of Nakagami distribution were estimated. These parameters were used to detect high-intensity focused ultrasound-induced thermal lesions. Also, the effects of changing the acoustic power of the high-intensity focused ultrasound transducer on the Nakagami parameters were studied. The results obtained suggest that the Nakagami distribution's scaling and Nakagami parameters can effectively be used to detect high-intensity focused ultrasound-induced thermal lesions in tissue ex vivo. These parameters can also be used to understand the degree of change in tissue caused by high-intensity focused ultrasound exposures, which could be interpreted as a measure of degree of variability in scatterer concentration in various parts of the high-intensity focused ultrasound lesion. PMID:24264647

Rangraz, Parisa; Behnam, Hamid; Tavakkoli, Jahan

2014-01-01

25

Modeling of nonlinear ultrasound propagation in tissue from array transducers  

Microsoft Academic Search

A computationally efficient model capable of simulating finite-amplitude ultrasound beam propagation in water and in tissue from phased linear arrays and other transducers of arbitrary quasiplanar geometry is described. It is based on a second-order operator splitting approach [Tavakkoli et al., J. Acoust. Soc. Am. 104, 2061-2072 (1998)], with a fractional step-marching scheme, whereby the effects of diffraction, attenuation, and

Roger J. Zemp; Jahangir Tavakkoli; Richard S. C. Cobbold

2003-01-01

26

Ultrasound therapy applicators for controlled thermal modification of tissue  

NASA Astrophysics Data System (ADS)

Heat therapy has long been used for treatments in dermatology and sports medicine. The use of laser, RF, microwave, and more recently, ultrasound treatment, for psoriasis, collagen reformation, and skin tightening has gained considerable interest over the past several years. Numerous studies and commercial devices have demonstrated the efficacy of these methods for treatment of skin disorders. Despite these promising results, current systems remain highly dependent on operator skill, and cannot effectively treat effectively because there is little or no control of the size, shape, and depth of the target zone. These limitations make it extremely difficult to obtain consistent treatment results. The purpose of this study was to determine the feasibility for using acoustic energy for controlled dose delivery sufficient to produce collagen modification for the treatment of skin tissue in the dermal and sub-dermal layers. We designed and evaluated a curvilinear focused ultrasound device for treating skin disorders such as psoriasis, stimulation of wound healing, tightening of skin through shrinkage of existing collagen and stimulation of new collagen formation, and skin cancer. Design parameters were examined using acoustic pattern simulations and thermal modeling. Acute studies were performed in 201 freshly-excised samples of young porcine underbelly skin tissue and 56 in-vivo treatment areas in 60- 80 kg pigs. These were treated with ultrasound (9-11MHz) focused in the deep dermis. Dose distribution was analyzed and gross pathology assessed. Tissue shrinkage was measured based on fiducial markers and video image registration and analyzed using NIH Image-J software. Comparisons were made between RF and focused ultrasound for five energy ranges. In each experimental series, therapeutic dose levels (60degC) were attained at 2-5mm depth. Localized collagen changes ranged from 1-3% for RF versus 8-15% for focused ultrasound. Therapeutic ultrasound applied at high frequencies can achieve temperatures and dose distributions which concentrate in a depth profile that coincides with the location of maximum structural collagen content in skin tissues. Using an appropriate transducer configuration produces coverage of significant lateral area, thus making this a practical approach for treatment of skin disorders.

Burdette, E. Clif; Lichtenstiger, Carol; Rund, Laurie; Keralapura, Mallika; Gossett, Chad; Stahlhut, Randy; Neubauer, Paul; Komadina, Bruce; Williams, Emery; Alix, Chris; Jensen, Tor; Schook, Lawrence; Diederich, Chris J.

2011-02-01

27

Investigation of Soft-Tissue Stiffness Alteration in Denervated Human Tissue Using an Ultrasound Indentation System  

PubMed Central

Background/Objective: Differences in soft-tissue stiffness may provide for a quantitative assessment and detection technique for pressure ulcers or deep-tissue injury. An ultrasound indentation system may provide a relatively convenient, simple, and noninvasive method for quantitative measurement of changes in soft-tissue stiffness in vivo. Methods: The Tissue Ultrasound Palpation System (TUPS) was used to quantitatively measure changes in soft-tissue stiffness at different anatomical locations within and between able-bodied persons and individuals with chronic spinal cord injury (SCI). The stiffness of soft tissue was measured at the ischial tuberosity, greater trochanter, posterior midthigh, and biceps brachii. Additionally, soft-tissue thickness and soft-tissue deformation were also measured. Results: Significant differences in soft-tissue stiffness were observed within the various anatomical locations tested, in both the able-bodied and SCI groups. Differences in soft-tissue stiffness were also observed between the 2 groups. Participants with SCI had significantly softer tissue in their buttock-thigh area. Conclusions: TUPS is a clinically feasible technology that can reliably and effectively detect changes in soft-tissue stiffness. The study has provided a better understanding of the tissue mechanical response to external loading, specifically in the SCI population, suggesting the use of tissue stiffness as a parameter to detect and assess pressure-related soft-tissue injury.

Makhsous, Mohsen; Venkatasubramanian, Ganapriya; Chawla, Aditya; Pathak, Yagna; Priebe, Michael; Rymer, William Z; Lin, Fang

2008-01-01

28

Theoretical and Experimental Studies of Ultrasound-Modulated Optical Tomography in Biological Tissue  

Microsoft Academic Search

Ultrasound-modulated optical tomography in biological tissue was studied both theoretically and exper- imentally. An ultrasonic beam was focused into biological tissue samples to modulate the laser light passing through the ultrasonic beam inside the tissue. The ultrasound-modulated laser light reflects the local optical and mechanical properties in the ultrasonic beam and permits tomographic imaging of biological tissues by scanning. Parallel

Gang Yao; Lihong V. Wang

2000-01-01

29

Ultrasonic atomization of tissue and its role in tissue fractionation by high intensity focused ultrasound.  

PubMed

Atomization and fountain formation is a well-known phenomenon that occurs when a focused ultrasound wave in liquid encounters an air interface. High intensity focused ultrasound (HIFU) has been shown to fractionate a tissue into submicron-sized fragments in a process termed boiling histotripsy, wherein the focused ultrasound wave superheats the tissue at the focus, producing a millimetre-sized boiling or vapour bubble in several milliseconds. Yet the question of how this millimetre-sized boiling bubble creates submicron-sized tissue fragments remains. The hypothesis of this work is that the tissue can behave as a liquid such that it atomizes and forms a fountain within the vapour bubble produced in boiling histotripsy. We describe an experiment, in which a 2 MHz HIFU transducer (maximum in situ intensity of 24?000 W cm(-2)) was aligned with an air-tissue interface meant to simulate the boiling bubble. Atomization and fountain formation was observed with high-speed photography and resulted in tissue erosion. Histological examination of the atomized tissue showed whole and fragmented cells and nuclei. Air-liquid interfaces were also filmed. Our conclusion was that HIFU can fountain and atomize tissue. Although this process does not entirely mimic what was observed in liquids, it does explain many aspects of tissue fractionation in boiling histotripsy. PMID:23159812

Simon, Julianna C; Sapozhnikov, Oleg A; Khokhlova, Vera A; Wang, Yak-Nam; Crum, Lawrence A; Bailey, Michael R

2012-12-01

30

Ultrasonic atomization of tissue and its role in tissue fractionation by high intensity focused ultrasound  

NASA Astrophysics Data System (ADS)

Atomization and fountain formation is a well-known phenomenon that occurs when a focused ultrasound wave in liquid encounters an air interface. High intensity focused ultrasound (HIFU) has been shown to fractionate a tissue into submicron-sized fragments in a process termed boiling histotripsy, wherein the focused ultrasound wave superheats the tissue at the focus, producing a millimetre-sized boiling or vapour bubble in several milliseconds. Yet the question of how this millimetre-sized boiling bubble creates submicron-sized tissue fragments remains. The hypothesis of this work is that the tissue can behave as a liquid such that it atomizes and forms a fountain within the vapour bubble produced in boiling histotripsy. We describe an experiment, in which a 2 MHz HIFU transducer (maximum in situ intensity of 24?000 W cm-2) was aligned with an air-tissue interface meant to simulate the boiling bubble. Atomization and fountain formation was observed with high-speed photography and resulted in tissue erosion. Histological examination of the atomized tissue showed whole and fragmented cells and nuclei. Air-liquid interfaces were also filmed. Our conclusion was that HIFU can fountain and atomize tissue. Although this process does not entirely mimic what was observed in liquids, it does explain many aspects of tissue fractionation in boiling histotripsy.

Simon, Julianna C.; Sapozhnikov, Oleg A.; Khokhlova, Vera A.; Wang, Yak-Nam; Crum, Lawrence A.; Bailey, Michael R.

2012-12-01

31

Ultrasonic atomization of tissue and its role in tissue fractionation by high intensity focused ultrasound  

PubMed Central

Atomization and fountain formation is a well-known phenomenon that occurs when a focused ultrasound wave in liquid encounters an air interface. High intensity focused ultrasound (HIFU) has been shown to fractionate tissue into submicron-size fragments in a process termed boiling histotripsy, wherein the focused ultrasound wave superheats the tissue at the focus, producing a millimetre-size boiling or vapour bubble in several milliseconds. Yet the question of how this millimetre-size boiling bubble creates submicron-size tissue fragments remains. The hypothesis of this work is that tissue can behave as a liquid such that it forms a fountain and atomization within the vapour bubble produced in boiling histotripsy. We describe an experiment, in which a 2-MHz HIFU transducer (maximum in situ intensity of 24,000 W/cm2) was aligned with an air-tissue interface meant to simulate the boiling bubble. Atomization and fountain formation were observed with high-speed photography and resulted in tissue erosion. Histological examination of the atomized tissue showed whole and fragmented cells and nuclei. Air-liquid interfaces were also filmed. Our conclusion was that HIFU can fountain and atomize tissue. Although this process does not entirely mimic what was observed in liquids, it does explain many aspects of tissue fractionation in boiling histotripsy.

Simon, Julianna C.; Sapozhnikov, Oleg A.; Khokhlova, Vera A.; Wang, Yak-Nam; Crum, Lawrence A.; Bailey, Michael R.

2012-01-01

32

The disruption of tissue structure using high intensity pulsed ultrasound  

NASA Astrophysics Data System (ADS)

Recent investigations of pulsed ultrasound at high acoustic intensities have revealed a regime in which significant breakdown of tissue structure can be achieved. This therapeutic modality, which might be termed histotripsy, is dependent on the presence of highly active cavitation evidenced by significant temporal fluctuations in acoustic backscatter. In the presence of tissue interfaces, erosion can result yielding, for example, well-defined perforations potentially useful in creating temporary shunts for the treatment of hypoplastic left heart syndrome. When applied in bulk tissue, the process results in a near emulsification with little structural integrity remaining or chance of cellular survival. In each case, the process is dependent on acoustic parameters of the field to not only produce damage for a given pulse but also to sustain the cavitation nuclei population for subsequent pulses. Fluctuations in acoustic backscatter indicate both initiation and extinction of the appropriate cavitation activity during application of therapeutic ultrasound, which leads to a potential feedback mechanism to minimize acoustic exposure. This presentation will discuss the observed tissue damage as affected by acoustic parameters and the ability to monitor the presence of cavitation activity expected to be responsible for these effects. [Work supported by NIH grants RO1 RR14450.

Fowlkes, J. Brian; Parsons, Jessica E.; Xu, Zhen; Cooper, Michol; Tran, Binh C.; Hall, Timothy L.; Roberts, William W.; Cain, Charles A.

2005-04-01

33

Measurement of Mechanical Properties of Soft Tissue with Ultrasound Vibrometry  

NASA Astrophysics Data System (ADS)

The cardiovascular diseases atherosclerosis, coronary artery disease, hypertension and heart failure have been related to stiffening of vessels and myocardium. Noninvasive measurements of mechanical properties of cardiovascular tissue would facilitate detection and treatment of disease in early stages, thus reducing mortality and possibly reducing cost of treatment. While techniques capable of measuring tissue elasticity have been reported, the knowledge of both elasticity and viscosity is necessary to fully characterize mechanical properties of soft tissues. In this article, we summarize the Shearwave Dispersion Ultrasound Vibrometry (SDUV) method developed by our group and report on advances made in characterizing stiffness of large vessels and myocardium. The method uses radiation forceFadiation force to excite shear waves in soft tissue and pulse echo ultrasound to measure the motion. The speed of propagation of shear waves at different frequencies is used to generate dispersions curves for excised porcine left-ventricular free-wall myocardium and carotid arteries. An antisymmetric Lamb wave model was fitted to the LV myocardium dispersion curves to obtain elasticity and viscosity moduli. The results suggest that the speed of shear wave propagation in four orthogonal directions on the surface of the excised myocardium is similar. These studies show that the SDUV method has potential for clinical application in noninvasive quantification of elasticity and viscosity of vessels and myocardium.

Nenadich, I.; Bernal, M.; Greenleaf, J. F.

34

Quantitative ultrasound (QUS) assessment of tissue properties for Achilles tendons  

NASA Astrophysics Data System (ADS)

Quantitative ultrasound (QUS) techniques have recently been widely applied for the characterization of tissues. For example, they can be used for the quantification of Achilles tendon properties based on the broadband ultrasound attenuation (BUA) and the speed of sound (SOS) when the ultrasound wave passes through the tissues. This study is to develop an integrated system to investigate the properties of Achilles tendons using QUS images from UBIS 5000 (DMS, Montpellier, France) and B-mode ultrasound images from HDI 5000 (ATL, Ultramark, USA). Subjects including young (32 females and 17 males; mean age: 23.7 ± 2.0) and middle-aged groups (8 female and 8 males; mean age: 47.3 ± 8.5 s) were recruited and tested for this study. Only subjects who did not exercise regularly and had no record of tendon injury were studied. The results show that the BUA is significantly higher for the young group (45.2 ± 1.6 dB MHz-1) than the middle-age group (40.5 ± 1.9 dB MHz-1), while the SOS is significantly lower for the young (1601.9 ± 11.2 ms-1) compared to the middle-aged (1624.1 ± 8.7 m s-1). On the other hand, the thicknesses of Achilles tendons for both groups (young: 4.31 ± 0.23 mm; middle age: 4.24 ± 0.23 mm) are very similar. For one patient who had an Achilles tendon lengthening (ATL) surgery, the thickness of the Achilles tendon increased from 4 mm to 4.33 mm after the surgery. In addition, the BUA increased by about 7.2% while the SOS decreased by about 0.6%. In conclusion, noninvasive ultrasonic assessment of Achilles tendons is useful for assisting clinical diagnosis and for the evaluation of a therapeutic regimen.

Du, Yi-Chun; Chen, Yung-Fu; Chen, Pei-Jarn; Lin, Yu-Ching; Chen, Tainsong; Lin, Chii-Jeng

2007-09-01

35

Modeling nonlinear ultrasound propagation in tissue from array transducers and application to tissue harmonic imaging  

Microsoft Academic Search

A computational model is presented to simulate nonlinear propagation of ultrasound in tissue from array transducers. The model is based on an operator splitting approach with a fractional step marching scheme, whereby the effects of diffraction, attenuation and nonlinearity can be considered independent over small steps. This algorithm avoids the use of the parabolic approximation used by the KZK model,

Roger J. Zemp; Jahangir Tavakkoli; R. S. C. Cobbold

2002-01-01

36

Measuring tissue blood flow using ultrasound modulated diffused light  

NASA Astrophysics Data System (ADS)

We demonstrate the ability of a novel device employing ultrasound modulation of near infrared light (referred as "Ultrasound tagged light" or UTL) to perform non-invasive monitoring of blood flow in the microvascular level in tissue. Monitoring microcirculatory blood flow is critical in clinical situations affecting flow to different organs, such as the brain or the limbs. . However, currently there are no non-invasive devices that measure microcirculatory blood flow in deep tissue continuously. Our prototype device (Ornim Medical, Israel) was used to monitor tissue blood flow on anesthetized swine during controlled manipulations of increased and decreased blood flow. Measurements were done on the calf muscle and forehead of the animal and compared with Laser Doppler (LD). ROC analysis of the sensitivity and specificity for detecting an increase in blood flow on the calf muscle, demonstrated AUC = 0.951 for 23 systemic manipulations of cardiac output by Epinephrine injection, which is comparable to AUC = 0.943 using laser Doppler. Some examples of cerebral blood flow monitoring are presented, along with their individual ROC curves. UTL flowmetry is shown to be effective in detecting changes in cerebral and muscle blood flow in swine, and has merit in clinical applications.

Ron, A.; Racheli, N.; Breskin, I.; Metzger, Y.; Silman, Z.; Kamar, M.; Nini, A.; Shechter, R.; Balberg, M.

2012-02-01

37

Ultrasound-guided tissue fractionation by high intensity focused ultrasound in an in vivo porcine liver model.  

PubMed

The clinical use of high intensity focused ultrasound (HIFU) therapy for noninvasive tissue ablation has been recently gaining momentum. In HIFU, ultrasound energy from an extracorporeal source is focused within the body to ablate tissue at the focus while leaving the surrounding organs and tissues unaffected. Most HIFU therapies are designed to use heating effects resulting from the absorption of ultrasound by tissue to create a thermally coagulated treatment volume. Although this approach is often successful, it has its limitations, such as the heat sink effect caused by the presence of a large blood vessel near the treatment area or heating of the ribs in the transcostal applications. HIFU-induced bubbles provide an alternative means to destroy the target tissue by mechanical disruption or, at its extreme, local fractionation of tissue within the focal region. Here, we demonstrate the feasibility of a recently developed approach to HIFU-induced ultrasound-guided tissue fractionation in an in vivo pig model. In this approach, termed boiling histotripsy, a millimeter-sized boiling bubble is generated by ultrasound and further interacts with the ultrasound field to fractionate porcine liver tissue into subcellular debris without inducing further thermal effects. Tissue selectivity, demonstrated by boiling histotripsy, allows for the treatment of tissue immediately adjacent to major blood vessels and other connective tissue structures. Furthermore, boiling histotripsy would benefit the clinical applications, in which it is important to accelerate resorption or passage of the ablated tissue volume, diminish pressure on the surrounding organs that causes discomfort, or insert openings between tissues. PMID:24843132

Khokhlova, Tatiana D; Wang, Yak-Nam; Simon, Julianna C; Cunitz, Bryan W; Starr, Frank; Paun, Marla; Crum, Lawrence A; Bailey, Michael R; Khokhlova, Vera A

2014-06-01

38

Statistical Parameter Estimation in Ultrasound Backscattering from Tissue Mimicking Media.  

NASA Astrophysics Data System (ADS)

Several tissue characterization parameters, including the effective scatterer number density and the backscatter coefficient, were derived from the statistical properties of ultrasonic echo signals. The effective scatterer number density is the actual scatterer number density in a medium multiplied by a frequency-dependent factor that depends on the differential scattering cross-sections of all scatterers. The method described in this thesis for determining the scatterer number density explicitly retains both the temporal nature of the data acquisition and the properties of the ultrasound field in the data reduction. Moreover, it accounts for the possibility that different sets of scatterers may dominate the echo signal at different frequencies. The random processes involved in forming ultrasound echo signals from random media give rise to an uncertainty in the estimated effective scatterer number density. This uncertainty is evaluated using error propagation. The statistical uncertainty depends on the effective number of scatterers contributing to the segmented echo signal, increasing when the effective number of scatterers increases. Tests of the scatterer number density data reduction method and the statistical uncertainty estimator were done using phantoms with known ultrasound scattering properties. Good agreement was found between measured values and those calculated from first-principles. The properties of the non-Gaussian and non-Rayleigh parameters of ultrasound echo signals are also studied. Both parameters depend on the measurement system, including the transducer field and pulse frequency content, as well as on the medium's properties. The latter is expressed in terms of the scatterer number density and the second and fourth moments of the medium's scattering function. A simple relationship between the non-Gaussian and non-Rayleigh parameters is derived and verified experimentally. Finally, a reference phantom method is proposed for measuring the effective scatterer number density in vivo. Various groups are using the frequency dependent backscatter coefficient (or the spatial autocorrelation function) to characterize scatterer sizes in biological tissue. Generally, sparse scatterer concentrations are assumed in relating scattering parameters to this tissue property. For dense scattering media, we study whether the frequency dependent backscatter coefficient changes with the scatterer volume fraction. Two scattering models suggested by Debye and Yagi are reviewed. In these models, the spatial autocorrelation function describing mass density and compressibility fluctuations in the scattering medium has a characteristic length that depends on the scatterer volume fraction as well as the scatterer size. The models predict the frequency dependence of the backscatter coefficient will vary with the scatterer volume fraction. Qualitative agreement between the model predictions and experimental results are seen for sephadex-in-agar phantoms.

Chen, Jian-Feng

39

Optimal conditions for tissue perforation using high intensity focused ultrasound  

NASA Astrophysics Data System (ADS)

To perforate tissue lying deep part in body, a large size transducer was assembled by combining four spherical-shaped transducers, and the optimal conditions for tissue perforation have studied using ventricle muscle of chicken as a target. The ex vivo experiments showed that ventricle muscle was successfully perforated both when it was exposed to High Intensity Focused Ultrasound (HIFU) directly and when it was exposed to HIFU through atrial muscle layer. Moreover, it was shown that calculated acoustic power distributions are well similar to the perforation patterns, and that the acoustic energy distributes very complexly near the focus. Lastly, perforation on the living rabbit bladder wall was demonstrated as a preliminary in vivo experiment.

Mochizuki, Takashi; Kihara, Taizo; Ogawa, Kouji; Tanabe, Ryoko; Yosizawa, Shin; Umemura, Shin-ichiro; Kakimoto, Takashi; Yamashita, Hiromasa; Chiba, Toshio

2012-10-01

40

Modeling ultrasound echoes in skin tissues using symmetric ?-stable processes.  

PubMed

Starting from the widely accepted point-scattering model, this paper establishes, through analytical developments, that ultrasound signals backscattered from skin tissues converge to a complex Levy flight random process with non- Gaussian ?-stable statistics. The envelope signal follows a generalized (heavy-tailed) Rayleigh distribution. It is shown that these signal statistics imply that scatterers have heavy-tailed power-law cross sections. This model generalizes the Gaussian framework and provides a formal representation for a new case of non-Gaussian statistics, in which both the number of scatterers and the variance of their cross sections tend to infinity. In addition, analytical expressions are derived to relate the ?-stable parameters to scatterer properties. Simulations show that these expressions can be used as rigorous interpretation tools for tissue characterization. Several experimental results supported by excellent goodness-of-fit tests confirm the proposed analytical model. Finally, these fundamental results set the basis for new echography processing methods and quantitative ultrasound characterization tools. PMID:22293736

Pereyra, Marcelo; Batatia, Hadj

2012-01-01

41

INVESTIGATION OF INTENSITY THRESHOLDS FOR ULTRASOUND TISSUE EROSION  

PubMed Central

Our previous studies have shown that short intense pulses delivered at certain pulse repetition frequencies (PRF) can achieve localized, clean erosion in soft tissue. In this paper, the intensity thresholds for ultrasound induced erosion and the effects of pulse intensity on erosion characterized by axial erosion rate, perforation area and volume erosion rate were investigated on in vitro porcine atrial wall tissue. Ultrasound pulses with a 3-cycle pulse duration and a 20-kHz PRF were delivered by a 788-kHz single element focused transducer. ISPPA values of 1000 to 9000 W/cm2 were tested. Results show the following: (1) the estimated intensity threshold for generating erosion was at ISPPA of 3220 W/cm2; (2) the axial erosion rate increased with higher intensity at ISPPA ? 5000 W/cm2, while decreased with higher intensity at ISPPA ? 5000 W/cm2; and (3) the perforation area and the volume erosion rate increased with higher intensity.

Xu, Zhen; Fowlkes, J. Brian; Ludomirsky, Achi; Cain, Charles A.

2009-01-01

42

Diagnostic ultrasound exposimetry using a tissue-mimicking liquid  

NASA Astrophysics Data System (ADS)

Accurate measurements of acoustic output parameters (e.g., PII, pr, MI, TI) are necessary for ensuring the continued safety of diagnostic ultrasound. Under the current methodology, pressure waveforms are measured in water and derated to attempt to correct for the large difference in attenuation between water and tissue. Derating refers to multiplying each recorded pressure value by a factor equivalent to a pre-determined amount of attenuation of the sound field, viz. 0.30 dB cm-1 MHz-1. Because of nonlinear acoustic propagation effects, ultrasound propagation in water is not necessarily lossless, but can be accompanied by significant loss of signal. Derating does not consider this signal loss; thus, derated values of the acoustic output parameters may significantly underestimate in situ values. The goals of this work are to produce a tissue-mimicking liquid that can be used as the propagation medium for acoustic output measurements and to compare parameter values obtained in this liquid to values obtained using the current methodology. Chapter 4 provides a description of the method used to create a TM liquid based on fat-free bovine milk concentrated by a factor of three and details the successful search for a satisfactory method of preservation. Chapter 5 describes the incorporation of this liquid into an apparatus designed to measure acoustic output parameters in this liquid or in water. Chapters 6 and 7 provide an in-depth accounting of results obtained with this system for forty-six configurations encompassing six diagnostic ultrasound scanners. The results indicate that values of several acoustic output parameters obtained through the derating procedure are generally less than those in tissue-mimicking liquid. Specifically, the pulse intensity integral is, on average, underestimated by a factor of about 2, the peak rarefactional pressure is underestimated by a factor of about 1.8 and the total power is underestimated by a factor of about 2.3. The use of a system incorporating tissue-mimicking liquid would eliminate the need to use derating and allow for direct measurements of acoustic output parameters.

Stiles, Timothy A.

43

Comprehensive approach to breast cancer detection using light: photon localization by ultrasound modulation and tissue characterization by spectral discrimination  

Microsoft Academic Search

A new technique called Ultrasound Tagging of Light (UTL) for imaging breast tissue is described. In this approach, photon localization in turbid tissue is achieved by cross- modulating a laser beam with focussed, pulsed ultrasound. Light which passes through the ultrasound focal spot is `tagged' with the frequency of the ultrasound pulse. The experimental system uses an Argon-Ion laser, a

Fay A. Marks; Harold W. Tomlinson; Glen W. Brooksby

1993-01-01

44

A real-time measure of cavitation induced tissue disruption by ultrasound imaging backscatter reduction  

Microsoft Academic Search

A feedback method for obtaining real-time information on the mechanical disruption of tissue through ultrasound cavitation is presented. This method is based on a substantial reduction in ultrasound imaging backscatter from the target volume as the tissue structure is broken down. Ex-vivo samples of porcine liver were exposed to successive high-intensity ultrasound pulses at a low duty cycle to induce

Timothy L. Hall; B. Fowlkes; Charles A. Cain

2007-01-01

45

Error in estimates of tissue material properties from shear wave dispersion ultrasound vibrometry  

Microsoft Academic Search

Shear wave velocity measurements are used in elasticity imaging to find the shear elasticity and viscosity of tissue. A technique called shear wave dispersion ultrasound vibrometry (SDUV) has been introduced to use the dispersive nature of shear wave velocity to locally estimate the material properties of tissue. Shear waves are created using a multifrequency ultrasound radiation force, and the propagating

Matthew W. Urban; Shigao Chen; James Greenleaf

2009-01-01

46

Probability of cavitation for single ultrasound pulses applied to tissues and tissue-mimicking materials  

PubMed Central

In this article, the negative pressure values at which inertial cavitation consistently occurs in response to a single, 2-cycle, focused ultrasound pulse were measured in several media relevant to cavitation-based ultrasound therapy. The pulse was focused into a chamber containing one of the media, which included liquids, tissue-mimicking materials, and ex-vivo canine tissue. Focal waveforms were measured by two separate techniques using a fiber-optic hydrophone. Inertial cavitation was identified by high-speed photography in optically transparent media and an acoustic passive cavitation detector. The probability of cavitation (Pcav) for a single pulse as a function of peak negative pressure (p?) followed a sigmoid curve, with the probability approaching 1 when the pressure amplitude was sufficient. The statistical threshold (defined as Pcav = 0.5) was between p? = 26.0–30.0 MPa in all samples with a high water content, but varied between p? = 13.7 to > 36 MPa for other media. A model for radial cavitation bubble dynamics was employed to evaluate the behavior of cavitation nuclei at these pressure levels. A single bubble nucleus with an inertial cavitation threshold of p? = 28.2 MPa was estimated to have a 2.5 nm radius in distilled water. These data may be valuable for cavitation-based ultrasound therapy to predict the likelihood of cavitation at different pressure levels and dimensions of cavitation-induced lesions in tissue.

Maxwell, Adam D.; Cain, Charles A.; Hall, Timothy L.; Fowlkes, J. Brian; Xu, Zhen

2012-01-01

47

Ultrasound accelerates transport of recombinant tissue plasminogen activator into clots  

Microsoft Academic Search

Fibrinolysis is accelerated in vitro in an ultrasound field, and externally applied high frequency ultrasound also accelerates thrombolysis in animal models. Although the mechanism of this effect is not known, ultrasound does not cause mechanical disruption of clots but rather accelerates enzymatic fibrinolysis. To determine if accelerated fibrinolysis could be related to increased transport of enzyme into clot, we have

Charles W. Francis; Ales Blinc; Simone Lee; Christopher Cox

1995-01-01

48

Window-modulated compounding Nakagami imaging for ultrasound tissue characterization.  

PubMed

Ultrasound Nakagami parametric imaging is a useful tool for tissue characterization. Previous literature has suggested using a square with side lengths corresponding to 3 times the transducer pulse length as the minimum window for constructing the Nakagami image. This criterion does not produce sufficiently smooth images for the Nakagami image to characterize homogeneous tissues. To improve image smoothness, we proposed window-modulated compounding (WMC) Nakagami imaging based on summing and averaging the Nakagami images formed using sliding windows with varying window side lengths from 1 to N times the transducer pulse length in 1 pulse length step. Simulations (the number densities of scatterers: 2-16 scatterers/mm(2)) and experiments on fully developed speckle phantoms (the scatterer diameters: 20-106?m) were conducted to suggest an appropriate number of frames N and to evaluate the image smoothness and resolution by analyzing the full width at half maximum (FWHM) of the parameter distribution and the widths of the image autocorrelation function (ACF), respectively. In vivo ultrasound measurements on rat livers without and with cirrhosis were performed to validate the practical performance of the WMC Nakagami image in tissue characterization. The simulation results showed that using a range of N from 7 to 10 as the number of frames for image compounding reduces the estimation error to less than 5%. Based on this criterion, the Nakagami parameter obtained from the WMC Nakagami image increased from 0.45 to 0.95 after increasing the number densities of scatterers from 2 to 16 scatterers/mm(2). The FWHM of the parameter distribution (bins=40) was 13.5±1.4 for the Nakagami image and 9.1±1.43 for the WMC Nakagami image, respectively (p-value<.05). The widths of the ACF for the Nakagami and WMC Nakagami images were 454±5.36 and 458±4.33, respectively (p-value>.05). In the phantom experiments, we also found that the FWHM of the parameter distribution for the WMC Nakagami image was smaller than that of the conventional Nakagami image (p-value<.05), and there was no significant difference of the ACF width between the Nakagami and WMC Nakagami images (p-value>.05). In the animal experiments, the Nakagami parameters obtained from the WMC Nakagami image for normal and cirrhotic rat livers were 0.62±0.08 and 0.92±0.07, respectively (p-value<.05). The results demonstrated that the WMC technique significantly improved the image smoothness of Nakagami imaging without resolution degradation, giving Nakagami model-based imaging the ability to visualize scatterer properties with enhanced image quality. PMID:24835004

Tsui, Po-Hsiang; Ma, Hsiang-Yang; Zhou, Zhuhuang; Ho, Ming-Chih; Lee, Yu-Hsin

2014-08-01

49

Neuropathic tissue responds preferentially to stimulation by intense focused ultrasound  

PubMed Central

We tested the hypothesis that neuropathic tissue is more sensitive to stimulation by intense focused ultrasound (iFU) than control tissue. We created a diffusely neuropathic paw in rats via partial ligation of the sciatic nerve, whose sensitivity to iFU stimulation we compared with sham-surgery and normal control paws. We then applied increasing amounts of iFU (individual 0.2 second pulses at 1.15 MHz) to the rats’ paws, assaying for their reliable withdrawal from that stimulation. Neuropathic rats preferentially withdrew their injured paw from iFU at smaller values of iFU intensity (176 W/cmˆ2 +/- 56) than did sham surgery (217 W/cmˆ2 +/- 25) and normal control (>280 W/cmˆ2) animals, with greater sensitivity and specificity (85% for neuropathic rats and 50% each of sham surgery and normal control rats). These results directly support our hypothesis as well as Gavrilov’s idea that doctors may some day use iFU stimulation to diagnose patients with neuropathies.

Tych, Rowen E.; Gofeld, Michael; Jarvik, Jeffrey G.; Kliot, Michel; Loeser, John D.; McClintic, Abbi M.; Ollos, Ryan J.; Pederson, Kristin D.; Sparks, Rachel E.; Terman, Gregory W.; Mourad, Pierre D.

2014-01-01

50

Two-dimensional tissue imaging by use of parallel detection of ultrasound-modulated laser speckles  

Microsoft Academic Search

Ultrasound-modulated optical tomography in biological tissue was studied. An ultrasonic beam was focused into a biological tissue sample to modulate the laser light passing through the ultrasonic beam inside the tissue. The speckle field formed by the transmitted laser light was detected by a CCD camera with the source-synchronous-illumination lock- in technique. The ultrasound-modulated laser light reflects the local optical

Gang Yao; Lihong V. Wang

2000-01-01

51

Intense focused ultrasound preferentially stimulates subcutaneous and focal neuropathic tissue: preliminary results  

PubMed Central

Objective Potential peripheral sources of pain from subcutaneous tissue can require invasive evocative tests for their localization and assessment. Here we describe studies whose ultimate goal is development of a non-invasive evocative test for subcutaneous, painful tissue. Design We used a rat model of a focal and subcutaneous neuroma to test the hypothesis that intense focused ultrasound can differentiate focal and subcutaneous neuropathic tissue from control tissue. To do so we first applied intense focused ultrasound (2 MHz, with individual pulses of 0.1 seconds in duration) to the rat’s neuroma while the rat was under light anesthesia. We started with low values of intensity which we increased until intense focused ultrasound stimulation caused the rat to reliably flick its paw. We then applied that same intense focused ultrasound protocol to control tissue away from the neuroma and assayed for the rat’s response to that stimulation. Results Intense focused ultrasound of sufficient strength (I_sata of 600 +/? 160 W/cm^2) applied to the neuroma caused the rat to flick its paw, while the same intense focused ultrasound applied millimeters to a centimeter away failed to induce a paw flick. Conclusion Successful stimulation of the neuroma by intense focused ultrasound required co-localization of the neuroma and intense focused ultrasound, supporting our hypothesis.

McClintic, Abbi M.; Dickey, Trevor C.; Gofeld, Michael; Kliot, Michel; Loeser, John D.; Richebe, Philippe; Mourad, Pierre D.

2012-01-01

52

Targeted damage effects of high intensity focused ultrasound (HIFU) on liver tissues of Guizhou province miniswine  

Microsoft Academic Search

HIFU can pass through tissues and accurately damage target tissues inside organisms. This article reports on the oriented damage effects of HIFU upon miniswine internal and external liver tissues, and suggests a new conception of the ‘biological focal field’. The results revealed that: (1) HIFU can be used to damage accurately liver tissues under the guide of a B-modal ultrasound

Zhi B. Wang; Feng Wu; Zhi L. Wang; Zhe Zhang; Jian Z. Zou; Chuan Liu; Yu G. Liu; Xun Cheng; Yong H. Du; Zheng C. He; Mei L. Gu; Zhi G. Wang; Ruo Feng

1997-01-01

53

Measurement of tissue mechanical properties with shear wave dispersion ultrasound vibrometry (SDUV)  

Microsoft Academic Search

Shear wave dispersion vibrometry (SDUV) produces motion in tissue using sequential pulses of ultrasound radiation pressure. The resulting motion of the tissue in the form of propagating shear waves can provide information about the material properties of the tissue given the appropriate equations of motion for the geometry of the tissue. An example application of the method is described to

James F. Greenleaf; Matthew W. Urban; Shigao Chen

2009-01-01

54

Semi-automated Ultrasound Facial Soft Tissue Depth Registration: Method and Validation  

Microsoft Academic Search

ABSTRACT: A mobile and fast, semi-automatic ultrasound (US) system was developed for facial soft tissue depth registration. The system consists of an A-Scan ultrasound device connected to a portable PC with interfacing and controlling software. For 52 cephalometric landmarks, the system was tested for repeatability and accuracy,by evaluating intra-observer agreement,and comparing,ultrasound and CT-scan results on 12 subjects planned for craniofacial

Sven De Greef; Peter Claes; Wouter Mollemans; Miet Loubele; Dirk Vandermeulen; Paul Suetens; Guy Willems

2005-01-01

55

Heating in vascular tissue and flow-through tissue phantoms induced by focused ultrasound  

NASA Astrophysics Data System (ADS)

High intensity focused ultrasound (HIFU) can be used to control bleeding, both from individual blood vessels as well as from gross damage to the capillary bed. This process, called acoustic hemostasis, is being studied in the hope that such a method would ultimately provide a lifesaving treatment during the so-called "golden hour", a brief grace period after a severe trauma in which prompt therapy can save the life of an injured person. Thermal effects play a major role in occlusion of small vessels and also appear to contribute to the sealing of punctures in major blood vessels. However, aggressive ultrasound-induced tissue heating can also impact healthy tissue and can lead to deleterious mechanical bioeffects. Moreover, the presence of vascularity can limit one's ability to elevate the temperature of blood vessel walls owing to convective heat transport. In an effort to better understand the heating process in tissues with vascular structure we have developed a numerical simulation that couples models for ultrasound propagation, acoustic streaming, ultrasound heating and blood cooling in Newtonian viscous media. The 3-D simulation allows for the study of complicated biological structures and insonation geometries. We have also undertaken a series of in vitro experiments, in non-uniform flow-through tissue phantoms, designed to provide a ground truth verification of the model predictions. The calculated and measured results were compared over a range of values for insonation pressure, insonation time, and flow rate; we show good agreement between predictions and measurements. We then conducted a series of simulations that address two limiting problems of interest: hemostasis in small and large vessels. We employed realistic human tissue properties and considered more complex geometries. Results show that the heating pattern in and around a blood vessel is different for different vessel sizes, flow rates and for varying beam orientations relative to the flow axis. Complete occlusion and wall-puncture sealing are both possible depending on the exposure conditions. These results concur with prior clinical observations and may prove useful for planning of a more effective procedure in HIFU treatments.

Huang, Jinlan

56

Novel Applications of Ultrasound Technology to Visualize and Characterize Myofascial Trigger Points and Surrounding Soft Tissue  

PubMed Central

Objective Apply ultrasound (US) imaging techniques to better describe the characteristics of myofascial trigger points (MTrPs) and the immediately adjacent soft tissue. Design Descriptive (exploratory) study. Setting Biomedical research center. Participants 9 subjects meeting Travell and Simons’s criteria for MTrPs in a taut band in the upper trapezius. Interventions (None) Main Outcome Measures MTrPs were evaluated by 1) physical examination, 2) pressure algometry, and 3) three types of ultrasound imaging including grayscale (2D US), vibration sonoelastography (VSE), and Doppler. Methods Four sites in each patient were labeled based on physical examination as either active MTrP (spontaneously-painful, A-MTrP), latent MTrP (non-painful, L-MTrP), or normal myofascial tissue. US examination was performed on each subject by a team blinded to the physical findings. A 12-5 MHz US transducer was used. VSE was performed by color Doppler variance imaging while simultaneously inducing vibrations (~92Hz) with a handheld massage vibrator. Each site was assigned a tissue imaging score (TIS) as follows: 0 = uniform echogenicity and stiffness; 1 = focal hypoechoic region with stiff nodule; 2 = multiple hypoechoic regions with stiff nodules. Blood flow in the neighborhood of MTrPs was assessed using Doppler imaging. Each site was assigned a blood flow waveform score (BFS) as follows: 0 = normal arterial flow in muscle; 1 = elevated diastolic flow; 2 = high-resistance flow waveform with retrograde diastolic flow. Results MTrPs appeared as focal, hypoechoic regions on 2D US, indicating local changes in tissue echogenicity, and as focal regions of reduced vibration amplitude on VSE, indicating a localized stiff nodule. MTrPs were elliptical in shape, with a size of 0.16 ± 0.11 cm2. There were no significant differences in size between A-MTrPs and L-MTrPs. Sites containing MTrPs were more likely to have higher TIS compared to normal myofascial tissue (p<0.002). Small arteries (or enlarged arterioles) near A-MTrPs showed retrograde flow in diastole indicating a highly resistive vascular bed. A-MTrP sites were more likely to have higher BFS compared to L-MTrPs (p<0.021). Conclusions Preliminary findings show that, under the conditions of this investigation, US imaging techniques can be used to distinguish myofascial tissue containing MTrPs from normal myofascial tissue (lacking trigger points). Ultrasound enables visualization and some characterization of MTrPs and adjacent soft tissue.

Sikdar, Siddhartha; Shah, Jay P.; Gebreab, Tadesse; Yen, Ru-Huey; Gilliams, Elizabeth; Danoff, Jerome; Gerber, Lynn H.

2009-01-01

57

Ultrasound Doppler tissue image analysis based on neural network  

NASA Astrophysics Data System (ADS)

A new method for quantitative analysis of ultrasound Doppler tissue images (DTI) has been developed based on a neural network. The method aims to extract numerical data of velocity or acceleration from DTI images and analyze them quantitatively. A three-layered back propagation (BP) neural network is used to accomplish this task. The input of the network is the differences between the red, green and blue components of pixels and the output is the acceleration or velocity values. The network is trained with the color bars in the DTI images. The result of analyzing the movement of the left ventricle anterior free wall (LVAW) from DTA (DTI acceleration mode) image sequences is presented. The result of time-acceleration curve is highly correlated with the electrocardiogram (ECG) curve and gives us a quantitative and graphic description of the ventricle movement in cardiac cycles. It shows the movement characteristics of the left ventricle in cardiac cycles and also shows the excitation differences among the three layers of the myocardium. It is demonstrated that the method has great potential to characterize myocardial movement, which may provide a new way to characterize cardiac activities.

Zhao, Shukui; Li, Deyu; Yin, Lixue; Wang, Tianfu; Zheng, Changqiong; Zheng, Yi

2001-09-01

58

Focused ultrasound to displace renal calculi: threshold for tissue injury  

PubMed Central

Background The global prevalence and incidence of renal calculi is reported to be increasing. Of the patients that undergo surgical intervention, nearly half experience symptomatic complications associated with stone fragments that are not passed and require follow-up surgical intervention. In a clinical simulation using a clinical prototype, ultrasonic propulsion was proven effective at repositioning kidney stones in pigs. The use of ultrasound to reposition smaller stones or stone fragments to a location that facilitates spontaneous clearance could therefore improve stone-free rates. The goal of this study was to determine an injury threshold under which stones could be safely repositioned. Methods Kidneys of 28 domestic swine were treated with exposures that ranged in duty cycle from 0%–100% and spatial peak pulse average intensities up to 30 kW/cm2 for a total duration of 10 min. The kidneys were processed for morphological analysis and evaluated for injury by experts blinded to the exposure conditions. Results At a duty cycle of 3.3%, a spatial peak intensity threshold of 16,620 W/cm2 was needed before a statistically significant portion of the samples showed injury. This is nearly seven times the 2,400-W/cm2 maximum output of the clinical prototype used to move the stones effectively in pigs. Conclusions The data obtained from this study show that exposure of kidneys to ultrasonic propulsion for displacing renal calculi is well below the threshold for tissue injury.

2014-01-01

59

Characterization of biomechanical properties of agar based tissue mimicking phantoms for ultrasound stiffness imaging techniques.  

PubMed

Pathological changes of the body have been observed to change the mechanical properties of soft tissue types which can be imaged by ultrasound elastography. Though initial clinical results using ultrasound elastography in detection of tumors are promising, quantification of signal to noise ratio, resolution and strain image patterns are the best achieved under a controlled study using phantoms with similar biomechanical properties of normal and abnormal tissues. The purpose of this work is to characterize the biomechanical properties of agar based tissue mimicking phantoms by varying the agar concentration from 1.7 to 6.6% by weight and identify the optimum property to be used in classification of cancerous tissues. We performed quasi-static uniaxial compression test under a strain rate of 0.5mm/min up to 15% strain and measured Young's modulus of phantom samples which are from 50kPa to 450kPa. Phantoms show nonlinear stress-strain characteristics at finite strain which were characterized using hyperelastic parameters by fitting Neo-Hookean, Mooney Rivlin, Ogden and Veronda Westmann models. We also investigated viscoelastic parameters of the samples by conducting oscillatory shear rheometry at various precompression levels (2-5%). Loss modulus values are always less than storage modulus which represents the behavior of soft tissues. The increase in agar concentration increases the shear modulus of the samples as well as decreases the linear viscoelastic region. The results suggest that dynamic shear modul are more promising than linear and nonlinear elastic modul in differentiation of various classes of abnormal tissues. PMID:24769915

Manickam, Kavitha; Machireddy, Ramasubba Reddy; Seshadri, Suresh

2014-07-01

60

Optical and acoustic monitoring of bubble cloud dynamics at a tissue-fluid interface in ultrasound tissue erosion  

PubMed Central

Short, high-intensity ultrasound pulses have the ability to achieve localized, clearly demarcated erosion in soft tissue at a tissue-fluid interface. The primary mechanism for ultrasound tissue erosion is believed to be acoustic cavitation. To monitor the cavitating bubble cloud generated at a tissue-fluid interface, an optical attenuation method was used to record the intensity loss of transmitted light through bubbles. Optical attenuation was only detected when a bubble cloud was seen using high speed imaging. The light attenuation signals correlated well with a temporally changing acoustic backscatter which is an excellent indicator for tissue erosion. This correlation provides additional evidence that the cavitating bubble cloud is essential for ultrasound tissue erosion. The bubble cloud collapse cycle and bubble dissolution time were studied using the optical attenuation signals. The collapse cycle of the bubble cloud generated by a high intensity ultrasound pulse of 4–14 ?s was ~40–300 ?s depending on the acoustic parameters. The dissolution time of the residual bubbles was tens of ms long. This study of bubble dynamics may provide further insight into previous ultrasound tissue erosion results.

Xu, Zhen; Hall, Timothy L.; Fowlkes, J. Brian; Cain, Charles A.

2009-01-01

61

Multispectral photoacoustic imaging of tissue denaturation induced by high-intensity focused ultrasound treatment  

NASA Astrophysics Data System (ADS)

This paper presents an ex vivo study in imaging high-intensity focused ultrasound induced tissue denaturation with multispectral photoacoustic approach. Beef tissues treated by both water bath and high-intensity focused ultrasound were imaged and evaluated by photoacoustic imaging method, where light in multiple optical wavelengths between 700nm and 900nm is applied. Tissue denaturation after being treated by water bath and high-intensity focused ultrasound has been observed in multispectral photoacoustic images. The denaturation is more striking in relatively shorter optical wavelength photoacoustic images than in relatively longer optical wavelength photoacoustic images. This study suggests that multispectral photoacoustic imaging method is promising in the evaluation of tissue denaturation induced by high- intensity focused ultrasound treatment.

Sun, Yao; Li, King C. P.; O'Neill, Brian

2013-03-01

62

Ultrasound-based transient elastography compared to magnetic resonance elastography in soft tissue-mimicking gels  

Microsoft Academic Search

Ultrasound-based transient elastography (TE) and magnetic resonance elastography (MRE) are increasingly used methods for the clinical evaluation of soft tissue mechanical properties and their alteration under diseased conditions. This study proposes a comparison between magnetic resonance elastography (MRE) and ultrasound-based transient elastography (TE). Both methods were tested on the same soft tissue-mimicking gels in a common frequency range in order

Jennifer Oudry; Jonathan Vappou; Philippe Choquet; Rémy Willinger; Laurent Sandrin; André Constantinesco

2009-01-01

63

Ultrasound Screening of Periarticular Soft Tissue Abnormality Around Metal-on-Metal Bearings  

Microsoft Academic Search

Although metal hypersensitivity or pseudotumors are concerns for metal-on-metal (MoM) bearings, detailed pathologies of patterns, severity, and incidence of periprosthetic soft tissue lesions are incompletely understood. We examined the potential of ultrasound for screening of periarticular soft tissue lesions around MoM bearings. Ultrasound examinations were conducted in 88 hips (79 patients) with MoM hip resurfacings or MoM total hip arthroplasties

Takashi Nishii; Takashi Sakai; Masaki Takao; Hideki Yoshikawa; Nobuhiko Sugano

64

Safety and tissue yield for percutaneous native kidney biopsy according to practitioner and ultrasound technique  

PubMed Central

Background Although percutaneous renal biopsy remains an essential tool in the diagnosis and treatment of renal diseases, in recent times the traditional procedure of nephrologists has been performed by non-nephrologists rather than nephrologists at many institutions. The present study assessed the safety and adequacy of tissue yield during percutaneous renal biopsy according to practitioners and techniques based on ultrasound. Methods This study included 658 native renal biopsies performed from 2005 to 2010 at a single centre. The biopsies were performed by nephrologists or expert ultrasound radiologists using the ultrasound-marked blind or real-time ultrasound-guided techniques. Results A total of 271 ultrasound-marked blind biopsies were performed by nephrologists, 170 real-time ultrasound-guided biopsies were performed by nephrologists, and 217 real-time ultrasound-guided biopsies were performed by radiologists during the study period. No differences in post-biopsy complications such as haematoma, need for transfusion and intervention, gross haematuria, pain, or infection were observed among groups. Glomerular numbers of renal specimens from biopsies performed by nephrologists without reference to any technique were higher than those obtained from real-time ultrasound-guided biopsies performed by expert ultrasound radiologists. Conclusions Percutaneous renal biopsy performed by nephrologists was not inferior to that performed by expert ultrasound radiologists as related to specimen yield and post-biopsy complications.

2014-01-01

65

Endoscopic ultrasound guided fine needle tissue acquisition: Where we stand in 2013?  

PubMed Central

Since its introduction, endoscopic ultrasound (EUS) guided fine needle aspiration and fine needle biopsy have become an indispensable tool for the diagnosis of lesions within the gastrointestinal tract and surrounding organs. It has proved to be an effective diagnostic method with high accuracy and low complication rates. Several factors can influence the accuracy and the diagnostic yield of this procedure including experience of the endosonographer, availability of onsite cytopathology services, the method of cytopathology preparation, the location and physical characteristics of the lesion, sampling techniques and the type and size of the needle used. In this review we will outline the recent studies evaluating EUS-guided tissue acquisition and will provide practical recommendations to maximize tissue yield.

Karadsheh, Zeid; Al-Haddad, Mohammad

2014-01-01

66

A novel noncontact ultrasound indentation system for measurement of tissue material properties using water jet compression  

Microsoft Academic Search

This study is aimed to develop a novel noncontact ultrasonic indentation system for measuring quantitative mechanical properties of soft tissues, which are increasingly important for tissue assessment and characterization. The key idea of this method is to use a water jet as an indenter to compress the soft tissue while at the same time as a medium for an ultrasound

M. H. Lu; Y. P. Zheng; Q. H. Huang

2005-01-01

67

Measurement of tissue mechanical properties with shear wave dispersion ultrasound vibrometry (SDUV).  

PubMed

Shear wave dispersion vibrometry (SDUV) produces motion in tissue using sequential pulses of ultrasound radiation pressure. The resulting motion of the tissue in the form of propagating shear waves can provide information about the material properties of the tissue given the appropriate equations of motion for the geometry of the tissue. An example application of the method is described to measure material properties in bovine tissue. PMID:19964364

Greenleaf, James F; Urban, Matthew W; Chen, Shigao

2009-01-01

68

Temperature elevation of biological tissue model exposed by focused ultrasound with acoustic radiation force  

NASA Astrophysics Data System (ADS)

Focused ultrasound with acoustic radiation force (ARF) is beginning to be used for imaging and measuring tissue elasticity. On the other hand, it was suggested that the temperature elevation near bone at focus may be significant within the limits of acoustic output regulation in diagnostic ultrasound devices (Herman; 2002). In this study, with the aim of obtaining the relationships between temperature elevations and parameters of ultrasound exposure with ARF, temperature elevations in two kinds of tissue models with or without bone were numerically evaluated. The results showed that the temperature elevation at focus on the surface of bone may exceed an allowable temperature elevation which WFUMB guideline recommends, even though the acoustic intensity is within the limits of acoustic output regulation in diagnostic ultrasound devices.

Nitta, Naotaka; Kudo, Nobuki; Akiyama, Iwaki

2012-09-01

69

Ultrasound  

MedlinePLUS

Sonogram ... An ultrasound machine creates images that allow various organs in the body to be examined. The machine sends out ... this test. The test is done in the ultrasound or radiology department. You will be lying down ...

70

Development and characterization of an innovative synthetic tissue-mimicking material for high intensity focused ultrasound (HIFU) exposures  

Microsoft Academic Search

While many tissue-mimicking phantoms have been developed for ultrasound imaging applications, none is suitable for exploration of the high temperature and pressure regimes involved in High Intensity Focused Ultrasound (HIFU). HIFU dosimetry studies are usually performed on biological tissues, but this approach has two drawbacks: 1) tissues are opaque and development of coagulative lesions cannot be visually observed in real-time,

Cyril Lafon; Peter J. Kaczkowski; Shahram Vaezy; Misty Noble; Oleg A. Sapozhnikov

2001-01-01

71

A pilot study using Tissue Velocity Ultrasound Imaging (TVI) to assess muscle activity pattern in patients with chronic trapezius myalgia  

Microsoft Academic Search

BACKGROUND: Different research techniques indicate alterations in muscle tissue and in neuromuscular control of aching muscles in patients with chronic localized pain. Ultrasound can be used for analysis of muscle tissue dynamics in clinical practice. AIM: This study introduces a new muscle tissue sensitive ultrasound technique in order to provide a new methodology for providing a description of local muscle

Michael Peolsson; Britt Larsson; Lars-Åke Brodin; Björn Gerdle

2008-01-01

72

Endoscopic Ultrasound Elastography - a New Imaging Technique for the Visualization of Tissue Elasticity Distribution  

Microsoft Academic Search

Endoscopic ultrasound (EUS) elastography is an imaging procedure used for the visualization of tissue elasticity during usual EUS examinations. EUS elastography can be accomplished real-time with state-of-the-art ultrasound systems, with the images being represented in transparent color superimposed on the conventional gray-scale B-mode scans. The aim of this review was to introduce the potential range of applications of EUS elastography.

Adrian Sãftoiu; Peter Vilman

73

Real-Time Monitoring Of Regional Tissue Elasticity During FUS Focused Ultrasound Therapy Using Harmonic Motion Imaging  

Microsoft Academic Search

The feasibility of the Harmonic Motion Imaging (HMI) technique for simultaneous monitoring and generation of focused ultrasound therapy using two separate focused ultrasound transducer elements has previously been shown. In this study, a new HMI technique is described that images tissue displacement induced by a harmonic radiation force induced using a single focused ultrasound element. First, wave propagation simulation models

Caroline Maleke; Mathieu Pernot; Elisa Konofagou

2006-01-01

74

Nonlinear ultrasound propagation through layered liquid and tissue-equivalent media: computational and experimental results at high frequency  

Microsoft Academic Search

Nonlinear propagation has been demonstrated to have a significant impact on ultrasound imaging. An efficient computational algorithm is presented to simulate nonlinear ultrasound propagation through layered liquid and tissue-equivalent media. Results are compared with hydrophone measurements. This study was undertaken to investigate the role of nonlinear propagation in high frequency ultrasound micro-imaging. The acoustic field of a focused transducer (20

Ross Williams; Emmanuel Cherin; Toby Y. J. Lam; Jahangir Tavakkoli; Roger J. Zemp; F. Stuart Foster

2006-01-01

75

Multi-Push (MP) Acoustic Radiation Force (ARF) Ultrasound for Assessing Tissue Viscoelasticity, In Vivo*  

PubMed Central

Acoustic radiation force (ARF) ultrasound is a method of elastographic imaging in which micron-scale tissue displacements, induced and tracked by ultrasound, reflect clinically relevant tissue mechanical properties. Our laboratory has recently shown that tissue viscoelasticity is assessed using the novel Multi-Push (MP) ARF method. MP ARF applies the Voigt model for viscoelastic materials and compares the displacements achieved by successive ARF excitations to qualitatively or quantitatively represent the relaxation time for constant stress, which is a direct descriptor of the viscoelastic response of the tissue. We have demonstrated MP ARF in custom viscoelastic tissue mimicking materials and implemented the method in vivo in canine muscle and human renal allografts, with strong spatial correlation between MP ARF findings and histochemical features and previously reported mechanical changes with renal disease. These data support that noninvasive MP ARF is capable of clinically relevant assessment of tissue viscoelastic properties.

Scola, Mallory R.; Baggesen, Leslie M.; Gallippi, Caterina M.

2013-01-01

76

Non-invasive estimation of thermal tissue properties by high-intensity focused ultrasound  

NASA Astrophysics Data System (ADS)

Magnetic Resonance guided High-intensity Focused Ultrasound (MR-HIFU) can be used to locally heat tissue while non-invasively monitoring tissue temperature via MR-based thermometry. The goal of this study was to investigate the use of a computational technique based on inverse heat-transfer modeling for the non-invasive measurement of thermal tissue properties from data collected using an MR-HIFU system.

Appanaboyina, Sunil; Partanen, Ari; Haemmerich, Dieter

2013-02-01

77

PE-CMOS based C-scan ultrasound for foreign object detection in soft tissue.  

PubMed

In this paper, we introduce a C-scan ultrasound prototype and three imaging modalities for the detection of foreign objects inserted in porcine soft tissue. The object materials include bamboo, plastics, glass and aluminum alloys. The images of foreign objects were acquired using the C-scan ultrasound, a portable B-scan ultrasound, film-based radiography, and computerized radiography. The C-scan ultrasound consists of a plane wave transducer, a compound acoustic lens system, and a newly developed ultrasound sensor array based on the complementary metal-oxide semiconductor coated with piezoelectric material (PE-CMOS). The contrast-to-noise ratio (CNR) of the images were analyzed to quantitatively evaluate the detectability using different imaging modalities. The experimental results indicate that the C-scan prototype has better CNR values in 4 out of 7 objects than other modalities. Specifically, the C-scan prototype provides more detail information of the soft tissues without the speckle artifacts that are commonly seen with conventional B-scan ultrasound, and has the same orientation as the standard radiographs but without ionizing radiation. PMID:20036873

Liu, Chu-Chuan; Lo, Shih-Chung Ben; Freedman, Matthew T; Lasser, Marvin E; Kula, John; Sarcone, Anita; Wang, Yue

2010-01-01

78

Algorithms and Results of Eye Tissues Differentiation Based on RF Ultrasound  

PubMed Central

Algorithms and software were developed for analysis of B-scan ultrasonic signals acquired from commercial diagnostic ultrasound system. The algorithms process raw ultrasonic signals in backscattered spectrum domain, which is obtained using two time-frequency methods: short-time Fourier and Hilbert-Huang transformations. The signals from selected regions of eye tissues are characterized by parameters: B-scan envelope amplitude, approximated spectral slope, approximated spectral intercept, mean instantaneous frequency, mean instantaneous bandwidth, and parameters of Nakagami distribution characterizing Hilbert-Huang transformation output. The backscattered ultrasound signal parameters characterizing intraocular and orbit tissues were processed by decision tree data mining algorithm. The pilot trial proved that applied methods are able to correctly classify signals from corpus vitreum blood, extraocular muscle, and orbit tissues. In 26 cases of ocular tissues classification, one error occurred, when tissues were classified into classes of corpus vitreum blood, extraocular muscle, and orbit tissue. In this pilot classification parameters of spectral intercept and Nakagami parameter for instantaneous frequencies distribution of the 1st intrinsic mode function were found specific for corpus vitreum blood, orbit and extraocular muscle tissues. We conclude that ultrasound data should be further collected in clinical database to establish background for decision support system for ocular tissue noninvasive differentiation.

Jurkonis, R.; Janusauskas, A.; Marozas, V.; Jegelevicius, D.; Daukantas, S.; Patasius, M.; Paunksnis, A.; Lukosevicius, A.

2012-01-01

79

Algorithms and results of eye tissues differentiation based on RF ultrasound.  

PubMed

Algorithms and software were developed for analysis of B-scan ultrasonic signals acquired from commercial diagnostic ultrasound system. The algorithms process raw ultrasonic signals in backscattered spectrum domain, which is obtained using two time-frequency methods: short-time Fourier and Hilbert-Huang transformations. The signals from selected regions of eye tissues are characterized by parameters: B-scan envelope amplitude, approximated spectral slope, approximated spectral intercept, mean instantaneous frequency, mean instantaneous bandwidth, and parameters of Nakagami distribution characterizing Hilbert-Huang transformation output. The backscattered ultrasound signal parameters characterizing intraocular and orbit tissues were processed by decision tree data mining algorithm. The pilot trial proved that applied methods are able to correctly classify signals from corpus vitreum blood, extraocular muscle, and orbit tissues. In 26 cases of ocular tissues classification, one error occurred, when tissues were classified into classes of corpus vitreum blood, extraocular muscle, and orbit tissue. In this pilot classification parameters of spectral intercept and Nakagami parameter for instantaneous frequencies distribution of the 1st intrinsic mode function were found specific for corpus vitreum blood, orbit and extraocular muscle tissues. We conclude that ultrasound data should be further collected in clinical database to establish background for decision support system for ocular tissue noninvasive differentiation. PMID:22654643

Jurkonis, R; Janušauskas, A; Marozas, V; Jegelevi?ius, D; Daukantas, S; Patašius, M; Paunksnis, A; Lukoševi?ius, A

2012-01-01

80

Shearwave dispersion ultrasound vibrometry (SDUV) for measuring tissue elasticity and viscosity.  

PubMed

Characterization of tissue elasticity (stiffness) and viscosity has important medical applications because these properties are closely related to pathological changes. Quantitative measurement is more suitable than qualitative measurement (i.e., mapping with a relative scale) of tissue viscoelasticity for diagnosis of diffuse diseases where abnormality is not confined to a local region and there is no normal background tissue to provide contrast. Shearwave dispersion ultrasound vibrometry (SDUV) uses shear wave propagation speed measured in tissue at multiple frequencies (typically in the range of hundreds of Hertz) to solve quantitatively for both tissue elasticity and viscosity. A shear wave is stimulated within the tissue by an ultrasound push beam and monitored by a separate ultrasound detect beam. The phase difference of the shear wave between 2 locations along its propagation path is used to calculate shear wave speed within the tissue. In vitro SDUV measurements along and across bovine striated muscle fibers show results of tissue elasticity and viscosity close to literature values. An intermittent pulse sequence is developed to allow one array transducer for both push and detect function. Feasibility of this pulse sequence is demonstrated by in vivo SDUV measurements in swine liver using a dual transducer prototype simulating the operation of a single array transducer. PMID:19213632

Chen, Shigao; Urban, Matthew W; Pislaru, Cristina; Kinnick, Randall; Zheng, Yi; Yao, Aiping; Greenleaf, James F

2009-01-01

81

Shearwave Dispersion Ultrasound Vibrometry (SDUV) for Measuring Tissue Elasticity and Viscosity  

PubMed Central

Characterization of tissue elasticity (stiffness) and viscosity has important medical applications because these properties are closely related to pathological changes. Quantitative measurement is more suitable than qualitative measurement (i.e., mapping with a relative scale) of tissue viscoelasticity for diagnosis of diffuse diseases where abnormality is not confined to a local region and there is no normal background tissue to provide contrast. Shearwave dispersion ultrasound vibrometry (SDUV) uses shear wave propagation speed measured in tissue at multiple frequencies (typically in the range of hundreds of Hertz) to solve quantitatively for both tissue elasticity and viscosity. A shear wave is stimulated within the tissue by an ultrasound push beam and monitored by a separate ultrasound detect beam. The phase difference of the shear wave between 2 locations along its propagation path is used to calculate shear wave speed within the tissue. In vitro SDUV measurements along and across bovine striated muscle fibers show results of tissue elasticity and viscosity close to literature values. An intermittent pulse sequence is developed to allow one array transducer for both push and detect function. Feasibility of this pulse sequence is demonstrated by in vivo SDUV measurements in swine liver using a dual transducer prototype simulating the operation of a single array transducer.

Chen, Shigao; Urban, Matthew W.; Pislaru, Cristina; Kinnick, Randall; Zheng, Yi; Yao, Aiping; Greenleaf, James F.

2009-01-01

82

Ultrasound-enhanced tissue plasminogen activator thrombolysis in an in vitro porcine clot model  

PubMed Central

Introduction Thrombolytics such as recombinant tissue plasminogen activator (rt-PA) have advanced the treatment of ischemic stroke, myocardial infarction, deep vein thrombosis and pulmonary embolism. Objective To improve the efficacy of this thrombolytic therapy, the synergistic effect of rt-PA and 120 kHz or 1.0 MHz ultrasound was assessed in vitro using a porcine clot model. Materials and methods Fully retracted whole blood clots prepared from fresh porcine blood were employed to compare rt-PA thrombolytic treatment with and without exposure to 120-kHz or 1-MHz ultrasound. For sham studies (without ultrasound), clot mass loss was measured as a function of rt-PA concentration from 0.003 to 0.107 mg/ml. For combined ultrasound and rt-PA treatments, peak-to-peak pressure amplitudes of 0.35, 0.70 or 1.0 MPa were employed. The range of duty cycles varied from 10% to 100% (continuous wave) and the pulse repetition frequency was fixed at 1.7 KHz. Results For rt-PA alone, the mass loss increased monotonically as a function of rt-PA concentration up to approximately 0.050 mg/ml. With ultrasound and rt-PA exposure, clot mass loss increased by as much as 104% over rt-PA alone. Ultrasound without the presence of rt-PA did not significantly enhance thrombolysis compared to control treatment. The ultrasound-mediated clot mass loss enhancement increased with the square root of the overall treatment duration. Conclusions Both 120-kHz and 1-MHz pulsed and CW ultrasound enhanced rt-PA thrombolysis in a porcine whole blood clot model in vitro. No clear dependence of the observed thrombolytic enhancement on ultrasound duty cycle was evident. The lack of duty cycle dependence suggests a more complex mechanism that could not be sustained by merely increasing the pulse duration.

Holland, Christy K.; Vaidya, Sampada S.; Datta, Saurabh; Coussios, Constantin-C.; Shaw, George J.

2007-01-01

83

Estimation of Ultrasound Attenuation and its Application to Tissue Heterogeneity Study Using Nonlinear Least Square Data Fitting  

Microsoft Academic Search

The aim of this paper is to provide a local attenuation method with applications to tissue heterogeneity estimation based on the peaks of ultrasound echo envelop data. To handle the frequency shift in the broadband ultrasound system, we use nonlinear least squares (NLS) data fitting directly to the local amplitude changes due to the tissue attenuation. By looking at the

Xiaoying Li; Dong C. Liu

2009-01-01

84

8C-2 Error Estimates in Shear Wave Speed and Tissue Material Properties in Shear Wave Dispersion Ultrasound Vibrometry  

Microsoft Academic Search

Shear wave speed measurements are used in elasticity imaging to find the shear elasticity and viscosity of tissue. A technique called shear wave dispersion ultrasound vibrometry (SDUV) has been introduced to use the dispersive nature of shear wave speed to locally estimate the material properties of tissue. Shear waves are created using a multifrequency ultrasound radiation force, and the propagating

Matthew W. Urban; Shigao Chen; James F. Greenleaf

2007-01-01

85

Ultrasound and Doppler US in Evaluation of Superficial Soft-tissue Lesions  

PubMed Central

Improved developments in digital ultrasound technology and the use of high-frequency broadband transducers make ultrasound (US) imaging the first screening tool in investigating superficial tissue lesions. US is a safe (no ionizing radiation), portable, easily repeatable, and cheap form of imaging compared to other imaging modalities. US is an excellent imaging modality to determine the nature of a mass lesion (cystic or solid) and its anatomic relation to adjoining structures. Masses can be characterized in terms of their size, number, component, and vascularity with US and Doppler US especially with power Doppler US. US, however, is operator dependent and has a number of artifacts that can result in misinterpretation. In this review, we emphasize the role of ultrasound, particularly power Doppler, in superficial soft-tissue lesions.

Toprak, Huseyin; Kilic, Erkan; Serter, Asli; Kocakoc, Ercan; Ozgocmen, Salih

2014-01-01

86

High-Resolution Ultrasound and Magnetic Resonance Imaging to Document Tissue Repair After Prolotherapy: A Report of 3 Cases  

Microsoft Academic Search

Fullerton BD. High-resolution ultrasound and magnetic resonance imaging to document tissue repair after prolotherapy: a report of 3 cases.High-resolution ultrasound imaging of musculoskeletal tissue is increasing in popularity because of patient tolerability, low cost, ability to visualize tissue in real-time motion, and superior resolution of highly organized tissue such as a tendon. Prolotherapy, defined as the injection of growth factors

Bradley D. Fullerton

2008-01-01

87

A review on ultrasound-based thyroid cancer tissue characterization and automated classification.  

PubMed

In this paper, we review the different studies that developed Computer Aided Diagnostic (CAD) for automated classification of thyroid cancer into benign and malignant types. Specifically, we discuss the different types of features that are used to study and analyze the differences between benign and malignant thyroid nodules. These features can be broadly categorized into (a) the sonographic features from the ultrasound images, and (b) the non-clinical features extracted from the ultrasound images using statistical and data mining techniques. We also present a brief description of the commonly used classifiers in ultrasound based CAD systems. We then review the studies that used features based on the ultrasound images for thyroid nodule classification and highlight the limitations of such studies. We also discuss and review the techniques used in studies that used the non-clinical features for thyroid nodule classification and report the classification accuracies obtained in these studies. PMID:24206204

Acharya, U R; Swapna, G; Sree, S V; Molinari, F; Gupta, S; Bardales, R H; Witkowska, A; Suri, J S

2014-08-01

88

Combined chirp coded tissue harmonic and fundamental ultrasound imaging for intravascular ultrasound: 20-60 MHz phantom and ex vivo results.  

PubMed

The application of chirp coded excitation to pulse inversion tissue harmonic imaging can increase signal to noise ratio. On the other hand, the elevation of range side lobe level, caused by leakages of the fundamental signal, has been problematic in mechanical scanners which are still the most prevalent in high frequency intravascular ultrasound imaging. Fundamental chirp coded excitation imaging can achieve range side lobe levels lower than -60dB with Hanning window, but it yields higher side lobes level than pulse inversion chirp coded tissue harmonic imaging (PI-CTHI). Therefore, in this paper a combined pulse inversion chirp coded tissue harmonic and fundamental imaging mode (CPI-CTHI) is proposed to retain the advantages of both chirp coded harmonic and fundamental imaging modes by demonstrating 20-60MHz phantom and ex vivo results. A simulation study shows that the range side lobe level of CPI-CTHI is 16dB lower than PI-CTHI, assuming that the transducer translates incident positions by 50?m when two beamlines of pulse inversion pair are acquired. CPI-CTHI is implemented for a proto-typed intravascular ultrasound scanner capable of combined data acquisition in real-time. A wire phantom study shows that CPI-CTHI has a 12dB lower range side lobe level and a 7dB higher echo signal to noise ratio than PI-CTHI, while the lateral resolution and side lobe level are 50?m finer and -3dB less than fundamental chirp coded excitation imaging respectively. Ex vivo scanning of a rabbit trachea demonstrates that CPI-CTHI is capable of visualizing blood vessels as small as 200?m in diameter with 6dB better tissue contrast than either PI-CTHI or fundamental chirp coded excitation imaging. These results clearly indicate that CPI-CTHI may enhance tissue contrast with less range side lobe level than PI-CTHI. PMID:22871273

Park, Jinhyoung; Li, Xiang; Zhou, Qifa; Shung, K Kirk

2013-02-01

89

Realization of a poro-elastic ultrasound replica of pulmonary tissue.  

PubMed

In this work we describe the fabrication of a biocompatible hydrophilic scaffold composed of cross-linked gelatin that mimics the porous three-dimensional structure of pulmonary tissue as well as its water content and mechanical properties. The lung replica also reproduces the characteristic sonographic signs of pulmonary interstitial syndrome, the B-lines or ultrasound lung comets. PMID:23507784

Spinelli, Andrea; Vinci, Bruna; Tirella, Annalisa; Matteucci, Marco; Gargani, Luna; Ahluwalia, Arti; Domenici, Claudio; Picano, Eugenio; Chiarelli, Piero

2012-01-01

90

Dynamic morphometric characterization of local connective tissue network structure in humans using ultrasound  

Microsoft Academic Search

BACKGROUND: In humans, connective tissue forms a complex, interconnected network throughout the body that may have mechanosensory, regulatory and signaling functions. Understanding these potentially important phenomena requires non-invasive measurements of collagen network structure that can be performed in live animals or humans. The goal of this study was to show that ultrasound can be used to quantify dynamic changes in

Helene M Langevin; Donna M Rizzo; James R Fox; Gary J Badger; Junru Wu; Elisa E Konofagou; Debbie Stevens-Tuttle; Nicole A Bouffard; Martin H Krag

2007-01-01

91

Estimating cell concentration in three-dimensional engineered tissues using high frequency quantitative ultrasound.  

PubMed

Histology and biochemical assays are standard techniques for estimating cell concentration in engineered tissues. However, these techniques are destructive and cannot be used for longitudinal monitoring of engineered tissues during fabrication processes. The goal of this study was to develop high-frequency quantitative ultrasound techniques to nondestructively estimate cell concentration in three-dimensional (3-D) engineered tissue constructs. High-frequency ultrasound backscatter measurements were obtained from cell-embedded, 3-D agarose hydrogels. Two broadband single-element transducers (center frequencies of 30 and 38 MHz) were employed over the frequency range of 13-47 MHz. Agarose gels with cell concentrations ranging from 1 × 10(4) to 1 × 10(6) cells mL(-1) were investigated. The integrated backscatter coefficient (IBC), a quantitative ultrasound spectral parameter, was calculated and used to estimate cell concentration. Accuracy and precision of this technique were analyzed by calculating the percent error and coefficient of variation of cell concentration estimates. The IBC increased linearly with increasing cell concentration. Axial and lateral dimensions of regions of interest that resulted in errors of less than 20% were determined. Images of cell concentration estimates were employed to visualize quantitatively regional differences in cell concentrations. This ultrasound technique provides the capability to rapidly quantify cell concentration within 3-D tissue constructs noninvasively and nondestructively. PMID:24627179

Mercado, Karla P; Helguera, María; Hocking, Denise C; Dalecki, Diane

2014-06-01

92

Left Ventricular Myocardial Impairment in Subclinical Hypothyroidism Assessed by a New Ultrasound Tool: Pulsed Tissue Doppler  

Microsoft Academic Search

Pulsed tissue Doppler (TD) is a new ultrasound tool that al- lows quantification of myocardial regional wall motion. To investigate the cardiac effects of subclinical hypothyroidism (SH), the present study assessed left ventricular (LV) myocar- dial regional function in SH by pulsed TD. Twenty women with SH and 20 healthy women underwent standard Doppler echocardiograms and pulsed TD, placing a

GIOVANNI VITALE; MAURIZIO GALDERISI; GELSY ARIANNA LUPOLI; ALDO CELENTANO; ILARIA PIETROPAOLO; NICOLA PARENTI; ORESTE DE DIVITIIS; GIOVANNI LUPOLI

93

A theoretical and experimental investigation of nonlinear ultrasound propagation through tissue mimicking fluids  

Microsoft Academic Search

A numerical model is used to investigate finite amplitude ultrasound propagation through multiple layers of tissue-like media. This model uses a finite difference method to solve the nonlinear parabolic KZK wave equation. The code is modified to include an arbitrary frequency dependence of absorption and transmission effects for wave propagation across a plane interface at normal incidence. Measurements are taken

Matthew Rielly; Victor Humphrey; Francis Duck

2000-01-01

94

Frequency-swept ultrasound-modulated optical tomography in biological tissue by use of parallel detection  

Microsoft Academic Search

A frequency-swept ultrasonic beam was focused into a biological tissue sample to modulate the laser light passing through the ultrasonic beam inside the tissue. Parallel detection of the speckle field formed by the transmitted laser light was implemented with the source-synchronous-illumination lock-in technique to improve the signal-to-noise ratio. The ultrasound-modulated laser light ref lects the local optical and mechanical properties

Gang Yao; Shuliang Jiao; Lihong V. Wang

2000-01-01

95

Study of ultrasound-modulated optical tomography in biological tissue with parallel detection  

Microsoft Academic Search

An ultrasonic beam was focused into a biological tissue sample to modulate the laser light passing through the ultrasonic beam inside the tissue. The speckle field formed by the transmitted laser light was detected by a CCD camera with the source-synchronous-illumination lock-in technique. The ultrasound-modulated laser light reflects the local optical and mechanical properties within the ultrasonic beam and can

Gang Yao; Lihong V. Wang

2000-01-01

96

Ultrasound and photoacoustic imaging to monitor vascular growth in tissue engineered constructs  

NASA Astrophysics Data System (ADS)

Quantitative and qualitative monitoring of neovascular growth is required in many vascular tissue engineering applications. For example, the contribution of progenitor cells in growing microvasculature has been demonstrated; however, the process of vascularization from progenitor cells is not well understood. Therefore, there is a need for an imaging technique that is consistent, easy to use, and can quantitatively assess the dynamics of vascular growth or regression in a three-dimensional environment. In this study, we evaluate the ability of combined ultrasound and photoacoustic imaging to assess the dynamics of vascular growth. The experiments were performed using hydrogels that spontaneously promote tube formation from implanted mesenchymal stem cells (MSCs). Specifically, PEGylated fibrin gels, supporting the development of capillary growth were implanted in a Lewis rat. After one week, the rat was euthanized and the gel implants were excised and positioned in water cuvettes for imaging. Simultaneous ultrasound and photoacoustic images were obtained using single-element, focused ultrasound transducers interfaced with a nanosecond pulsed laser source. To image samples, ultrasound transducers operating at either 25 MHz or 48 MHz and interfaced with laser sources operating at either 532 nm or within 680-800 nm wavelengths were used. The 3-D ultrasound and photoacoustic images were acquired by mechanically scanning the transducer over the region of interest and capturing spatially co-registered and temporally consecutive photoacoustic transients and ultrasound pulse-echo signals. The ultrasound and photoacoustic images agree well with the overall anatomy and vascular structure in the gel samples. The results suggest that the photoacoustic and ultrasound imaging could be used to sequentially monitor the growth of neovasculature in-vivo.

Nam, Seung Yun; Mallidi, Srivalleesha; Zhang, Ge; Suggs, Laura J.; Emelianov, Stanislav

2009-02-01

97

Can pulsed ultrasound increase tissue damage during ischemia? A study of the effects of ultrasound on infarcted and non-infarcted myocardium in anesthetized pigs  

PubMed Central

Background The same mechanisms by which ultrasound enhances thrombolysis are described in connection with non-beneficial effects of ultrasound. The present safety study was therefore designed to explore effects of beneficial ultrasound characteristics on the infarcted and non-infarcted myocardium. Methods In an open chest porcine model (n = 17), myocardial infarction was induced by ligating a coronary diagonal branch. Pulsed ultrasound of frequency 1 MHz and intensity 0.1 W/cm2 (ISATA) was applied during one hour to both infarcted and non-infarcted myocardial tissue. These ultrasound characteristics are similar to those used in studies of ultrasound enhanced thrombolysis. Using blinded assessment technique, myocardial damage was rated according to histopathological criteria. Results Infarcted myocardium exhibited a significant increase in damage score compared to non-infarcted myocardium: 6.2 ± 2.0 vs. 4.3 ± 1.5 (mean ± standard deviation), (p = 0.004). In the infarcted myocardium, ultrasound exposure yielded a further significant increase of damage scores: 8.1 ± 1.7 vs. 6.2 ± 2.0 (p = 0.027). Conclusion Our results suggest an instantaneous additive effect on the ischemic damage in myocardial tissue when exposed to ultrasound of stated characteristics. The ultimate damage degree remains to be clarified.

Olivecrona, Goran K; Hardig, Bjarne Madsen; Roijer, Anders; Block, Mattias; Grins, Edgars; Persson, Hans W; Johansson, Leif; Olsson, Bertil

2005-01-01

98

Measurement of Mechanical Properties of Soft Tissue with Ultrasound Vibrometry  

Microsoft Academic Search

\\u000a The cardiovascular diseases atherosclerosis, coronary artery disease, hypertension and heart failure have been related to\\u000a stiffening of vessels and myocardium. Noninvasive measurements of mechanical properties of cardiovascular tissue would facilitate\\u000a detection and treatment of disease in early stages, thus reducing mortality and possibly reducing cost of treatment. While\\u000a techniques capable of measuring tissue elasticity have been reported, the knowledge of

I. Nenadich; M. Bernal; J. F. Greenleaf

99

Ultrasound measurements of brain tissue pulsatility correlate with the volume of MRI white-matter hyperintensity.  

PubMed

White-matter hyperintensity (WMH) is frequently seen in magnetic resonance imaging (MRI), but the complete physiopathology of WMH remains to be elucidated. In this study, we sought to determine whether there is an association between the maximum brain tissue displacement (maxBTD), as assessed by ultrasound, and the WMH, as observed by MRI. Nine healthy women aged 60 to 85 years underwent ultrasound and MRI assessments. We found a significant negative correlation between maxBTD and WMH (?=-0.86, P<0.001), suggesting a link between cerebral hypoperfusion and WMH. PMID:24714033

Ternifi, Redouane; Cazals, Xavier; Desmidt, Thomas; Andersson, Frédéric; Camus, Vincent; Cottier, Jean-Philippe; Patat, Frédéric; Remenieras, Jean-Pierre

2014-06-01

100

Localized Ablation of Thyroid Tissue by High-Intensity Focused Ultrasound: an Alternative to Surgery?  

NASA Astrophysics Data System (ADS)

PURPOSE: The aim of this study was to evaluate the feasibility of using a High-intensity focused ultrasound (HIFU) device to obtain a localised destruction of the thyroid with no damage to adjacent tissues. MATERIALS AND METHODS: The ewe model was used because its thyroid gland is easily accessible with ultrasound. The animals were anaesthetised with 10 mg / kg IV injection of Penthothal. The HIFU pulses were generated by a 3-MHz spherical transducer under ultrasound guidance. Macroscopic and microscopic tissue lesions were identified after formalin fixation of the anterior part of the ewe's neck. RESULTS: After determining the optimal instrument settings to obtain localized thyroid ablation, the repeatability of the method was evaluated using a HIFU prototype designed specifically for human use: in 13 ewes (26 treated lobes), an average of 20 (range: 14-27) ultrasound pulses (pulse duration: 3 s) per lobe covering a mean volume of 0.5 cm3 (range: 0.3-0.7 cm3) were delivered. The ewes were sacrificed 2-5 weeks after treatment delivery. No damage to the nerves, trachea, esophagus or muscle was observed. Only 3 ewes suffered superficial skin burns. The desired thyroid lesions were obtained in 25/26 treated lobes, as demonstrated by fibrotic tissues, which replaced necrotic areas. CONCLUSION: These results obtained in the ewe model show that thyroid lesions of defined volume can be induced safely and suggest that the HIFU device is now ready for human trials.

Esnault, Olivier; Franc, Brigitte; Chapelon, Jean-Yves; Lacoste, Francois

2006-05-01

101

Mathematical modeling of ultrasound in tissue engineering: From bioreactors to the cellular scale  

NASA Astrophysics Data System (ADS)

Tissue engineering seeks to provide a means to treat injuries that are beyond the body's natural ability to repair without the issues associated with allografts. Autologous cells are cultured in a bioreactor which controls the cellular environment (including mechanical stimulation) for optimal tissue growth. We investigate ultrasound as an effective means of mechanical stimulation by predicting the ultrasonic field in a bioreactor, as well as ultrasonic bioeffects at the cellular level. The Transfer Matrix Angular Spectrum Approach was found to be the most accurate and computationally efficient bioreactor model. Three critical factors influence experimental results: (1) the diameter of the tissue engineering scaffold greatly affects the ultrasonic field; (2) the position of the ultrasonic transducer and liquid level in the tissue culture well determines the maximum pressure amplitude in the bioreactor, but the pressure can be controlled by measuring the transducer input electrical impedance and manipulating the applied voltage; and (3) the position of pressure nodes are influenced by ultrasonic frequency and liquid level; this will affect the response of cells to applied ultrasound. On the cellular level, it was shown that chondrocytes respond to ultrasound with frequency dependence. A predicted resonance frequency near 5MHz matched experimental results showing maximum expression of load inducible genes at 5MHz. Mechanical stresses are concentrated near the nucleus at resonance, alluding to the possibility that the nucleus may directly sense ultrasonic stimulation. We postulate that ultrasound influences the transport of p-ERK to the nucleus or causes minor chromatin reorganization, leading to the observed frequency dependent gene expression. We linked in vitro ultrasonic stimulation to in vivo mechanical stimulation generated by natural movement. The chondrocyte's response to impact is under-damped, and the cell oscillates with a frequency close to the model predicted resonance. It appears that ultrasound applied close to the cell's resonant frequency effectively recreates the mechanical stimulation experienced by cells during natural movement. Ultrasonic bioreactors may therefore reproduce physiological conditions just as well as more complex bioreactors.

Louw, Tobias M.

102

Ultrasound Transient Shear Wave Elasticity Imaging for Tendon Tissue  

Microsoft Academic Search

Degeneration of tendon tissue is a common cause of tendon dysfunction with the symptoms of repeated episodes of pain and palpable increase of tendon thickness. Tendon mechanical properties are directly related to its physiological composition and the structural organization of the interior collagen fibers which could be altered by tendon degeneration due to overuse or injury. Thus, measuring mechanical properties

Pengfei Song

2010-01-01

103

Higher order nonlinear ultrasound propagation in tissue-simulation study  

Microsoft Academic Search

Nonlinear wave propagation in tissue has been simulated using typical propagation parameters for liver. The results indicate that the amplitude level of higher order harmonics can exceed the level of the second harmonic component. In that case detection of the higher order components can be achieved with increased signal to noise ratio due to the fact that the amplitude of

Bruno Haider; Kajoli Krishnan; Kai Thomenius

2002-01-01

104

Elastography: Imaging the elastic properties of soft tissues with ultrasound  

Microsoft Academic Search

Elastography is a method that can ultimately generate several new kinds of images, called elastograms. As such, all the properties\\u000a of elastograms are different from the familiar properties of sonograms. While sonograms convey information related to the\\u000a local acoustic backscatter energy from tissue components, elastograms relate to its local strains, Young's moduli or Poisson's\\u000a ratios. In general, these elasticity parameters

Jonathan Ophir; S. Kaisar Alam; Brian S. Garra; Faouzi Kallel; Elisa E. Konofagou; Thomas Krouskop; Christopher R. B. Merritt; Raffaella Righetti; Remi Souchon; Seshadri Srinivasan; Tomy Varghese

2002-01-01

105

Pulsed cavitational ultrasound therapy for controlled tissue homogenization  

Microsoft Academic Search

Methods were investigated to acoustically control the extent to which cavitation-mediated tissue homogenization is responsible for lesion formation in vitro. These results may guide potential therapeutic procedures that induce damage predominantly via mechanical disruption and, thereby, avoid limitations associated with thermal ablative modalities. Porcine myocardium was insonified at 750 kHz using pulse sequences consisting of high-amplitude pulses (22 MPa Pr)

Jessica E. Parsons; Charles A. Cain; Gerald D. Abrams; J. Brian Fowlkes

2006-01-01

106

Noninvasive surgery of prostate tissue by high-intensity focused ultrasound: an updated report  

NASA Astrophysics Data System (ADS)

High Intensity Focused Ultrasound (HIFU) has been clinically used for the treatment of benign prostatic hyperplasia (BPH) and it is experimentally applied for the treatment of localized prostate caner (PC). Recent advances in the transducer material and technology have permitted to combine the ultrasound visualization capability and HIFU on the same ceramic crystal. Also, the transducer efficiency has increased to a level that a smaller size intracavity probe can be made to produce sufficient acoustic power required for the focused ultrasound surgery of the prostate. Using this technology, 4 MHz mechanically scanning transrectal ultrasound probes has been designed. The transrectal probes are used with Sonablate (SB-200, manufactured by Focus Surgery, Inc., Indianapolis, IN) device. The SB-200 produces both transverse and longitudinal images of the prostate. The transverse and longitudinal images are used for selection of tissue volume, treatment planning and monitoring of tissue during the HIFU treatment cycle. The paper reviews the present operation of the device and recent clinical protocol that has improved efficiency, efficacy and safety of the device. The two years follow-up clinical results from the multi-site US Pilot Study (USPS) and The Male Health Centre are compared with the Kitasato-study (Kitasato School of Medicine, Sagamihara, Japan).

Sanghvi, Narendra T.; Syrus, J.; Foster, Richard S.; Bihrle, Richard; Casey, Richard W.; Uchida, Toyoak

2000-05-01

107

Limited damage of tissue mimic caused by a collapsing bubble under low-frequency ultrasound exposure.  

PubMed

In this study, we investigated the bubble induced serious damage to tissue mimic exposed to 27-kHz ultrasound. The initial bubble radius ranged from 80 to 100?m, which corresponded approximately to the experimentally-evaluated resonant radius of the given ultrasound frequency. The tissue mimic consisted of 10wt% gelatine gel covered with cultured canine kidney epithelial cells. The collapsing bubble behaviour during the ultrasound exposure with negative peak pressures of several hundred kPa was captured by a high-speed camera system. After ultrasound exposure, a cell viability test was conducted based on microscopic bright-field images and fluorescence images for living and dead cells. In the viability test, cells played a role in indicating the damaged area. The bubble oscillations killed the cells, and on occasion detached layers of cultured cells from the gel. The damaged area was comparable or slightly larger than the initial bubble size, and smaller than the maximum bubble size. We concluded that only a small area in close proximity to the bubble could be damaged even above transient cavitation threshold. PMID:24751130

Yoshida, Kenji; Obata, Kazuya; Tsukamoto, Akira; Ushida, Takashi; Watanabe, Yoshiaki

2014-08-01

108

Ultrasound Assessment of ex Vivo Lung Tissue Properties Using a Fluid-Filled Negative Pressure Bath.  

PubMed

A relationship between tendon stress and strain and ultrasonic echo intensity has previously been defined in tendons, demonstrating a correlation between tissue stiffness and echo intensity. An analogous relationship between volume-dependent pressure changes and echo intensity changes in inflating lungs would indicate a correlation between lung compliance and echo intensity. Lung compliance is an important metric to diagnose pathologies which affect lung tissue mechanics, such as emphysema and cystic fibrosis. The goal of this study is to demonstrate a correlation between ultrasound echo intensity and lung tissue mechanics in an ex vivo model using a fluid-filled negative pressure bath design which provides a controlled environment for ultrasonic and mechanical measurements. Lungs from 4 male Sprague-Dawley rats were removed and mechanically tested via inflation and deflation in a negative pressure chamber filled with hetastarch. Specific volumes (1, 2, 3, and 4?mL) were removed from the chamber using a syringe to create negative pressure, which resulted in lung inflation. A pressure transducer recorded the pressure around the lungs. From these data, lung compliance was calculated. Ultrasound images were captured through the chamber wall to determine echo intensity (grayscale brightness in the ultrasound image), which was then related to mechanical parameters. Ultrasound images of the lung were successfully captured through the chamber wall with sufficient resolution to deduce echo intensity changes in the lung tissue. Echo intensity (0-255 scale) increased with volumetric changes (18.4?±?5.5, 22.6?±?5.1, 26.1?±?7.5, and 42.9?±?19.5 for volumetric changes of 1, 2, 3, and 4?mL) in a pattern similar to pressure (-6.8?±?1.7, -6.8?±?1.4, -9.4?±?0.7, and -16.9?±?6.8?cm H2O for 1, 2, 3, and 4?mL), reflecting changes in lung compliance. Measured rat lung tissue compliance was comparable to reported values from ex vivo lungs (0.178?±?0.067, 0.378?±?0.051, 0.427?±?0.062, and 0.350?±?0.160?mL/cm H20 for 1, 2, 3, and 4?mL), supporting proof of concept for the experimental method. Changes in echo intensity reflected changes in lung compliance in this ex vivo model, thus, supporting our hypothesis that the stiffness-related changes in echo intensity originally seen in tendon can be similarly detected in lung tissue. The presented ultrasound-based methods allowed measurement of local lung tissue compliance in a controlled environment, however, the methods could be expanded to facilitate both ex vivo and in vivo studies. PMID:24805068

Duenwald-Kuehl, Sarah; Bates, Melissa L; Cortes, Sonia Y; Eldridge, Marlowe W; Vanderby, Ray

2014-07-01

109

Correlation of Fetal Abdominal Subcutaneous Tissue Thickness by Ultrasound to Predict Birth Weight  

PubMed Central

Introduction: Fetal growth abnormality is associated with changes in the soft tissue mass, which is decreased in growth restricted fetuses and increased in macrosomia. Objective: To correlate fetal abdominal subcutaneous tissue thickness (FASTT) measured by ultrasound at term and birth weight and to obtain a cut-off value of FASTT to predict large and small for gestational age babies in our population. Methods: FASTT was measured at the anterior 1/3rd of abdominal circumference by ultrasound after 36 weeks and weight of the baby measured after birth. Results:There was positive correlation between FASTT and birth weight. FASTT of 6.25 mm was sensitive to predict large for gestational age (LGA) babies and had a high negative predictive value; FASTT measurement for prediction of small babies with birth weight < 2500 g was not sensitive. Conclusion: FASTT can be used as an additional indicator to predict large for gestational age babies along with other known birth weight indicators.

Nathan, Anitha; R, Amar; Vasudeva, Akhila; Adiga, Prashanth; Bhat, Parvati V; Kumar N, Pratap

2014-01-01

110

Ultrasound-based transient elastography compared to magnetic resonance elastography in soft tissue-mimicking gels  

NASA Astrophysics Data System (ADS)

Ultrasound-based transient elastography (TE) and magnetic resonance elastography (MRE) are increasingly used methods for the clinical evaluation of soft tissue mechanical properties and their alteration under diseased conditions. This study proposes a comparison between magnetic resonance elastography (MRE) and ultrasound-based transient elastography (TE). Both methods were tested on the same soft tissue-mimicking gels in a common frequency range in order to allow for direct quantitative comparison. For the four gels tested, relatively good agreement was found between the shear moduli measured by both methods, with an averaged relative difference of 23%. This study demonstrates that under the assumption of homogeneous media that are significantly more elastic than viscous, quantitative results obtained by both methods are comparable.

Oudry, Jennifer; Vappou, Jonathan; Choquet, Philippe; Willinger, Rémy; Sandrin, Laurent; Constantinesco, André

2009-11-01

111

Novel tissue mimicking materials for high frequency breast ultrasound phantoms.  

PubMed

The development and acoustical characterisation of a range of novel agar-based tissue mimicking material (TMMs) for use in clinically relevant, quality assurance (QA) and anthropomorphic breast phantoms are presented. The novel agar-based TMMs described in this study are based on a comprehensive, systematic variation of the ingredients in the International Electrotechnical Commission (IEC) TMM. A novel, solid fat-mimicking material was also developed and acoustically characterised. Acoustical characterisation was carried out using an in-house scanning acoustic macroscope at low (7.5 MHz) and high frequencies (20 MHz), using the pulse-echo insertion technique. The speeds of sound range from 1490 to 1570 m. s(-1), attenuation coefficients range from 0.1 to 0.9 dB. cm(?1). MHz(-1) and relative backscatter ranges from 0 to -20 dB. It was determined that tissues can be mimicked in terms of independently controllable speeds of sound and attenuation coefficients. These properties make these novel TMMs suitable for use in clinically relevant QA and anthropomorphic phantoms and would potentially be useful for other high frequency applications such as intravascular and small animal imaging. PMID:21084158

Cannon, Louise M; Fagan, Andrew J; Browne, Jacinta E

2011-01-01

112

Cavitation Detection in Ex Vivo Bovine Liver Tissue Exposed to High Intensity Focued Ultrasound (HIFU)  

Microsoft Academic Search

A study of the feasibility of detecting broadband high frequency emissions (6-12 MHz) generated by acoustic cavitation activity during clinical high intensity focused ultrasound (HIFU) exposures are presented. The ability to monitor acoustic emissions, drive power fluctuations and audible (1-20 kHz) emissions is demonstrated in ex vivo tissue, and the utility of active cavitation detection (ACD) is shown. It is

James Mclaughlan; Ian Rivens; Gail Ter Haar

2007-01-01

113

Numerical characterization of quasi-static ultrasound elastography for the detection of deep tissue injuries.  

PubMed

Deep tissue injuries are subcutaneous regions of tissue breakdown associated with excessive mechanical pressure for extended period of time. These wounds are currently clinically undetectable in their early stages and result in severe burdens on not only the patients who suffer from them, but the health care system as well. The goal of this work was to numerically characterize the use of quasi-static ultrasound elastography for detecting formative and progressive deep tissue injuries. In order to numerically characterize the technique, finite-element models of sonographic B-mode imaging and tissue deformation were created. These models were fed into a local strain-estimation algorithm to determine the detection sensitivity of the technique on various parameters. Our work showed that quasi-static ultrasound elastography was able to detect and characterize deep tissue injuries over a range of lesion parameters. Simulations were validated using a physical phantom model. This work represents a step along the path to developing a clinically relevant technique for detecting and diagnosing early deep tissue injuries. PMID:24691120

Hamaluik, Kenton; Moussa, Walied; Ferguson-Pell, Martin

2014-07-01

114

Ultrasound.  

National Technical Information Service (NTIS)

This report deals with the technical issues in ultrasound, both for combat and civilian care, which are most likely to benefit from support from an agency like DARPA which is responsive to long-horizon problems requiring innovative technology. This report...

J. Cornwall H. Abarbanel W. Dally S. Flatte R. Westervelt

1996-01-01

115

EGFP gene transfection into the synovial joint tissues of rats with rheumatoid arthritis by ultrasound-mediated microbubble destruction  

PubMed Central

The aim of the present study was to explore the feasibility of enhancing green fluorescent protein (EGFP) gene transfection into the synovial joint tissues of rats with rheumatoid arthritis (RA) by ultrasound-mediated microbubble destruction. An optimal SonoVue dose was determined using 40 normal rats categorized into five groups according to the various doses of microbubbles used. At 1 week after ultrasound irradiation, the rats were sacrificed. Damage to the joint synovial tissues was observed with hematoxylin and eosin histopathological staining under a microscope. A further 44 normal rats were used to establish a rat model of RA, and were then categorized into four groups: EGFP, ultrasound + EGFP, microbubbles + EGFP and ultrasound + microbubbles + EGFP. The last group was irradiated with ultrasound for 10 min following the injection of 300 ?l SonoVue and 10 ?g EGFP into the joint cavity. Rats were sacrificed after 3 days and synovial tissue was collected from the knee joints for observation of EGFP with fluorescence microscopy and analysis by quantitative polymerase chain reaction. EGFP expression was observed in the synovial tissues of all groups. However, high EGFP expression levels were observed in the ultrasound + microbubbles + EGFP group. No statistically significant differences (P>0.05) were observed in the EGFP expression levels between the EGFP, ultrasound + EGFP and microbubbles + EGFP groups. However, EGFP expression levels in the EGFP, ultrasound + EGFP and microbubbles + EGFP groups significantly differed (P<0.05) from that in the ultrasound + microbubbles + EGFP group. Therefore, ultrasound-mediated microbubble destruction improved EGFP transfection efficiency into the joint synovial tissues of rats with RA.

JING, XIANG-XIANG; LIU, JIE; YANG, BING-ANG; FU, SHAO-QING; WU, TANG-NA; WANG, DONG-LIN

2014-01-01

116

A tissue mimicking polyacrylamide hydrogel phantom for visualizing thermal lesions generated by high intensity focused ultrasound.  

PubMed

An optically transparent tissue-mimicking (TM) phantom whose acoustic properties are close to those of tissue was constructed for visualizing therapeutic effects by high intensity focused ultrasound (HIFU). The TM phantom was designed to improve a widely used standard bovine serum albumin (BSA) polyacrylamide hydrogel (PAG), which attenuated ultrasound far less than tissue and, unlike tissue, did not scatter ultrasound. A modified recipe has been proposed in the study by adding scattering glass beads with diameters of 40-80 ?m (0.002% w/v) and by raising the concentration of acrylamide (30% v/v). The TM BSA-PAG constructed has an acoustic impedance of 1.67 MRayls, a speed of sound of 1576 m/s, an attenuation coefficient of 0.52 dB/cm at 1 MHz, a backscattering coefficient of 0.242 × 10(-3) 1/sr/cm at 1 MHz and a nonlinear parameter (B/A) of 5.7. These parameters are close to those of liver. The thermal and optical properties are almost the same as the standard BSA-PAG. The characteristic features of the thermal lesions by HIFU were observed to be more accurately visualized in the TM BSA-PAG than in the standard BSA-PAG. In conclusion, the proposed TM BSA-PAG acoustically mimics tissue better than the standard BSA-PAG and is expected to be preferentially used for assuring if a clinical HIFU device produces the thermal lesion as planned. PMID:23312531

Choi, Min Joo; Guntur, Sitaramanjaneya Reddy; Lee, Kang Il; Paeng, Dong Guk; Coleman, Andrew

2013-03-01

117

Ultrasound evidence of altered lumbar connective tissue structure in human subjects with chronic low back pain  

PubMed Central

Background Although the connective tissues forming the fascial planes of the back have been hypothesized to play a role in the pathogenesis of chronic low back pain (LBP), there have been no previous studies quantitatively evaluating connective tissue structure in this condition. The goal of this study was to perform an ultrasound-based comparison of perimuscular connective tissue structure in the lumbar region in a group of human subjects with chronic or recurrent LBP for more than 12 months, compared with a group of subjects without LBP. Methods In each of 107 human subjects (60 with LBP and 47 without LBP), parasagittal ultrasound images were acquired bilaterally centered on a point 2 cm lateral to the midpoint of the L2-3 interspinous ligament. The outcome measures based on these images were subcutaneous and perimuscular connective tissue thickness and echogenicity measured by ultrasound. Results There were no significant differences in age, sex, body mass index (BMI) or activity levels between LBP and No-LBP groups. Perimuscular thickness and echogenicity were not correlated with age but were positively correlated with BMI. The LBP group had ~25% greater perimuscular thickness and echogenicity compared with the No-LBP group (ANCOVA adjusted for BMI, p < 0.01 and p < 0.001 respectively). Conclusion This is the first report of abnormal connective tissue structure in the lumbar region in a group of subjects with chronic or recurrent LBP. This finding was not attributable to differences in age, sex, BMI or activity level between groups. Possible causes include genetic factors, abnormal movement patterns and chronic inflammation.

2009-01-01

118

Investigation of optimal method for inducing harmonic motion in tissue using a linear ultrasound phased array--a simulation study.  

PubMed

Many noninvasive ultrasound techniques have been developed to explore mechanical properties of soft tissues. One of these methods, Localized Harmonic Motion Imaging (LHMI), has been proposed to be used for ultrasound surgery monitoring. In LHMI, dynamic ultrasound radiation-force stimulation induces displacements in a target that can be measured using pulse-echo imaging and used to estimate the elastic properties of the target. In this initial, simulation study, the use of a one-dimensional phased array is explored for the induction of the tissue motion. The study compares three different dual-frequency and amplitude-modulated single-frequency methods for the inducing tissue motion. Simulations were computed in a homogeneous soft-tissue volume. The Rayleigh integral was used in the simulations of the ultrasound fields and the tissue displacements were computed using a finite-element method (FEM). The simulations showed that amplitude-modulated sonication using a single frequency produced the largest vibration amplitude of the target tissue. These simulations demonstrate that the properties of the tissue motion are highly dependent on the sonication method and that it is important to consider the full three-dimensional distribution of the ultrasound field for controlling the induction of tissue motion. PMID:17094690

Heikkilä, Janne; Hynynen, Kullervo

2006-04-01

119

Coregistered three-dimensional ultrasound and photoacoustic imaging system for ovarian tissue characterization  

PubMed Central

Ovarian cancer has the highest mortality of all gynecologic cancers, with a five-year survival rate of only 30% or less. Current imaging techniques are limited in sensitivity and specificity in detecting early stage ovarian cancer prior to its widespread metastasis. New imaging techniques that can provide functional and molecular contrasts are needed to reduce the high mortality of this disease. One such promising technique is photoacoustic imaging. We develop a 1280-element coregistered 3-D ultrasound and photoacoustic imaging system based on a 1.75-D acoustic array. Volumetric images over a scan range of 80 deg in azimuth and 20 deg in elevation can be achieved in minutes. The system has been used to image normal porcine ovarian tissue. This is an important step toward better understanding of ovarian cancer optical properties obtained with photoacoustic techniques. To the best of our knowledge, such data are not available in the literature. We present characterization measurements of the system and compare coregistered ultrasound and photoacoustic images of ovarian tissue to histological images. The results show excellent coregistration of ultrasound and photoacoustic images. Strong optical absorption from vasculature, especially highly vascularized corpora lutea and low absorption from follicles, is demonstrated.

Aguirre, Andres; Guo, Puyun; Gamelin, John; Yan, Shikui; Sanders, Mary M.; Brewer, Molly; Zhu, Quing

2009-01-01

120

Trans-urethral ultrasound (TUUS) imaging for visualization and analysis of the prostate and associated tissues  

NASA Astrophysics Data System (ADS)

Accurate assessment of pathological conditions in the prostate is difficult. Screening methods include palpation if the prostate gland, blood chemical testing, and diagnostic imaging. Trans-rectal Ultrasound (TRUS) is commonly used for the assessment of pathological conditions, however, TRUS is severely constrained by the relative distal location of the imaging probe. Trans-urethral Ultrasound (TUUS) may overcome some limitations of TRUS. A TUUS catheter was used to image the prostate, rectum, bladder, ureter, neuro-vascular bundles, arteries, and surrounding tissue. In addition, 360 degrees rotational scans were recorded for reconstruction into 3D volumes. Segmentation was challenging, however, new techniques such as active contour methods show potential. 3D visualizations, including both volume and surface rendering, were provided to clinicians off-line. On-line 3D visualization techniques are currently being developed. Potential applications of TUUS include: prostate cancer diagnosis and staging as well as image guided biopsy and therapy.

Holmes, David R.; Robb, Richard A.

2000-04-01

121

Towards the Development of a Thyroid Ultrasound Biometric Scheme Based on Tissue Echo-morphological Features  

NASA Astrophysics Data System (ADS)

This paper proposes a biometric system based on features extracted from the thyroid tissue accessed through 2D ultrasound. Tissue echo-morphology, which accounts for the intensity (echogenicity), texture and structure has started to be used as a relevant parameter in a clinical setting. In this paper, features related to texture, morphology and tissue reflectivity are extracted from the ultrasound images and the most discriminant ones are selected as an input for a prototype biometric identification system. Several classifiers were tested, with the best results being achieved by a combination of classifiers (k-Nearest Neighbors, MAP and entropy distance). Using leave-one-out cross-validation method the identification rate was up to 94%. Features related to texture and echogenicity were tested individually with high identification rates up to 78% and 70%, respectively. This suggests that the acoustic impedance (reflectivity or echogenicity) of the tissue as well as texture are feasible parameters to discriminate between distinct subjects. This paper shows the effectiveness of the proposed classification, which can be used not only as a new biometric modality but also as a diagnostic tool.

Seabra, Josè C. R.; Fred, Ana L. N.

122

Integrated optical coherence tomography, ultrasound and photoacoustic imaging for ovarian tissue characterization.  

PubMed

Ovarian cancer has the lowest survival rate of the gynecologic cancers because it is predominantly diagnosed in Stages III or IV due to the lack of reliable symptoms, as well as the lack of efficacious screening techniques. Detection before the malignancy spreads or at the early stage would greatly improve the survival and benefit patient health. In this report, we present an integrated optical coherence tomography (OCT), ultrasound (US) and photoacoustic imaging (PAI) prototype endoscopy system for ovarian tissue characterization. The overall diameter of the prototype endoscope is 5 mm which is suitable for insertion through a standard 5-12.5mm endoscopic laparoscopic port during minimally invasive surgery. It consists of a ball-lensed OCT sample arm probe, a multimode fiber having the output end polished at 45 degree angle so as to deliver the light perpendicularly for PAI, and a high frequency ultrasound transducer with 35MHz center frequency. System characterizations of OCT, US and PAI are presented. In addition, results obtained from ex vivo porcine and human ovarian tissues are presented. The optical absorption contrast provided by PAI, the high resolution subsurface morphology provided by OCT, and the deeper tissue structure imaged by US demonstrate the synergy of the combined endoscopy and the superior performance of this hybrid device over each modality alone in ovarian tissue characterization. PMID:21991547

Yang, Yi; Li, Xiang; Wang, Tianheng; Kumavor, Patrick D; Aguirre, Andres; Shung, Kirk K; Zhou, Qifa; Sanders, Melinda; Brewer, Molly; Zhu, Quing

2011-09-01

123

The effect of electronically steering a phased array ultrasound transducer on near-field tissue heating  

PubMed Central

Purpose: This study presents the results obtained from both simulation and experimental techniques that show the effect of mechanically or electronically steering a phased array transducer on proximal tissue heating. Methods: The thermal response of a nine-position raster and a 16-mm diameter circle scanning trajectory executed through both electronic and mechanical scanning was evaluated in computer simulations and experimentally in a homogeneous tissue-mimicking phantom. Simulations were performed using power deposition maps obtained from the hybrid angular spectrum (HAS) method and applying a finite-difference approximation of the Pennes’ bioheat transfer equation for the experimentally used transducer and also for a fully sampled transducer to demonstrate the effect of acoustic window, ultrasound beam overlap and grating lobe clutter on near-field heating. Results: Both simulation and experimental results show that electronically steering the ultrasound beam for the two trajectories using the 256-element phased array significantly increases the thermal dose deposited in the near-field tissues when compared with the same treatment executed through mechanical steering only. In addition, the individual contributions of both beam overlap and grating lobe clutter to the near-field thermal effects were determined through comparing the simulated ultrasound beam patterns and resulting temperature fields from mechanically and electronically steered trajectories using the 256-randomized element phased array transducer to an electronically steered trajectory using a fully sampled transducer with 40 401 phase-adjusted sample points. Conclusions: Three distinctly different three distinctly different transducers were simulated to analyze the tradeoffs of selected transducer design parameters on near-field heating. Careful consideration of design tradeoffs and accurate patient treatment planning combined with thorough monitoring of the near-field tissue temperature will help to ensure patient safety during an MRgHIFU treatment.

Payne, Allison; Vyas, Urvi; Todd, Nick; Bever, Joshua de; Christensen, Douglas A.; Parker, Dennis L.

2011-01-01

124

Size Measurement of Tissue Debris Particles Generated from Pulsed Ultrasound Cavitational Therapy - Histotripsy  

PubMed Central

Extensive mechanical tissue fractionation can be achieved using successive high intensity ultrasound pulses (“histotripsy”). Histotripsy has many potential medical applications where non-invasive tissue removal is needed (e.g., tumor ablation). There is a concern that debris generated by histotripsy-induced tissue fractionation might be an embolization hazard. The aim of this study is to measure the size distribution of these tissue debris particles. Histotripsy pulses were produced by a 513-element 1MHz array transducer, an 18-element 750kHz array transducer, and a 788kHz single element transducer. Peak negative pressures of 11-25 MPa, pulse durations of 3 – 50 cycles, pulse repetition frequencies of 100 Hz – 2 kHz were used. Tissue debris particles created by histotripsy were collected and measured with a particle sizing system. In the resulting samples, debris < 6 ?m in diameter constituted >99% of the total number of tissue particles. The largest particle generated by one of the parameter sets tested was 54 ?m in diameter, which is smaller than the clinic filter size (100 ?m) used to prevent embolization. The largest particles generated using other parameter sets were larger than 60 ?m, but the value could not be specified using our current setup. Exposures with shorter pulses produced lower percentages of large tissue debris (>30 ?m) in comparison to longer pulses. These results suggest that the tissue debris particle size distribution is adjustable by altering acoustic parameters if necessary.

Xu, Zhen; Fan, Zhenzhen; Hall, Timothy L.; Winterroth, Frank; Fowlkes, J. Brian; Cain, Charles A.

2009-01-01

125

Deep-tissue focal fluorescence imaging with digitally time-reversed ultrasound-encoded light  

NASA Astrophysics Data System (ADS)

Fluorescence imaging is one of the most important research tools in biomedical sciences. However, scattering of light severely impedes imaging of thick biological samples beyond the ballistic regime. Here we directly show focusing and high-resolution fluorescence imaging deep inside biological tissues by digitally time-reversing ultrasound-tagged light with high optical gain (~5×105). We confirm the presence of a time-reversed optical focus along with a diffuse background—a corollary of partial phase conjugation—and develop an approach for dynamic background cancellation. To illustrate the potential of our method, we image complex fluorescent objects and tumour microtissues at an unprecedented depth of 2.5 mm in biological tissues at a lateral resolution of 36 ?m×52 ?m and an axial resolution of 657 ?m. Our results set the stage for a range of deep-tissue imaging applications in biomedical research and medical diagnostics.

Wang, Ying Min; Judkewitz, Benjamin; Dimarzio, Charles A.; Yang, Changhuei

2012-06-01

126

Shear wave dispersion ultrasound vibrometry based on a different mechanical model for soft tissue characterization.  

PubMed

Ultrasound vibrometry can measure the propagation velocity of shear waves in soft tissue noninvasively, and the shear moduli of tissue can be estimated inversely from the velocities at multiple frequencies. It is possible to choose the appropriate model for tissue characterization from mathematical methods and analysis of model behaviors. The three classic models, Voigt, Maxwell, and Zener, were applied to fit the velocity measurements and estimate shear moduli of porcine livers with different thermal damage levels and different storage times. The Zener model always provided the best estimation of the moduli with the minimum errors in our experiments. Unlike the Voigt and Maxwell models, the moduli of the Zener model cannot be used to indicate damage levels in porcine livers directly, but the creep and relaxation behaviors of the Zener model are effective. PMID:23197554

Chen, Ke; Yao, Aiping; Zheng, Eugene E; Lin, Jiangli; Zheng, Yi

2012-12-01

127

High-intensity-focused-ultrasound (HIFU) induced homeostasis and tissue ablation  

NASA Astrophysics Data System (ADS)

At high intensity levels, ultrasound energy focused into remote tissue targets in human body has shown to produce thermal necrosis in circumscribed regions with sub-millimeter accuracy. The non-invasive modality known as HIFU has enormous potential for thermal ablation of cancers/tumors of the human body without any adverse effects in the surrounding normal tissue. In this paper, empirical results for parametric assessment and interdependence of several exposure variables are presented for producing thermal necrosis as well as hemostasis. Multiple HIFU transducers in selective spatial configuration have been deployed using a suitably designed experiemntal harness, with and without motorized jig scanning. The pre-planning and on-line procedure for treatment and specified instrumentation is described. Custom designed 25mm aperture HIFU probes resonating at 2 MHz focused at 64 and 80 mm are used. Results have been obtained in ex-vivo animal tissue and in vitro biological phantoms for hemostasis.

Chauhan, Sunita; Michel, M. S.; Alken, Peter; Kohrmann, K. U.; Haecker, Axel

2003-06-01

128

Deep-tissue focal fluorescence imaging with digitally time-reversed ultrasound-encoded light  

PubMed Central

Fluorescence imaging is one of the most important research tools in biomedical sciences. However, scattering of light severely impedes imaging of thick biological samples beyond the ballistic regime. Here we directly show focusing and high-resolution fluorescence imaging deep inside biological tissues by digitally time-reversing ultrasound-tagged light with high optical gain (~5×105). We confirm the presence of a time-reversed optical focus along with a diffuse background—a corollary of partial phase conjugation—and develop an approach for dynamic background cancellation. To illustrate the potential of our method, we image complex fluorescent objects and tumour microtissues at an unprecedented depth of 2.5 mm in biological tissues at a lateral resolution of 36 ?m×52 ?m and an axial resolution of 657 ?m. Our results set the stage for a range of deep-tissue imaging applications in biomedical research and medical diagnostics.

Wang, Ying Min; Judkewitz, Benjamin; DiMarzio, Charles A.; Yang, Changhuei

2012-01-01

129

Synergy of ultrasound, elasticity, and optoacoustic imaging for improved detection and differentiation of cancerous tissue  

NASA Astrophysics Data System (ADS)

The effective management of cancer requires early yet reliable detection, localization, and diagnosis. Therefore, there is a definite and urgent clinical need for an imaging technique that is widely available, is simple to perform, is safe, and that can detect and adequately diagnose cancer. In this paper we present a hybrid imaging technology based on fusion of complementary imaging modalities ultrasound, optoacoustics, and elastography to take full advantage of the many synergistic features of these modalities and thus to significantly improve sensitivity and specificity of cancer imaging. To evaluate our approach, numerical and experimental studies were performed using heterogeneous phantoms where ultrasonic, optical, and viscoelastic properties of the materials were chosen to closely mimic soft tissue. The results of this study suggest that combined ultrasound-based imaging is possible and can provide more accurate, reliable and earlier detection and diagnosis of tissue pathology. In addition, monitoring of cancer treatment and guidance of tissue biopsy are possible with combined imaging system. Practical and experimental aspects of combined imaging will be discussed with emphasis on data capture and signal/image processing algorithms. The paper will conclude with a discussion of the advantages, limitations, and potential clinical applications of the combined imaging technique.

Emelianov, Stanislav; Aglyamov, Salavat; Shah, Jignesh; Sethuraman, Shriram; Scott, Guy; Schmitt, Rainer; Karpiouk, Andrei; Motamedi, Massoud; Oraevsky, Alexander

2001-05-01

130

The velocity of ultrasound in human primary melanoma tissue - implications for the clinical use of high resolution sonography  

PubMed Central

Background Ultrasonography with 20 MHz frequency can be used to estimate tumour thickness preoperatively in malignant melanoma (MM) of the skin. The vertical invasion depth is the single most important prognostic factor for localised MM, and its preoperative knowledge would be very useful for the planning of surgical procedures. Since ultrasonographic distance measurements directly depend upon the tissue specific ultrasound velocity, we determined the ultrasound velocity in primary melanoma. Results Ultrasound velocity was calculated from runtime differences of a 20 MHz ultrasound signal along a known distance either through water alone or through thick specimens of primary MM. The ultrasound velocities varied between 1553 m/s and 1588 m/s with a mean of 1564 m/s in four different MM specimens. The analysis of different parts of the specimens showed that the variation of the calculated velocities was larger between different specimens than within one individual specimen. Conclusions The ultrasound velocity in MM tissue may be slightly lower than normally assumed, thereby explaining a part of the overestimation usually found in sonographic measurement of melanoma invasion depth. Additionally, the variation of ultrasound velocity between individual tumours may contribute to the impairment of the correlation found between sonometry and Breslow's measurement of MM invasion depth. For practical reasons, a setting of 1580 m/s will be appropriate for ultrasonography of primary malignant melanoma.

Weichenthal, Michael; Mohr, Peter; Breitbart, Eckard W

2001-01-01

131

Synergistic ablation of liver tissue and liver cancer cells with high-intensity focused ultrasound and ethanol.  

PubMed

We investigated the combined effect of ethanol and high-intensity focused ultrasound (HIFU), first, on heating and cavitation bubble activity in tissue-mimicking phantoms and porcine liver tissues and, second, on the viability of HepG2 liver cancer cells. Phantoms or porcine tissues were injected with ethanol and then subjected to HIFU at acoustic power ranging from 1.2 to 20.5 W (HIFU levels 1-7). Cavitation events and the temperature around the focal zone were measured with a passive cavitation detector and embedded type K thermocouples, respectively. HepG2 cells were subjected to 4% ethanol solution in growth medium (v/v) just before the cells were exposed to HIFU at 2.7, 8.7 or 12.0 W for 30 s. Cell viability was measured 2, 24 and 72 h post-treatment. The results indicate that ethanol and HIFU have a synergistic effect on liver cancer ablation as manifested by greater temperature rise and lesion volume in liver tissues and reduced viability of liver cancer cells. This effect is likely caused by reduction of the cavitation threshold in the presence of ethanol and the increased rate of ethanol diffusion through the cell membrane caused by HIFU-induced streaming, sonoporation and heating. PMID:24798386

Hoang, Nguyen H; Murad, Hakm Y; Ratnayaka, Sithira H; Chen, Chong; Khismatullin, Damir B

2014-08-01

132

Effects of acoustic parameters on bubble cloud dynamics in ultrasound tissue erosion (histotripsy)  

PubMed Central

High intensity pulsed ultrasound can produce significant mechanical tissue fractionation with sharp boundaries (“histotripsy”). At a tissue-fluid interface, histotripsy produces clearly demarcated tissue erosion and the erosion efficiency depends on pulse parameters. Acoustic cavitation is believed to be the primary mechanism for the histotripsy process. To investigate the physical basis of the dependence of tissue erosion on pulse parameters, an optical method was used to monitor the effects of pulse parameters on the cavitating bubble cloud generated by histotripsy pulses at a tissue-water interface. The pulse parameters studied include pulse duration, peak rarefactional pressure, and pulse repetition frequency (PRF). Results show that the duration of growth and collapse (collapse cycle) of the bubble cloud increased with increasing pulse duration, peak rarefactional pressure, and PRF when the next pulse arrived after the collapse of the previous bubble cloud. When the PRF was too high such that the next pulse arrived before the collapse of the previous bubble cloud, only a portion of histotripsy pulses could effectively create and collapse the bubble cloud. The collapse cycle of the bubble cloud also increased with increasing gas concentration. These results may explain previous in vitro results on effects of pulse parameters on tissue erosion.

Xu, Zhen; Hall, Timothy L.; Fowlkes, J. Brian; Cain, Charles A.

2009-01-01

133

High-resolution vascular tissue characterization in mice using 55MHz ultrasound hybrid imaging.  

PubMed

Ultrasound and Duplex ultrasonography in particular are routinely used to diagnose cardiovascular disease (CVD), which is the leading cause of morbidity and mortality worldwide. However, these techniques may not be able to characterize vascular tissue compositional changes due to CVD. This work describes an ultrasound-based hybrid imaging technique that can be used for vascular tissue characterization and the diagnosis of atherosclerosis. Ultrasound radiofrequency (RF) data were acquired and processed in time, frequency, and wavelet domains to extract six parameters including time integrated backscatter (T(IB)), time variance (T(var)), time entropy (T(E)), frequency integrated backscatter (F(IB)), wavelet root mean square value (W(rms)), and wavelet integrated backscatter (W(IB)). Each parameter was used to reconstruct an image co-registered to morphological B-scan. The combined set of hybrid images were used to characterize vascular tissue in vitro and in vivo using three mouse models including control (C57BL/6), and atherosclerotic apolipoprotein E-knockout (APOE-KO) and APOE/A(1) adenosine receptor double knockout (DKO) mice. The technique was tested using high-frequency ultrasound including single-element (center frequency=55 MHz) and commercial array (center frequency=40 MHz) systems providing superior spatial resolutions of 24 ?m and 40 ?m, respectively. Atherosclerotic vascular lesions in the APOE-KO mouse exhibited the highest values (contrast) of -10.11±1.92 dB, -12.13±2.13 dB, -7.54±1.45 dB, -5.10±1.06 dB, -5.25±0.94 dB, and -10.23±2.12 dB in T(IB), T(var), T(E), F(IB), W(rms), W(IB) hybrid images (n=10, p<0.05), respectively. Control segments of normal vascular tissue showed the lowest values of -20.20±2.71 dB, -22.54±4.54 dB, -14.94±2.05 dB, -9.64±1.34 dB, -10.20±1.27 dB, and -19.36±3.24 dB in same hybrid images (n=6, p<0.05). Results from both histology and optical images showed good agreement with ultrasound findings within a maximum error of 3.6% in lesion estimation. This study demonstrated the feasibility of a high-resolution hybrid imaging technique to diagnose atherosclerosis and characterize plaque components in mouse. In the future, it can be easily implemented on commercial ultrasound systems and eventually translated into clinics as a screening tool for atherosclerosis and the assessment of vulnerable plaques. PMID:23218908

Mahmoud, Ahmed M; Sandoval, Cesar; Teng, Bunyen; Schnermann, Jurgen B; Martin, Karen H; Mustafa, S Jamal; Mukdadi, Osama M

2013-03-01

134

Modeling elastic waves in coupled media: Estimate of soft tissue influence and application to quantitative ultrasound.  

PubMed

The effect of medium coupling on propagation of elastic waves is a general concern in a variety of engineering and bio-medical applications. Although some theories and analytical models are available for describing waves in multi-layered engineering structures, they do not focus on canvassing ultrasonic waves in human bones with coupled soft tissues, where the considerable differences in acoustic impedance between bone and soft tissue may pose a challenge in using these models (the soft tissues having an acoustic impedance around 80% less than that of a typical bone). Without proper treatment of this coupling effect, the precision of quantitative ultrasound (QUS) for clinical bone assessment can be compromised. The coupling effect of mimicked soft tissues on the first-arriving signal (FAS) and second-arriving signal (SAS) in a series of synthesized soft-tissue-bone phantoms was investigated experimentally and calibrated quantitatively. Understanding of the underlying mechanism of the coupling effect was supplemented by a dedicated finite element analysis. As revealed, the medium coupling impacts influence on different wave modes to different degrees: for FAS and SAS, the most significant changes take place when the soft tissues are initially introduced, and the decrease in signal peak energy continues with increase in the thickness or elastic modulus of the soft tissues, but the changes in propagation velocity fluctuate within 5% regardless of further increase in the thickness or elastic modulus of the soft tissues. As an application, the calibrated effects were employed to enhance the precision of SAS-based QUS when used for predicting the simulated healing status of a mimicked bone fracture, to find prediction of healing progress of bone fracture based on changes in velocity of the FAS or the SAS is inaccurate without taking into account the effect of soft tissue coupling, entailing appropriate compensation for the coupling effect. PMID:22858152

Chen, Jiangang; Cheng, Li; Su, Zhongqing; Qin, Ling

2013-02-01

135

A Feed-forward Neural Network Algorithm to Detect Thermal Lesions Induced by High Intensity Focused Ultrasound in Tissue.  

PubMed

Non-invasive ultrasound surgeries such as high intensity focused ultrasound have been developed to treat tumors or to stop bleeding. In this technique, incorporation of a suitable imaging modality to monitor and control the treatments is essential so several imaging methods such as X-ray, Magnetic resonance imaging and ultrasound imaging have been proposed to monitor the induced thermal lesions. Currently, the only ultrasound imaging technique that is clinically used for monitoring this treatment is standard pulse-echo B-mode ultrasound imaging. This paper describes a novel method for detecting high intensity focused ultrasound-induced thermal lesions using a feed forward neural-network. This study was carried on in vitro animal tissue samples. Backscattered radio frequency signals were acquired in real-time during treatment in order to detect induced thermal lesions. Changes in various tissue properties including tissue's attenuation coefficient, integrated backscatter, scaling parameter of Nakagami distribution, frequency dependent scatterer amplitudes and tissue vibration derived from the backscattered radio frequency data acquired 10 minutes after treatment regarding to before treatment were used in this study. These estimated parameters were used as features of the neural network. Estimated parameters of two sample tissues including two thermal lesions and their segmented B-mode images were used along with the pathological results as training data for the neural network. The results of the study shows that the trained feed forward neural network could effectively detect thermal lesions in vitro. Comparing the estimated size of the thermal lesion (9.6 mm × 8.5 mm) using neural network with the actual size of that from physical examination (10.1 mm × 9 mm) shows that we could detect high intensity focused ultrasound thermal lesions with the difference of 0.5 mm × 0.5 mm. PMID:23724369

Rangraz, Parisa; Behnam, Hamid; Shakhssalim, Naser; Tavakkoli, Jahan

2012-10-01

136

A Feed-forward Neural Network Algorithm to Detect Thermal Lesions Induced by High Intensity Focused Ultrasound in Tissue  

PubMed Central

Non-invasive ultrasound surgeries such as high intensity focused ultrasound have been developed to treat tumors or to stop bleeding. In this technique, incorporation of a suitable imaging modality to monitor and control the treatments is essential so several imaging methods such as X-ray, Magnetic resonance imaging and ultrasound imaging have been proposed to monitor the induced thermal lesions. Currently, the only ultrasound imaging technique that is clinically used for monitoring this treatment is standard pulse-echo B-mode ultrasound imaging. This paper describes a novel method for detecting high intensity focused ultrasound-induced thermal lesions using a feed forward neural-network. This study was carried on in vitro animal tissue samples. Backscattered radio frequency signals were acquired in real-time during treatment in order to detect induced thermal lesions. Changes in various tissue properties including tissue's attenuation coefficient, integrated backscatter, scaling parameter of Nakagami distribution, frequency dependent scatterer amplitudes and tissue vibration derived from the backscattered radio frequency data acquired 10 minutes after treatment regarding to before treatment were used in this study. These estimated parameters were used as features of the neural network. Estimated parameters of two sample tissues including two thermal lesions and their segmented B-mode images were used along with the pathological results as training data for the neural network. The results of the study shows that the trained feed forward neural network could effectively detect thermal lesions in vitro. Comparing the estimated size of the thermal lesion (9.6 mm × 8.5 mm) using neural network with the actual size of that from physical examination (10.1 mm × 9 mm) shows that we could detect high intensity focused ultrasound thermal lesions with the difference of 0.5 mm × 0.5 mm.

Rangraz, Parisa; Behnam, Hamid; Shakhssalim, Naser; Tavakkoli, Jahan

2012-01-01

137

Lesions in Porcine Liver Tissues Created by Continuous High Intensity Ultrasound Exposures in Vitro  

NASA Astrophysics Data System (ADS)

Lesions in porcine liver tissues created by continuous high intensity focused ultrasound (HIFU) exposures in vitro are theoretically and experimentally investigated, with the transmitter moving along a linear path at a fixed speed. Numerical simulations of the lesion formation are performed based on the Khokhlov—Zabolotskaya—Kuznetov equation and the bio-heat equation. In order to verify the theoretical predictions, experiments are performed in the one-dimensional scanning mode to measure the cross-sectional area of lesions created in the in vitro porcine liver exposed to 1.01-MHz HIFU pulses with the acoustic power of 70 W. The results indicate that, compared to the traditional discrete treatment protocol, the application of a continuous scanning model can create more uniform lesions in tissues and significantly reduces the total treatment time from 47s to 30s.

Zhang, Zhe; Chen, Tao; Zhang, Dong

2013-02-01

138

Changes in backscatter of liver tissue due to thermal coagulation induced by focused ultrasound.  

PubMed

Ultrasonic imaging has advantages in its self-consistency in guiding and monitoring ultrasonic treatment such as high-intensity focused ultrasound (HIFU) treatment. Changes in ultrasonic backscatter of tissues due to HIFU treatment have been observed, but their mechanism is still under discussion. In this paper, ultrasonic backscatter of excised and degassed porcine liver tissue was observed before and after HIFU exposure using a diagnostic scanner, and its acoustic impedance was mapped using an ultrasonic microscope. The histology of its pathological specimen was also observed using an optical microscope. The observed decrease in backscatter intensity due to HIFU exposure was consistent with a spatial Fourier analysis of the histology, which also showed changes due to the exposure. The observed increase in acoustic impedance due to the exposure was also consistent with the histological change assuming that the increase was primarily caused by the increase in the concentration of hepatic cells. PMID:23927213

Shishitani, Takashi; Matsuzawa, Ryo; Yoshizawa, Shin; Umemura, Shin-ichiro

2013-08-01

139

Ultrasound beam simulations in inhomogeneous tissue geometries using the hybrid angular spectrum method.  

PubMed

The angular spectrum method is a fast, accurate and computationally efficient method for modeling wave propagation. However, the traditional angular spectrum method assumes that the region of propagation has homogenous properties. In this paper, the angular spectrum method is extended to calculate ultrasound wave propagation in inhomogeneous tissue geometries, important for clinical efficacy, patient safety, and treatment reliability in MR-guided focused ultrasound surgery. The inhomogeneous tissue region to be modeled is segmented into voxels, each voxel having a unique speed of sound, attenuation coefficient, and density. The pressure pattern in the 3-D model is calculated by alternating between the space domain and the spatial-frequency domain for each plane of voxels in the model. The new technique was compared with the finite-difference time-domain technique for a model containing attenuation, refraction, and reflection and for a segmented human breast model; although yielding essentially the same pattern, it results in a reduction in calculation times of at least two orders of magnitude. PMID:22711405

Vyas, Urvi; Christensen, Douglas

2012-06-01

140

Characterization of lamina propria and vocal muscle in human vocal fold tissue by ultrasound Nakagami imaging  

PubMed Central

Purpose: A number of ultrasound techniques have been applied to identify the biomechanical properties of the vocal folds. These conventional ultrasound methods, however, are not capable of visually mapping the concentration of collagen and elastic fibers in the vocal folds in the form of a parametric image. This study proposes to use a statistical parameter, the Nakagami factor estimated from the statistical distribution of the ultrasonic signals backscattered from tissues, as a means for parametric imaging of the biomechanical properties of the vocal folds. Methods: The ultrasonic backscattered signals were acquired from four larynges (eight vocal folds) obtained from individuals without vocal fold pathology for constructing the Nakagami images. The textures of the Nakagami image in the lamina propria (LP) and the vocal muscle (VM) were observed and compared. The average and standard deviation of the Nakagami parameter for the LP and the VM were also calculated. Results: The results showed that the Nakagami parameter of the LP is larger than that of the VM. Moreover, the LP and the VM have different shading features in the Nakagami images. It was found that the Nakagami parameter may depend on the concentration of collagen and elastic fibers, demonstrating that the Nakagami imaging may allow visual differentiation between the LP and the VM in the vocal folds. Conclusions: Current preliminary results suggested that the high-frequency Nakagami imaging may allow real-time visual characterization of the vocal fold tissues in clinical routine examinations.

Tsui, Po-Hsiang; Huang, Chih-Chung; Sun, Lei; Dailey, Seth H.; Shung, K. Kirk

2011-01-01

141

Temperature dependence of the shear modulus of soft tissues assessed by ultrasound  

NASA Astrophysics Data System (ADS)

Soft tissue stiffness was shown to significantly change after thermal ablation. To better understand this phenomenon, the study aims (1) to quantify and explain the temperature dependence of soft tissue stiffness for different organs, (2) to investigate the potential relationship between stiffness changes and thermal dose and (3) to study the reversibility or irreversibility of stiffness changes. Ex vivo bovine liver and muscle samples (N = 3 and N = 20, respectively) were slowly heated and cooled down into a thermally controlled saline bath. Temperatures were assessed by thermocouples. Sample stiffness (shear modulus) was provided by the quantitative supersonic shear imaging technique. Changes in liver stiffness are observed only after 45 °C. In contrast, between 25 °C and 65 °C, muscle stiffness varies in four successive steps that are consistent with the thermally induced proteins denaturation reported in the literature. After a 6 h long heating and cooling process, the final muscle stiffness can be either smaller or bigger than the initial one, depending on the stiffness at the end of the heating. Another important result is that stiffness changes are linked to thermal dose. Given the high sensitivity of ultrasound to protein denaturation, this study gives promising prospects for the development of ultrasound-guided HIFU systems.

Sapin-de Brosses, E.; Gennisson, J.-L.; Pernot, M.; Fink, M.; Tanter, M.

2010-03-01

142

Considering Angle Selection When Using Ultrasound Electrode Displacement Elastography to Evaluate Radiofrequency Ablation of Tissues  

PubMed Central

Percutaneous radiofrequency ablation (RFA) is a minimally invasive treatment to thermally destroy tumors. Ultrasound-based electrode-displacement elastography is an emerging technique for evaluating the region of RFA-induced lesions. The angle between the imaging probe and the RFA electrode can influence electrode-displacement elastography when visualizing the ablation zone. We explored the angle effect on electrode-displacement elastography to measure the ablation zone. Phantoms embedded with meatballs were fabricated and then ablated using an RFA system to simulate RFA-induced lesions. For each phantom, a commercial ultrasound scanner with a 7.5?MHz linear probe was used to acquire raw image data at different angles, ranging from 30° to 90° at increments of 10°, to construct electrode-displacement images and facilitate comparisons with tissue section images. The results revealed that the ablation regions detected using electrode-displacement elastography were highly correlated with those from tissue section images when the angle was between 30° and 60°. However, the boundaries of lesions were difficult to distinguish, when the angle was larger than 60°. The experimental findings suggest that angle selection should be considered to achieve reliable electrode-displacement elastography to describe ablation zones.

Li, Qiang; Chen, Pin-Yu; Wang, Chiao-Yin; Liu, Hao-Li; Teng, Jianfu

2014-01-01

143

‘Saviour Siblings’? The Distinction between PGD with HLA Tissue Typing and Preimplantation HLA Tissue Typing  

Microsoft Academic Search

One of the more controversial uses of preimplantation genetic diagnosis (PGD) involves selecting embryos with a specific tissue\\u000a type so that the child to be born can act as a donor to an existing sibling who requires a haematopoietic stem cell transplant.\\u000a PGD with HLA tissue typing is used to select embryos that are free of a familial genetic disease

Crystal K. Liu

2007-01-01

144

High-resolution ultrasound and magnetic resonance imaging to document tissue repair after prolotherapy: a report of 3 cases.  

PubMed

High-resolution ultrasound imaging of musculoskeletal tissue is increasing in popularity because of patient tolerability, low cost, ability to visualize tissue in real-time motion, and superior resolution of highly organized tissue such as a tendon. Prolotherapy, defined as the injection of growth factors or growth factor production stimulants to grow normal cells or tissue, has been a controversial procedure for decades; it is currently gaining in popularity among physiatrists and other musculoskeletal physicians. This report describes imaging of tendons, ligaments, and medial meniscus disease (from trauma or degeneration). Although these tissues have been poorly responsive to nonsurgical treatment, it is proposed that tissue growth and repair after prolotherapy in these structures can be documented with ultrasound and confirmed with magnetic resonance imaging. Directions for future research application are discussed. PMID:18226666

Fullerton, Bradley D

2008-02-01

145

Determination of tissue thermal conductivity by measuring and modeling temperature rise induced in tissue by pulsed focused ultrasound.  

PubMed

A tissue thermal conductivity (Ks) is an important parameter which knowledge is essential whenever thermal fields induced in selected organs are predicted. The main objective of this study was to develop an alternative ultrasonic method for determining Ks of tissues in vitro suitable for living tissues. First, the method involves measuring of temperature-time T(t) rises induced in a tested tissue sample by a pulsed focused ultrasound with measured acoustic properties using thermocouples located on the acoustic beam axis. Measurements were performed for 20-cycle tone bursts with a 2 MHz frequency, 0.2 duty-cycle and 3 different initial pressures corresponding to average acoustic powers equal to 0.7 W, 1.4 W and 2.1 W generated from a circular focused transducer with a diameter of 15 mm and f-number of 1.7 in a two-layer system of media: water/beef liver. Measurement results allowed to determine position of maximum heating located inside the beef liver. It was found that this position is at the same axial distance from the source as the maximum peak-peak pressure calculated for each nonlinear beam produced in the two-layer system of media. Then, the method involves modeling of T(t) at the point of maximum heating and fitting it to the experimental data by adjusting Ks. The averaged value of Ks determined by the proposed method was found to be 0.5±0.02 W/(m·°C) being in good agreement with values determined by other methods. The proposed method is suitable for determining Ks of some animal tissues in vivo (for example a rat liver). PMID:24743838

Kujawska, Tamara; Secomski, Wojciech; Kruglenko, Eleonora; Krawczyk, Kazimierz; Nowicki, Andrzej

2014-01-01

146

Determination of Tissue Thermal Conductivity by Measuring and Modeling Temperature Rise Induced in Tissue by Pulsed Focused Ultrasound  

PubMed Central

A tissue thermal conductivity (Ks) is an important parameter which knowledge is essential whenever thermal fields induced in selected organs are predicted. The main objective of this study was to develop an alternative ultrasonic method for determining Ks of tissues in vitro suitable for living tissues. First, the method involves measuring of temperature-time T(t) rises induced in a tested tissue sample by a pulsed focused ultrasound with measured acoustic properties using thermocouples located on the acoustic beam axis. Measurements were performed for 20-cycle tone bursts with a 2 MHz frequency, 0.2 duty-cycle and 3 different initial pressures corresponding to average acoustic powers equal to 0.7 W, 1.4 W and 2.1 W generated from a circular focused transducer with a diameter of 15 mm and f-number of 1.7 in a two-layer system of media: water/beef liver. Measurement results allowed to determine position of maximum heating located inside the beef liver. It was found that this position is at the same axial distance from the source as the maximum peak-peak pressure calculated for each nonlinear beam produced in the two-layer system of media. Then, the method involves modeling of T(t) at the point of maximum heating and fitting it to the experimental data by adjusting Ks. The averaged value of Ks determined by the proposed method was found to be 0.5±0.02 W/(m·°C) being in good agreement with values determined by other methods. The proposed method is suitable for determining Ks of some animal tissues in vivo (for example a rat liver).

Kujawska, Tamara; Secomski, Wojciech; Kruglenko, Eleonora; Krawczyk, Kazimierz; Nowicki, Andrzej

2014-01-01

147

Ex Vivo characterization of canine liver tissue viscoelasticity after high-intensity focused ultrasound ablation.  

PubMed

The potential of elasticity imaging to detect high-intensity focused ultrasound (HIFU) lesions on the basis of their distinct biomechanical properties is promising. However, information on the quantitative mechanical properties of the tissue and the optimal intensity at which to determine the best contrast parameters is scarce. In this study, fresh canine livers were ablated using combinations of ISPTA intensities of 5.55, 7.16 and 9.07 kW/cm(2) and durations of 10 and 30 s ex vivo, resulting in six groups of ablated tissues. Biopsy samples were then interrogated using dynamic shear mechanical testing within the range of 0.1-10 Hz to characterize the tissue's post-ablation viscoelastic properties. All mechanical parameters were found to be frequency dependent. Compared with unablated cases, all six groups of ablated tissues had statistically significant higher complex shear modulus and shear viscosity. However, among the ablated groups, both complex shear modulus and shear viscosity were found to monotonically increase in groups 1-4 (5.55 kW/cm(2) for 10 s, 7.16 kW/cm(2) for 10 s, 9.07 kW/cm(2) for 10 s, and 5.55 kW/cm(2) for 30 s, respectively), but to decrease in groups 5 and 6 (7.16 kW/cm(2) for 30 s, and 9.07 kW/cm(2) for 30 s, respectively). For groups 5 and 6, the temperature was expected to exceed the boiling point, and therefore, the decreased stiffening could be due to the compromised integrity of the tissue microstructure. Future studies will entail estimation tissue mechanical properties in vivo and perform real-time monitoring of tissue alterations during ablation. PMID:24315395

Shahmirzadi, Danial; Hou, Gary Y; Chen, Jiangang; Konofagou, Elisa E

2014-02-01

148

Ultrasound backscatter measurements of intact human proximal femurs-Relationships of ultrasound parameters with tissue structure and mineral density.  

PubMed

Ultrasound reflection and backscatter parameters are related to the mechanical and structural properties of bone in vitro. However, the potential of ultrasound reflection and backscatter measurements has not been tested with intact human proximal femurs ex vivo. We hypothesize that ultrasound backscatter can be measured from intact femurs and that the measured backscattered signal is associated with cadaver age, bone mineral density (BMD) and trabecular bone microstructure. In this study, human femoral bones of 16 male cadavers (47.0±16.1years, range: 21-77years) were investigated using pulse-echo ultrasound measurements at the femoral neck in the antero-posterior direction and at the trochanter major in the anteroposterior and lateromedial directions. Recently introduced ultrasound backscatter parameters, independent of cortical thickness, e.g., time slope of apparent integrated backscatter (TSAB) and mean of the backscatter difference technique (MBD) were obtained and compared with the structural properties of trabecular bone samples, extracted from the locations of ultrasound measurements. Moreover, more conventional backscatter parameters, e.g., apparent integrated backscatter (AIB) and frequency slope of apparent integrated backscatter (FSAB) were analyzed. Bone mineral density of the intact femurs was evaluated using dual energy X-ray absorptiometry (DXA). AIB and MDB measured from the femoral neck correlated significantly (p<0.01) with the neck BMD (R(2)=0.44 and 0.45), cadaver age (R(2)=0.61 and 0.41) and several structural parameters, e.g., bone volume fraction (R(2)=0.33 and 0.39, p<0.05 and p<0.01), respectively. To conclude, ultrasound backscatter parameters, measured from intact proximal femurs, are significantly related (p<0.05) to structural properties and mineral density of trabecular bone. PMID:24769331

Malo, M K H; Töyräs, J; Karjalainen, J P; Isaksson, H; Riekkinen, O; Jurvelin, J S

2014-07-01

149

Ultrasound backscatter tensor imaging (BTI): analysis of the spatial coherence of ultrasonic speckle in anisotropic soft tissues.  

PubMed

The assessment of fiber architecture is of major interest in the progression of myocardial disease. Recent techniques such as magnetic resonance diffusion tensor imaging (MR-DTI) or ultrasound elastic tensor imaging (ETI) can derive the fiber directions by measuring the anisotropy of water diffusion or tissue elasticity, but these techniques present severe limitations in a clinical setting. In this study, we propose a new technique, backscatter tensor imaging (BTI), which enables determination of the fiber directions in skeletal muscles and myocardial tissues, by measuring the spatial coherence of ultrasonic speckle. We compare the results to ultrasound ETI. Acquisitions were performed using a linear transducer array connected to an ultrasonic scanner mounted on a motorized rotation device with angles from 0° to 355° by 5° increments to image ex vivo bovine skeletal muscle and porcine left ventricular myocardial samples. At each angle, multiple plane waves were transmitted and the backscattered echoes recorded. The coherence factor was measured as the ratio of coherent intensity over incoherent intensity of backscattered echoes. In skeletal muscle, maximal/minimal coherence factor was found for the probe parallel/perpendicular to the fibers. In myocardium, the coherence was assessed across the entire myocardial thickness, and the position of maxima and minima varied transmurally because of the complex fibers distribution. In ETI, the shear wave speed variation with the probe angle was found to follow the coherence variation. Spatial coherence can thus reveal the anisotropy of the ultrasonic speckle in skeletal muscle and myocardium. BTI could be used on any type of ultrasonic scanner with rotating phased-array probes or 2-D matrix probes for noninvasive evaluation of myocardial fibers. PMID:24859662

Papadacci, Clement; Tanter, Mickael; Pernot, Mathieu; Fink, Mathias

2014-06-01

150

FUNDAMENTAL AREAS OF PHENOMENOLOGY (INCLUDING APPLICATIONS): Modeling of Nonlinear Propagation in Multi-layer Biological Tissues for Strong Focused Ultrasound  

NASA Astrophysics Data System (ADS)

A theoretical model of the nonlinear propagation in multi-layered tissues for strong focused ultrasound is proposed. In this model, the spheroidal beam equation (SBE) is utilized to describe the nonlinear sound propagation in each layer tissue, and generalized oblique incidence theory is used to deal with the sound transmission between two layer tissues. Computer simulation is performed on a fat-muscle-liver tissue model under the irradiation of a 1 MHz focused transducer with a large aperture angle of 35°. The results demonstrate that the tissue layer would change the amplitude of sound pressure at the focal region and cause the increase of side petals.

Fan, Ting-Bo; Liu, Zhen-Bo; Zhang, Zhe; Zhang, Dong; Gong, Xiu-Fen

2009-08-01

151

Prediction of Difficult Laryngoscopy in Obese Patients by Ultrasound Quantification of Anterior Neck Soft Tissue1  

PubMed Central

Prediction of difficult laryngoscopy in obese patients is challenging. In 50 morbidly obese patients, we quantified the neck soft tissue from skin to anterior aspect of trachea at the vocal cords using ultrasound. Thyromental distance <6 cm, mouth opening <4 cm, limited neck mobility, Mallampati score >2, abnormal upper teeth, neck circumference >45 cm, and sleep apnoea were considered predictors of difficult laryngoscopy. Of the nine (18%) difficult laryngoscopy cases, seven had obstructive sleep apnoea history; whereas, only 2 of the 41 easy laryngoscopy patients did (P<0.001). Difficult laryngoscopy patients had larger neck circumference [50 (3.8) vs. 43.5 (2.2) cm; P<0.001] and more pre-tracheal soft tissue [28 (2.7) mm vs. 17.5 (1.8) mm; P<0.001] [mean (SD)]. Soft tissue values completely separated difficult and easy laryngoscopies. None of the other predictors correlated with difficult laryngoscopy. Thus, an abundance of pretracheal soft tissue at the level of vocal cords is a good predictor of difficult laryngoscopy in obese patients.

Ezri, T.; Gewurtz, G.; Sessler, D.I.; Medalion, B.; Szmuk, P.; Hagberg, C.; Susmallian, S.

2005-01-01

152

Comprehensive approach to breast cancer detection using light: photon localization by ultrasound modulation and tissue characterization by spectral discrimination  

NASA Astrophysics Data System (ADS)

A new technique called Ultrasound Tagging of Light (UTL) for imaging breast tissue is described. In this approach, photon localization in turbid tissue is achieved by cross- modulating a laser beam with focussed, pulsed ultrasound. Light which passes through the ultrasound focal spot is `tagged' with the frequency of the ultrasound pulse. The experimental system uses an Argon-Ion laser, a single PIN photodetector, and a 1 MHz fixed-focus pulsed ultrasound transducer. The utility of UTL as a photon localization technique in scattering media is examined using tissue phantoms consisting of gelatin and intralipid. In a separate study, in vivo optical reflectance spectrophotometry was performed on human breast tumors implanted intramuscularly and subcutaneously in nineteen nude mice. The validity of applying a quadruple wavelength breast cancer discrimination metric (developed using breast biopsy specimens) to the in vivo condition was tested. A scatter diagram for the in vivo model tumors based on this metric is presented using as the `normal' controls the hands and fingers of volunteers. Tumors at different growth stages were studied; these tumors ranged in size from a few millimeters to two centimeters. It is expected that when coupled with a suitable photon localization technique like UTL, spectral discrimination methods like this one will prove useful in the detection of breast cancer by non-ionizing means.

Marks, Fay A.; Tomlinson, Harold W.; Brooksby, Glen W.

1993-09-01

153

Error in Estimates of Tissue Material Properties from Shear Wave Dispersion Ultrasound Vibrometry  

PubMed Central

Shear wave velocity measurements are used in elasticity imaging to find the shear elasticity and viscosity of tissue. A technique called shear wave dispersion ultrasound vibrometry (SDUV) has been introduced to use the dispersive nature of shear wave velocity to locally estimate the material properties of tissue. Shear waves are created using a multifrequency ultrasound radiation force, and the propagating shear waves are measured a few millimeters away from the excitation point. The shear wave velocity is measured using a repetitive pulse-echo method and Kalman filtering to find the phase of the harmonic shear wave at 2 different locations. A viscoelastic Voigt model and the shear wave velocity measurements at different frequencies are used to find the shear elasticity (?1) and viscosity (?2) of the tissue. The purpose of this paper is to report the accuracy of the SDUV method over a range of different values of ?1 and ?2. A motion detection model of a vibrating scattering medium was used to analyze measurement errors of vibration phase in a scattering medium. To assess the accuracy of the SDUV method, we modeled the effects of phase errors on estimates of shear wave velocity and material properties while varying parameters such as shear stiffness and viscosity, shear wave amplitude, the distance between shear wave measurements (?r), signal-to-noise ratio (SNR) of the ultrasound pulse-echo method, and the frequency range of the measurements. We performed an experiment in a section of porcine muscle to evaluate variation of the aforementioned parameters on the estimated shear wave velocity and material property measurements and to validate the error prediction model. The model showed that errors in the shear wave velocity and material property estimates were minimized by maximizing shear wave amplitude, pulse-echo SNR, ?r, and the bandwidth used for shear wave measurements. The experimental model showed optimum performance could be obtained for ?r = 3-6 mm, SNR ?35 dB, with a frequency range of 100 to 600 Hz, and with a shear wave amplitude on the order of a few microns down to 0.5 ?m. The model provides a basis to explore different parameters related to implementation of the SDUV method. The experiment confirmed conclusions made by the model, and the results can be used for optimization of SDUV.

Urban, Matthew W.; Chen, Shigao; Greenleaf, James F.

2009-01-01

154

Error in estimates of tissue material properties from shear wave dispersion ultrasound vibrometry.  

PubMed

Shear wave velocity measurements are used in elasticity imaging to find the shear elasticity and viscosity of tissue. A technique called shear wave dispersion ultrasound vibrometry (SDUV) has been introduced to use the dispersive nature of shear wave velocity to locally estimate the material properties of tissue. Shear waves are created using a multifrequency ultrasound radiation force, and the propagating shear waves are measured a few millimeters away from the excitation point. The shear wave velocity is measured using a repetitive pulse-echo method and Kalman filtering to find the phase of the harmonic shear wave at 2 different locations. A viscoelastic Voigt model and the shear wave velocity measurements at different frequencies are used to find the shear elasticity (mu(1)) and viscosity (mu(2)) of the tissue. The purpose of this paper is to report the accuracy of the SDUV method over a range of different values of mu(1) and mu(2). A motion detection model of a vibrating scattering medium was used to analyze measurement errors of vibration phase in a scattering medium. To assess the accuracy of the SDUV method, we modeled the effects of phase errors on estimates of shear wave velocity and material properties while varying parameters such as shear stiffness and viscosity, shear wave amplitude, the distance between shear wave measurements (delta r), signal-to-noise ratio (SNR) of the ultrasound pulse-echo method, and the frequency range of the measurements. We performed an experiment in a section of porcine muscle to evaluate variation of the aforementioned parameters on the estimated shear wave velocity and material property measurements and to validate the error prediction model. The model showed that errors in the shear wave velocity and material property estimates were minimized by maximizing shear wave amplitude, pulse-echo SNR, delta r, and the bandwidth used for shear wave measurements. The experimental model showed optimum performance could be obtained for delta r = 3 - 6 mm, SNR =35 dB, with a frequency range of 100 to 600 Hz, and with a shear wave amplitude on the order of a few microns down to 0.5 microm. The model provides a basis to explore different parameters related to implementation of the SDUV method. The experiment confirmed conclusions made by the model, and the results can be used for optimization of SDUV. PMID:19406703

Urban, Matthew W; Chen, Shigao; Greenleaf, James F

2009-04-01

155

MRI monitoring of the effect of tissue interfaces in the penetration of high intensity focused ultrasound in kidney in vivo.  

PubMed

In this paper, we studied the effect of interfaces during the application of high intensity focused ultrasound (HIFU) ablation in rabbit kidney in vivo. In kidney ablation, mainly two types of interfaces are encountered: these are muscle-kidney and fat-kidney. It was observed that the intensity for which the probability of cavitation (POC) is one was decreased when HIFU penetrated through interfaces, meaning that an interface is a potential site of cavitation. We utilized the concept of scanning the area to be treated in two dimensions (rectangular grid) by applying low intensity ultrasound (diagnostic scan). When all the points of the grid show decrease of signal in T1-weighted fast spoiled gradient (FSPGR) which indicated heating, complete necrosis was observed in the targeted area during the application of HIFU (therapeutic scan). If ultrasound goes through an interface that includes air spaces, the diagnostic scan indicates spaces with poor ultrasound penetration and as a result, during the application of the therapeutic scan, some sites remain untreated. The muscle-kidney and fat-kidney interfaces cause reflection of ultrasound, which prevents the penetration of ultrasound. Microscopic bubbles in the interface may initiate cavitation, especially at high intensities. However, sometimes these types of interfaces do not include any bubbles and therefore the propagation of ultrasound is not inhibited. PMID:15550324

Damianou, Christakis

2004-09-01

156

Comparison of three models at high frequency for ultrasound tissue scattering  

NASA Astrophysics Data System (ADS)

A mammary carcinoma was grown in mice and imaged with an ultrasound transducer operating with a center frequency of 65 MHz. Quantitative ultrasound (QUS) analysis was used to characterize the tumors using the bandwidth of 30 to 85 MHz. Three models (Gaussian scatterer, fluid-filled sphere, and a new cell scatterer) for scattering were examined and scatterer property estimates were compared to real tissue morphology as seen from optical microscope images of the tumors. The Gaussian scattering model did not fit the data well compared to the fluid-filled sphere and new cell scatterer models. The fluid-filled sphere model fit the measurements better than any other model but did not yield scatterer property estimates that resembled underlying structure. Using the fluid-filled sphere model, the average estimated scatterer diameter was 25.5+/-0.14 ?m. A new cell scatterer model was developed, which was based on scattering from a cell by incorporating the effects of the cytoskeleton and nucleus. The new cell scatterer model yielded estimates that appeared to reflect underlying structure more accurately. Using the new cell scatterer model, the average estimated nuclear diameter was 15.6+/-2.2 ?m compared with 13.2 ?m as measured from optical microscope images.

Oelze, Michael; O'Brien, William; Zachary, James

2005-04-01

157

Ultrasound phase contrast thermal imaging with reflex transmission imaging methods in tissue phantoms  

PubMed Central

Thermal imaging measurements using ultrasound phase contrast have been performed in tissue phantoms heated with a focused ultrasound source. Back projection and reflex transmission imaging principles were employed to detect sound speed-induced changes in the phase caused by an increase in the temperature. The temperature was determined from an empirical relationship for the temperature dependence on sound speed. The phase contrast was determined from changes in the sound field measured with a hydrophone scan conducted before and during applied heating. The lengthy scanning routine used to mimic a large two-dimensional array required a steady-state temperature distribution within the phantom. The temperature distribution in the phantom was validated with magnetic resonance (MR) thermal imaging measurements. The peak temperature was found to agree within 1°C with MR and good agreement was found between the temperature profiles. The spatial resolution was 0.3 × 0.3 × 0.3 mm, comparing favorably with the 0.625 × 0.625 × 1.5 mm MR spatial resolution.

Farny, Caleb H.; Clement, Gregory T.

2009-01-01

158

Multiparametric MRI Analysis for the Identification of High Intensity Focused Ultrasound-Treated Tumor Tissue  

PubMed Central

Purpose In this study endogenous magnetic resonance imaging (MRI) biomarkers for accurate segmentation of High Intensity Focused Ultrasound (HIFU)-treated tumor tissue and residual or recurring non-treated tumor tissue were identified. Methods Multiparametric MRI, consisting of quantitative T1, T2, Apparent Diffusion Coefficient (ADC) and Magnetization Transfer Ratio (MTR) mapping, was performed in tumor-bearing mice before (n?=?14), 1 h after (n?=?14) and 72 h (n?=?7) after HIFU treatment. A non-treated control group was included (n?=?7). Cluster analysis using the Iterative Self Organizing Data Analysis (ISODATA) technique was performed on subsets of MRI parameters (feature vectors). The clusters resulting from the ISODATA segmentation were divided into a viable and non-viable class based on the fraction of pixels assigned to the clusters at the different experimental time points. ISODATA-derived non-viable tumor fractions were quantitatively compared to histology-derived non-viable tumor volume fractions. Results The highest agreement between the ISODATA-derived and histology-derived non-viable tumor fractions was observed for feature vector {T1, T2, ADC}. R1 (1/T1), R2 (1/T2), ADC and MTR each were significantly increased in the ISODATA-defined non-viable tumor tissue at 1 h after HIFU treatment compared to viable, non-treated tumor tissue. R1, ADC and MTR were also significantly increased at 72 h after HIFU. Conclusions This study demonstrates that non-viable, HIFU-treated tumor tissue can be distinguished from viable, non-treated tumor tissue using multiparametric MRI analysis. Clinical application of the presented methodology may allow for automated, accurate and objective evaluation of HIFU treatment.

Strijkers, Gustav J.; Nicolay, Klaas

2014-01-01

159

In vitro and in vivo ablation of porcine renal tissues using high-intensity focused ultrasound.  

PubMed

The aim of this paper is to present issues regarding the thermal ablation of porcine renal tissues in vitro and in vivo using high-intensity focused ultrasound (HIFU). Production of lesions in the cortex in vitro is consistent, whereas lesions in the medulla are created whenever there are no air spaces in the medulla. Typically, the lesion length at 2000 W/cm2 and 5-s pulse duration is around 20 mm and the corresponding width around 3 mm. Lesioning of a large volume was achieved by moving the transducer in a grid formation. Lesioning through a fat layer is possible provided that there are no air spaces between the fat and kidney interface. It was found that, above 3200 W/cm2 with 5-s pulse duration at 4 MHz, cavitation activity occurred in most of the lesions created. PMID:14553810

Damianou, Christakis

2003-09-01

160

High resolution imaging beyond the acoustic diffraction limit in deep tissue via ultrasound-switchable NIR fluorescence  

PubMed Central

Fluorescence imaging in deep tissue with high spatial resolution is highly desirable because it can provide details about tissue's structural, functional, and molecular information. Unfortunately, current fluorescence imaging techniques are limited either in penetration depth (microscopy) or spatial resolution (diffuse light based imaging) as a result of strong light scattering in deep tissue. To overcome this limitation, we developed an ultrasound-switchable fluorescence (USF) imaging technique whereby ultrasound was used to switch on/off the emission of near infrared (NIR) fluorophores. We synthesized and characterized unique NIR USF contrast agents. The excellent switching properties of these agents, combined with the sensitive USF imaging system developed in this study, enabled us to image fluorescent targets in deep tissue with spatial resolution beyond the acoustic diffraction limit.

Pei, Yanbo; Wei, Ming-Yuan; Cheng, Bingbing; Liu, Yuan; Xie, Zhiwei; Nguyen, Kytai; Yuan, Baohong

2014-01-01

161

High resolution imaging beyond the acoustic diffraction limit in deep tissue via ultrasound-switchable NIR fluorescence.  

PubMed

Fluorescence imaging in deep tissue with high spatial resolution is highly desirable because it can provide details about tissue's structural, functional, and molecular information. Unfortunately, current fluorescence imaging techniques are limited either in penetration depth (microscopy) or spatial resolution (diffuse light based imaging) as a result of strong light scattering in deep tissue. To overcome this limitation, we developed an ultrasound-switchable fluorescence (USF) imaging technique whereby ultrasound was used to switch on/off the emission of near infrared (NIR) fluorophores. We synthesized and characterized unique NIR USF contrast agents. The excellent switching properties of these agents, combined with the sensitive USF imaging system developed in this study, enabled us to image fluorescent targets in deep tissue with spatial resolution beyond the acoustic diffraction limit. PMID:24732947

Pei, Yanbo; Wei, Ming-Yuan; Cheng, Bingbing; Liu, Yuan; Xie, Zhiwei; Nguyen, Kytai; Yuan, Baohong

2014-01-01

162

Dual-mode registration of dynamic contrast-enhanced ultrasound combining tissue and contrast sequences.  

PubMed

This study proposes a new method for automatic, iterative image registration in the context of dynamic contrast-enhanced ultrasound (DCE-US) imaging. By constructing a cost function of image registration using a combination of the tissue and contrast-microbubble responses, this new method, referred to as dual-mode registration, performs alignment based on both tissue and vascular structures. Data from five focal liver lesions (FLLs) were used for the evaluation. Automatic registration based on the dual-mode registration technique and tissue-mode registration obtained using the linear response image sequence alone were compared to manual alignment of the sequence by an expert. Comparison of the maximum distance between the transformations applied by the automatic registration techniques and those from expert manual registration reference showed that the dual-mode registration provided better precision than the tissue-mode registration for all cases. The reduction of maximum distance ranged from 0.25 to 9.3mm. Dual-mode registration is also significantly better than tissue-mode registration for the five sequences with p-values lower than 0.03. The improved sequence alignment is also demonstrated visually by comparison of images from the sequences and the video playbacks of the motion-corrected sequences. This new registration technique better maintains a selected region of interest (ROI) within a fixed position of the image plane throughout the DCE-US sequence. This should reduce motion-related variability of the echo-power estimations and, thus, contribute to more robust perfusion quantification with DCE-US. PMID:24529339

Bouhlel, Nizar; Coron, Alain; Barrois, Guillaume; Lucidarme, Olivier; Bridal, S Lori

2014-07-01

163

Contrast-enhanced ultrasound analysis of tissue perfusion in tumor-bearing mice following treatment with endostatin combined with radiotherapy  

PubMed Central

The aim of this study was to observe the effects of Endostar (recombinant human endostatin) and radiotherapy, singly or in combination, on blood flow in mouse tumour tissue using ultrasound imaging. The ultrasound contrast agent, SonoVue, was used for the contrast-enhanced ultrasound examinations. SonoLiver software was used to analyse dynamic vascular patterns (DVPs) in the contrast process. Blood perfusion data were collected and statistical analysis was performed for data processing. Results were presented as DVP curves and quantitative parameters. Quantitative parameters showed statistically significant (P<0.05) differences in peak strength, rise time, time to peak and mean transit time among the various treatment groups. Changes in tumour blood perfusion were quantified by the assessment of contrast-enhanced ultrasound parameters. The results indirectly reflected the degree of change in angiogenesis in the tumour following experimental intervention. Ultrasound contrast imaging effectively showed the extent of the changes in vascularity and flow state. Therefore, contrast-enhanced ultrasound is suitable for use as an indicator of blood flow changes in an experimental model.

GE, WEI; ZHENG, YONGFA; TAO, ZEZHANG

2014-01-01

164

2-D Locally Regularized Tissue Strain Estimation From Radio-Frequency Ultrasound Images: Theoretical Developments and Results on Experimental Data  

Microsoft Academic Search

In this paper, a 2-D locally regularized strain estimation method for imaging deformation of soft biological tissues from radio-frequency (RF) ultrasound (US) data is introduced. Contrary to most 2-D techniques that model the compression-induced local displacement as a 2-D shift, our algorithm also considers a local scaling factor in the axial direction. This direction-dependent model of tissue motion and deformation

Elisabeth Brusseau; Jan Kybic; Jean-françois Deprez; Olivier Basset

2008-01-01

165

Effects of Nonlinear Propagation in Ultrasound Contrast Agent Imaging  

Microsoft Academic Search

This paper investigates two types of nonlinear propagation and their effects on image intensity and contrast-to-tissue ratio (CTR) in contrast ultrasound images. Previous studies have shown that nonlinear propagation can occur when ultrasound travels through tissue and microbubble clouds, making tissue farther down the acoustic path appear brighter in pulse inversion (PI) images, thus reducing CTR. In this study, the

Meng-Xing Tang; Naohisa Kamiyama; Robert J. Eckersley

2010-01-01

166

A histopathologic differentiation of tissue types in human osteoarthritic cartilage.  

PubMed

A histopathologic system of classifying minced human hip and knee osteoarthritic cartilage often used in organ cultures was developed. The tissue types characterizing the cartilage fragments were correlated with characteristics noted in full thickness cartilage specimens from young normal, aged and osteoarthritic cartilage. In the minced tissue specimens 3 distinct tissue types (A, B, and C) were discerned. Tissue types A and B were seen in nonfibrillated discolored as well as fibrillated osteoarthritic cartilage. Type C tissue was derived principally from chondroosteophytic spurs. Each tissue type differed in the number and organization of chondrocytes and orthochromatic and metachromatic staining of the perilacunar region and interterritorial matrix. No A, B or C tissue types were seen in normal cartilage samples derived from patients below the age of 50. Cartilage from patients above this age contained elements of all 3 tissue types. PMID:7097679

Sachs, B L; Goldberg, V M; Getzy, L L; Moskowitz, R W; Malemud, C J

1982-01-01

167

Usefulness of High Suction Pressure for Sufficient Tissue Collection During Endobronchial Ultrasound Guided Transbronchial Needle Aspiration  

PubMed Central

Introduction The optimal suction pressure during endobronchial ultrasound guided transbronchial needle aspiration (EBUS-TBNA) remains to be determined. The aim of this study was to compare suction pressures for performance in collecting sufficient tissue specimens from mediastinal and hilar lymph nodes during EBUS-TBNA. Methods Retrospective analysis of consecutive patients with mediastinal and hilar lymphadenopathy who underwent EBUS-TBNA over a 3-year period. Results from patients who underwent EBUS-TBNA using a dedicated 20-mL VacLoc (Merit Medical Systems, Inc, South Jordan, UT) syringe (conventional method, group C) were compared with results from patients in whom a disposable 30-mL syringe (high pressure group, group H) was used. The yield for sufficient histologic specimen retrieval and amount of tissue obtained were compared between the 2 groups. Results Of 178 patients who underwent EBUS-TBNA, 131 had lung cancer confirmed by EBUS-TBNA: 35 in group C and 96 in group H. There were 7 patients in group C and 6 in group H who received final diagnoses by cytology alone. There were 28 in group C and 90 in group H who were diagnosed by both cytology and histology. There was a statistically significant difference between the groups in terms of the rate of sufficient sampling for histological specimens (p = 0.04). The H group revealed a tissue area approximately twice that of the C group (p = 0.003). There were no major procedure-related complications in either group. Conclusion Higher suction pressures with larger syringe volumes during EBUS-TBNA may be useful for safely collecting sufficient tissue specimens.

Shiroyama, Takayuki; Okamoto, Norio; Suzuki, Hidekazu; Tamiya, Motohiro; Yamadori, Tadahiro; Morishita, Naoko; Otsuka, Tomoyuki; Morita, Satomu; Kurata, Kanako; Okimura, Akira; Kawahara, Kunimitsu; Sasada, Shinji; Hirashima, Tomonori; Kawase, Ichiro

2013-01-01

168

Ultrasound-stimulated vibro-acoustography for high-resolution differentiation based on viscoelastic properties of tissue mimicking phantoms.  

PubMed

In the absence of an imaging technique that provides imagery of diseased tissue with high diagnostic accuracy and contrast, surgeons must often excise excess healthy tissue surrounding neoplasms to ensure complete removal of malignant tissues. Additional approaches that are commonly used in the detection of tumor regions include palpation and conventional ultrasound to locate the affected area. However, these techniques suffer from limitations such as minimal specificity and lack of depth penetration. Lack of specificity results in the production of unclear diseased tissue regions, and therefore fails to offer surgeons a reliable and accurate image guidance tool. The proposed work provides an alternative diagnostic modality termed ultrasound-stimulated vibro-acoustography (USVA) that aims to generate detailed images characterized by viscoelastic properties of tissues. We demonstrate selective imaging using phantom tissue samples of polyvinyl alcohol (PVA) that are altered and arranged into unique geometries of varying elastic topology. Determining the precision and sensitivity of the USVA imaging system in identifying boundary regions as well as intensity ranges associated with tissue phantom targets will provide additional important information to allow for a non-invasive tool to distinguish diseased tissues from normal tissues in an in vivo setting. PMID:24732519

Maccabi, Ashkan; Arshi, Armin; Garritano, James; Saddik, George; Kohanbash, Elnaz; Tajudeen, Bobby A; St John, Maie; Grundfest, Warren S; Taylor, Zachary D

2014-01-01

169

Detection of tissue harmonic motion induced by ultrasonic radiation force using pulse-echo ultrasound and Kalman filter.  

PubMed

A method using pulse echo ultrasound and the Kalman filter is developed for detecting submicron harmonic motion induced by ultrasonic radiation force. The method estimates the amplitude and phase of the motion at desired locations within a tissue region with high sensitivity. The harmonic motion generated by the ultrasound radiation force is expressed as extremely small oscillatory Doppler frequency shifts in the fast time (A-line) of ultrasound echoes, which are difficult to estimate. In slow time (repetitive ultrasound echoes) of the echoes, the motion also is presented as oscillatory phase shifts, from which the amplitude and phase of the harmonic motion can be estimated with the least mean squared error by Kalman filter. This technique can be used to estimate the traveling speed of a harmonic shear wave by tracking its phase changes during propagation. The shear wave propagation speed can be used to solve for the elasticity and viscosity of tissue as reported in our earlier study. Validation and in vitro experiments indicate that the method provides excellent estimations for very small (submicron) harmonic vibrations and has potential for noninvasive and quantitative stiffness measurements of tissues such as artery. PMID:17328326

Zheng, Yi; Chen, Shigao; Tan, Wei; Kinnick, Randall; Greenleaf, James F

2007-02-01

170

Early detection of breast cancer: benefits and risks of supplemental breast ultrasound in asymptomatic women with mammographically dense breast tissue. A systematic review  

PubMed Central

Background Mammographic screening alone will miss a certain fraction of malignancies, as evidenced by retrospective reviews of mammograms following a subsequent screening. Mammographic breast density is a marker for increased breast cancer risk and is associated with a higher risk of interval breast cancer, i.e. cancer detected between screening tests. The purpose of this review is to estimate risks and benefits of supplemental breast ultrasound in women with negative mammographic screening with dense breast tissue. Methods A systematic search and review of studies involving mammography and breast ultrasound for screening of breast cancer was conducted. The search was performed for the period 1/2000-8/2008 within the data source of PubMed, DARE, and Cochrane databases. Inclusion and exclusion criteria were determined prospectively, and the Oxford evidence classification system for diagnostic studies was used for evidence level. The parameters biopsy rate, positive predictive value (PPV) for biopsy, cancer yield for breast ultrasound alone, and carcinoma detection rate by breast density were extracted or constructed. Results The systematic search identified no randomized controlled trials or systematic reviews, six cohort studies of intermediate level of evidence (3b) were found. Only two of the studies included adequate follow-up of subjects with negative or benign findings. Supplemental breast ultrasound after negative mammographic screening permitted diagnosis of primarily invasive carcinomas in 0.32% of women in breast density type categories 2-4 of the American College of Radiology (ACR); mean tumor size for those identified was 9.9 mm, 90% with negative lymph node status. Most detected cancers occurred in mammographically dense breast ACR types 3 and 4. Biopsy rates were in the range 2.3%-4.7%, with PPV of 8.4-13.7% for those biopsied due to positive ultrasound, or about one third of the PPV of biopsies due to mammography. Limitations: The study populations included wide age ranges, and the application to women age 50-69 years as proposed for mammographic screening could result in less striking benefit. Further validation studies should employ a uniform assessment system such as BI-RADS and report not only PPV, but also negative predictive value, sensitivity and specificity. Conclusion Supplemental breast ultrasound in the population of women with mammographically dense breast tissue (ACR 3 and 4) permits detection of small, otherwise occult, breast cancers. Potential adverse impacts for women in this intermediate risk group are associated with an increased biopsy rate.

2009-01-01

171

Spectral hole burning for ultrasound-modulated optical tomography of thick tissue  

PubMed Central

We apply spectral hole burning (SHB)-aided detection in ultrasound-modulated optical tomography (UOT) to image optical heterogeneities in thick tissue-mimicking phantom samples and chicken breast tissue. The efficiency of SHB is improved by using a Tm3+:YAG crystal of higher doping concentration (2.0-atomic%) and a double-pass pumping configuration, in which the pump beam is transmitted through the crystal twice to burn a deeper spectral hole with the available optical intensity. With the improved SHB-UOT system, we image absorbing, scattering, and phase objects that are embedded in the middle plane of a 30-mm-thick phantom sample. The imaging resolution was 0.5 mm in the lateral direction, as defined by the focal width of the ultrasonic transducer, and 1.5 mm in the axial direction, as determined by the ultrasonic burst length. We also image two absorbing objects embedded in a 32-mm-thick chicken breast sample. The results suggest that the improved SHB-UOT system is one step closer to the practical optical imaging application in biological and clinical studies.

Xu, Xiao; Kothapalli, Sri-Rajasekhar; Liu, Honglin; Wang, Lihong V.

2010-01-01

172

High-frequency ultrasound M-mode monitoring of HIFU ablation in cardiac tissue  

NASA Astrophysics Data System (ADS)

Effective real-time HIFU lesion detection is important for expanded use of HIFU in interventional electrophysiology (e.g., epicardial ablation of cardiac arrhythmia). The goal of this study was to investigate rapid, high-frequency M-mode ultrasound imaging for monitoring spatiotemporal changes in tissue during HIFU application. The HIFU application (4.33 MHz, 1000 Hz PRF, 50% duty cycle, 1 s exposure, 6100 W/cm2) was perpendicularly applied to porcine cardiac tissue with a high-frequency imaging system (Visualsonics Vevo 770, 55 MHz, 4.5 mm focal distance) confocally aligned. Radiofrequency (RF) M-mode data (1 kHz PRF, 4 s × 7 mm) was acquired before, during, and after HIFU treatment. Gross lesions were compared with M-mode data to correlate lesion and cavity formation. Integrated backscatter, echo-decorrelation parameters, and their cumulative extrema over time were analyzed for automatically identifying lesion width and bubble formation. Cumulative maximum integrated backscatter showed the best results for identifying the final lesion width, and a criterion based on line-to-line decorrelation was proposed for identification of transient bubble activity.

Kumon, R. E.; Gudur, M. S. R.; Zhou, Y.; Deng, C. X.

2012-10-01

173

Nonlinear inversion modeling for Ultrasound Computer Tomography: transition from soft to hard tissues imaging  

NASA Astrophysics Data System (ADS)

Ultrasound Computer Tomography (UCT) is an imaging technique which has proved effective for soft-tissue (breast, liver,...) characterization. More recently, the use of UCT has been envisaged for bone imaging. In this field, the large variations of impedance distribution (high contrast) require that a finer model of wave propagation be integrated into the reconstruction scheme. Here, the tomographic procedure used is adapted to broadband data acquired in scattering configurations while the heterogeneous objects (Born approximation) are probed by spherical waves. An "elliptical" Fourier transform has been derived to solve the near-field inverse problem. This transform differs from the standard Fourier Transform in that, instead of plane waves, families of harmonic ellipsoidal waves are considered. For soft tissues it is possible to separate the impedance and speed of sound contributions and to reconstruct their cartographies using dedicated near-field Radon transforms. In the case of highly heterogeneous media such as bones, iterative inversion schemes are proposed. The various reconstruction procedures are set against experiments.

Lasaygues, Philippe; Mensah, Serge; Guillermin, Régine; Rouyer, Julien; Franceschini, Emilie

2012-02-01

174

Adipose tissue lymphocytes: types and roles.  

PubMed

Besides adipocytes, specialized in lipid handling and involved in energy balance regulation, white adipose tissue (WAT) is mainly composed of other cell types among which lymphocytes represent a non-negligible proportion. Different types of lymphocytes (B, alphabetaT, gammadeltaT, NK and NKT) have been detected in WAT of rodents or humans, and vary in their relative proportion according to the fat pad anatomical location. The lymphocytes found in intra-abdominal, visceral fat pads seem representative of innate immunity, while those present in subcutaneous fat depots are part of adaptive immunity, at least in mice. Both the number and the activity of the different lymphocyte classes, except B lymphocytes, are modified in obesity. Several of these modifications in the relative proportions of the lymphocyte classes depend on the degree of obesity, or on leptin concentration, or even fat depot anatomical location. Recent studies suggest that alterations of lymphocyte number and composition precede the macrophage increase and the enhanced inflammatory state of WAT found in obesity. Lymphocytes express receptors to adipokines while several proinflammatory chemokines are produced in WAT, rendering intricate crosstalk between fat and immune cells. However, the evidences and controversies available so far are in favour of an involvement of lymphocytes in the control of the number of other cells in WAT, either adipocytes or immune cells and of their secretory and metabolic activities. Therefore, immunotherapy deserves to be considered as a promising approach to treat the endocrino-metabolic disorders associated to excessive fat mass development. PMID:20358356

Caspar-Bauguil, S; Cousin, B; Bour, S; Casteilla, L; Castiella, L; Penicaud, L; Carpéné, C

2009-12-01

175

A comparison of theoretical and experimental ultrasound field distributions in canine muscle tissue in vivo.  

PubMed

Relative ultrasound field distributions were measured using thermal techniques in canine thighs in vivo and in water. The experimental results were compared with distributions obtained from a numerical model based on the one-dimensional integration of the Rayleigh-Sommerfeld diffraction integral. The comparisons showed that the theoretical model is a good approximation to the distributions measured in water, with the agreement decreasing for regions in front of the acoustic focus. The main lobe profiles obtained in the muscle tissue also agreed well with both theoretical results and results measured in water (focussing was not lost). However, these in vivo distributions showed enlargement of the side lobes indicating scattering of the waves. It was also found that the interfaces between muscle groups produced considerable beam distortions as well as increased side lobe levels. Scattering of energy from the main lobe to the side lobes was verified by measurements of the peak intensity and the total acoustic power attenuation coefficients for passage of the beams through the thighs which showed that the former was about 40% higher than the latter. Also, absolute intensity values at the acoustic focus were measured in water using a hydrophone (0.5 mm active diameter) for 11 transducers ranging in frequency from 0.246 to 3.54 MHz. When these absolute values were compared with the model predictions, it was found that the model consistently overestimated the experimental data by a factor of less than 2. That is, the model can also be used to obtain upper bounds for absolute intensity values. Consequences of these results on ultrasound hyperthermia treatments are discussed. PMID:1566529

Moros, E G; Hynynen, K

1992-01-01

176

Real-Time Monitoring Of Regional Tissue Elasticity During FUS Focused Ultrasound Therapy Using Harmonic Motion Imaging  

NASA Astrophysics Data System (ADS)

The feasibility of the Harmonic Motion Imaging (HMI) technique for simultaneous monitoring and generation of focused ultrasound therapy using two separate focused ultrasound transducer elements has previously been shown. In this study, a new HMI technique is described that images tissue displacement induced by a harmonic radiation force induced using a single focused ultrasound element. First, wave propagation simulation models were used to compare the use of a single Amplitude-Modulated (AM) focused beam versus two overlapping focused beams as previously implemented for HMI. Simulation results indicated that, unlike in the two-beam configuration, the AM beam produced a consistent, stable focus for the applied harmonic radiation force. The AM beam thus offered the unique advantage of sustaining the application of the spatially-invariant radiation force. Experiments were then performed on gelatin gel phantoms and tissue in vitro bovine liver. The radiation force was generated by a 4.68 MHz focused transducer using a low-frequency Amplitude-Modulated (AM) RF-signal. RF data were acquired at 7.5 MHz with a PRF of 6.5 kHz and displacements were estimated using a 1D cross-correlation algorithm on successive RF signals. Furthermore, taking advantage of the real-time capability of our method, the change in the elastic properties was monitored during focused ultrasound (FUS) ablation of tissue in vitro bovine liver. Based on the harmonic displacements, their temperature-dependence, and the calculated acoustic radiation force, the change in the relative, regional stiffness could be monitored during heating and ablation, both using the displacement amplitude and the resulting phase shift change of the displacement relative to the radiation force temporal profile. In conclusion, the feasibility of using an AM radiation force for HMI for simultaneous monitoring and treatment during ultrasound therapy was demonstrated in phantoms and tissues in vitro. Further study of this method will include, ex vivo and in vivo, stiffness and temperature.

Maleke, Caroline; Pernot, Mathieu; Konofagou, Elisa

2006-05-01

177

Temperature distributions in tissues during local hyperthermia by stationary or steered beams of unfocused or focused ultrasound.  

PubMed Central

Temperature distributions resulting from insonation with stationary or steered beams of unfocused or focused ultrasound were measured in tissue-equivalent phantom, beef muscle in vitro, dog muscle mass, and transplanted murine tumours in vivo. Arrays of 4 to 6 thermocouples stepped through the volume of interest under computer control were used to measure the steady-state temperatures at 600 to 800 locations in both in vitro and in vivo experiments. The results were confirmed in spontaneous tumours in dog patients using fewer multi-thermocouple probes. Plane wave ultrasound was found to result in spatially non-uniform hyperthermia even in superficial tumours. The region of maximum temperature rise was small in extent and was situated at a depth which varied in the different models from 0.5 to 1.0 cm. Neither its location nor its extent could be varied by spatial manipulations of the transducer or by changing the insonation parameters except the ultrasonic frequency. A second region of hyperthermia was produced at depth by reflective heating if an ultrasonically reflective target, such as bone or air-containing tissue, was located below the target tissue. On the other hand, using available steered, focused ultrasound techniques, tumours (whether situated superficially or at depth) could be heated to a uniform, controllable temperature without undesirable temperature elevation in surrounding normal tissues. The use of steered, focused ultrasound permits deposition of energy to be tailored to the specific needs of each individual tumour. The small size of the focal region enables heating of tumours even when located near ultrasound reflecting targets.

Lele, P. P.; Parker, K. J.

1982-01-01

178

Full 2D displacement vector and strain tensor estimation for superficial tissue using beam-steered ultrasound imaging.  

PubMed

Ultrasound strain imaging is used to measure local tissue deformations. Usually, only strains along the ultrasound beam are estimated, because those estimates are most precise, due to the availability of phase information. For estimating strain in other directions we propose to steer the ultrasound beam at an angle, which allows estimating different projections of the 2D strain tensor, while phase information remains available. This study investigates beam steering at maximally three different angles to determine the full 2D strain tensor. The method was tested on simulated and experimental data of an inclusion phantom and a vessel phantom. The combination of data from a non-steered acquisition and acquisitions at a large positive and an equally large but negative steering angle enabled the most precise estimation of the strain components. The method outperforms conventional methods that do not use beam steering. PMID:20479516

Hansen, H H G; Lopata, R G P; Idzenga, T; de Korte, C L

2010-06-01

179

3-D Visualization and Non-linear Tissue Classification of Breast Tumors Using Ultrasound Elastography In Vivo.  

PubMed

The goal of the study described here was to introduce new methods for the classification and visualization of human breast tumors using 3-D ultrasound elastography. A tumor's type, shape and size are key features that can help the physician to decide the sort and extent of necessary treatment. In this work, tumor type, being either benign or malignant, was classified non-invasively for nine volunteer patients. The classification was based on estimating four parameters that reflect the tumor's non-linear biomechanical behavior, under multi-compression levels. Tumor prognosis using non-linear elastography was confirmed with biopsy as a gold standard. Three tissue classification parameters were found to be statistically significant with a p-value < 0.05, whereas the fourth non-linear parameter was highly significant, having a p-value < 0.001. Furthermore, each breast tumor's shape and size were estimated in vivo using 3-D elastography, and were enhanced using interactive segmentation. Segmentation with level sets was used to isolate the stiff tumor from the surrounding soft tissue. Segmentation also provided a reliable means to estimate tumors volumes. Four volumetric strains were investigated: the traditional normal axial strain, the first principal strain, von Mises strain and maximum shear strain. It was noted that these strains can provide varying degrees of boundary enhancement to the stiff tumor in the constructed elastograms. The enhanced boundary improved the performance of the segmentation process. In summary, the proposed methods can be employed as a 3-D non-invasive tool for characterization of breast tumors, and may provide early prognosis with minimal pain, as well as diminish the risk of late-stage breast cancer. PMID:24768484

Sayed, Ahmed; Layne, Ginger; Abraham, Jame; Mukdadi, Osama M

2014-07-01

180

Data Analysis and Tissue Type Assignment for Glioblastoma Multiforme  

PubMed Central

Glioblastoma multiforme (GBM) is characterized by high infiltration. The interpretation of MRSI data, especially for GBMs, is still challenging. Unsupervised methods based on NMF by Li et al. (2013, NMR in Biomedicine) and Li et al. (2013, IEEE Transactions on Biomedical Engineering) have been proposed for glioma recognition, but the tissue types is still not well interpreted. As an extension of the previous work, a tissue type assignment method is proposed for GBMs based on the analysis of MRSI data and tissue distribution information. The tissue type assignment method uses the values from the distribution maps of all three tissue types to interpret all the information in one new map and color encodes each voxel to indicate the tissue type. Experiments carried out on in vivo MRSI data show the feasibility of the proposed method. This method provides an efficient way for GBM tissue type assignment and helps to display information of MRSI data in a way that is easy to interpret.

Li, Yuqian; Pi, Yiming; Liu, Xin; Liu, Yuhan; Van Cauter, Sofie

2014-01-01

181

Experiences Using a Special Purpose Robot for Focal Ultrasound Based Tissue Ablation  

NASA Astrophysics Data System (ADS)

This paper describes implementation, empirical set-up and ex vivo trial results of a non-invasive robotic surgery system, called FUSBOT-BS, to treat tumours/cancers by the use of High Intensity Focused Ultrasound (HIFU). The desired surgical effects of ultrasonic irradiation are decided by a pre-planned delivered dosage and the temporal aspects of wave propagation. The temperature rise in the target site depends upon the exposure conditions. A multiple transducer approach is adopted in this research. Surgical planning and deployment of the probes in a given location and specified trajectory is accomplished using robotic techniques. The test results for ablation were conducted in biological phantoms and in various animal tissues, in vitro, such as fat, muscle, and kidney from lamb, beef and pork. The representative results obtained in these empirical studies are presented, which help to understand dependence of crucial HIFU parameters to decide the treatment planning and surgical protocols. The robotic system achieved an end-point accuracy of +/-0.5mm. It is possible to precisely position target lesions and ablate remote target sites of varying shapes and sizes with flexible protocols.

Chauhan, S.; Li, J. R.; Mishral, R.; Lim, W. K.; Hacker, A.; Michel, M. S.; Alken, P.; Köhrmann, K. U.

2005-03-01

182

Quality assurance for ultrasound scanners using a durable tissue-mimicking phantom and radial MTF  

NASA Astrophysics Data System (ADS)

For the use in routine technical quality assurance (TQA) we developed a tissue-mimicking phantom and an evaluation algorithm. Key properties of US phantom materials are sound velocity and acoustic attenuation. For daily clinical use the material also has to be nontoxic, durable and easy in handling and maintenance. The base material of our phantom is Poly(vinyl alcohol) (PVA), a synthetic polymer. By freezing the phantom body during the production process, it changes its sound velocity to closely match the one of the human body. The phantom's base form is a cuboid containing a large anechoic cylindric target. In routine QA it is required to gain comparable and reproducible results from a single image. To determine spatial resolution of phantom images, we calculate a modulation transfer function (MTF). We developed an algorithm, that calculates a radial MTF from a circular structure representing spatial resolution averaged across all directions. For evaluation of the algorithm, we created a set of synthetic images. A comparison of the results from a traditional slanted edge algorithm and our solution showed a close correlation. The US phantom was imaged with a commercial US-scanner at different sound frequencies. The computed MTFs of higher frequency images show higher transfer percentages in all spatial frequencies than the MTFs of lower frequency images. The results suggest that the proposed method produces clear statements about the spatial resolution of evaluated imaging devices. We therefore consider the method as suitable for application in technical quality assurance of diagnostic ultrasound scanners.

Kaar, Marcus; Semturs, Friedrich; Figl, Michael; Hoffmann, Rainer; Hummel, Johann

2014-03-01

183

Classification algorithm of ovarian tissue based on co-registered ultrasound and photoacoustic tomography  

NASA Astrophysics Data System (ADS)

Human ovarian tissue features extracted from photoacoustic spectra data, beam envelopes and co-registered ultrasound and photoacoustic images are used to characterize cancerous vs. normal processes using a support vector machine (SVM) classifier. The centers of suspicious tumor areas are estimated from the Gaussian fitting of the mean Radon transforms of the photoacoustic image along 0 and 90 degrees. Normalized power spectra are calculated using the Fourier transform of the photoacoustic beamformed data across these suspicious areas, where the spectral slope and 0-MHz intercepts are extracted. Image statistics, envelope histogram fitting and maximum output of 6 composite filters of cancerous or normal patterns along with other previously used features are calculated to compose a total of 17 features. These features are extracted from 169 datasets of 19 ex vivo ovaries. Half of the cancerous and normal datasets are randomly chosen to train a SVM classifier with polynomial kernel and the remainder is used for testing. With 50 times data resampling, the SVM classifier, for the training group, gives 100% sensitivity and 100% specificity. For the testing group, it gives 89.68+/- 6.37% sensitivity and 93.16+/- 3.70% specificity. These results are superior to those obtained earlier by our group using features extracted from photoacoustic raw data or image statistics only.

Li, Hai; Kumavor, Patrick D.; Alqasemi, Umar; Zhu, Quing

2014-03-01

184

Controlled ultrasound tissue erosion: The role of dynamic interaction between insonation and microbubble activity  

PubMed Central

Previous studies showed that ultrasound can mechanically remove tissue in a localized, controlled manner. Moreover, enhanced acoustic backscatter is highly correlated with the erosion process. “Initiation” and “extinction” of this highly backscattering environment were studied in this paper. The relationship between initiation and erosion, variability of initiation and extinction, and effects of pulse intensity and gas saturation on time to initiation (initiation delay time) were investigated. A 788-kHz single-element transducer was used. Multiple pulses at a 3-cycle pulse duration and a 20-kHz pulse repetition frequency were applied. ISPPA values between 1000 and 9000 W/cm2 and gas saturation ranges of 24%–28%, 39%–49%, and 77%–81% were tested. Results show the following: (1) without initiation, erosion was never observed; (2) initiation and extinction of the highly backscattering environment were stochastic in nature and dependent on acoustic parameters; (3) initiation delay times were shorter with higher intensity and higher gas saturation (e.g., the mean initiation delay time was 66.9 s at ISPPA of 4000 W/cm2 and 3.6 ms at ISPPA of 9000 W/cm2); and (4) once initiated by high-intensity pulses, the highly backscattering environment and erosion can be sustained using a significantly lower intensity than that required to initiate the process.

Xu, Zhen; Fowlkes, J. Brian; Rothman, Edward D.; Levin, Albert M.; Cain, Charles A.

2009-01-01

185

Radio Frequency Signal Analysis for Tissue Characterization of Coronary Artery: In Vivo Intravascular Ultrasound Study  

NASA Astrophysics Data System (ADS)

Intravascular ultrasound (IVUS) is an important clinical tool that provides high resolution cross-sectional image of coronary artery. However, it is difficult to accurately classify plaque composition by conventional IVUS images. In the present study, we apply self-organizing map (SOM) of radiofrequency (RF) signal spectra for automatic plaque classification in IVUS diagnosis. IVUS data were acquired with a commercially available IVUS system with the central frequency of 40 MHz. We used double SOM classifier. The 1st classifier is supervised-SOM, learned four structures (blood, catheter, shadow, and outer lumen) based on spectral parameters. The 2nd classifier is unsupervised-SOM, used for classifying remained data, which were not classified the 1st classifier. We defined categories on the 2nd SOM by using K-means clustering method. Finally, color codes were assigned to the plaque component values, and the tissue color coded maps were reconstructed. Results suggest that the proposed technique is useful for automatic characterization of plaque components in IVUS image.

Iwamoto, T.; Saijo, Y.; Tanaka, A.; Filho, E. S.; Li, S.; Yoshizawa, M.

186

Evaluation of an algorithm for semiautomated segmentation of thin tissue layers in high-frequency ultrasound images  

Microsoft Academic Search

An algorithm consisting of speckle reduction by median filtering, contrast enhancement using top- and bottom-hat morphological filters, and segmentation with a discrete dynamic contour (DDC) model was implemented for nondestructive measurements of soft tissue layer thickness. Algorithm performance was evaluated by segmenting simulated images of three-layer phantoms and high-frequency (40 MHz) ultrasound images of porcine aortic valve cusps in vitro.

Qiang Qiu; J. Dunmore-Buyze; D. R. Boughner; J. C. Lacofield

2006-01-01

187

Ex vivo viscoelastic characterization of head and neck tissue abnormalities using ultrasound-stimulated vibro-acoustography (USVA)  

NASA Astrophysics Data System (ADS)

In the absence of an imaging technique that offers a highly dynamic range detection of malignant tissue intra-operatively, surgeons are often forced to excise excess healthy tissue to ensure clear margins of resection. Techniques that are currently used in the detection of tumor regions include palpation, optical coherence tomography (OCT) elastography, dye injections, and conventional ultrasound to pinpoint the affected area. However, these methods suffer from limitations such as minimal specificity, low contrast, and limited depth of penetration. Lack of specificity and low contrast result in the production of vague disease margins and fail to provide a reliable guidance tool for surgeons. The proposed work presents an alternative diagnostic technique, ultrasound-stimulated vibro-acoustography (USVA), which may potentially provide surgeons with detailed intra-operative imagery characterized by enhanced structural boundaries and well-defined borders based on the viscoelastic properties of tissues. We demonstrate selective imaging using ex vivo tissue samples of head and neck squamous cell carcinoma (HNSCC) with the presence of both malignant and normal areas. Spatially resolved maps of varying acoustic properties were generated and show good contrast between the areas of interest. While the results are promising, determining the precision and sensitivity of the USVA imaging system in identifying boundary regions as well as intensities of ex vivo tissue targets may provide additional information to non-invasively assess confined regions of diseased tissues from healthy areas.

Maccabi, Ashkan; Garritano, James; Arshi, Armin; Saddik, George; Tajudeen, Bobby A.; St. John, Maie; Grundfest, Warren S.; Taylor, Zachary D.

2014-03-01

188

A new nonlinear parameter in the developed strain-to-applied strain of the soft tissues and its application in ultrasound elasticity imaging  

PubMed Central

Strain developed under quasi-static deformation has been mostly used in ultrasound elasticity imaging (UEI) to determine the stiffness change of tissues. However, the strain measure in UEI is often less sensitive to a subtle change of stiffness. This is particularly true for Crohn’s disease where we have applied strain imaging to the differentiation of acutely inflamed bowel from chronically fibrotic bowel. In this study, a new nonlinear elastic parameter of the soft tissues is proposed to overcome this limit. The purpose of this study is to evaluate the newly proposed method and demonstrate its feasibility in the UEI. A non-linear characteristic of soft tissues over a relatively large dynamic range of strain was investigated. A simplified tissue model based on a finite element (FE) analysis was integrated with a laboratory developed ultrasound radio frequency (RF) signal synthesis program. Two dimensional speckle tracking was applied to this model to simulate the nonlinear behavior of the strain developed in a target inclusion over the applied average strain to the surrounding tissues. A nonlinear empirical equation was formulated and optimized to best match the developed strain-to-applied strain relation obtained from the FE simulation. The proposed nonlinear equation was applied to in vivo measurements and nonlinear parameters were further empirically optimized. For an animal model, acute and chronic inflammatory bowel disease was induced in Lewis rats with trinitrobenzene sulfonic acid (TNBS)-ethanol treatments. After UEI, histopathology and direct mechanical measurements were performed on the excised tissues. The extracted non-linear parameter from the developed strain-to-applied strain relation differentiated the three different tissue types with 1.96 ± 0.12 for normal, 1.50 ± 0.09 for the acutely inflamed, and 1.03 ± 0.08 for the chronically fibrotic tissue. T-tests determined that the non-linear parameters between normal, acutely inflamed and fibrotic tissue types were statistically significantly different (normal/fibrotic (P = 0.0000185), normal/acutely inflamed (P = 0.0013), and fibrotic/acutely inflamed (P = 0.0029)). This technique may provide a sensitive and robust tool to assess subtle stiffness changes in tissues such as in acutely inflamed bowel wall. (E-mail: kangkim@upmc.edu)

Xu, Jingping; Tripathy, Sakya.; Rubin, Jonathan. M.; Stidham, Ryan. W.; Johnson, Laura. A.; Higgins, Peter. D.; Kim, Kang.

2011-01-01

189

A new nonlinear parameter in the developed strain-to-applied strain of the soft tissues and its application in ultrasound elasticity imaging.  

PubMed

Strain developed under quasi-static deformation has been mostly used in ultrasound elasticity imaging (UEI) to determine the stiffness change of tissues. However, the strain measure in UEI is often less sensitive to a subtle change of stiffness. This is particularly true for Crohn's disease where we have applied strain imaging to the differentiation of acutely inflamed bowel from chronically fibrotic bowel. In this study, a new nonlinear elastic parameter of the soft tissues is proposed to overcome this limit. The purpose of this study is to evaluate the newly proposed method and demonstrate its feasibility in the UEI. A nonlinear characteristic of soft tissues over a relatively large dynamic range of strain was investigated. A simplified tissue model based on a finite element (FE) analysis was integrated with a laboratory developed ultrasound radio-frequency (RF) signal synthesis program. Two-dimensional speckle tracking was applied to this model to simulate the nonlinear behavior of the strain developed in a target inclusion over the applied average strain to the surrounding tissues. A nonlinear empirical equation was formulated and optimized to best match the developed strain-to-applied strain relation obtained from the FE simulation. The proposed nonlinear equation was applied to in vivo measurements and nonlinear parameters were further empirically optimized. For an animal model, acute and chronic inflammatory bowel disease was induced in Lewis rats with trinitrobenzene sulfonic acid (TNBS)-ethanol treatments. After UEI, histopathology and direct mechanical measurements were performed on the excised tissues. The extracted nonlinear parameter from the developed strain-to-applied strain relation differentiated the three different tissue types with 1.96 ± 0.12 for normal, 1.50 ± 0.09 for the acutely inflamed and 1.03 ± 0.08 for the chronically fibrotic tissue. T-tests determined that the nonlinear parameters between normal, acutely inflamed and fibrotic tissue types were statistically significantly different (normal/ fibrotic [p = 0.0000185], normal/acutely inflamed [p = 0.0013] and fibrotic/acutely inflamed [p = 0.0029]). This technique may provide a sensitive and robust tool to assess subtle stiffness changes in tissues such as in acutely inflamed bowel wall. PMID:22266232

Xu, Jingping; Tripathy, Sakya; Rubin, Jonathan M; Stidham, Ryan W; Johnson, Laura A; Higgins, Peter D R; Kim, Kang

2012-03-01

190

Fibroid-Associated Heavy Menstrual Bleeding: Correlation Between Clinical Features, Doppler Ultrasound Assessment of Vasculature, and Tissue Gene Expression Profiles  

PubMed Central

Despite the prevalence of uterine fibroids (Fs), few studies have investigated the links between clinical features and the cellular or molecular mechanisms that drive F growth and development. Such knowledge will ultimately help to differentiate symptomatic from asymptomatic Fs and could result in the development of more effective and individualized treatments. The aim of this study was to investigate the relationship between ultrasound appearance, blood flow, and angiogenic gene expression in F, perifibroid (PM), and distant myometrial (DM) tissues. We hypothesized that angiogenic gene expression would be increased in tissues and participants that showed increased blood flow by Doppler ultrasound. The study was performed using Doppler ultrasound to measure blood flow prior to hysterectomy, with subsequent tissue samples from the F, PM, and DM being investigated for angiogenic gene expression. Overall, PM blood flow (measured as peak systolic velocity [PSV]) was higher than F blood flow, although significant heterogeneity was seen in vascularity and blood flow between different Fs and their surrounding myometrium. We did not find any correlation between PSV and any other clinical or molecular parameter in this study. We identified 19 angiogenesis pathway-related genes with significant differences in expression between F and DM, and 2 genes, matrix metalloproteinase 9 (MMP9) and Neuropilin 2 (NRP2), that were significantly different between F and PM. These results are consistent with subtle differences between PM and DM. Understanding the differences between symptomatic versus asymptomatic Fs may eventually lead to more effective treatments that directly target the source of heavy menstrual bleeding.

Tsiligiannis, Sophia E.; Zaitseva, Marina; Coombs, Peter R.; Shekleton, Paul; Olshansky, Moshe; Hickey, Martha; Vollenhoven, Beverley

2013-01-01

191

Can pulsed ultrasound increase tissue damage during ischemia? A study of the effects of ultrasound on infarcted and non-infarcted myocardium in anesthetized pigs  

Microsoft Academic Search

BACKGROUND: The same mechanisms by which ultrasound enhances thrombolysis are described in connection with non-beneficial effects of ultrasound. The present safety study was therefore designed to explore effects of beneficial ultrasound characteristics on the infarcted and non-infarcted myocardium. METHODS: In an open chest porcine model (n = 17), myocardial infarction was induced by ligating a coronary diagonal branch. Pulsed ultrasound

Göran K Olivecrona; Bjarne Madsen Härdig; Anders Roijer; Mattias Block; Edgars Grins; Hans W Persson; Leif Johansson; Bertil Olsson

2005-01-01

192

Partial shrinkage of venous tissues near valves using High Intensity Focused Ultrasound  

NASA Astrophysics Data System (ADS)

The cross-section of a vein can be reduced by exposing the collagen of the vein wall to high temperature (85° C) for a few seconds. Partial shrinkage of the vein is appropriate for correcting deformations of valvular tissues that can cause the abnormal blood reflux which is the main cause of varicose veins and Superficial Venous Insufficiency. Due to its suitability for inducing localized heating, High Intensity Focused Ultrasound (HIFU) is a good method for correcting valvular tissue. In the present study, the feasibility of using HIFU for inducing partial shrinkage of the saphenous vein wall is demonstrated. The position and size of valvular deformations are well suited to being heated and, consequently, reduced with HIFU. The resulting shrinkage of deformations should restore normal function of the valve. An experimental protocol was used in which several in vitro segments of human saphenous vein were exposed with a monochromatic signal produced by a real-time imaging HIFU probe. The probe has a focal length of 45 mm, a diameter of 52.5 mm and operates at 3 MHz. Ultrasonic imaging, obtained with an 8-MHz 128-element linear array placed at the centre of the HIFU probe, was used to target the vein. The segment was inserted in a porcine muscle sample, and both were placed into a PVC cylinder. Individual sonications of the vein wall were performed for acoustic power values ranging between 8.75 and 35 W at a constant sonication duration of 5 s. Different durations ranging between 3 and 7 s at constant power were also tested. Finally, a long duration of 18 s was tested while the focal point was displaced along the vein wall at a speed of 0.5 mm/s. Results showed that shrinkage of the vein wall was observed using echographic and macroscopic analysis. In particular, the vein diameter was reduced by 15% for a sonication-duration of 18 s with continuous displacement of the focal point. Results showed that HIFU is suitable for partial shrinkage of the saphenous vein and suggest that correction of dysfunctional valvular tissue is feasible.

Pichardo, Samuel; Curiel, Laura; Milleret, René; Pichot, Olivier; Lacoste, François; Chapelon, Jean-Yves

2005-03-01

193

Intense acoustic burst ultrasound modulated optical tomography for elasticity mapping of soft biological tissue mimicking phantom: a laser speckle contrast analysis study  

NASA Astrophysics Data System (ADS)

This report addresses the assessment of variation in elastic property of soft biological tissues non-invasively using laser speckle contrast measurement. The experimental as well as the numerical (Monte-Carlo simulation) studies are carried out. In this an intense acoustic burst of ultrasound (an acoustic pulse with high power within standard safety limits), instead of continuous wave, is employed to induce large modulation of the tissue materials in the ultrasound insonified region of interest (ROI) and it results to enhance the strength of the ultrasound modulated optical signal in ultrasound modulated optical tomography (UMOT) system. The intensity fluctuation of speckle patterns formed by interference of light scattered (while traversing through tissue medium) is characterized by the motion of scattering sites. The displacement of scattering particles is inversely related to the elastic property of the tissue. We study the feasibility of laser speckle contrast analysis (LSCA) technique to reconstruct a map of the elastic property of a soft tissue-mimicking phantom. We employ source synchronized parallel speckle detection scheme to (experimentally) measure the speckle contrast from the light traversing through ultrasound (US) insonified tissue-mimicking phantom. The measured relative image contrast (the ratio of the difference of the maximum and the minimum values to the maximum value) for intense acoustic burst is 86.44 % in comparison to 67.28 % for continuous wave excitation of ultrasound. We also present 1-D and 2-D image of speckle contrast which is the representative of elastic property distribution.

Singh, M. Suheshkumar; Rajan, K.; Vasu, R. M.

2014-03-01

194

Modified multi-element synthetic transmit aperture method for ultrasound imaging: A tissue phantom study.  

PubMed

The paper presents the modified multi-element synthetic transmit aperture (MSTA) method for ultrasound imaging. It is based on coherent summation of RF echo signals with apodization weights taking into account the finite size of the transmit subaperture and of the receive element. The work presents extension of the previous study where the modified synthetic transmit aperture (STA) method was considered and verified [1]. In the case of MSTA algorithm the apodization weights were calculated for each imaging point and all combinations of the transmit subaperture and receive element using their angular directivity functions (ADFs). The ADFs were obtained from the exact solution of the corresponding mixed boundary-value problem for periodic baffle system modeling the transducer array. Performance of the developed method was tested using Field II simulated synthetic aperture data of point reflectors for 4MHz 128-element transducer array with 0.3mm pitch and 0.02mm kerf to estimate the visualization depth and lateral resolution. Also experimentally determined data of the tissue-mimicking phantom (Dansk Fantom Service, model 571) obtained using 128 elements, 4MHz, linear transducer array (model L14-5/38) and Ultrasonix SonixTOUCH Research platform were used for qualitative assessment of imaging contrast improvement. Comparison of the results obtained by the modified and conventional MSTA algorithms indicated 15dB improvement of the noise reduction in the vicinity of transducer's surface (1mm depth), and concurrent increase in the visualization depth (86% augment of the scattered amplitude at the depth of 90mm). However, this increase was achieved at the expense of minor degradation of the lateral resolution of approximately 8% at the depth of 50mm and 5% at the depth of 90mm. PMID:23131337

Tasinkevych, Y; Klimonda, Z; Lewandowski, M; Nowicki, A; Lewin, P A

2013-02-01

195

Visualization of multimodal polymer-shelled contrast agents using ultrasound contrast sequences: an experimental study in a tissue mimicking flow phantom  

PubMed Central

Background A multimodal polymer-shelled contrast agent (CA) with target specific potential was recently developed and tested for its acoustic properties in a single element transducer setup. Since the developed polymeric CA has different chemical composition than the commercially available CAs, there is an interest to study its acoustic response when using clinical ultrasound systems. The aim of this study was therefore to investigate the acoustic response by studying the visualization capability and shadowing effect of three polymer-shelled CAs when using optimized sequences for contrast imaging. Methods The acoustic response of three types of the multimodal CA was evaluated in a tissue mimicking flow phantom setup by measuring contrast to tissue ratio (CTR) and acoustic shadowing using five image sequences optimized for contrast imaging. The measurements were performed over a mechanical index (MI) range of 0.2-1.2 at three CA concentrations (106, 105, 104 microbubbles/ml). Results The CTR-values were found to vary with the applied contrast sequence, MI and CA. The highest CTR-values were obtained when a contrast sequence optimized for higher MI imaging was used. At a CA concentration of 106 microbubbles/ml, acoustic shadowing was observed for all contrast sequences and CAs. Conclusions The CAs showed the potential to enhance ultrasound images generated by available contrast sequences. A CA concentration of 106 MBs/ml implies a non-linear relation between MB concentration and image intensity.

2013-01-01

196

A Tissue-Mimicking Ultrasound Test Object Using Droplet Vaporization to Create Point Targets  

PubMed Central

Ultrasound test objects containing reference point targets could be useful for evaluating ultrasound systems and phase aberration correction methods. Polyacrylamide gels containing albumin-stabilized droplets (3.6 µm mean diameter) of dodecafluoropentane (DDFP) are being developed for this purpose. Perturbation by ultrasound causes spontaneous vaporization of the superheated droplets to form gas bubbles, a process termed acoustic droplet vaporization (ADV). The resulting bubbles (20 to 160 µm diameter) are small compared with acoustic wavelengths in diagnostic ultrasound and are theoretically suitable for use as point targets (phase errors <20° for typical f-numbers). Bubbles distributed throughout the material are convenient for determining the point spread function in an imaging plane or volume. Cooling the gel causes condensation of the DDFP droplets, which may be useful for storage. Studying ADV in such viscoelastic media could provide insight into potential bioeffects from rapid bubble formation.

Carneal, Catherine M.; Kripfgans, Oliver D.; Krucker, Jochen; Carson, Paul L.; Fowlkes, J. Brian

2012-01-01

197

Monitoring tissue inflammation and responses to drug treatments in early stages of mice bone fracture using 50 MHz ultrasound  

PubMed Central

Bone fracture induces moderate inflammatory responses that are regulated by cyclooxygenase-2 (COX-2) or 5-lipoxygenase (5-LO) for initiating tissue repair and bone formation. Only a handful of non-invasive techniques focus on monitoring acute inflammation of injured bone currently exists. In the current study, we monitored in vivo inflammation levels during the initial 2 weeks of the inflammatory stage after mouse bone fracture utilizing 50 MHz ultrasound. The acquired ultrasonic images were correlated well with histological examinations. After the bone fracture in the tibia, dynamic changes in the soft tissue at the medial-posterior compartment near the fracture site were monitored by ultrasound on the days of 0, 2, 4, 7, and 14. The corresponding echogenicity increased on the 2nd, 4th, and 7th day, and subsequently declined to basal levels after the 14th day. An increase of cell death was identified by the positive staining of deoxynucleotidyl transferase dUTP nick end-labeling (TUNEL) assay and was consistent with ultrasound measurements. The increases of both COX-2 and Leukotriene B4 receptor 1 (BLT1, 5- LO-relative receptor), which are regulators for tissue inflammation, in the immunohistochemistry staining revealed their involvement in bone fracture injury. Monitoring the inflammatory response to various non-steroidal anti-inflammatory drugs (NSAIDs) treatments was investigated by treating injured mice with a daily oral intake of aspirin (Asp), indomethacin (IND), and a selective COX-2 inhibitor (SC-236). The Asp treatment significantly reduced fracture-increased echogenicity (hyperechogenicity, p < 0.05) in ultrasound images as well as inhibited cell death, and expression of COX-2 and BLT1. In contrast, treatment with IND or SC-236 did not reduce the hyperechogenicity, as confirmed by cell death (TUNEL) and expression levels of COX-2 or BLT1. Taken together, the current study reports the feasibility of a noninvasive ultrasound method capable of monitoring post-fracture tissue inflammation that positively correlates with histological findings. Results of this study also suggest that this approach may be further applied to elucidate the underlying mechanisms of inflammatory processes and to develop therapeutic strategies for facilitating fracture healing.

Chen, Yen-Chu; Lin, Yi-Hsun; Wang, Shyh-Hau; Lin, Shih-Ping; Shung, K. Kirk; Wu, Chia-Ching

2014-01-01

198

Vascular and metabolic effects of adrenaline in adipose tissue in type 2 diabetes  

PubMed Central

Objective: The aim was to investigate adipose tissue vascular and metabolic effects of an adrenaline infusion in vivo in subjects with and without type 2 diabetes mellitus (T2DM). Design: Clinical intervention study with 1-h intravenous adrenaline infusion. Subjects: Eight male overweight T2DM subjects and eight male weight-matched, non-T2DM subjects were studied before, during and after an 1-h intravenous adrenaline infusion. Adipose tissue blood flow (ATBF) was determined by 133Xenon wash-out technique, and microvascular volume in the adipose tissue was studied by contrast-enhanced ultrasound imaging. Adipose tissue fluxes of glycerol, non-esterified fatty acids (NEFA), triacylglycerol and glucose were measured by Fick's principle after catherisation of a radial artery and a vein draining the abdominal, subcutaneous adipose tissue. Results: ATBF increased similarly in both groups during the adrenaline infusion. One hour post adrenaline, ATBF was still increased in overweight T2DM subjects. Adrenaline increased microvascular volume in non-T2DM subjects while this response was impaired in overweight T2DM subjects. Adrenaline-induced increase in lipolysis was similar in both groups, but NEFA output from adipose tissue was delayed in overweight T2DM subjects. Glucose uptake in adipose tissue increased in non-T2DM subjects during adrenaline infusion but was unchanged in overweight T2DM subjects. This results in a delayed excess release of NEFA from the adipose tissue in overweight T2DM subjects after cessation of the adrenaline infusion. Conclusion: Capillaries in the adipose tissue are recruited by adrenaline in non-T2DM subjects; however, this response is impaired in overweight T2DM subjects. NEFA, released in adipose tissue during adrenaline stimulation, is insufficiently re-esterified in situ in overweight T2DM subjects, probably owing to increased ATBF after adrenaline infusion and inability to increase adipose tissue glucose uptake.

Tobin, L; Simonsen, L; Galbo, H; Bulow, J

2012-01-01

199

Correlation of preoperative MRI and intraoperative 3D ultrasound to measure brain tissue shift  

NASA Astrophysics Data System (ADS)

B-Mode ultrasound is often used during neurosurgery to provide intra-operative images of the brain though a craniotomy, but the use of 3D ultrasound during surgery is still in its infancy. We have developed a system that provides real-time freehand 3D ultrasound reconstruction at a reduced resolution. The reconstruction proceeds incrementally and the 3D image is overlayed, via a computer, on a pre-operative 3D MRI scan. This provides the operator with the necessary feedback to maintain a constant freehand sweep-rate, and also ensures that the sweep covers the desired anatomical volume. All of the ultrasound video frames are buffered, and a full-resolution, compounded reconstruction proceeds once the manual sweep is complete. We have also developed tools for manual tagging of homologous landmarks in the 3D MRI and 3D ultrasound volumes that use a piecewise cubic approximation of thin-plate spline interpolation to achieve interactive nonlinear registration and warping of the MRI volume to the ultrasound volume: Each time a homologous point-pair is identified by the use, the image of the warped MRI is updated on the computer screen after less than 0.5 s.

Gobbi, David G.; Lee, Belinda K. H.; Peters, Terence M.

2001-05-01

200

The effects of Magnetic Resonance Imaging-guided High-Intensity Focused Ultrasound ablation on human cadaver breast tissue.  

PubMed

Magnetic Resonance Imaging-guided High-Intensity Focused Ultrasound (MR-HIFU) is a promising technique for non-invasive breast tumor ablation. The purpose of this study was to investigate the effects of HIFU ablation and thermal exposure on ex vivo human breast tissue. HIFU ablations were performed in three unembalmed cadaveric breast specimens using a clinical MR-HIFU system. Sonications were performed in fibroglandular and adipose tissue. During HIFU ablation, time-resolved anatomical MR images were acquired to monitor macroscopic tissue changes. Furthermore, the breast tissue temperature was measured using a thermocouple to investigate heating and cooling under HIFU exposure. After HIFU ablation, breast tissue samples were excised and prepared for histopathological analysis. In addition, thermal exposure experiments were performed to distinguish between different levels of thermal damage using immunohistochemical staining. Irreversible macroscopic deformations up to 3.7 mm were observed upon HIFU ablation both in fibroglandular and in adipose tissue. No relationship was found between the sonication power or the maximum tissue temperature and the size of the deformations. Temperature measurements after HIFU ablation showed a slow decline in breast tissue temperature. Histopathological analysis of sonicated regions demonstrated ablated tissue and morphologically complete cell death. After thermal exposure, samples exposed to three different temperatures could readily be distinguished. In conclusion, the irreversible macroscopic tissue deformations in ex vivo human breast tissue observed during HIFU ablation suggest that it might be relevant to monitor tissue deformations during MR-HIFU treatments. Furthermore, the slow decrease in breast tissue temperature after HIFU ablation increases the risk of heat accumulation between successive sonications. Since cell death was inflicted after already 5 minutes at 75°C, MR-HIFU may find a place in non-invasive treatment of breast tumors. PMID:23583321

Merckel, Laura G; Deckers, Roel; Baron, Paul; Bleys, Ronald L A W; van Diest, Paul J; Moonen, Chrit T W; Mali, Willem P Th M; van den Bosch, Maurice A A J; Bartels, Lambertus W

2013-10-01

201

Real-Time Tissue Change Monitoring on the Sonablate® 500 during High Intensity Focused Ultrasound (HIFU) Treatment of Prostate Cancer  

NASA Astrophysics Data System (ADS)

Sonablate® 500 (SB-500) HIFU devices have been successfully used to treat prostate cancer non-invasively. In addition, Visually Directed HIFU with the SB-500 has demonstrated higher efficacy. Visually Directed HIFU works by displaying hyperechoic changes on the B-mode ultrasound images. However, small changes in the grey-scale images are not detectable by Visually Directed HIFU. To detect all tissue changes reliably, the SB-500 was enhanced with quantitative, real-time Tissue Change Monitoring (TCM) software. TCM uses pulse-echo ultrasound backscattered RF signals in 2D to estimate changes in the tissue properties caused by HIFU. The RF signal energy difference is calculated in selected frequency bands (pre and post HIFU) for each treatment site. The results are overlaid on the real-time ultrasound image in green, yellow and orange to represent low, medium and high degree of change in backscattered energy levels. The color mapping scheme was derived on measured temperature and backscattered RF signals from in vitro chicken tissue experiments. The TCM software was installed and tested in a clinical device to obtain human RF data. Post HIFU contrast enhanced MRI scans verified necrotic regions of the prostate. The color mapping success rate at higher HIFU power levels was 94% in the initial clinical test. Based on these results, TCM software has been released for wider usage. The clinical studies with TCM in Japan and The Bahamas have provided the following PSA (ng/ml) results. Japan (n = 97), PSA pre-treatment/post-treatment minimum 0.7/0.0, maximum 76.0/4.73, median 6.89/0.07, standard deviation 11.19/0.62. The Bahamas (n = 59), minimum 0.4/0.0, maximum 13.0/1.4, median 4.7/0.1, standard deviation 2.8/0.3.

Chen, Wo-Hsing; Sanghvi, Narendra T.; Carlson, Roy; Uchida, Toyoaki

2011-09-01

202

Ultrasound Transducer and System for Real-Time Simultaneous Therapy and Diagnosis for Noninvasive Surgery of Prostate Tissue  

PubMed Central

For noninvasive treatment of prostate tissue using high intensity focused ultrasound (HIFU), this paper proposes a design of an integrated multi-functional confocal phased array (IMCPA) and a strategy to perform both imaging and therapy simultaneously with this array. IMCPA is composed of triple-row phased arrays: a 6 MHz array in the center row for imaging and two 4 MHz arrays in the outer rows for therapy. Different types of piezoelectric materials and stack configurations may be employed to maximize their respective functionalities, i.e., therapy and imaging. Fabrication complexity of IMCPA may be reduced by assembling already constructed arrays. In IMCPA, reflected therapeutic signals may corrupt the quality of imaging signals received by the center row array. This problem can be overcome by implementing a coded excitation approach and/or a notch filter when B-mode images are formed during therapy. The 13-bit Barker code, which is a binary code with unique autocorrelation properties, is preferred for implementing coded excitation, although other codes may also be used. From both Field II simulation and experimental results, whether these remedial approaches would make it feasible to simultaneously carry out imaging and therapy by IMCPA was verifeid. The results showed that the 13-bit Barker code with 3 cycles per bit provided acceptable performances. The measured ?6 dB and ?20 dB range mainlobe widths were 0.52 mm and 0.91 mm, respectively, and a range sidelobe level was measured to be ?48 dB regardless of whether a notch filter was used. The 13-bit Barker code with 2 cycles per bit yielded ?6dB and ?20dB range mainlobe widths of 0.39 mm and 0.67 mm. Its range sidelobe level was found to be ?40 dB after notch filtering. These results indicate the feasibility of the proposed transducer design and system for real-time imaging during therapy.

Jeong, Jong Seob; Chang, Jin Ho; Shung, K. Kirk

2009-01-01

203

Integrated photoacoustic, ultrasound and fluorescence platform for diagnostic medical imaging-proof of concept study with a tissue mimicking phantom  

PubMed Central

The structural and molecular heterogeneities of biological tissues demand the interrogation of the samples with multiple energy sources and provide visualization capabilities at varying spatial resolution and depth scales for obtaining complementary diagnostic information. A novel multi-modal imaging approach that uses optical and acoustic energies to perform photoacoustic, ultrasound and fluorescence imaging at multiple resolution scales from the tissue surface and depth is proposed in this paper. The system comprises of two distinct forms of hardware level integration so as to have an integrated imaging system under a single instrumentation set-up. The experimental studies show that the system is capable of mapping high resolution fluorescence signatures from the surface, optical absorption and acoustic heterogeneities along the depth (>2cm) of the tissue at multi-scale resolution (<1µm to <0.5mm).

James, Joseph; Murukeshan, Vadakke Matham; Woh, Lye Sun

2014-01-01

204

Integrated photoacoustic, ultrasound and fluorescence platform for diagnostic medical imaging-proof of concept study with a tissue mimicking phantom.  

PubMed

The structural and molecular heterogeneities of biological tissues demand the interrogation of the samples with multiple energy sources and provide visualization capabilities at varying spatial resolution and depth scales for obtaining complementary diagnostic information. A novel multi-modal imaging approach that uses optical and acoustic energies to perform photoacoustic, ultrasound and fluorescence imaging at multiple resolution scales from the tissue surface and depth is proposed in this paper. The system comprises of two distinct forms of hardware level integration so as to have an integrated imaging system under a single instrumentation set-up. The experimental studies show that the system is capable of mapping high resolution fluorescence signatures from the surface, optical absorption and acoustic heterogeneities along the depth (>2cm) of the tissue at multi-scale resolution (<1µm to <0.5mm). PMID:25071954

James, Joseph; Murukeshan, Vadakke Matham; Woh, Lye Sun

2014-07-01

205

Development of a Tissue-Mimicking Phantom for Evaluating the Focusing Performance of High Intensity Focused Ultrasound  

NASA Astrophysics Data System (ADS)

Objectives: To develop a tissue mimicking phantom which can be used to evaluate the focusing performance of the HIFU transducer, and the phantom should has the same acoustic characteristic and thermotics characteristic as the biological tissue. Materials and methods: The tissue mimicking phantom was made from water, gelatin, fresh biologic tissue Its ultrasonic parameters (attenuation coefficient) of the phantom was measured by the method of radiation pressure, and thermotics parameters of the phantom, including thermal conductivity, specific heat/fusion point et al were tested under the Measurement meter. The HIFU biological effect of the phantom was evaluated under the Model JC focused ultrasound tumor therapeutic system, developed and produced by Chongqing HIFU Technology Co. Ltd (working frequency: 0.7MHz; acoustic power: 200W; focal distance: 135mm; Acoustic focal region: 3×3×25 cubic mm). Results: The self-made phantom is sable, has smooth and glossy appearance, well-distributed construction, and good elasticity. We measured the followed values for acoustic and thermal properties: density 1049+/-2 kg/m3; attenuation 0.532+/-0.017 dB/cm (0.8 MHz), 0.612+/-0.021 dB/cm (1.0 MHz) thermal conductivity 0.76+/-0.08 W/m/-°C specific heat 3653+/-143 J/kg-°C fusion point154+/-8°C. The BFR induced in the phantom after HIFU exposure was stable in its size and appearance. Conclusion: We produced and improved one tissue mimicking phantom successfully which had semblable ultrasound and thermphysical properties like the soft tissue, and can replace the bovine liver to investigate the HIFU biological effect and to detect the focusing performance of the HIFU energy transducer. The research was supported by Chongqing University of Medical Science (CX200320).

Zongyu, Jing; Faqi, Li; Jiangzhong, Zou; Zhibiao, Wang

2006-05-01

206

Emergency Ultrasound-assisted Examination of Skin and Soft Tissue Infections in the Pediatric Emergency Department  

PubMed Central

Objectives To evaluate the test characteristics of clinical examination (CE) with the addition of bedside emergency ultrasound (CE+EUS) compared to CE alone in determining skin and soft tissue infections (SSTIs) that require drainage in pediatric patients. Methods This was a prospective study of CE+EUS as a diagnostic test for the evaluation of patients 2 months to 19 years of age evaluated for SSTIs in a pediatric emergency department (ED). Two physicians clinically and independently evaluated each lesion, and the reliability of the CE for diagnosing lesions requiring drainage was calculated. Trained pediatric emergency physicians (EPs) performed US following their CEs. The authors determined and compared the test characteristics for evaluating a SSTI requiring drainage for CE alone and for CE+EUS for those lesions in which the two EPs agreed and were certain regarding their CE diagnosis (clinically evident). The performance of CE+EUS was evaluated in those lesions in which the two EPs either disagreed or were uncertain of their diagnosis (not clinically evident). The reference standard for determining if a lesion required drainage was defined as pus expressed at the time of the ED visit, or within two days by follow-up assessment. Results Three hundred and eighty-seven lesions underwent CE+EUS and were analyzed. CE agreement between physicians was fair (K = 0.38). For the 228 lesions for which physicians agreed and were certain of their diagnoses, sensitivity was 94.7% for CE and 93.1% for CE+EUS (difference ?1.7%, 95% CI = ?3.4% to 0%). The specificity of CE was 84.2% compared to 81.4% for CE+EUS (difference ?2.8%, 95% CI = ?9.7% to 4.1%). For lesions not clinically evident based on CE, the sensitivity of CE was 43.7%, compared with 77.6% for CE+EUS (difference 33.9%, 95% CI = 1.2% to 66.6%). The specificity of CE for this group was 42.0%, compared with 61.3% for CE+EUS (difference 19.3%, 95% CI = ?13.8% to 52.4%). Conclusions For clinically evident lesions, the addition of US did not significantly improve the already highly accurate CE for diagnosing lesions requiring drainage in this study population. However, there were many lesions that were not clinically evident, and in these cases, US may improve the accuracy of the CE.

Marin, Jennifer R.; Dean, Anthony J.; Bilker, Warren B.; Panebianco, Nova L.; Brown, Naomi J.; Alpern, Elizabeth R.

2013-01-01

207

The activation of tissue factor by high intensity focused ultrasound-a pathway to acoustic-biochemical hemostasis  

NASA Astrophysics Data System (ADS)

High intensity focused ultrasound (HIFU) is believed to have great potential for inducing hemostasis in severely bleeding trauma victims. The addition of HIFU-activated biomolecular substances to the blood during treatment could significantly reduce the time required to achieve hemostasis, but such substances must remain inactive everywhere except at the site of injury. The integral-membrane protein, tissue factor (TF), is by far the most potent known trigger for the blood clotting cascade. We propose to employ liposomes with the extracellular domain of TF facing the lumen (``encrypted TF'') to allow the TF molecules to be introduced into the blood stream without causing systemic activation of coagulation. HIFU sonication at the site of injury will be used to break up the liposomes and thereby expose TF to the plasma, thus combining the hemostatic potential of HIFU along with an increase in the rate of clot formation triggered by TF. In our initial studies we have produced a range of concentrations of liposomes containing encrypted TF in a buffer solution and exposed them to ultrasound at a number of different intensity levels and duty cycles. Clotting assays were performed to determine the level of the desired effect of the ultrasound. The results suggest that HIFU can be effective in exposing active TF from the encrypted liposomes to accelerate blood clotting at the site of exposure.

Yang, Xinmai; Barber, Frank E.; Morrissey, James H.; Church, Charles C.

2006-05-01

208

Nondestructive Evaluation of Tissue Engineered Articular Cartilage Using Time-Resolved Fluorescence Spectroscopy and Ultrasound Backscatter Microscopy  

PubMed Central

The goal of this study is to evaluate the ability of a bimodal technique integrating time-resolved fluorescence spectroscopy (TRFS) and ultrasound backscatter microscopy (UBM) for nondestructive detection of changes in the biochemical, structural, and mechanical properties of self-assembled engineered articular cartilage constructs. The cartilage constructs were treated with three chemical agents (collagenase, chondroitinase-ABC, and ribose) to induce changes in biochemical content (collagen and glycosaminoglycan [GAG]) of matured constructs (4 weeks); and to subsequently alter the mechanical properties of the construct. The biochemical changes were evaluated using TRFS. The microstructure and the thickness of the engineered cartilage samples were characterized by UBM. The optical and ultrasound results were validated against those acquired via conventional techniques including collagen and GAG quantification and measurement of construct stiffness. Current results demonstrated that a set of optical parameters (e.g., average fluorescence lifetime and decay constants) showed significant correlation (p<0.05) with biochemical and mechanical data. The high-resolution ultrasound images provided complementary cross-section information of the cartilage samples morphology. Therefore, the technique was capable of nondestructively evaluating the composition of extracellular matrix and the microstructure of engineered tissue, demonstrating great potential as an alternative to traditional destructive assays.

Responte, Donald; Xie, Hongtao; Liu, Jing; Fatakdawala, Hussain; Hu, Jerry; Athanasiou, Kyriacos A.

2012-01-01

209

Stereotypic Laryngeal and Respiratory Motor Patterns Generate Different Call Types in Rat Ultrasound Vocalization  

PubMed Central

Rodents produce highly variable ultrasound whistles as communication signals unlike many other mammals, who employ flow-induced vocal fold oscillations to produce sound. The role of larynx muscles in controlling sound features across different call types in ultrasound vocalization (USV) was investigated using laryngeal muscle electromyographic (EMG) activity, subglottal pressure measurements and vocal sound output in awake and spontaneously behaving Sprague–Dawley rats. Results support the hypothesis that glottal shape determines fundamental frequency. EMG activities of thyroarytenoid and cricothyroid muscles were aligned with call duration. EMG intensity increased with fundamental frequency. Phasic activities of both muscles were aligned with fast changing fundamental frequency contours, for example in trills. Activities of the sternothyroid and sternohyoid muscles, two muscles involved in vocal production in other mammals, are not critical for the production of rat USV. To test how stereotypic laryngeal and respiratory activity are across call types and individuals, sets of ten EMG and subglottal pressure parameters were measured in six different call types from six rats. Using discriminant function analysis, on average 80% of parameter sets were correctly assigned to their respective call type. This was significantly higher than the chance level. Since fundamental frequency features of USV are tightly associated with stereotypic activity of intrinsic laryngeal muscles and muscles contributing to build-up of subglottal pressure, USV provide insight into the neurophysiological control of peripheral vocal motor patterns.

RIEDE, TOBIAS

2014-01-01

210

Non-invasive Characterization of Polyurethane-based Tissue Constructs in a Rat Abdominal Repair Model Using High Frequency Ultrasound Elasticity Imaging  

PubMed Central

The evaluation of candidate materials and designs for soft tissue scaffolds would benefit from the ability to monitor the mechanical remodeling of the implant site without the need for periodic animal sacrifice and explant analysis. Toward this end, the ability of non-invasive ultrasound elasticity imaging (UEI) to assess temporal mechanical property changes in three different types of porous, biodegradable polyurethane scaffolds was evaluated in a rat abdominal wall repair model. The polymers utilized were salt-leached scaffolds of poly(carbonate urethane) urea, poly(ester urethane) urea and poly(ether ester urethane) urea at 85% porosity. A total of 60 scaffolds (20 each type) were implanted in a full thickness muscle wall replacement in the abdomens of 30 rats. The constructs were ultrasonically scanned every 2 weeks and harvested at weeks 4, 8 and 12 for compression testing or histological analysis. UEI demonstrated different temporal stiffness trends among the different scaffold types, while the stiffness of the surrounding native tissue remained unchanged. The changes in average normalized strains developed in the constructs from UEI compared well with the changes of mean compliance from compression tests and histology. The average normalized strains and the compliance for the same sample exhibited a strong linear relationship. The ability of UEI to identify herniation and to characterize the distribution of local tissue in-growth with high resolution was also investigated. In summary, the reported data indicate that UEI may allow tissue engineers to sequentially evaluate the progress of tissue construct mechanical behavior in vivo and in some cases may reduce the need for interim time point animal sacrifice.

Yu, Jiao; Takanari, Keisuke; Hong, Yi; Lee, Kee-Won; Amoroso, Nicholas J.; Wang, Yadong; Wagner, William R.; Kim, Kang

2013-01-01

211

5A-3 Spatial and Temporal Controlled Tissue Heating on a Modified Clinical Ultrasound Scanner for Generating Mild Hyperthermia in Tumors  

Microsoft Academic Search

We present a new system for generating controlled tissue heating with a clinical ultrasound scanner and initial in vitro and in vivo results that demonstrate both transient and sustained heating in the mild- hyperthermia range of 37-42degC. The system consists of a Siemens Antarestrade ultrasound scanner, a custom dual-frequency 3-row transducer array, and an external temperature feedback control system. The

Dustin E. Kruse; Douglas N. Stephens; Eric E. Paoli; Stephen H. Barnes; Katherine W. Ferrara

2007-01-01

212

Design and implementation of therapeutic ultrasound generating circuit for dental tissue formation and tooth-root healing.  

PubMed

Biological tissue healing has recently attracted a great deal of research interest in various medical fields. Trauma to teeth, deep and root caries, and orthodontic treatment can all lead to various degrees of root resorption. In our previous study, we showed that low-intensity pulsed ultrasound (LIPUS) enhances the growth of lower incisor apices and accelerates their rate of eruption in rabbits by inducing dental tissue growth. We also performed clinical studies and demonstrated that LIPUS facilitates the healing of orthodontically induced teeth-root resorption in humans. However, the available LIPUS devices are too large to be used comfortably inside the mouth. In this paper, the design and implementation of a low-power LIPUS generator is presented. The generator is the core of the final intraoral device for preventing tooth root loss and enhancing tooth root tissue healing. The generator consists of a power-supply subsystem, an ultrasonic transducer, an impedance-matching circuit, and an integrated circuit composed of a digital controller circuitry and the associated driver circuit. Most of our efforts focus on the design of the impedance-matching circuit and the integrated system-on-chip circuit. The chip was designed and fabricated using 0.8- ¿m high-voltage technology from Dalsa Semiconductor, Inc. The power supply subsystem and its impedance-matching network are implemented using discrete components. The LIPUS generator was tested and verified to function as designed and is capable of producing ultrasound power up to 100 mW in the vicinity of the transducer's resonance frequency at 1.5 MHz. The power efficiency of the circuitry, excluding the power supply subsystem, is estimated at 70%. The final products will be tailored to the exact size of teeth or biological tissue, which is needed to be used for stimulating dental tissue (dentine and cementum) healing. PMID:23853309

Woon Tiong Ang; Scurtescu, C; Wing Hoy; El-Bialy, T; Ying Yin Tsui; Jie Chen

2010-02-01

213

PSF dedicated to estimation of displacement vectors for tissue elasticity imaging with ultrasound  

Microsoft Academic Search

This paper investigates a new approach devoted to displacement vector estimation in ultrasound imaging. The main idea is to adapt the image formation to a given displacement estimation method to increase the precision of the estimation. The displacement is identified as the zero crossing of the phase of the complex cross-correlation between signals extracted from the lateral direction of the

Herve Liebgott; J. E. Wilhjehm; Jørgen A. Jensen; Didier Vray; Philippe Delachartre

2007-01-01

214

How can Tissue Types be Identified? A Lesson on Identifying and Classifying Animal Tissues  

NSDL National Science Digital Library

The purpose of this inquiry is for students to develop and test a scheme to identify the major types of tissues and to identify similarities and differences in animal tissue types. This is an advanced lab recommended for second year Biology students, 11th or 12th grade. Students should have knowledge of cells and cell organelles. Upon completion of this activity, students will be able to: discuss how tissues can be categorized and recognized, recognize the differences between major types of tissues, and develop a scheme to identify/categorize tissues into related groups. This teaching resource was developed by a K-12 science teacher in the American Physiological SocietyÃÂs 2006 Frontiers in Physiology Program. For more information on this program, please visit www.frontiersinphys.org.

Ramona Lundberg (Deuel High School)

2006-08-01

215

Noninvasive quantification of in vitro osteoblastic differentiation in 3D engineered tissue constructs using spectral ultrasound imaging.  

PubMed

Non-destructive monitoring of engineered tissues is needed for translation of these products from the lab to the clinic. In this study, non-invasive, high resolution spectral ultrasound imaging (SUSI) was used to monitor the differentiation of MC3T3 pre-osteoblasts seeded within collagen hydrogels. SUSI was used to measure the diameter, concentration and acoustic attenuation of scatterers within such constructs cultured in either control or osteogenic medium over 21 days. Conventional biochemical assays were used on parallel samples to determine DNA content and calcium deposition. Construct volume and morphology were accurately imaged using ultrasound. Cell diameter was estimated to be approximately 12.5-15.5 µm using SUSI, which corresponded well to measurements of fluorescently stained cells. The total number of cells per construct assessed by quantitation of DNA content decreased from 5.6±2.4×10(4) at day 1 to 0.9±0.2×10(4) at day 21. SUSI estimation of the equivalent number of acoustic scatters showed a similar decreasing trend, except at day 21 in the osteogenic samples, which showed a marked increase in both scatterer number and acoustic impedance, suggestive of mineral deposition by the differentiating MC3T3 cells. Estimation of calcium content by SUSI was 41.7±11.4 µg/ml, which agreed well with the biochemical measurement of 38.7±16.7 µg/ml. Color coded maps of parameter values were overlaid on B-mode images to show spatiotemporal changes in cell diameter and calcium deposition. This study demonstrates the use of non-destructive ultrasound imaging to provide quantitative information on the number and differentiated state of cells embedded within 3D engineered constructs, and therefore presents a valuable tool for longitudinal monitoring of engineered tissue development. PMID:24465680

Gudur, Madhu Sudhan Reddy; Rao, Rameshwar R; Peterson, Alexis W; Caldwell, David J; Stegemann, Jan P; Deng, Cheri X

2014-01-01

216

The role of quantitative Schlieren assessment of physiotherapy ultrasound fields in describing variations between tissue heating rates of different transducers.  

PubMed

Differences in tissue heating rates between ultrasound transducers have been well documented; however, comparative analysis between ultrasound fields to determine why tissue heating rates may differ is lacking. We selected three transducers from the same manufacturer with similar effective radiating area, output power, effective intensity and beam nonuniformity ratio [as defined by the FDA, 21 CFR Chap. 1, part 1,050 (10)], but markedly different Schlieren images. Each transducer was utilized to heat tissue with a standardized ultrasound application to determine whether Schlieren analysis may be useful in understanding variability in tissue heating rates. Thermocouples were inserted into the left triceps surae of 12 volunteers at a depth of 1.5 cm below one half the measured skin fold thickness (estimated average depth of the thermocouple was 1.99 +/- 0.27 cm). Each subject received one treatment from each transducer in a single session (n = 3); 3 MHz at 1.2 W/cm(2) for 8 min with a 100% duty cycle. Each transducer increased the IM temperature over time (p < 0.0001). IM temperatures were not significantly different between transducers from time zero to the fourth minute of treatment. After the fourth min, transducers B and C generated significantly higher tissue temperatures (p < 0.01). Transducer A, B and C increased IM temperature from 34.9 +/- 0.5 to 41.2 +/- 1.3 degrees C, 34.9 +/- 0.6 to 42.5 +/- 1.4 degrees C and 34.9 +/- 0.5 to 42.7 +/- 1.7 degrees C, respectively. Interestingly, transducer C emitted 22% lower output power but heated 24% higher than transducer A and our Schlieren images demonstrate that transducers B and C produced a more concentrated field compared with transducer A. The data we present here supports the general contention that a more concentrated field will heat to a higher temperature than a more disperse field, however, technical challenges in estimating output power, ERA and Schlieren analysis remain an issue. PMID:17698281

Johns, Lennart D; Demchak, Timothy J; Straub, Stephen J; Howard, Samuel M

2007-12-01

217

Effect of ethanol injection on cavitation and heating of tissues exposed to high-intensity focused ultrasound  

NASA Astrophysics Data System (ADS)

Cavitation activity and temperature rise have been investigated in a tissue-mimicking material and excised bovine liver treated with ethanol and insonated with a 0.825 MHz focused acoustic transducer. The acoustic power was varied from 1.3 to 26.8 W to find the threshold leading to the onset of inertial cavitation. Cavitation events were quantified by three independent techniques: B-mode ultrasound imaging, needle hydrophone measurements and passive cavitation detection. Temperature in or near the focal zone was measured by thermocouples embedded in the samples. The results of this study indicate that the treatment of tissue phantoms and bovine liver samples with ethanol reduces their threshold power for inertial cavitation. This in turn leads to a sudden rise in temperature in ethanol-treated samples at a lower acoustic power than that in untreated ones. The analysis of passive cavitation detection data shows that once the threshold acoustic power is reached, inertial cavitation becomes a major contributor to acoustic scattering in ethanol-treated phantoms and bovine liver samples as compared to control. This study opens up the possibility of improved tumor ablation therapy via a combination of percutaneous ethanol injection and high-intensity focused ultrasound.

Chen, C.; Liu, Y.; Maruvada, S.; Myers, M.; Khismatullin, D.

2012-02-01

218

Mechanical bioeffects of ultrasound.  

PubMed

Ultrasound is used widely in medicine as both a diagnostic and therapeutic tool. Through both thermal and nonthermal mechanisms, ultrasound can produce a variety of biological effects in tissues in vitro and in vivo. This chapter provides an overview of the fundamentals of key nonthermal mechanisms for the interaction of ultrasound with biological tissues. Several categories of mechanical bioeffects of ultrasound are then reviewed to provide insight on the range of ultrasound bioeffects in vivo, the relevance of these effects to diagnostic imaging, and the potential application of mechanical bioeffects to the design of new therapeutic applications of ultrasound in medicine. PMID:15255769

Dalecki, Diane

2004-01-01

219

Ultrasound and hypersound generation of new-type solitons and bisolitons in crystals  

NASA Astrophysics Data System (ADS)

It has been shown that the principally new-type solitons and bisolitons are generated during the pulse impact of ultrasound and hypersound on crystal monatomic materials in addition to the known solitons. New-type bisolitons analogous to the bisolitons previously found by an analytical approach have been discovered with the use of the molecular dynamics method. It has been shown that the dispersion curve of these bisolitons is close to the dispersion curve of the conventional solitons. A subsonic compression soliton, the dispersion curve of which crosses the phonon dispersion curve, has been found along with the known supersonic compression soliton. The characteristics of the new-type solitons and bisolitons in uranium and plutonium crystal lattices are presented.

Dubovsky, O. A.; Orlov, A. V.

2012-12-01

220

Speckle Tracking Ultrasound for Assessment of the Relative Motion of Flexor Tendon and Subsynovial Connective Tissue in the Human Carpal Tunnel  

PubMed Central

The objective of this study was to compare tissue Doppler imaging and speckle tracking ultrasound to assess the relative motion of flexor tendon and surrounding subsynovial connective tissue (SSCT). Twenty normal human wrists were imaged with an ultrasound scanner. The two ultrasound methods measured the excursion and maximum velocity of the tendon and SSCT while subjects gripped three different sized acrylic tubes, and these were correlated with tendon excursions estimated from finger joint angle changes. The maximum velocity ratio (=SSCT/tendon velocity) and the shear index (=[(Tendon excursion?SSCT excursion)/Tendon excursion]×100%) were calculated. The intraclass correlation coefficient was higher for joint angle/speckle tracking tendon excursion (0.642) than for joint angle/tissue Doppler excursion (0.377). The speckle tracking method could also discriminate differences in maximum velocity ratio and shear index for different tube sizes. We conclude that speckle tracking may be useful in assessing the relative motion of tendon and SSCT.

Yoshii, Yuichi; Villarraga, Hector R.; Henderson, Jacqueline; Zhao, Chunfeng; An, Kai-Nan; Amadio, Peter C.

2009-01-01

221

Shock-induced heating and millisecond boiling in gels and tissue due to high intensity focused ultrasound.  

PubMed

Nonlinear propagation causes high-intensity ultrasound waves to distort and generate higher harmonics, which are more readily absorbed and converted to heat than the fundamental frequency. Although such nonlinear effects have been investigated previously and found to not significantly alter high-intensity focused ultrasound (HIFU) treatments, two results reported here change this paradigm. One is that at clinically relevant intensity levels, HIFU waves not only become distorted but form shock waves in tissue. The other is that the generated shock waves heat the tissue to boiling in much less time than predicted for undistorted or weakly distorted waves. In this study, a 2-MHz HIFU source operating at peak intensities up to 25,000 W/cm(2) was used to heat transparent tissue-mimicking phantoms and ex vivo bovine liver samples. Initiation of boiling was detected using high-speed photography, a 20-MHz passive cavitation detector and fluctuation of the drive voltage at the HIFU source. The time to boil obtained experimentally was used to quantify heating rates and was compared with calculations using weak shock theory and the shock amplitudes obtained from nonlinear modeling and measurements with a fiber optic hydrophone. As observed experimentally and predicted by calculations, shocked focal waveforms produced boiling in as little as 3 ms and the time to initiate boiling was sensitive to small changes in HIFU output. Nonlinear heating as a result of shock waves is therefore important to HIFU, and clinicians should be aware of the potential for very rapid boiling because it alters treatments. PMID:20018433

Canney, Michael S; Khokhlova, Vera A; Bessonova, Olga V; Bailey, Michael R; Crum, Lawrence A

2010-02-01

222

Shearwave dispersion ultrasound vibrometry (SDUV) for measuring tissue elasticity and viscosity  

Microsoft Academic Search

Characterization of tissue elasticity (stiffness) and viscosity has important medical applications because these properties are closely related to pathological changes. Quantitative measurement is more suitable than qualitative measurement (i.e., mapping with a relative scale) of tissue viscoelasticity for diagnosis of diffuse diseases where abnormality is not confined to a local region and there is no normal background tissue to provide

Shigao Chen; M. Urban; C. Pislaru; R. Kinnick; Yi Zheng; Aiping Yao; J. Greenleaf

2009-01-01

223

Optimization of Contrast-to-Tissue Ratio by Adaptation of Transmitted Ternary Signal in Ultrasound Pulse Inversion Imaging  

PubMed Central

Ultrasound contrast imaging has provided more accurate medical diagnoses thanks to the development of innovating modalities like the pulse inversion imaging. However, this latter modality that improves the contrast-to-tissue ratio (CTR) is not optimal, since the frequency is manually chosen jointly with the probe. However, an optimal choice of this command is possible, but it requires precise information about the transducer and the medium which can be experimentally difficult to obtain, even inaccessible. It turns out that the optimization can become more complex by taking into account the kind of generators, since the generators of electrical signals in a conventional ultrasound scanner can be unipolar, bipolar, or tripolar. Our aim was to seek the ternary command which maximized the CTR. By combining a genetic algorithm and a closed loop, the system automatically proposed the optimal ternary command. In simulation, the gain compared with the usual ternary signal could reach about 3.9?dB. Another interesting finding was that, in contrast to what is generally accepted, the optimal command was not a fixed-frequency signal but had harmonic components.

Girault, Jean-Marc

2013-01-01

224

DNA methylation age of human tissues and cell types  

PubMed Central

Background It is not yet known whether DNA methylation levels can be used to accurately predict age across a broad spectrum of human tissues and cell types, nor whether the resulting age prediction is a biologically meaningful measure. Results I developed a multi-tissue predictor of age that allows one to estimate the DNA methylation age of most tissues and cell types. The predictor, which is freely available, was developed using 8,000 samples from 82 Illumina DNA methylation array datasets, encompassing 51 healthy tissues and cell types. I found that DNA methylation age has the following properties: first, it is close to zero for embryonic and induced pluripotent stem cells; second, it correlates with cell passage number; third, it gives rise to a highly heritable measure of age acceleration; and, fourth, it is applicable to chimpanzee tissues. Analysis of 6,000 cancer samples from 32 datasets showed that all of the considered 20 cancer types exhibit significant age acceleration, with an average of 36 years. Low age-acceleration of cancer tissue is associated with a high number of somatic mutations and TP53 mutations, while mutations in steroid receptors greatly accelerate DNA methylation age in breast cancer. Finally, I characterize the 353 CpG sites that together form an aging clock in terms of chromatin states and tissue variance. Conclusions I propose that DNA methylation age measures the cumulative effect of an epigenetic maintenance system. This novel epigenetic clock can be used to address a host of questions in developmental biology, cancer and aging research.

2013-01-01

225

Analysis of Temperature Rise Induced by High-Intensity Focused Ultrasound in Tissue-Mimicking Gel Considering Cavitation Bubbles  

NASA Astrophysics Data System (ADS)

High-intensity focused ultrasound (HIFU) causes a selective temperature rise in tissue and is used as a noninvasive method for tumor treatment. However, there is a problem in that it typically takes several hours to treat a large tumor. The development of a highly efficient method is required to shorten the treatment time. It is known that cavitation bubbles generated by HIFU enhance HIFU heating. In this study, the enhancement of the heating effect by cavitation was estimated in a numerical simulation solving a bio-heat transfer equation (BHTE) by increasing the absorption coefficients in and out of the volume of cavitation bubbles. The absorption coefficients were obtained by a curve fitting the temperature rise near the focal point between experiment and simulation. The results show that cavitation bubbles caused the increase in ultrasonic absorption not only in but also near the volume of cavitation bubbles.

Asai, Ayumu; Okano, Hiroki; Yoshizawa, Shin; Umemura, Shin-ichiro

2013-07-01

226

Simultaneous Measurement of Thermophysical Properties of Tissue-Mimicking Phantoms for High Intensity Focused Ultrasound (HIFU) Exposures  

NASA Astrophysics Data System (ADS)

Tissue-mimicking phantoms, including bovine serum albumin phantoms and egg white phantoms, have been developed for, and in laboratory use for, real-time visualization of high intensity focused ultrasound-induced thermal coagulative necrosis since 2001. However, until now, very few data are available concerning their thermophysical properties. In this article, a step-wise transient plane source method has been used to determine the values of thermal conductivity, thermal diffusivity, and specific heat capacity of egg white phantoms with elevated egg white concentrations (0 v/v% to 40 v/v%, by 10 v/v% interval) at room temperature (~20 °C). The measured thermophysical properties were close to previously reported values; the thermal conductivity and thermal diffusivity were linearly proportional to the egg white concentration within the investigation range, while the specific heat capacity decreased as the egg white concentration increased. Taking account of large differences between real experiment and ideal model, data variations within 20 % were accepted.

Gao, Jing; You, Jiang; Huang, Zhihong; Cochran, Sandy; Corner, George

2012-03-01

227

Listening to speech recruits specific tongue motor synergies as revealed by transcranial magnetic stimulation and tissue-Doppler ultrasound imaging.  

PubMed

The activation of listener's motor system during speech processing was first demonstrated by the enhancement of electromyographic tongue potentials as evoked by single-pulse transcranial magnetic stimulation (TMS) over tongue motor cortex. This technique is, however, technically challenging and enables only a rather coarse measurement of this motor mirroring. Here, we applied TMS to listeners' tongue motor area in association with ultrasound tissue Doppler imaging to describe fine-grained tongue kinematic synergies evoked by passive listening to speech. Subjects listened to syllables requiring different patterns of dorso-ventral and antero-posterior movements (/ki/, /ko/, /ti/, /to/). Results show that passive listening to speech sounds evokes a pattern of motor synergies mirroring those occurring during speech production. Moreover, mirror motor synergies were more evident in those subjects showing good performances in discriminating speech in noise demonstrating a role of the speech-related mirror system in feed-forward processing the speaker's ongoing motor plan. PMID:24778384

D'Ausilio, A; Maffongelli, L; Bartoli, E; Campanella, M; Ferrari, E; Berry, J; Fadiga, L

2014-01-01

228

Thermal fixation of Swine liver tissue after magnetic resonance-guided high-intensity focused ultrasound ablation.  

PubMed

The aim of this study was to investigate experimental conditions for efficient and controlled in vivo liver tissue ablation by magnetic resonance (MR)-guided high-intensity focused ultrasound (HIFU) in a swine model, with the ultimate goal of improving clinical treatment outcome. Histological changes were examined both acutely (four animals) and 1 wk after treatment (five animals). Effects of acoustic power and multiple sonication cycles were investigated. There was good correlation between target size and observed ablation size by thermal dose calculation, post-procedural MR imaging and histopathology, when temperature at the focal point was kept below 90°C. Structural histopathology investigations revealed tissue thermal fixation in ablated regions. In the presence of cavitation, mechanical tissue destruction occurred, resulting in an ablation larger than the target. Complete extra-corporeal MR-guided HIFU ablation in the liver is feasible using high acoustic power. Nearby large vessels were preserved, which makes MR-guided HIFU promising for the ablation of liver tumors adjacent to large veins. PMID:24768489

Courivaud, Frédéric; Kazaryan, Airazat M; Lund, Alice; Orszagh, Vivian C; Svindland, Aud; Marangos, Irina Pavlik; Halvorsen, Per Steinar; Jebsen, Peter; Fosse, Erik; Hol, Per Kristian; Edwin, Bjørn

2014-07-01

229

Feasibility of optoacoustic visualization of high-intensity focused ultrasound-induced thermal lesions in live tissue  

PubMed Central

A 3-D optoacoustic imaging system was used to visualize thermal lesions produced in vivo using high-intensity focused ultrasound (HIFU). A 7.5-MHz, surgical, focused transducer with a radius of curvature of 35 mm and an aperture diameter of 23 mm was used to generate HIFU. A pulsed laser, which could operate at 755 nm and 1064 nm, was used to illuminate excised tissue and mice using a bifurcated fiber bundle resulting in two wide beams of light. Tomographic images were obtained while the specimens were rotated within a sphere outlined by a concave arc-shaped array of 64 piezo-composite transducers. These images were then combined to reconstruct 3-D volume images (voxel resolution 0.5 mm), which were acquired before and after HIFU exposure. In vivo optoacoustic images acquired at 1064 nm provided visualization of HIFU lesions. The lesion was indicated by a negative optoacoustic contrast. The molecular nature of such contrast may possibly be associated with reduction of the optical absorption due to reduced concentration of blood, tissue dehydration, denaturation of proteins and porphyrins, and reduction of thermoacoustic efficiency in the thermally treated tissue. These preliminary results demonstrate the potential of optoacoustic imaging to assess and monitor the progress of HIFU therapy.

Chitnis, Parag V.; Brecht, Hans-Peter; Su, Richard; Oraevsky, Alexander A.

2010-01-01

230

Feasibility of optoacoustic visualization of high-intensity focused ultrasound-induced thermal lesions in live tissue.  

PubMed

A 3-D optoacoustic imaging system was used to visualize thermal lesions produced in vivo using high-intensity focused ultrasound (HIFU). A 7.5-MHz, surgical, focused transducer with a radius of curvature of 35 mm and an aperture diameter of 23 mm was used to generate HIFU. A pulsed laser, which could operate at 755 nm and 1064 nm, was used to illuminate excised tissue and mice using a bifurcated fiber bundle resulting in two wide beams of light. Tomographic images were obtained while the specimens were rotated within a sphere outlined by a concave arc-shaped array of 64 piezo-composite transducers. These images were then combined to reconstruct 3-D volume images (voxel resolution 0.5 mm), which were acquired before and after HIFU exposure. In vivo optoacoustic images acquired at 1064 nm provided visualization of HIFU lesions. The lesion was indicated by a negative optoacoustic contrast. The molecular nature of such contrast may possibly be associated with reduction of the optical absorption due to reduced concentration of blood, tissue dehydration, denaturation of proteins and porphyrins, and reduction of thermoacoustic efficiency in the thermally treated tissue. These preliminary results demonstrate the potential of optoacoustic imaging to assess and monitor the progress of HIFU therapy. PMID:20459235

Chitnis, Parag V; Brecht, Hans-Peter; Su, Richard; Oraevsky, Alexander A

2010-01-01

231

Backward-mode multiwavelength photoacoustic scanner using a planar Fabry-Perot polymer film ultrasound sensor for high-resolution three-dimensional imaging of biological tissues  

Microsoft Academic Search

A multiwavelength backward-mode planar photoacoustic scanner for 3D imaging of soft tissues to depths of several millimeters with a spatial resolution in the tens to hundreds of micrometers range is described. The system comprises a tunable optical parametric oscillator laser system that provides nanosecond laser pulses between 600 and 1200 nm for generating the photoacoustic signals and an optical ultrasound

Edward Zhang; Jan Laufer; Paul Beard

2008-01-01

232

Comparative Study of the Topical Application of Aloe Vera Gel, Therapeutic Ultrasound and Phonophoresis on the Tissue Repair in Collagenase-Induced Rat Tendinitis  

Microsoft Academic Search

The aim of our study was to compare topical use of Aloe vera gel, pulsed mode ultrasound (US) and Aloe vera phonophoresis on rat paw with collagenase-induced tendinitis. Edema size, tensile tendon strength, tendon elasticity, number of inflammatory cells and tissue histology were studied at 7 and 14 days after tendinitis induction. Pulse mode US parameters were: 1 MHz frequency,

Antonio Luiz Martins Maia Filho; Antonio Balbin Villaverde; Egberto Munin; Flávio Aimbire; Regiane Albertini

2010-01-01

233

Heart rate, conduction and ultrasound abnormalities in adults with joint hypermobility syndrome/Ehlers-Danlos syndrome, hypermobility type.  

PubMed

Joint hypermobility syndrome (JHS) and Ehlers-Danlos syndrome, hypermobility type (EDS-HT) are two clinically overlapping heritable connective tissue disorders strongly associating with pain, fatigue and other secondary aspects. Though not considered a diagnostic criterion for most EDS subtypes, cardiovascular involvement is a well-known complication in EDS. A case-control study was carried out on 28 adults with JHS/EDS-HT diagnosed according to current criteria, compared to 29 healthy subjects evaluating resting electrocardiographic (ECG), 24-h ECG and resting heart ultrasound data. Results obtained in the ECG studies showed a moderate excess in duration of the PR interval and P wave, an excess of heart conduction and rate abnormalities and an increased rate of mitral and tricuspid valve insufficiency often complicating with "true" mitral valve prolapse in the ecocardiographic study. These variable ECG subclinical anomalies reported in our sample may represent the resting surrogate of such a subnormal cardiovascular response to postural changes that are known to be present in patients with JHS/EDS-HT. Our findings indicate the usefulness of a full cardiologic evaluation of adults with JHS/EDS-HT for the correct management. PMID:24752348

Camerota, Filippo; Castori, Marco; Celletti, Claudia; Colotto, Marco; Amato, Silvia; Colella, Alessandra; Curione, Mario; Danese, Chiara

2014-07-01

234

Facial soft tissue thickness in skeletal type I Japanese children.  

PubMed

Facial reconstruction techniques used in forensic anthropology require knowledge of the facial soft tissue thickness of each race if facial features are to be reconstructed correctly. If this is inaccurate, so also will be the reconstructed face. Knowledge of differences by age and sex are also required. Therefore, when unknown human skeletal remains are found, the forensic anthropologist investigates for race, sex, and age, and for other variables of relevance. Cephalometric X-ray images of living persons can help to provide this information. They give an approximately 10% enlargement from true size and can demonstrate the relationship between soft and hard tissue. In the present study, facial soft tissue thickness in Japanese children was measured at 12 anthropological points using X-ray cephalometry in order to establish a database for facial soft tissue thickness. This study of both boys and girls, aged from 6 to 18 years, follows a previous study of Japanese female children only, and focuses on facial soft tissue thickness in only one skeletal type. Sex differences in thickness of tissue were found from 12 years of age upwards. The study provides more detailed and accurate measurements than past reports of facial soft tissue thickness, and reveals the uniqueness of the Japanese child's facial profile. PMID:17298871

Utsuno, Hajime; Kageyama, Toru; Deguchi, Toshio; Umemura, Yasunobu; Yoshino, Mineo; Nakamura, Hiroshi; Miyazawa, Hiroo; Inoue, Katsuhiro

2007-10-25

235

The role of acoustic nonlinearity in tissue heating behind the rib cage using high intensity focused ultrasound phased array  

PubMed Central

The goal of this study was to investigate theoretically the effects of nonlinear propagation in a high intensity focused ultrasound (HIFU) field produced by a therapeutic phased array and the resultant heating of tissue behind a rib cage. Three configurations of focusing were simulated: in water, in water with ribs in the beam path, and in water with ribs backed by a layer of soft tissue. The Westervelt equation was used to model the nonlinear HIFU field and a 1 MHz phased array consisting of 254 circular elements was used as a boundary condition to the model. The temperature rise in tissue was modelled using the bioheat equation, and thermally necrosed volumes were calculated using the thermal dose formulation. The shapes of lesions predicted by the modelling were compared with those previously obtained in in vitro experiments at low power sonications. Intensity levels at the face of the array elements that corresponded to formation of high amplitude shock fronts in the focal region were determined as 10 W·cm?2 in the free field in water and 40 W·cm?2 in the presence of ribs. It was shown that exposures with shocks provided a substantial increase in tissue heating, and its better spatial localization in the main focal region only. The relative effects of overheating ribs and splitting of the focus due to the periodic structure of the ribs were therefore reduced. These results suggest that utilizing nonlinear propagation and shock formation effects can be beneficial for inducing confined HIFU lesions when irradiating through obstructions such as ribs. Design of compact therapeutic arrays to provide maximum power outputs with lower intensity levels at the elements is necessary to achieve shock wave regimes for clinically relevant sonication depths in tissue.

Yuldashev, Petr V.; Shmeleva, Svetlana M.; Ilyin, Sergey A.; Sapozhnikov, Oleg A.; Gavrilov, Leonid R.; Khokhlova, Vera A.

2013-01-01

236

Advances in Ultrasound Elastography  

Microsoft Academic Search

The purpose of elastography is to characterize from mechanical point of view a material (the soft biological tissues in the medical field). Ultrasound elastography is based on the comparison of ultrasound images, when the material is submitted under axial force (compression). This work presents the advances in the instrumentation of an ultrasound scanner, to acquire a sequence of images which

A. Basarab; J. F. Nava A; E. Royer; P. de Boissieu; P. Delachartre

2006-01-01

237

Two types of brown adipose tissue in humans  

PubMed Central

During the last years the existence of metabolically active brown adipose tissue in adult humans has been widely accepted by the research community. Its unique ability to dissipate chemical energy stored in triglycerides as heat makes it an attractive target for new drugs against obesity and its related diseases. Hence the tissue is now subject to intense research, the hypothesis being that an expansion and/or activation of the tissue is associated with a healthy metabolic phenotype. Animal studies provide evidence for the existence of at least two types of brown adipocytes. Apart from the classical brown adipocyte that is found primarily in the interscapular region where it constitutes a thermogenic organ, a second type of brown adipocyte, the so-called beige adipocyte, can appear within white adipose tissue depots. The fact that the two cell types develop from different precursors suggests that they might be recruited and stimulated by different cues and therefore represent two distinct targets for therapeutic intervention. The aim of this commentary is to discuss recent work addressing the question whether also humans possess two types of brown adipocytes and to highlight some issues when looking for molecular markers for such cells.

Lidell, Martin E; Betz, Matthias J; Enerback, Sven

2014-01-01

238

CAROTID ULTRASOUND, BLOOD LIPIDS AND WAIST DETERMINATION CAN PREDICT A FUTURE CORONARY REVASCULARISATION IN THE TYPE 2 DIABETIC COHORT  

Microsoft Academic Search

A b s t r a c t: The aim of the study was to identify incremental values of carotid ultrasound measurements (carotid plaques and stenosis) on the prediction of future coronary revascularization among type 2 diabetic patients. The second objective was to determine the predictive value of the assessment of blood lipids, BMI, abdominal obesity and the ankle-brachial index

Georgievska-Ismail Lj

239

Miniaturized fiber-optic ultrasound probes for endoscopic tissue analysis by micro-opto-mechanical technology.  

PubMed

A new Micro-Opto-Mechanical System (MOMS) technology for the fabrication of optoacoustic probes on optical fiber is presented. The technology is based on the thermoelastic emission of ultrasonic waves from patterned carbon films for generation and on extrinsic polymer Fabry-Perot acousto-optical transducers for detection, both fabricated on miniaturized single-crystal silicon frames used to mount the ultrasonic transducers on the tip of an optical fiber. Thanks to the fabrication process adopted, high miniaturization levels are reached in the MOMS devices, demonstrating fiber-optic emitters and detectors with minimum diameter around 350 and 250 ?m respectively. A thorough functional testing of the ultrasound emitters mounted on 200 and 600 ?m diameter optical fibers is presented, in which the fiber-optic emitter with a diameter of 200 ?m shows generated acoustic pressures with peak-to-peak value up to 2.8 MPa with rather flat emission spectra extended beyond 150 MHz. The possibility to use the presented optoacoustic sources in conjunction with the fiber-optic acousto-optical detectors within a minimally invasive probe is also demonstrated by successfully measuring the ultrasonic echo reflected from a rigid surface immersed in water with various concentration of scatterers. The resulting spectra highlight the possibility to discriminate the effects due to frequency selective attenuation in a very wide range of frequencies within a biological medium using the presented fiber-optic probes. PMID:24573502

Vannacci, E; Belsito, L; Mancarella, F; Ferri, M; Veronese, G P; Roncaglia, A; Biagi, E

2014-06-01

240

Thresholds for nonlinear effects in high- intensity focused ultrasound propagation and tissue heating.  

PubMed

For a variety of reasons, including their simplicity and ability to capitalize upon superposition, linear acoustic propagation models are preferable to nonlinear ones in modeling the propagation of high-intensity focused ultrasound (HIFU) beams. However, under certain conditions, nonlinear models are necessary to accurately model the beam propagation and heating. In analyzing the performance of a HIFU system, it is advantageous to know before the analysis whether a linear model suffices. This paper examines the problem of determining the thresholds at which nonlinear effects become important. It is demonstrated that nonlinear interaction has different effects on different physical and derived quantities, such as compressional pressure, rarefactional pressure, intensity, heat rate, temperature rise, and thermal lesion volume. Thresholds are determined as a function of the dimensionless gain, nonlinearity, and absorption parameters. The relative difference between linear and nonlinear predictions is plotted as a series of contours, enabling practitioners to locate their system in parameter space and determine whether nonlinearity significantly affects the quantities of interest. PMID:21041132

Soneson, Joshua E; Myers, Matthew R

2010-11-01

241

Measurement of Viscoelastic Properties of Polyacrylamide-Based Tissue-Mimicking Phantoms for Ultrasound Elastography Applications  

Microsoft Academic Search

Many ailments and\\/or malfunctions of the body have been observed to change the viscous behavior and elastic properties of biological soft tissues. The technique of elastography has evolved to image such properties. The clinical evidence gathered during studies involving elastography to identify cancerous lesions is very promising. However, the quantification of the resolution and specificity of elastography is best achieved

Kishore Kumar; Maneesha E. Andrews; V. Jayashankar; Ashok K. Mishra; S. Suresh

2010-01-01

242

Measuring the acoustoelectric interaction constant in cardiac tissue using ultrasound current source density imaging  

Microsoft Academic Search

This paper demonstrates the first measurement of the acoustoelectric (AE) interaction constant in cardiac tissue. Radiofrequency catheter ablation is performed in clinics as a standard treatment for cardiac arrhythmia with a high success rate. The procedure requires a detailed map of the heart's activation wave prior to treatment. Conventional electrical mapping techniques are slow, prone to registration errors and have

Qian Li; Ragnar Olafsson; Pier Ingram; Zhaohui Wang; Russell S. Witte

2010-01-01

243

Collection of villous tissue under ultrasound guidance to improve the cytogenetic study of early pregnancy failure  

Microsoft Academic Search

BACKGROUND: The cytogenetic study of spontaneous miscarriage has been limited by poor karyotype success rates obtained from cell culture after surgical evacuation of retained products of conception. The aim of this study was to assess the effect of improving the method of collection of villous tissues at the time of surgery on the karyotype success rate of cell culture. METHODS:

Natalie Greenwold; Eric Jauniaux

244

No effect of bipolar interferential electrotherapy and pulsed ultrasound for soft tissue shoulder disorders: a randomised controlled trial  

PubMed Central

OBJECTIVE—To assess the efficacy of bipolar interferential electrotherapy (ET) and pulsed ultrasound (US) as adjuvants to exercise therapy for soft tissue shoulder disorders (SD).?METHODS—Randomised placebo controlled trial with a two by two factorial design plus an additional control group in 17 primary care physiotherapy practices in the south of the Netherlands. Patients with shoulder pain and/or restricted shoulder mobility, because of a soft tissue impairment without underlying specific or generalised condition, were enrolled if they had not recovered after six sessions of exercise therapy in two weeks. They were randomised to receive (1) active ET plus active US; (2) active ET plus dummy US; (3) dummy ET plus active US; (4) dummy ET plus dummy US; or (5) no adjuvants. Additionally, they received a maximum of 12 sessions of exercise therapy in six weeks. Measurements at baseline, 6 weeks and 3, 6, 9, and 12 months later were blinded for treatment. Outcome measures: recovery, functional status, chief complaint, pain, clinical status, and range of motion.?RESULTS—After written informed consent 180 patients were randomised: both the active treatments were given to 73 patients, both the dummy treatments to 72 patients, and 35 patients received no adjuvants. Prognosis of groups appeared similar at baseline. Blinding was successfully maintained. At six weeks seven patients (20%) without adjuvants reported very large improvement (including complete recovery), 17 (23%) and 16 (22%) with active and dummy ET, and 19 (26%) and 14 (19%) with active and dummy US. These proportions increased to about 40% at three months, but remained virtually stable thereafter. Up to 12 months follow up the 95% CI for differences between groups for all outcomes include zero.?CONCLUSION—Neither ET nor US prove to be effective as adjuvants to exercise therapy for soft tissue SD.??

van der Heijden, G. J M G; Leffers, P.; Wolters, P.; Verheijden, J.; van Mameren, H.; Houben, J.; Bouter, L.; Knipschild, P.

1999-01-01

245

Increasing frame rate in ultrasound imaging by temporal morphing using tissue Doppler  

Microsoft Academic Search

The diagnostic value of echocardiographic images seems to diminish when the frame rate is low. In this work, morphing based on velocity information was used to improve the perceived smoothness of B-mode cine-loops with low frame rate. Based on an estimate of the velocity field calculated from B-mode speckle tracking and tissue Doppler measurements, morphed cine-loops with arbitrarily high frame

Svein Brekke; Charlotte B. Ingul; Svein A. Aase; Hans G. Torp

2006-01-01

246

Cardiac motion analysis from ultrasound sequences using nonrigid registration: Validation against Doppler tissue velocity  

Microsoft Academic Search

Early detection of cardiac motion abnormalities is one of the main goals of quantitative cardiac image processing. This article presents a new method to compute the 2-D myocardial motion parameters from gray-scale 2-D echocardiographic sequences, making special emphasis on the validation of the proposed technique in comparison with Doppler tissue imaging. Myocardial motion is computed using a frame-to-frame nonrigid registration

M. J. Ledesma-Carbayo; P. Mahía-Casado; A. Santos; E. Pérez-David; M. A. García-Fernández; M. Desco

2006-01-01

247

Recent developments in tissue-type imaging (TTI) for planning and monitoring treatment of prostate cancer.  

PubMed

Because current methods of imaging prostate cancer are inadequate, biopsies cannot be effectively guided and treatment cannot be effectively planned and targeted. Therefore, our research is aimed at ultrasonically characterizing cancerous prostate tissue so that we can image it more effectively and thereby provide improved means of detecting, treating and monitoring prostate cancer. We base our characterization methods on spectrum analysis of radiofrequency (rf) echo signals combined with clinical variables such as prostate-specific antigen (PSA). Tissue typing using these parameters is performed by artificial neural networks. We employed and evaluated different approaches to data partitioning into training, validation, and test sets and different neural network configuration options. In this manner, we sought to determine what neural network configuration is optimal for these data and also to assess possible bias that might exist due to correlations among different data entries among the data for a given patient. The classification efficacy of each neural network configuration and data-partitioning method was measured using relative-operating-characteristic (ROC) methods. Neural network classification based on spectral parameters combined with clinical data generally produced ROC-curve areas of 0.80 compared to curve areas of 0.64 for conventional transrectal ultrasound imaging combined with clinical data. We then used the optimal neural network configuration to generate lookup tables that translate local spectral parameter values and global clinical-variable values into pixel values in tissue-type images (TTIs). TTIs continue to show cancerous regions successfully, and may prove to be particularly useful clinically in combination with other ultrasonic and nonultrasonic methods, e.g., magnetic-resonance spectroscopy. PMID:15754797

Feleppa, Ernest J; Porter, Christopher R; Ketterling, Jeffrey; Lee, Paul; Dasgupta, Shreedevi; Urban, Stella; Kalisz, Andrew

2004-07-01

248

Evaluation of Virtual Touch Tissue Imaging Quantification, a New Shear Wave Velocity Imaging Method, for Breast Lesion Assessment by Ultrasound  

PubMed Central

Objectives. To evaluate virtual touch tissue imaging quantification (VTIQ) as a new elastography method concerning its intra- and interexaminer reliability and its ability to differentiate benign from malignant breast lesions in comparison to and in combination with ultrasound (US) B-mode breast imaging reporting and data system (BI-RADS) assessment. Materials and Methods. US and VTIQ were performed by two examiners in 103 women with 104 lesions. Intra- and interexaminer reliability of VTIQ was assessed. The area under the receiver operating curve (AUC), sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) of BIRADS, VTIQ, and combined data were compared. Results. Fifty-four of 104 lesions were malignant. Intraexaminer reliability was consistent, and interexaminer agreement showed a strong positive correlation (r = 0.93). The mean VTIQ values in malignant lesions were significantly higher than those in benign (7.73?m/s ± 1.02 versus 4.46?m/s ± 1.87; P < 0.0001). The combination of US-BIRADS with the optimal cut-off for clinical decision making of 5.18?m/s yielded a sensitivity of 98%, specificity of 82%, PPV of 86%, and NPV of 98%. The combination of BIRADS and VTIQ led to improved test validity. Conclusion. VTIQ is highly reliable and reproducible. There is a significant difference regarding the mean maximum velocity of benign and malignant lesions. Adding VTIQ to BIRADS assessment improves the specificity.

Harcos, Aba; Schott, Sarah; Gomez, Christina; Stieber, Anne; Rauch, Geraldine; Domschke, Christoph; Rom, Joachim; Schutz, Florian; Sohn, Christof; Heil, Jorg

2014-01-01

249

Characterizing tissue microstructure using an ultrasound system-independent spatial autocorrelation function  

NASA Astrophysics Data System (ADS)

The research described in this dissertation is related to characterization of tissue microstructure using a system- independent spatial autocorrelation function (SAF). The function was determined using a reference phantom method, which employed a well-defined ``point- scatterer'' reference phantom to account for instrumental factors. The SAF's were estimated for several tissue-mimicking (TM) phantoms and fresh dog livers. Both phantom tests and in vitro dog liver measurements showed that the reference phantom method is relatively simple and fairly accurate, providing the bandwidth of the measurement system is sufficient for the size of the scatterer being involved in the scattering process. Implementation of this method in clinical scanner requires that distortions from patient's body wall be properly accounted for. The SAF's were estimated for two phantoms with body-wall-like distortions. The experimental results demonstrated that body wall distortions have little effect if echo data are acquired from a large scattering volume. One interesting application of the SAF is to form a ``scatterer size image''. The scatterer size image may help providing diagnostic tools for those diseases in which the tissue microstructure is different from the normal. Another method, the BSC method, utilizes information contained in the frequency dependence of the backscatter coefficient to estimate the scatterer size. The SAF technique produced accurate scatterer size images of homogeneous TM phantoms and the BSC method was capable of generating accurate size images for heterogeneous phantoms. In the scatterer size image of dog kidneys, the contrast-to-noise-ratio (CNR) between renal cortex and medulla was improved dramatically compared to the gray- scale image. The effect of nonlinear propagation was investigated by using a custom-designed phantom with overlaying TM fat layer. The results showed that the correlation length decreased when the transmitting power increased. The measurement results support the assumption that nonlinear propagation generates harmonic energies and causes underestimation of scatterer diameters. Nonlinear propagation can be further enhanced by those materials with high B/A value-a parameter which characterizes the degree of nonlinearity. Nine versions of TM fat and non-fat materials were measured for their B/A values using a new measurement technique, the ``simplified finite amplitude insertion substitution'' (SFAIS) method.

Dong, Fang

1999-09-01

250

Basic Physics of Ultrasound Imaging.  

National Technical Information Service (NTIS)

Presents a history of ultrasound, explaining the principles of transducer design and operation. Focuses on the physics of sound, the basic interactions of sound and tissue, sound detection and imaging and imaging instruments. Primary audience: ultra-sound...

1994-01-01

251

Doppler ultrasound findings correlate with tissue vascularity and inflammation in surgical pathology specimens from patients with small intestinal Crohn's disease  

PubMed Central

Background Crohn’s disease (CD) is routinely evaluated using clinical symptoms, laboratory variables, and the CD activity index (CDAI). However, clinical parameters are often nonspecific and do not precisely reflect the actual activity of CD small-intestinal lesions. The purposes of this prospective study were to compare color Doppler ultrasound (US) findings with histological findings from surgically resected specimens and confirm the hypothesis that color Doppler US can distinguish tissue inflammation and fibrosis. Methods Among 1764 consecutive patients who underwent color Doppler US examinations, 10 patients with CD (12 small-intestinal CD lesions) who underwent US examinations before elective small-intestine resection were evaluated in the present study. Areas of thickened intestinal walls were evaluated in terms of blood flow using color Doppler US imaging. The blood flow was semiquantitatively classified as “hyper-flow” and “hypo-flow” according to the Limberg score. Resected lesions were macroscopically and histopathologically processed. Inflammatory cell infiltration, fibrosis and vascularity were evaluated by myeloperoxidase (granulocytes), CD163 (macrophages), CD79a (B cells), CD3 (T cells), Masson’s trichrome (fibrosis), and factor VIII staining (vascular walls). All histopathological images were entered into virtual slide equipment and quantified using a quantitative microscopy integrated system (TissueMorph™). Results There were no significant differences in disease features or laboratory findings between “hypo-flow” lesions (n?=?4) and “hyper-flow” lesions (n?=?8). Histopathologically, “hyper-flow” lesions showed significantly greater bowel wall vascularity (factor VIII) (p?=?0.047) and inflammatory cell infiltration, including CD163 macrophages (p?=?0.008), CD3 T cells, and CD79a B cells (p?=?0.043), than did “hypo-flow” lesions. There was no apparent association between the blood flow and CDAI. Conclusions In this study, active CD lesions were macroscopically visible in surgical specimens of patients with increased blood flow on preoperative color Doppler US imaging. Additionally, these CD lesions exhibited significantly greater vascularity and numbers of inflammatory leukocytes microscopically. Color Doppler US may predict tissue inflammation and fibrosis in small-intenstinal CD lesions.

2014-01-01

252

The Speed of Sound and Attenuation of an IEC Agar-Based Tissue-Mimicking Material for High Frequency Ultrasound Applications  

PubMed Central

This study characterized the acoustic properties of an International Electromechanical Commission (IEC) agar-based tissue mimicking material (TMM) at ultrasound frequencies in the range 10–47 MHz. A broadband reflection substitution technique was employed using two independent systems at 21°C ± 1°C. Using a commercially available preclinical ultrasound scanner and a scanning acoustic macroscope, the measured speeds of sound were 1547.4 ± 1.4 m?s?1 and 1548.0 ± 6.1 m?s?1, respectively, and were approximately constant over the frequency range. The measured attenuation (dB?cm?1) was found to vary with frequency f (MHz) as 0.40f + 0.0076f2. Using this polynomial equation and extrapolating to lower frequencies give values comparable to those published at lower frequencies and can estimate the attenuation of this TMM in the frequency range up to 47 MHz. This characterisation enhances understanding in the use of this TMM as a tissue equivalent material for high frequency ultrasound applications.

Sun, Chao; Pye, Stephen D.; Browne, Jacinta E.; Janeczko, Anna; Ellis, Bill; Butler, Mairead B.; Sboros, Vassilis; Thomson, Adrian J.W.; Brewin, Mark P.; Earnshaw, Charles H.; Moran, Carmel M.

2012-01-01

253

Visibility of foreign bodies in soft tissue in plain radiographs, computed tomography, magnetic resonance imaging, and ultrasound. An in vitro study.  

PubMed

We compared conventional plain radiography, computed tomography (CT), magnetic resonance imaging (MRI), and ultrasound (US) with respect to their suitability for detecting foreign bodies in soft tissue in an in vitro model using a cow tongue to simulate orofacial soft tissues. Four samples of different sizes of fractured tooth crown, pieces of amalgam, glass, asphalt, composite, dry wood, and stone were each embedded under a 2-cm-thick flap on the caudal surface of the tongue. Plain radiographs revealed all the materials except wood, and there was some variation in the subjectively evaluated radiopacity of the materials which indicated the nature of the foreign bodies concerned. MRI proved to be the least suitable imaging method, as particles with a metallic content gave rise to powerful interference artifacts. CT and especially US proved to be suitable imaging methods for foreign-body detection in soft tissue. Amalgam produced a metallic streaking artifact in CT, which visualized wood as gas density, and depicted all the other materials as similar hyperdense masses. Ultrasound was both sensitive and specific in detecting foreign bodies in soft tissue. The particles were better defined in form and size with CT and US than with MRI or plain radiography. We conclude that when plain radiographs, history, and clinical examination fail to reveal the presence of superficial foreign bodies, US or CT can serve as an alternative method. PMID:8320449

Oikarinen, K S; Nieminen, T M; Mäkäräinen, H; Pyhtinen, J

1993-04-01

254

Simulation of ultrasound radio-frequency signals in deformed tissue for validation of 2D motion estimation with sub-sample accuracy.  

PubMed

Motion estimation in sequences of ultrasound echo signals is essential for a wide range of applications. In time domain cross correlation, which is a common motion estimation technique, the displacements are typically not integral multiples of the sampling period. Therefore, to estimate the motion with sub-sample accuracy, 1D and 2D interpolation methods such as parabolic, cosine, and ellipsoid fitting have been introduced in the literature. In this paper, a simulation framework is presented in order to compare the performance of currently available techniques. First, the tissue deformation is modeled using the finite element method (FEM) and then the corresponding pre-/post-deformation radio-frequency (RF) signals are generated using Field II ultrasound simulation software. Using these simulated RF data of deformation, both axial and lateral tissue motion are estimated with sub-sample accuracy. The estimated displacements are then evaluated by comparing them to the known displacements computed by the FEM. This simulation approach was used to evaluate three different lateral motion estimation techniques employing (i) two separate 1D sub-sampling, (ii) two consecutive 1D sub-sampling, and (iii) 2D joint sub-sampling estimators. The estimation errors during two different tissue compression tests are presented with and without spatial filtering. Results show that RF signal processing methods involving tissue deformation can be evaluated using the proposed simulation technique, which employs accurate models. PMID:18002416

Goksel, Orcun; Zahiri-Azar, Reza; Salcudean, Septimiu E

2007-01-01

255

Intravascular ultrasound  

MedlinePLUS

IVUS; Ultrasound - coronary artery; Endovascular ultrasound; Intravascular echocardiography ... A tiny ultrasound wand is attached to the top of a tiny tube called a catheter. This ultrasound catheter is inserted ...

256

Ultrasound thermometry in hyperthermia  

Microsoft Academic Search

A hyperthermia thermometry system using an ultrasound nonlinear effect caused by superposed pulses was developed. A feasibility study was made to obtain temperature mapping of tissue phantoms and of anesthetized pigs heated by an ultrasound applicator. The thermometry system consists of a mechanical sector scanner and a mainframe with a color monitor. The distribution of the temperature rise is calculated

S. Ueno; M. Hashimoto; H. Fukukita; T. Yano

1990-01-01

257

Diagnostic efficacy of the cell block method in comparison with smear cytology of tissue samples obtained by endoscopic ultrasound-guided fine-needle aspiration  

Microsoft Academic Search

Background  The diagnostic efficacy of endoscopic ultrasound-guided fine-needle aspiration (EUS-FNA) cytology may vary greatly depending\\u000a on the treatment of the samples obtained and the level of proficiency of the cytopathologist or cytoscreener.\\u000a \\u000a \\u000a \\u000a \\u000a Methods  We prospectively evaluated the diagnostic efficacy of the cell block (CB) method and that of smear cytology using tissue samples\\u000a obtained in the same needle pass at EUS-FNA in

Yutaka Noda; Naotaka Fujita; Go Kobayashi; Kei Itoh; Jun Horaguchi; Takasawa T. Obana; Takashi Obana; Shinsuke Koshita; Yoshihide Kanno; Takashi Suzuki; Dai Hirasawa; Toshiki Sugawara; Tetsuya Ohira; Yoshihiro Harada; Takashi Tsuchiya; Takashi Sawai; Miwa Uzuki; Akira Kurose

2010-01-01

258

Non-invasive temperature assessment at different tissue types based on average grey-level from B-mode ultrasonic images  

NASA Astrophysics Data System (ADS)

The average grey-levels calculated from B-Mode images were assessed for non-invasive temperature estimation in a porcine tissue sample containing two different tissue types, fat and muscle. The porcine sample was subjected to heating and cooling procedures with temperature varying from 35°C to 42°C. The sample was continuously imaged with an ultrasound scanner, and simultaneously the temperature was measured at each 5 seconds using Type-T thermocouples. The result shows that the average grey-level (AVGL)/temperature relations are different for the two studied regions, where the muscle tissue tends to present a bigger AVGL variation than the fat tissue considering the same temperature variation. Besides, the average grey-level/temperature functions estimated for each tissue region presented fitting errors inferior to +/- 0.21°C, indicating that it might be possible to track temperature changes from both tissues using AVGL. This result is innovative since it suggests that using the same B-mode image and an average grey-level/temperature function to each region it is possible to estimate non-invasively temperature variations from different tissue regions in the same tissue sample. Future work includes the investigation of the spatial limits of these average grey-level/temperature functions.

Alvarenga, A. V.; Teixeira, C. A.; Krüger, M. A. Von; Pereira, W. C. A.

2012-05-01

259

Infrared Thermography and Ultrasonography to Indirectly Monitor the Influence of Liner Type and Overmilking on Teat Tissue Recovery  

PubMed Central

Eight Danish Holstein cows were milked with a 1-mm thick specially designed soft liner on their right rear teat and a standard liner mounted under extra high tension on their left rear teat. Four of the animals were overmilked for 5 min. Rear teats were subjected to ultrasound examination on the first day and to infrared thermography on the second day. Teats were submersed in ethanol 20 min post-milking on the second day. Ultrasonography measurements showed that teat canal length increased by 30–41% during milking. Twenty minutes after milking, teats milked with modified standard liners still had elongated teat canals while teats milked with the soft liner were normalized. Overmilking tended to increase teat wall thickness. Approximately 80% of variability in teat canal length, from before teat preparation to after milking, could be explained by changes during teat preparation. Thermography indicated a general drop in teat temperature during teat preparation. Teat temperature increased during milking and continued to increase until the ethanol challenge induced a significant drop. Temperatures approached pre-challenge rather than pre-milking temperatures within 10 minutes after challenge. Teat temperatures were dependent on type of liner. Mid-teat temperatures post-challenge relative to pre-teat preparation were dependent on overmilking. Thermography and ultrasound were considered useful methods to indirectly and non invasively evaluate teat tissue integrity.

Paulrud, CO; Clausen, S; Andersen, PE; Rasmussen, MD

2005-01-01

260

High intensity focused ultrasound (HIFU) and ethanol induced tissue ablation: Thermal lesion volume and temperature ex vivo  

NASA Astrophysics Data System (ADS)

HIFU is the upcoming technology for noninvasive or minimally invasive tumor ablation via the localized acoustic energy deposition at the focal region within the tumor target. The presence of cavitation bubbles had been shown to improve the therapeutic effect of HIFU. In this study, we have investigated the effect of HIFU on temperature rise and cavitation bubble activity in ethanol-treated porcine liver and kidney tissues. We have also explored changes in the viability and proliferation rate of HepG2, SW1376, and FB1 cancer cells with their exposure to ethanol and HIFU. Tissues were submerged in 95% ethanol for five hours and then exposed to HIFU generated by a 1.1 MHz transducer or injected into focal spot before HIFU exposure. Cavitation events were measured by a passive cavitation detection technique for a range of acoustic power from 1.17 W to 20.52 W. The temperature around the focal zone was measured by type K or type E thermocouples embedded in the samples. In experiments with cancer cells, 2.7 millions cells were treated with concentration of ethanol at concentration 2%, 4%, 10%, 25%, and 50% and the cell were exposed to HIFU with power of 2.73 W, 8.72 W, and 12.0 W for 30 seconds. Our data show that the treatment of tissues with ethanol reduces the threshold power for inertial cavitation and increases the temperature rise. The exposure of cancer cells to various HIFU power only showed a higher number of viable cells 24 to 72 hours after HIFU exposure. On the other hand, both the viability and proliferation rate were significantly decreased in cells treated with ethanol and then HIFU at 8.7 W and 12.0 W even at ethanol concentration of 2 and 4 percent. In conclusion, the results of our study indicate that percutaneous ethanol injection (PEI) and HIFU have a synergistic effect on cancer cells ablation.

Hoang, Nguyen Hai

261

Advanced spectral analyses for real-time automatic echographic tissue-typing of simulated tumor masses at different compression stages.  

PubMed

Prototypal software algorithms for advanced spectral analysis of echographic images were developed to perform automatic detection of simulated tumor masses at two different pathological stages. Previously published works documented the possibility of characterizing macroscopic variation of mechanical properties of tissues through elastographic techniques, using different imaging modalities, including ultrasound (US); however, the accuracy of US-based elastography remains affected by the variable manual modality of the applied compression and several attempts are under investigation to overcome this limitation. Quantitative US (QUS), such as Fourier- and wavelet-based analyses of the RF signal associated with the US images, has been developed to perform a microscopic-scale tissue-type imaging offering new solutions for operator-independent examinations. Because materials able to reproduce the harmonic behavior of human liver can be realized, in this study, tissue-mimicking structures were US imaged and the related RF signals were analyzed using wavelet transform through an in-house-developed algorithm for tissue characterization. The classification performance and reliability of the procedure were evaluated on two different tumor stiffnesses (40 and 130 kPa) and with two different applied compression levels (0 and 3.5 N). Our results demonstrated that spectral components associated with different levels of tissue stiffness within the medium exist and can be mapped onto the original US images independently of the applied compressive forces. This wavelet-based analysis was able to identify different tissue stiffness with satisfactory average sensitivity and specificity: respectively, 72.01% ± 1.70% and 81.28% ± 2.02%. PMID:23221218

Soloperto, Giulia; Conversano, Francesco; Greco, Antonio; Casciaro, Ernesto; Franchini, Roberto; Casciaro, Sergio

2012-12-01

262

Ultrasound microneurosurgery.  

PubMed

This work focuses on the use of an ultrasound neurosurgical unit which includes frequency generator and acoustic converter with different types of surgical attachments according to the surgical peculiarity. These attachments were designed to be used for ultrasonic resection, ultrasonic aspiration, ultrasonic disintegration and other applications. High cutting ability, possibility of local disintegration, specific hemostatic effects and other benefits of ultrasonic surgical tools (in the experimental level) were behind the efforts to create the ultrasound microneurosurgical unit with different attachments of cutting, disintegration, aspiration and separation tools. We used the ultrasound microneurosurgical unit during 299 operations involving meningiomas; acoustic neurinomas; gliomas; hordomas; pituitary adenomas; craniopharyngiomas; tuberculoma; paroxysmal pain in the patients with brachial plexus injuries, facial pain, phantom limb pain, intercostal neuralgia, post-mastectomy syndrome, syringomyelia and tumors of nerve trunks. The experience of using the surgical instruments based on ultrasound oscillation of the working edge showed their high efficiency and good perspective in experimental research as well as in practical application in different ramifications of surgery. PMID:10048059

Ramazanov, R; Dreval, O N; Akatov, O V; Zaretsky, A A

1999-01-01

263

The cavitation threshold of human tissue exposed to 0.2-MHz pulsed ultrasound: preliminary measurements based on a study of clinical lithotripsy.  

PubMed

Evidence of acoustic cavitation was identified in the form of transient echoes in ultrasound B-scan images of patients receiving extracorporeal shock-wave lithotripsy treatment on a Storz Modulith SL20. This lithotripter generates 10-microseconds duration pulses with a centre frequency of 0.2 MHz at a pulse repetition frequency of 1 Hz. The visual appearance of B-scan images was examined in a total of 30 patients and a quantitative analysis of echogenicity changes was carried out in six cases involving lithotripsy treatment of stones in the renal pelvis. In these patients new echoes were identified in images unaffected by movement artefacts and were found to occur in perinephric fat and adjacent muscle and kidney tissue at positions close to the axis of the shock-wave field between 1 and 2 cm in advance of the indicated beam focus of the lithotripter. The echogenicity within each region increased significantly above the background level when the output of the lithotripter was increased above a threshold value. The acoustic pressures corresponding to this threshold were measured in water using a calibrated PVDF membrane hydrophone. After correction for attenuation in tissue the cavitation thresholds, in terms of the temporal peak negative pressure, are found to lie between 1.5 MPa and 3.5 MPa in all six cases. Interpretation of the measured values in terms of the likely threshold at the higher frequencies used in diagnostic ultrasound is considered using a theoretical model. PMID:7645132

Coleman, A J; Kodama, T; Choi, M J; Adams, T; Saunders, J E

1995-01-01

264

Accumulation of L-type Bovine Prions in Peripheral Nerve Tissues  

PubMed Central

We recently reported the intraspecies transmission of L-type atypical bovine spongiform encephalopathy (BSE). To clarify the peripheral pathogenesis of L-type BSE, we studied prion distribution in nerve and lymphoid tissues obtained from experimentally challenged cattle. As with classical BSE prions, L-type BSE prions accumulated in central and peripheral nerve tissues.

Imamura, Morikazu; Matsuura, Yuichi; Masujin, Kentaro; Shimizu, Yoshihisa; Shu, Yujing; Kurachi, Megumi; Kasai, Kazuo; Murayama, Yuichi; Fukuda, Shigeo; Onoe, Sadao; Hagiwara, Ken'ichi; Yamakawa, Yoshio; Sata, Tetsutaro; Mohri, Shirou; Okada, Hiroyuki; Yokoyama, Takashi

2010-01-01

265

Development of non-deterioration-type skin tissue phantom using silicone material  

NASA Astrophysics Data System (ADS)

We developed a new type of three-layered skin tissue phantom using silicone material. This phantom maintains its optical properties in a certain period of time, typically about three months, which is much longer than about 30 min with our previous agar-type phantom. Experiments on spectral reflectance measurements and color analysis indicate the possibility of silicone-type skin tissue phantom.

Iva, Saidatul; Tanabe, Akihiro; Maeda, Takaaki; Funamizu, Hideki; Aizu, Yoshihisa

2014-05-01

266

Finite element modeling of tissue for optimal ultrasonic transducer array design  

Microsoft Academic Search

Tissue characterization using ultrasound scattering has been routinely used to extract the cellular properties of tissue. Ultrasonic backscattered radio frequency (RF) data is analyzed to provide estimates of the size, shape and concentration of a wide range of tissues. These tissue parameters form a feature space that can be used to discriminate between tissue types as well as indicate the

Clyde Clarke; D. Carl White; Ralph Etienne-cummings

2008-01-01

267

Fibrin deposition in tissues from endotoxin-treated mice correlates with decreases in the expression of urokinase-type but not tissue-type plasminogen activator.  

PubMed Central

The primary hypothesis of this report is that the formation and subsequent removal of fibrin in specific tissues during pathologic processes reflects temporal changes in the local expression of key procoagulant and fibrinolytic genes. To begin to test this hypothesis, we have used quantitative PCR assays and in situ hybridization analysis to examine the effects of endotoxin on the expression of specific genes in murine tissues, and to relate these changes to fibrin deposition/dissolution using immunohistochemical approaches. Endotoxin caused large increases in plasminogen activator inhibitor-1 mRNA and modest increases in tissue factor mRNA in most tissues examined. However, fibrin was only detected in the kidneys and adrenals of endotoxin-treated mice, and it was transient. Unexpectedly, changes in urokinase-type plasminogen activator mRNA but not tissue-type plasminogen activator mRNA correlated with fibrin deposition/dissolution in these tissues. Pretreatment of mice with the fibrinolytic inhibitor epsilon-aminocaproic acid before endotoxin increased both the number of fibrin-positive tissues and the duration of fibrin deposition in the kidneys and adrenals. These results suggest that the absence of fibrin in some tissues reflects ongoing local fibrinolysis, and that increases in plasminogen activator inhibitory and tissue fac- tor gene expression and decreases in urokinase-type plasminogen activator expression are necessary for tissue-specific fibrin deposition. Changes in tissue-type plasminogen activator gene expression do not appear to be essential for fibrin deposition/dissolution in this murine model of sepsis.

Yamamoto, K; Loskutoff, D J

1996-01-01

268

Musculoskeletal Ultrasound  

MedlinePLUS

... waves. Ultrasound imaging, also called ultrasound scanning or sonography , involves the use of a small transducer (probe) and ultrasound gel placed directly on the skin. High-frequency sound waves are transmitted from the probe through ...

269

Ultrasound -- Vascular  

MedlinePLUS

... waves. Ultrasound imaging, also called ultrasound scanning or sonography , involves the use of a small transducer (probe) and ultrasound gel placed directly on the skin. High-frequency sound waves are transmitted from the probe through ...

270

Prostate Ultrasound  

MedlinePLUS

... waves. Ultrasound imaging, also called ultrasound scanning or sonography , involves the use of a small transducer (probe) and ultrasound gel placed directly on the skin. High-frequency sound waves are transmitted from the probe through ...

271

Scrotal Ultrasound  

MedlinePLUS

... waves. Ultrasound imaging, also called ultrasound scanning or sonography , involves the use of a small transducer (probe) and ultrasound gel placed directly on the skin. High-frequency sound waves are transmitted from the probe through ...

272

Hip Ultrasound  

MedlinePLUS

... waves. Ultrasound imaging, also called ultrasound scanning or sonography , involves the use of a small transducer (probe) and ultrasound gel placed directly on the skin. High-frequency sound waves are transmitted from the probe through ...

273

Abdominal Ultrasound  

MedlinePLUS

... waves. Ultrasound imaging, also called ultrasound scanning or sonography , involves the use of a small transducer (probe) and ultrasound gel placed directly on the skin. High-frequency sound waves are transmitted from the probe through ...

274

Obstetrical Ultrasound  

MedlinePLUS

... harmful effects on humans. top of page • Limitations Obstetric ultrasound cannot identify all fetal abnormalities. Consequently, when ... a Doppler ultrasound procedure on a ... Pelvic and Obstetric Ultrasound Explained placeholder Locate an ACR-accredited provider: ...

275

3D conformal MRI-controlled transurethral ultrasound prostate therapy: validation of numerical simulations and demonstration in tissue-mimicking gel phantoms  

NASA Astrophysics Data System (ADS)

MRI-controlled transurethral ultrasound therapy uses a linear array of transducer elements and active temperature feedback to create volumes of thermal coagulation shaped to predefined prostate geometries in 3D. The specific aims of this work were to demonstrate the accuracy and repeatability of producing large volumes of thermal coagulation (>10 cc) that conform to 3D human prostate shapes in a tissue-mimicking gel phantom, and to evaluate quantitatively the accuracy with which numerical simulations predict these 3D heating volumes under carefully controlled conditions. Eleven conformal 3D experiments were performed in a tissue-mimicking phantom within a 1.5T MR imager to obtain non-invasive temperature measurements during heating. Temperature feedback was used to control the rotation rate and ultrasound power of transurethral devices with up to five 3.5 × 5 mm active transducer elements. Heating patterns shaped to human prostate geometries were generated using devices operating at 4.7 or 8.0 MHz with surface acoustic intensities of up to 10 W cm-2. Simulations were informed by transducer surface velocity measurements acquired with a scanning laser vibrometer enabling improved calculations of the acoustic pressure distribution in a gel phantom. Temperature dynamics were determined according to a FDTD solution to Pennes' BHTE. The 3D heating patterns produced in vitro were shaped very accurately to the prostate target volumes, within the spatial resolution of the MRI thermometry images. The volume of the treatment difference falling outside ±1 mm of the target boundary was, on average, 0.21 cc or 1.5% of the prostate volume. The numerical simulations predicted the extent and shape of the coagulation boundary produced in gel to within (mean ± stdev [min, max]): 0.5 ± 0.4 [-1.0, 2.1] and -0.05 ± 0.4 [-1.2, 1.4] mm for the treatments at 4.7 and 8.0 MHz, respectively. The temperatures across all MRI thermometry images were predicted within -0.3 ± 1.6 °C and 0.1 ± 0.6 °C, inside and outside the prostate respectively, and the treatment time to within 6.8 min. The simulations also showed excellent agreement in regions of sharp temperature gradients near the transurethral and endorectal cooling devices. Conformal 3D volumes of thermal coagulation can be precisely matched to prostate shapes with transurethral ultrasound devices and active MRI temperature feedback. The accuracy of numerical simulations for MRI-controlled transurethral ultrasound prostate therapy was validated experimentally, reinforcing their utility as an effective treatment planning tool.

Burtnyk, Mathieu; Apoutou N'Djin, William; Kobelevskiy, Ilya; Bronskill, Michael; Chopra, Rajiv

2010-11-01

276

3D conformal MRI-controlled transurethral ultrasound prostate therapy: validation of numerical simulations and demonstration in tissue-mimicking gel phantoms.  

PubMed

MRI-controlled transurethral ultrasound therapy uses a linear array of transducer elements and active temperature feedback to create volumes of thermal coagulation shaped to predefined prostate geometries in 3D. The specific aims of this work were to demonstrate the accuracy and repeatability of producing large volumes of thermal coagulation (>10 cc) that conform to 3D human prostate shapes in a tissue-mimicking gel phantom, and to evaluate quantitatively the accuracy with which numerical simulations predict these 3D heating volumes under carefully controlled conditions. Eleven conformal 3D experiments were performed in a tissue-mimicking phantom within a 1.5T MR imager to obtain non-invasive temperature measurements during heating. Temperature feedback was used to control the rotation rate and ultrasound power of transurethral devices with up to five 3.5 × 5 mm active transducer elements. Heating patterns shaped to human prostate geometries were generated using devices operating at 4.7 or 8.0 MHz with surface acoustic intensities of up to 10 W cm(-2). Simulations were informed by transducer surface velocity measurements acquired with a scanning laser vibrometer enabling improved calculations of the acoustic pressure distribution in a gel phantom. Temperature dynamics were determined according to a FDTD solution to Pennes' BHTE. The 3D heating patterns produced in vitro were shaped very accurately to the prostate target volumes, within the spatial resolution of the MRI thermometry images. The volume of the treatment difference falling outside ± 1 mm of the target boundary was, on average, 0.21 cc or 1.5% of the prostate volume. The numerical simulations predicted the extent and shape of the coagulation boundary produced in gel to within (mean ± stdev [min, max]): 0.5 ± 0.4 [-1.0, 2.1] and -0.05 ± 0.4 [-1.2, 1.4] mm for the treatments at 4.7 and 8.0 MHz, respectively. The temperatures across all MRI thermometry images were predicted within -0.3 ± 1.6 °C and 0.1 ± 0.6 °C, inside and outside the prostate respectively, and the treatment time to within 6.8 min. The simulations also showed excellent agreement in regions of sharp temperature gradients near the transurethral and endorectal cooling devices. Conformal 3D volumes of thermal coagulation can be precisely matched to prostate shapes with transurethral ultrasound devices and active MRI temperature feedback. The accuracy of numerical simulations for MRI-controlled transurethral ultrasound prostate therapy was validated experimentally, reinforcing their utility as an effective treatment planning tool. PMID:21030751

Burtnyk, Mathieu; N'Djin, William Apoutou; Kobelevskiy, Ilya; Bronskill, Michael; Chopra, Rajiv

2010-11-21

277

Tissue cryobanking for conservation programs: effect of tissue type and storage time after death.  

PubMed

In this study, we investigated the temporal post-mortem limits, within which there will be guarantees of obtaining living cells from several tissues of sheep and cattle and the effect of vitrification on the ability of cells from tissue stored at different times. Muscle tissue and auricular cartilage were stored at 4°C for 5, 48, 72, 96 and 216 h post-mortem (hpm). Tissue samples were sorted into two groups: one group was in vitro cultured immediately after storage and the other was vitrified after storage and then in vitro cultured. In cattle and sheep, no differences in subconfluence rates were observed between the two experimental groups. At the same time, no significant differences were observed in the number of days required in culture to reach confluence between non-vitrified and vitrified groups when tissues were stored at 4°C for different times. In sheep, while the population doubling times (PDT) were similar in cartilage cells from vitrified and non-vitrified tissues and stored at 4°C for 5 and 216 hpm, PDT of muscle cells were longer in 216 hpm stored groups than in 5 hpm stored groups. In bovine, although the PDT of muscle cells were similar for 5 and 216 hpm and both vitrified and non-vitrified tissues and the PDT were longer in cartilage cells from vitrified than from non-vitrified tissues. In conclusion, although storage times and vitrification have different effects on tissues from cattle and sheep, this study showed that living cells could be obtained from all groups. Therefore, cartilage and muscle tissues can be stored at 4°C for 216 hpm and used for cyrobanking. PMID:22271151

Caputcu, Arzu Tas; Akkoc, Tolga; Cetinkaya, Gaye; Arat, Sezen

2013-03-01

278

Femtosecond-assisted preparation of donor tissue for Boston type 1 keratoprosthesis  

PubMed Central

We describe a technique for femtosecond laser-assisted preparation of donor tissue for Boston type 1 keratoprosthesis to provide accurate double punching of the donor tissue for optimized alignment in the visual axis. The technique was reproducibly performed in four donor corneas mounted in an artificial anterior chamber. This technique can provide optically centered donor tissue with smooth trephinated edges.

Moshirfar, Majid; Neuffer, Marcus C; Kinard, Krista; Lependu, Monette T; Sikder, Shameema

2011-01-01

279

Femtosecond-assisted preparation of donor tissue for Boston type 1 keratoprosthesis.  

PubMed

We describe a technique for femtosecond laser-assisted preparation of donor tissue for Boston type 1 keratoprosthesis to provide accurate double punching of the donor tissue for optimized alignment in the visual axis. The technique was reproducibly performed in four donor corneas mounted in an artificial anterior chamber. This technique can provide optically centered donor tissue with smooth trephinated edges. PMID:21845027

Moshirfar, Majid; Neuffer, Marcus C; Kinard, Krista; Lependu, Monette T; Sikder, Shameema

2011-01-01

280

Cranial Ultrasound/Head Ultrasound  

MedlinePLUS

... waves. Ultrasound imaging, also called ultrasound scanning or sonography , involves the use of a small transducer (probe) and ultrasound gel placed directly on the skin. High-frequency sound waves are transmitted from the probe through ...

281

Ultrasound indentation of bovine knee articular cartilage in situ  

Microsoft Academic Search

We have earlier developed a handheld ultrasound indentation instrument for the diagnosis of articular cartilage degeneration. In ultrasound indentation, cartilage is compressed with the ultrasound transducer. Tissue thickness and deformation are calculated from the A-mode ultrasound signal and the stress applied is registered with the strain gauges. In this study, the applicability of the ultrasound indentation instrument to quantify site-dependent

Mikko S. Laasanen; Simo Saarakkala; Juha Töyräs; Jani Hirvonen; Jarno Rieppo; Rami K. Korhonen; Jukka S. Jurvelin

2003-01-01

282

valuation of the in vivo contrast using fast spin echo MRI sequences between tissues and thermal lesions in rabbit produced by high intensity focused ultrasound  

NASA Astrophysics Data System (ADS)

In this paper the goal was to measure the contrast to noise ratio (CNR) of fast spin echo (FSE) magnetic resonance imaging (MRI) sequences in detecting thermal lesions created by high intensity focused ultrasound (HIFU) in rabbit kidney, liver, heart, and brain and lamb pancreas. A spherically focused transducer was used which is navigated inside MRI by a custom made positioning device. A simple simulation model was developed which predicts the CNR for the two FSE MRI sequences. The maximum contrast measured with T1-W FSE ranges from 10 to 25. For all 5 tissues of interest if one uses TR between 400 and 500 ms the contrast is maximized. The T1, and T2 value of lesion depends strongly on the host tissue and is always lower than the host tissue. The greater the difference in T1 value, the greater the CNR. The simulated model for predicting the CNR was proven successful. The CNR measured with T2-W FSE varies between 12 and 15 for all 5 tissues. With T2-W FSE if one uses TE between 40 and 50 ms, the contrast is maximized.

Damianou, Christakis; Ioannides, Kleanthis; Hadjisavas, Venediktos; Milonas, Nikos; Couppis, Andreas; Iosif, Demitris

2010-03-01

283

Facial soft tissue thickness in skeletal type I Japanese children  

Microsoft Academic Search

Facial reconstruction techniques used in forensic anthropology require knowledge of the facial soft tissue thickness of each race if facial features are to be reconstructed correctly. If this is inaccurate, so also will be the reconstructed face. Knowledge of differences by age and sex are also required. Therefore, when unknown human skeletal remains are found, the forensic anthropologist investigates for

Hajime Utsuno; Toru Kageyama; Toshio Deguchi; Yasunobu Umemura; Mineo Yoshino; Hiroshi Nakamura; Hiroo Miyazawa; Katsuhiro Inoue

2007-01-01

284

Ultrasound--biophysics mechanisms†  

PubMed Central

Ultrasonic biophysics is the study of mechanisms responsible for how ultrasound and biological materials interact. Ultrasound-induced bioeffect or risk studies focus on issues related to the effects of ultrasound on biological materials. On the other hand, when biological materials affect the ultrasonic wave, this can be viewed as the basis for diagnostic ultrasound. Thus, an understanding of the interaction of ultrasound with tissue provides the scientific basis for image production and risk assessment. Relative to the bioeffect or risk studies, that is, the biophysical mechanisms by which ultrasound affects biological materials, ultrasound-induced bioeffects are generally separated into thermal and nonthermal mechanisms. Ultrasonic dosimetry is concerned with the quantitative determination of ultrasonic energy interaction with biological materials. Whenever ultrasonic energy is propagated into an attenuating material such as tissue, the amplitude of the wave decreases with distance. This attenuation is due to either absorption or scattering. Absorption is a mechanism that represents that portion of ultrasonic wave that is converted into heat, and scattering can be thought of as that portion of the wave, which changes direction. Because the medium can absorb energy to produce heat, a temperature rise may occur as long as the rate of heat production is greater than the rate of heat removal. Current interest with thermally mediated ultrasound-induced bioeffects has focused on the thermal isoeffect concept. The non-thermal mechanism that has received the most attention is acoustically generated cavitation wherein ultrasonic energy by cavitation bubbles is concentrated. Acoustic cavitation, in a broad sense, refers to ultrasonically induced bubble activity occurring in a biological material that contains pre-existing gaseous inclusions. Cavitation-related mechanisms include radiation force, microstreaming, shock waves, free radicals, microjets and strain. It is more challenging to deduce the causes of mechanical effects in tissues that do not contain gas bodies. These ultrasonic biophysics mechanisms will be discussed in the context of diagnostic ultrasound exposure risk concerns.

O'Brien, William D.

2007-01-01

285

Ultrasound energy for biomedicine  

Microsoft Academic Search

For removing tissues and fragmenting stones, removing clots from blood vessels and other undesirable derivatives which can occur in a person's body, it is possible to use the ultrasound energy. Usually the energy generated to the environment by the waveguide is transmitted in the form of intensive acoustic waves of high frequency; tissues are destroyed under their influence, under the

A. Bubulis; V. Jurenas; V. Minchenya

2012-01-01

286

Enhancement of neointima formation with tissue-type plasminogen activator  

Microsoft Academic Search

Purpose: Indirect evidence suggests that tissue plasminogen activator (tPA) either limits or does not alter restenosis. However, tPA enhances tumor invasiveness through matrix remodeling, and several elements of degraded matrix enhance smooth muscle cell mitogenesis. We use either local adenoviral-mediated overexpression of tPA or systemic infusion of recombinant tPA combined with mechanical overdilation of rabbit common femoral arteries to evaluate

Paul R. Hilfiker; Jacob M. Waugh; Jia J. Li-Hawkins; Michael D. Kuo; Eser Yuksel; Robert S. Geske; Pamela N. Cifra; Muneesh Chawla; Adam B. Weinfeld; John W. Thomas; Saleh M. Shenaq; Michael D. Dake

2001-01-01

287

Computational study on the propagation of strongly focused nonlinear ultrasound in tissue with rib-like structures.  

PubMed

The presence of a rib cage is a significant hindrance to the potential applications of focused ultrasound as a noninvasive extracorporeal surgery modality for various internal organs. Here the influence of ribs on the propagation of strongly focused high-intensity nonlinear ultrasound beam inside the body is studied. Based on the spheroidal beam equation, a three-dimensional numerical algorithm is developed to solve the nonlinear acoustic field generated by a focused ultrasonic transducer with a large aperture angle. Idealized ribs, of rectangular cross sectional, with high absorption and impedance, and various dimensions, are used to simulate human anatomical configurations. The changes in the spatial distribution of acoustic intensity and the reduction of the acoustic pressure amplitude and heat deposition rate due to the presence of "ribs" are investigated. It is somewhat surprising that in some cases, the axial peak positions shift less than 2?mm and more than 80% of the sound energy can propagate through the space of the rib cage in the strongly focused sound field. This study also includes quantitative analyses of the effects of different rib configurations and transducers of various f-numbers. The results can be used as reference information for further study and clinical applications. PMID:23927211

Lin, Jiexing; Liu, Xiaozhou; Gong, Xiufen; Ping, Zihong; Wu, Junru

2013-08-01

288

Validation of tissue change monitoring (TCM) on the Sonablate® 500 during high intensity focused ultrasound (HIFU) treatment of prostate cancer with real-time thermometry  

NASA Astrophysics Data System (ADS)

The Sonablate® 500 has quantitative, real-time Tissue Change Monitoring (TCM) software that estimates changes in tissue properties due to HIFU treatment of prostate cancer. This study validates the Sonablate 500 TCM system using real-time thermometry. Five patients with histologically confirmed, organ-confined prostate cancer were enrolled. Four patients with focal cancer had hemiablation and one had whole gland ablation. TCM generates energy reading based on spectral analysis on the RF backscattered ultrasound signals; results are used as an estimator of tissue temperature. Needle thermocouples were placed transperineally under TRUS guidance in the prostate to monitor temperatures from focal zone, posterior to the focal zone and on the lateral gland where no HIFU was applied. The HIFU treatments averaged 37, 35 and 19.7 Watts for the treatment for anterior, middle and posterior zones. The measured temperatures (Average, Max, and Min) in the HIFU treatment zones were 84, 114 and 70 degrees C. The temperature estimated by TCM energy readings were 83% 75-100 degrees C and 17% 60-75 degrees C with an average of 91 degrees C. Outside the focal zone, average recorded temperature was 50 degrees C. Average temperature in the lateral lobe where no HIFU was applied was 40.7 degrees C.

Chen, Wo-Hsing; Sanghvi, Narendra T.; Carlson, Roy; Schatzl, Georg; Marberger, Michael

2012-10-01

289

The role of acoustic nonlinearity in tissue heating behind a rib cage using a high-intensity focused ultrasound phased array  

NASA Astrophysics Data System (ADS)

The goal of this study was to investigate theoretically the effects of nonlinear propagation in a high-intensity focused ultrasound (HIFU) field produced by a therapeutic phased array and the resultant heating of tissue behind a rib cage. Three configurations of focusing were simulated: in water, in water with ribs in the beam path and in water with ribs backed by a layer of soft tissue. The Westervelt equation was used to model the nonlinear HIFU field, and a 1 MHz phased array consisting of 254 circular elements was used as a boundary condition to the model. The temperature rise in tissue was modelled using the bioheat equation, and thermally necrosed volumes were calculated using the thermal dose formulation. The shapes of lesions predicted by the modelling were compared with those previously obtained in in vitro experiments at low-power sonications. Intensity levels at the face of the array elements that corresponded to the formation of high-amplitude shock fronts in the focal region were determined as 10 W cm-2 in the free field in water and 40 W cm-2 in the presence of ribs. It was shown that exposures with shocks provided a substantial increase in tissue heating, and its better spatial localization in the main focal region only. The relative effects of overheating ribs and splitting of the focus due to the periodic structure of the ribs were therefore reduced. These results suggest that utilizing nonlinear propagation and shock formation effects can be beneficial for inducing confined HIFU lesions when irradiating through obstructions such as ribs. Design of compact therapeutic arrays to provide maximum power outputs with lower intensity levels at the elements is necessary to achieve shock wave regimes for clinically relevant sonication depths in tissue.

Yuldashev, Petr V.; Shmeleva, Svetlana M.; Ilyin, Sergey A.; Sapozhnikov, Oleg A.; Gavrilov, Leonid R.; Khokhlova, Vera A.

2013-04-01

290

The role of acoustic nonlinearity in tissue heating behind a rib cage using a high-intensity focused ultrasound phased array.  

PubMed

The goal of this study was to investigate theoretically the effects of nonlinear propagation in a high-intensity focused ultrasound (HIFU) field produced by a therapeutic phased array and the resultant heating of tissue behind a rib cage. Three configurations of focusing were simulated: in water, in water with ribs in the beam path and in water with ribs backed by a layer of soft tissue. The Westervelt equation was used to model the nonlinear HIFU field, and a 1 MHz phased array consisting of 254 circular elements was used as a boundary condition to the model. The temperature rise in tissue was modelled using the bioheat equation, and thermally necrosed volumes were calculated using the thermal dose formulation. The shapes of lesions predicted by the modelling were compared with those previously obtained in in vitro experiments at low-power sonications. Intensity levels at the face of the array elements that corresponded to the formation of high-amplitude shock fronts in the focal region were determined as 10 W cm(-2) in the free field in water and 40 W cm(-2) in the presence of ribs. It was shown that exposures with shocks provided a substantial increase in tissue heating, and its better spatial localization in the main focal region only. The relative effects of overheating ribs and splitting of the focus due to the periodic structure of the ribs were therefore reduced. These results suggest that utilizing nonlinear propagation and shock formation effects can be beneficial for inducing confined HIFU lesions when irradiating through obstructions such as ribs. Design of compact therapeutic arrays to provide maximum power outputs with lower intensity levels at the elements is necessary to achieve shock wave regimes for clinically relevant sonication depths in tissue. PMID:23528338

Yuldashev, Petr V; Shmeleva, Svetlana M; Ilyin, Sergey A; Sapozhnikov, Oleg A; Gavrilov, Leonid R; Khokhlova, Vera A

2013-04-21

291

21 CFR 1271.85 - What donor testing is required for different types of cells and tissues?  

Code of Federal Regulations, 2010 CFR

...is required for different types of cells and tissues? 1271...required for different types of cells and tissues? (a) All...transmission of relevant cell-associated communicable...T-lymphotropic virus, type I; and (ii)...

2009-04-01

292

21 CFR 1271.85 - What donor testing is required for different types of cells and tissues?  

Code of Federal Regulations, 2010 CFR

...is required for different types of cells and tissues? 1271...required for different types of cells and tissues? (a) All...transmission of relevant cell-associated communicable...T-lymphotropic virus, type I; and (ii)...

2010-04-01

293

Towards enabling ultrasound guidance in cervical cancer high-dose-rate brachytherapy  

NASA Astrophysics Data System (ADS)

MRI and Computed Tomography (CT) are used in image-based solutions for guiding High Dose Rate (HDR) brachytherapy treatment of cervical cancer. MRI is costly and CT exposes the patients to ionizing radiation. Ultrasound, on the other hand, is affordable and safe. The long-term goal of our work is to enable the use of multiparametric ultrasound imaging in image-guided HDR for cervical cancer. In this paper, we report the development of enabling technology for ultrasound guidance and tissue typing. We report a system to obtain the 3D freehand transabdominal ultrasound RF signals and B-mode images of the uterus, and a method for registration of ultrasound to MRI. MRI and 3D ultrasound images of the female pelvis were registered by contouring the uterus in the two modalities, creating a surface model, followed by rigid and B-spline deformable registration. The resulting transformation was used to map the location of the tumor from the T2-weighted MRI to ultrasound images and to determine cancerous and normal areas in ultrasound. B-mode images show a contrast for cancer vs. normal tissue. Our study shows the potential and the challenges of ultrasound imaging in guiding cervical cancer treatments.

Wong, Adrian; Sojoudia, Samira; Gaudet, Marc; Yap, Wan Wan; Chang, Silvia D.; Abolmaesumi, Purang; Aquino-Parsons, Christina; Moradi, Mehdi

2014-03-01

294

Prostate tissue characterization/classification in 144 patient population using wavelet and higher order spectra features from transrectal ultrasound images.  

PubMed

In this work, we have proposed an on-line computer-aided diagnostic system called "UroImage" that classifies a Transrectal Ultrasound (TRUS) image into cancerous or non-cancerous with the help of non-linear Higher Order Spectra (HOS) features and Discrete Wavelet Transform (DWT) coefficients. The UroImage system consists of an on-line system where five significant features (one DWT-based feature and four HOS-based features) are extracted from the test image. These on-line features are transformed by the classifier parameters obtained using the training dataset to determine the class. We trained and tested six classifiers. The dataset used for evaluation had 144 TRUS images which were split into training and testing sets. Three-fold and ten-fold cross-validation protocols were adopted for training and estimating the accuracy of the classifiers. The ground truth used for training was obtained using the biopsy results. Among the six classifiers, using 10-fold cross-validation technique, Support Vector Machine and Fuzzy Sugeno classifiers presented the best classification accuracy of 97.9% with equally high values for sensitivity, specificity and positive predictive value. Our proposed automated system, which achieved more than 95% values for all the performance measures, can be an adjunct tool to provide an initial diagnosis for the identification of patients with prostate cancer. The technique, however, is limited by the limitations of 2D ultrasound guided biopsy, and we intend to improve our technique by using 3D TRUS images in the future. PMID:23745787

Pareek, Gyan; Acharya, U Rajendra; Sree, S Vinitha; Swapna, G; Yantri, Ratna; Martis, Roshan Joy; Saba, Luca; Krishnamurthi, Ganapathy; Mallarini, Giorgio; El-Baz, Ayman; Al Ekish, Shadi; Beland, Michael; Suri, Jasjit S

2013-12-01

295

Fourier Transform Infrared Imaging and Infrared Fiber Optic Probe Spectroscopy Identify Collagen Type in Connective Tissues  

PubMed Central

Hyaline cartilage and mechanically inferior fibrocartilage consisting of mixed collagen types are frequently found together in repairing articular cartilage. The present study seeks to develop methodology to identify collagen type and other tissue components using Fourier transform infrared (FTIR) spectral evaluation of matrix composition in combination with multivariate analyses. FTIR spectra of the primary molecular components of repair cartilage, types I and II collagen, and aggrecan, were used to develop multivariate spectral models for discrimination of the matrix components of the tissues of interest. Infrared imaging data were collected from bovine bone, tendon, normal cartilage, meniscus and human repair cartilage tissues, and composition predicted using partial least squares analyses. Histology and immunohistochemistry results were used as standards for validation. Infrared fiber optic probe spectral data were also obtained from meniscus (a tissue with mixed collagen types) to evaluate the potential of this method for identification of collagen type in a minimally-invasive clinical application. Concentration profiles of the tissue components obtained from multivariate analysis were in excellent agreement with histology and immunohistochemistry results. Bone and tendon showed a uniform distribution of predominantly type I collagen through the tissue. Normal cartilage showed a distribution of type II collagen and proteoglycan similar to the known composition, while in repair cartilage, the spectral distribution of both types I and II collagen were similar to that observed via immunohistochemistry. Using the probe, the outer and inner regions of the meniscus were shown to be primarily composed of type I and II collagen, respectively, in accordance with immunohistochemistry data. In summary, multivariate analysis of infrared spectra can indeed be used to differentiate collagen type I and type II, even in the presence of proteoglycan, in connective tissues, using both imaging and fiber optic methodology. This has great potential for clinical in situ applications for monitoring tissue repair.

Hanifi, Arash; McCarthy, Helen; Roberts, Sally; Pleshko, Nancy

2013-01-01

296

Gold nanoparticle targeted photoacoustic cavitation for potential deep tissue imaging and therapy  

PubMed Central

The laser generation of vapor bubbles around plasmonic nanoparticles can be enhanced through the application of an ultrasound field; a technique referred to as photoacoustic cavitation. The combination of light and ultrasound allows for bubble formation at lower laser fluence and peak negative ultrasound pressure than can be achieved using either modality alone. The growth and collapse of these bubbles leads to local mechanical disruption and acoustic emission, and can potentially be used to induce and monitor tissue therapy. Photoacoustic cavitation is investigated for a broad range of ultrasound pressures and nanoparticle concentrations for gold nanorods and nanospheres. The cavitation threshold fluences for both nanoparticle types are found to drastically reduce in the presence of an ultrasound field. The results indicate that photoacoustic cavitation can potentially be produced at depth in biological tissue without exceeding the safety limits for ultrasound or laser radiation at the tissue surface.

Ju, Hengyi; Roy, Ronald A.; Murray, Todd W.

2012-01-01

297

Gold nanoparticle targeted photoacoustic cavitation for potential deep tissue imaging and therapy.  

PubMed

The laser generation of vapor bubbles around plasmonic nanoparticles can be enhanced through the application of an ultrasound field; a technique referred to as photoacoustic cavitation. The combination of light and ultrasound allows for bubble formation at lower laser fluence and peak negative ultrasound pressure than can be achieved using either modality alone. The growth and collapse of these bubbles leads to local mechanical disruption and acoustic emission, and can potentially be used to induce and monitor tissue therapy. Photoacoustic cavitation is investigated for a broad range of ultrasound pressures and nanoparticle concentrations for gold nanorods and nanospheres. The cavitation threshold fluences for both nanoparticle types are found to drastically reduce in the presence of an ultrasound field. The results indicate that photoacoustic cavitation can potentially be produced at depth in biological tissue without exceeding the safety limits for ultrasound or laser radiation at the tissue surface. PMID:23304648

Ju, Hengyi; Roy, Ronald A; Murray, Todd W

2013-01-01

298

Simultaneous Real-time Monitoring of Thermal and Mechanical Tissue Responses to Pulsed HIFU Using Pulse-Echo Ultrasound  

NASA Astrophysics Data System (ADS)

Pulsed HIFU beams are being increasingly used in a number of therapeutic applications, including thermal therapy, drug and gene delivery, and hemostasis. This wide range of applications is based on a range of HIFU-tissue interactions from purely thermal to purely mechanical to produce the desired therapeutic effects. We have developed a real-time system for monitoring tissue displacements in response to pulsed HIFU beams at high PRFs. The imaging component of the system comprises an FPGA-based signal processing unit for real-time filtering of M-mode pulse-echo data followed by real-time speckle tracking for tissue displacements before, during, and after exposure to pulsed HIFU. The latter can be used in evaluating temperature and/or viscoelastic response to the applied HIFU beam. The high acquisition rate of the M-mode system, together with the real-time displacement tracking are necessary for simultaneous estimation and separation of the thermal and viscoelastic tissue responses. In addition, the system provides a real-time link to MATLAB-based nonlinear spectral estimation routines for cavitation detection. The system has been tested in vitro bovine heart tissue and the results show that the displacement tracking captures the full dynamics of tissue displacements for the full range of HIFU exposures of interest.

Liu, Dalong; Ebbini, Emad S.

2009-04-01

299

Advances in Ultrasound Elastography  

NASA Astrophysics Data System (ADS)

The purpose of elastography is to characterize from mechanical point of view a material (the soft biological tissues in the medical field). Ultrasound elastography is based on the comparison of ultrasound images, when the material is submitted under axial force (compression). This work presents the advances in the instrumentation of an ultrasound scanner, to acquire a sequence of images which will be processed in the aim of elastography. First, motion estimation between two or more images is processed. The estimated displacement gives the possibility to obtain detailed deformation elastograms. Thus, the presence of a hard inclusion (that simulates a tumor a pathological tissue) within a phantom mimicking soft tissues can be more easily detected, which may lead to a better cancer diagnosis.

Basarab, A.; Nava A., J. F.; Royer, E.; de Boissieu, P.; Delachartre, P.

2006-09-01

300

Ultrasound elastography in liver.  

PubMed

Conventional imaging techniques cannot provide information about tissue mechanical properties. Many injuries can cause changes in tissue stiffness, especially tumors and fibrosis. In recent years, various non-invasive ultrasound methods have been developed to study tissue elasticity for a large number of applications (breast, thyroid, prostate, kidneys, blood vessels, liver…). For non-invasive assessment of liver diseases, several ultrasound elastography techniques have been investigated: Transient elastography (the most extensively used), Real Time Elastography (RTE), Acoustic Radiation Force Impulse Imaging (ARFI) and more recently Shear Wave Elastography (SWE). Even if evaluation of liver fibrosis in chronic liver disease remains the principal application, there are many others applications for liver: predicting cirrhosis-related complications; monitoring antiviral treatments in chronic viral liver disease; characterizing liver tumors; monitoring local treatments, etc. The aim of this article is to report on the different hepatic ultrasound elastography techniques, their advantages and disadvantages, their diagnostic accuracy, their applications in clinical practice. PMID:23623211

Frulio, N; Trillaud, H

2013-05-01

301

General Ultrasound Imaging  

MedlinePLUS

... collects the sounds that bounce back and a computer then uses those sound waves to create an ... types of Doppler ultrasound: Color Doppler uses a computer to convert Doppler measurements into an array of ...

302

Wavelet-based feature extraction applied to small-angle x-ray scattering patterns from breast tissue: a tool for differentiating between tissue types  

Microsoft Academic Search

This paper reports on the application of wavelet decomposition to small-angle x-ray scattering (SAXS) patterns from human breast tissue produced by a synchrotron source. The pixel intensities of SAXS patterns of normal, benign and malignant tissue types were transformed into wavelet coefficients. Statistical analysis found significant differences between the wavelet coefficients describing the patterns produced by different tissue types. These

G. Falzon; S. Pearson; R. Murison; C. Hall; K. Siu; A. Evans; K. Rogers; R. Lewis

2006-01-01

303

Ultrasound mediated delivery of drugs and genes to solid tumors  

PubMed Central

It has long been shown that therapeutic ultrasound can be used effectively to ablate solid tumors, and a variety of cancers are presently being treated in the clinic using these types of ultrasound exposures. There is, however, an ever-increasing body of preclinical literature that demonstrates how ultrasound energy can also be used non-destructively for increasing the efficacy of drugs and genes for improving cancer treatment. In this review, a summary of the most important ultrasound mechanisms will be given with a detailed description of how each one can be employed for a variety of applications. This includes the manner by which acoustic energy deposition can be used to create changes in tissue permeability for enhancing the delivery of conventional agents, as well as for deploying and activating drugs and genes via specially tailored vehicles and formulations.

Frenkel, Victor

2008-01-01

304

Technical Advances in Endoscopic Ultrasound (EUS)-Guided Tissue Acquisition for Pancreatic Cancers: How Can We Get the Best Results with EUS-Guided Fine Needle Aspiration?  

PubMed Central

Endoscopic ultrasound-guided fine needle aspiration (EUS-FNA) is one of the least invasive and most effective modality in diagnosing pancreatic adenocarcinoma in solid pancreatic lesions, with a higher diagnostic accuracy than cystic tumors. EUS-FNA has been shown to detect tumors less than 3 mm, due to high spatial resolution allowing the detection of very small lesions and vascular invasion, particularly in the pancreatic head and neck, which may not be detected on transverse computed tomography. Furthermore, this minimally invasive procedure is often ideal in the endoscopic procurement of tissue in patients with unresectable tumors. While EUS-FNA has been increasingly used as a diagnostic tool, most studies have collectively looked at all primary pancreatic solid lesions, including lymphomas and pancreatic neuroendocrine neoplasms, whereas very few studies have examined the diagnostic utility of EUS-FNA of pancreatic ductal carcinoma only. As with any novel and advanced endoscopic procedure that may incorporate several practices and approaches, endoscopists have adopted diverse techniques to improve the tissue procurement practice and increase diagnostic accuracy. In this article, we present a review of literature to date and discuss currently practiced EUS-FNA technique, including indications, technical details, equipment, patient selection, and diagnostic accuracy.

Kedia, Prashant; Gaidhane, Monica

2013-01-01

305

Adaptive Thermal Therapy using Planar Ultrasound Transducers with Real-time MR Temperature Feedback: Demonstration in Gel Phantoms and Ex-vivo Tissues  

NASA Astrophysics Data System (ADS)

MRI-guided transurethral ultrasound therapy offers a minimally invasive approach for the treatment of localized prostate cancer. The main goal of this study was to evaluate active temperature feedback on a clinical 1.5T MR imager to control conformal thermal therapy. MR thermometry was performed during heating in both thermal gel phantoms and ex-vivo tissue with a single-element transurethral heating applicator. The applicator rotation rate and power were controlled based on MRI-temperature measurements. The influence of a cooling gradient (to simulate cooling of the rectum or urethra) was also investigated in gel phantoms. The 55°C isotherm generated during heating closely matched the targeted prostate shape, with an average distance error of 0.9 mm +/- 0.4 mm in turkey breasts, 1.3 mm +/- 0.5 mm in gel phantoms without rectal cooling and 1.4 mm +/- 0.6 mm in gel phantoms with rectal cooling. Accurate, MRI-guided, active feedback has been successfully demonstrated experimentally and has the capability to adjust for unpredictable and varying tissue properties during the treatment.

Tang, Kee; Choy, Vanessa; Chopra, Rajiv; Bronskill, Michael

2007-05-01

306

In vivo characterization of tissue thermal properties of the kidney during local hyperthermia induced by MR-guided high-intensity focused ultrasound.  

PubMed

The purpose of this study was to evaluate quantitatively in vivo the tissue thermal properties during high-intensity focused ultrasound (HIFU) heating. For this purpose, a total of 52 localized sonications were performed in the kidneys of six pigs with HIFU monitored in real time by volumetric MR thermometry. The kidney perfusion was modified by modulation of the flow in the aorta by insertion of an inflatable angioplasty balloon. The resulting temperature data were analyzed using the bio-heat transfer model in order to validate the model under in vivo conditions and to estimate quantitatively the absorption (?), thermal diffusivity (D) and perfusion (w(b)) of renal tissue. An excellent correspondence was observed between the bio-heat transfer model and the experimental data. The absorption and thermal diffusivity were independent of the flow, with mean values (± standard deviation) of 20.7 ± 5.1 mm(3) K J(-1) and 0.23 ± 0.11 mm(2) s(-1), respectively, whereas the perfusion decreased significantly by 84% (p < 0.01) with arterial flow (mean values of w(b) of 0.06 ± 0.02 and 0.008 ± 0.007 mL(-1) mL s(-1)), as predicted by the model. The quantitative analysis of the volumetric temperature distribution during nondestructive HIFU sonication allows the determination of the thermal parameters, and may therefore improve the quality of the planning of noninvasive therapy with MR-guided HIFU. PMID:21834004

Cornelis, François; Grenier, Nicolas; Moonen, Chrit T; Quesson, Bruno

2011-08-01

307

Vaspin gene expression in human adipose tissue: Association with obesity and type 2 diabetes  

Microsoft Academic Search

Recently, vaspin was identified as an adipokine with insulin-sensitizing effects, which is predominantly secreted from visceral adipose tissue in a rat model of type 2 diabetes. In this study, we examined whether vaspin mRNA expression is a marker of visceral obesity and correlates with anthropometric and metabolic parameters in paired samples of visceral and subcutaneous adipose tissue from 196 subjects

Nora Klöting; Janin Berndt; Susan Kralisch; Peter Kovacs; Mathias Fasshauer; Michael R. Schön; Michael Stumvoll; Matthias Blüher

2006-01-01

308

Reconstruction of viscoelastic tissue properties from MR elastography-type measurements  

Microsoft Academic Search

This study is concerned with an optimization-based approach to the identification of “background” viscoelastic properties of soft tissues from magnetic resonance (MR) elastography-type measurements. In this approach, the triaxial tissue displacements, captured by the MR scanner over a suitable subdomain that is free of major heterogeneities, are split into (i) a boundary subset that is used to formulate the forward

Huina Yuan; Bojan B. Guzina

2010-01-01

309

2-D PSTD Simulation of the time-reversed ultrasound-encoded deep-tissue imaging technique  

PubMed Central

We present a robust simulation technique to model the time-reversed ultrasonically encoded (TRUE) technique for deep-tissue imaging. The pseudospectral time-domain (PSTD) algorithm is employed to rigorously model the electromagnetic wave interaction of light propagating through a macroscopic scattering medium. Based upon numerical solutions of Maxwell’s equations, the amplitude and phase are accurately accounted for to analyze factors that affect the TRUE propagation of light through scattering media. More generally, we demonstrate the feasibility of modeling light propagation through a virtual tissue model of macroscopic dimensions with numerical solutions of Maxwell’s equations.

Tseng, Snow H.; Ting, Wei-Lun; Wang, Shiang-Jiu

2014-01-01

310

Intravascular Ultrasound  

MedlinePLUS

Intravascular ultrasound (IVUS) or intravascular echocardiography is a combination of echocardiography and a procedure called cardiac catheterization . IVUS uses ... IVUS uses high-frequency sound waves (also called ultrasound) that can provide a moving picture of your ...

311

Thyroid ultrasound  

PubMed Central

Thyroid ultrasonography has established itself as a popular and useful tool in the evaluation and management of thyroid disorders. Advanced ultrasound techniques in thyroid imaging have not only fascinated the radiologists but also attracted the surgeons and endocrinologists who are using these techniques in their daily clinical and operative practice. This review provides an overview of indications for ultrasound in various thyroid diseases, describes characteristic ultrasound findings in these diseases, and illustrates major diagnostic pitfalls of thyroid ultrasound.

Chaudhary, Vikas; Bano, Shahina

2013-01-01

312

Ultrasound (Sonography)  

NSDL National Science Digital Library

The Radiological Society of North America (RSNA) and the American College of Radiology (ACR) produce this website which provides information on 15 varieties of sonography including hysterosonography, obstetric ultrasound, and thyroid ultrasound. Sections on each variety of ultrasound provide information on common uses of the procedure, equipment, procedure results & interpretation, benefits and risks, and limitations. This is a great resource for instructors of courses related to diagnostic medical sonography and for the aspiring sonographer or ultrasound technician.

2007-04-30

313

Ultrasound-guided percutaneous delivery of tissue-engineered endothelial cells to the adventitia of stented arteries controls the response to vascular injury in a porcine model  

PubMed Central

Objective High restenosis rates are a limitation of peripheral vascular interventions. Previous studies have shown that surgical implantation of a tissue-engineered endothelium onto the adventitia surface of injured vessels regulates vascular repair. In the present study, we developed a particulate formulation of tissue-engineered endothelium and a method to deliver the formulation perivascular to injured blood vessels using a percutaneous, minimally invasive technique. Methods Stainless steel stents were implanted in 18 balloon-injured femoral arteries of nine domestic swine, followed by ultrasound-guided percutaneous perivascular injection of gelatin particles containing cultured allogeneic porcine aortic endothelial cells (PAE). Controls received injections of empty particles (matrix) or no perivascular injection (sham) after stent deployment. Animals were sacrificed after 90 days. Results Angiographic analysis revealed a significantly greater lumen diameter in the stented segments of arteries treated with PAE/matrix (4.72 ± 0.12 mm) compared with matrix (4.01 ± 0.20 mm) or sham (4.03 ± 0.16 mm) controls (P< .05). Similarly, histologic analysis revealed that PAE/matrix-treated arteries had the greatest lumen area(20.4 ± 0.7 mm2; P< .05) compared with controls (16.1 ± 0.9 mm2 and 17.1 ±1.0 mm2 for sham and matrix controls, respectively) and the smallest intimal area (3.3 ± 0.4 mm2; P < .05) compared with controls (6.2 ±0.5 mm2 and 4.4 ±0.5 mm2 for sham and matrix controls, respectively). Overall, PAE-treated arteries had a 33% to 50% decrease in percent occlusion (P < .05) compared with controls. Histopathological analysis revealed fewer leukocytes present in the intima in the PAE/matrix group compared with control groups, suggesting that the biological effects were in part due to inhibition of the inflammatory phase of the vascular response to injury. Conclusions Minimally invasive, perivascular delivery of PAE/matrix to stented arteries was performed safely using ultrasound-guided percutaneous injections and significantly decreased stenosis. Application at the time of or subsequent to peripheral interventions may decrease clinical restenosis rates.

Nugent, Helen M.; Ng, Yin-Shan; White, Desmond; Groothius, Adam; Kanner, Glenn; Edelman, Elazer R.

2013-01-01

314

Differences between Measurements of Bone Mineral Densities by Quantitative Ultrasound and Dual Energy X-Ray Absorptiometry in Type 2 Diabetic Postmenopausal Women  

Microsoft Academic Search

Context: Quantitative ultrasound (QUS) may be more helpful than dual-energy X-ray absorpti- ometry (DXA) in detecting bone deficits in patients with type 2 diabetes mellitus (T2DM). Objective: The objective of the study was to compare differences in bone mass measurement by DXA and QUS in T2DM and nondiabetic postmenopausal women. Design, Setting, and Participants: This clinical investigation was a cross-sectional

Bei Tao; Jian-Min Liu; Hong-Yan Zhao; Li-Hao Sun; Wei-Qing Wang; Xiao-Ying Li; Guang Ning

315

A comparison of laser ultrasound measurements and finite element simulations for evaluating the elastic properties of tissue mimicking phantoms  

NASA Astrophysics Data System (ADS)

Advances in the field of laser ultrasonics have opened up new possibilities in medical applications. This paper presents a finite element modelling technique, which studies laser generated surface acoustic waves in different concentration of soft tissue mimicking agar-agar phantoms. In addition, we propose a novel approach that utilises a low coherence interferometer to detect the laser-induced surface acoustic waves from the tissue mimicking phantoms. A Nd:YAG focused laser line-source is applied to the agar-agar phantoms, which as the same with the FE simulation. The generated SAW signals are detected by a time domain low coherence interferometry system. SAW phase velocity dispersion curves from both of the FE simulation and experiment are calculated. By comparison, we show that the experimental results agree well with those of the FE simulation and theoretical expectations. This study is the first report that a laser-generated SAW phase velocity dispersion technique is applied to soft materials. This technique may open a way for laser ultrasonics to detect the mechanical properties of soft tissues, such as skin.

Li, Chunhui; Li, Sinan; Guan, Guangying; Wei, Cheng; Huang, Zhihong; Wang, Ruikang K.

2012-06-01

316

American Institute of Ultrasound in Medicine  

MedlinePLUS

... Preclinical Imaging Interventional-Intraoperative Ultrasound Musculoskeletal Ultrasound Neurosonology Obstetric Ultrasound Gynecologic Ultrasound Pediatric Ultrasound Sonography Therapeutic Ultrasound ...

317

Collagen type II enhances chondrogenesis in adipose tissue-derived stem cells by affecting cell shape  

Microsoft Academic Search

Ideally, biomaterials have inductive properties, favoring specific lineage differentiation. For chondrogenic induction, these properties have been attributed to collagen type II. However, the underlying mechanisms are largely unknown. This study aimed to investigate whether collagen type II favors chondrogenic induction by affecting cell shape through ?1 integrins and Rho A\\/Rock signaling. For this purpose, adipose tissue–derived stem cells (ASCs) were

ZuFu Lu; Behrouz Zandieh Doulabi; ChunLing Huang; Ruud A. Bank; Marco N. Helder

2010-01-01

318

Measurements of bubble-enhanced heating from focused, MHz-frequency ultrasound in a tissue-mimicking material.  

PubMed

Time-resolved measurements of the temperature field in an agar-based tissue-mimicking phantom insonated with a large aperture 1-MHz focused acoustic transducer are reported. The acoustic pressure amplitude and insonation duration were varied. Above a critical threshold acoustic pressure, a large increase in the temperature rise during insonation was observed. Evidence for the hypothesis that cavitation bubble activity in the focal zone is the cause of enhanced heating is presented and discussed. Mechanisms for bubble-assisted heating are presented and modeled, and quantitative estimates for the thermal power generated by viscous dissipation and bubble acoustic radiation are given. PMID:11731053

Holt, R G; Roy, R A

2001-10-01

319

Pulse inversion chirp coded tissue harmonic imaging (PI-CTHI) of Zebrafish heart using high frame rate ultrasound biomicroscopy.  

PubMed

This paper reports a pulse inversion chirp coded tissue harmonic imaging (PI-CTHI) method for visualizing small animal hearts that provides fine spatial resolution at a high frame rate without sacrificing the echo signal to noise ratio (eSNR). A 40 MHz lithium niobate (LiNbO(3)) single element transducer is employed to evaluate the performance of PI-CTHI by scanning tungsten wire targets, spherical anechoic voids, and zebrafish hearts. The wire phantom results show that PI-CTHI improves the eSNR by 4 dB from that of conventional pulse inversion tissue harmonic imaging (PI-THI), while still maintaining a spatial resolution of 88 and 110 ?m in the axial and lateral directions, respectively. The range side lobe level of PI-CTHI is 11 dB lower than that of band-pass filtered CTHI (or F-CTHI). In the anechoic sphere phantom study, the contrast-to-noise ratio of PI-CTHI is found to be 2.7, indicating a 34% enhancement over conventional PI-THI. Due to such improved eSNR and contrast resolution, blood clots in zebrafish hearts can be readily visualized throughout heart regeneration after 20% of the ventricle is removed. Disappearance of the clots in the early stages of the regeneration has been observed for 7 days without sacrificing the fish. PMID:22930467

Park, Jinhyoung; Huang, Ying; Chen, Ruimin; Lee, Jungwoo; Cummins, Thomas M; Zhou, Qifa; Lien, Ching-Ling; Shung, K K

2013-01-01

320

Pulse Inversion Chirp Coded Tissue Harmonic Imaging (PI-CTHI) of Zebrafish Heart Using High Frame Rate Ultrasound Biomicroscopy  

PubMed Central

This paper reports a pulse inversion chirp coded tissue harmonic imaging (PI-CTHI) method for visualizing small animal hearts that provides fine spatial resolution at a high frame rate without sacrificing the echo signal to noise ratio (eSNR). A 40 MHz lithium niobate (LiNbO3) single element transducer is employed to evaluate the performance of PI-CTHI by scanning tungsten wire targets, spherical anechoic voids, and zebrafish hearts. The wire phantom results show that PI-CTHI improves the eSNR by 4 dB from that of conventional pulse inversion tissue harmonic imaging (PI-THI), while still maintaining a spatial resolution of 88 and 110 ?m in the axial and lateral directions, respectively. The range side lobe level of PI-CTHI is 11 dB lower than that of band-pass filtered CTHI (or F-CTHI). In the anechoic sphere phantom study, the contrast-to-noise ratio of PI-CTHI is found to be 2.7, indicating a 34% enhancement over conventional PI-THI. Due to such improved eSNR and contrast resolution, blood clots in zebrafish hearts can be readily visualized throughout heart regeneration after 20% of the ventricle is removed. Disappearance of the clots in the early stages of the regeneration has been observed for 7 days without sacrificing the fish.

Park, Jinhyoung; Huang, Ying; Chen, Ruimin; Lee, Jungwoo; Cummins, Thomas M.; Zhou, Qifa; Lien, Ching-Ling; Shung, K. K.

2012-01-01

321

Benign breast lesions: Ultrasound  

PubMed Central

Benign breast diseases constitute a heterogeneous group of lesions arising in the mammary epithelium or in other mammary tissues, and they may also be linked to vascular, inflammatory or traumatic pathologies. Most lesions found in women consulting a physician are benign. Ultrasound (US) diagnostic criteria indicating a benign lesion are described as well as US findings in the most frequent benign breast lesions.

Masciadri, N.; Ferranti, C.

2011-01-01

322

Phase-inversion tissue harmonic imaging compared with conventional B-mode ultrasound in the evaluation of pancreatic lesions.  

PubMed

The aim of this study was to compare the diagnostic sensitivity, specificity, and image quality of conventional B-mode US (BM) and phase-inversion tissue harmonic imaging (PTHI) regarding pancreatic pathology. In a prospective study, 107 patients, aged between 28 and 85 years, underwent US examinations of the pancreas with both BM and PTHI in a randomly chosen order. As diagnostic reference, either contrast-enhanced CT or MRI examinations of the upper abdomen were obtained in all patients. Sensitivity and specificity were evaluated using the Student's t test. Differences in overall image quality, lesion conspicuity, fluid-solid differentiation, and delineation of the pancreatic tail were analyzed using Wilcoxon's signed ranks test and Bowker's symmetry test. Sixteen of 107 examined patients (15%) were non-diagnostic and excluded due to technical limitations such as abdominal gas. A total of 60 pancreatic lesions (cysts, acute pancreatitis, dilatation of the pancreatic duct, calcifications, and solid tumors) were diagnosed by CT or MRI. Phase-inversion tissue harmonic imaging had a higher sensitivity of 70% (14 of 20) than BM (60%; 24 of 40) for the detection of pancreatic lesions; however, the difference was not statistically significant ( p=0.46). In the assessment of lesions <1 cm of size, PTHI had a sensitivity of 70% and BM 46.7%, whereby the difference again was not statistically significant. Phase-inversion tissue harmonic imaging proved to be superior to BM regarding overall image quality ( p<0.0001), lesion conspicuity ( p=0.0045), and fluid-solid differentiation ( p=0.0002), as well as the delineation of the pancreatic tail ( p<0.0001). These differences were statistically significant. The statistically significant improvement of image quality with regards to lesion conspicuity, fluid-solid differentiation, and delineation of the pancreatic tail favors the use of PTHI when evaluating the pancreas with US. Sensitivity for pancreatic lesions is increased with PTHI in comparison with conventional sonography (BM), especially in lesions <1 cm in diameter, although the difference was not statistically significant. PMID:14714139

Hohl, Christian; Schmidt, Thorsten; Haage, Patrick; Honnef, Dagmar; Blaum, Marcus; Staatz, Gundula; Guenther, Rolf W

2004-06-01

323

Medical ultrasound systems  

PubMed Central

Medical ultrasound imaging has advanced dramatically since its introduction only a few decades ago. This paper provides a short historical background, and then briefly describes many of the system features and concepts required in a modern commercial ultrasound system. The topics addressed include array beam formation, steering and focusing; array and matrix transducers; echo image formation; tissue harmonic imaging; speckle reduction through frequency and spatial compounding, and image processing; tissue aberration; Doppler flow detection; and system architectures. It then describes some of the more practical aspects of ultrasound system design necessary to be taken into account for today's marketplace. It finally discusses the recent explosion of portable and handheld devices and their potential to expand the clinical footprint of ultrasound into regions of the world where medical care is practically non-existent. Throughout the article reference is made to ways in which ultrasound imaging has benefited from advances in the commercial electronics industry. It is meant to be an overview of the field as an introduction to other more detailed papers in this special issue.

Powers, Jeff; Kremkau, Frederick

2011-01-01

324

Medical ultrasound systems.  

PubMed

Medical ultrasound imaging has advanced dramatically since its introduction only a few decades ago. This paper provides a short historical background, and then briefly describes many of the system features and concepts required in a modern commercial ultrasound system. The topics addressed include array beam formation, steering and focusing; array and matrix transducers; echo image formation; tissue harmonic imaging; speckle reduction through frequency and spatial compounding, and image processing; tissue aberration; Doppler flow detection; and system architectures. It then describes some of the more practical aspects of ultrasound system design necessary to be taken into account for today's marketplace. It finally discusses the recent explosion of portable and handheld devices and their potential to expand the clinical footprint of ultrasound into regions of the world where medical care is practically non-existent. Throughout the article reference is made to ways in which ultrasound imaging has benefited from advances in the commercial electronics industry. It is meant to be an overview of the field as an introduction to other more detailed papers in this special issue. PMID:22866226

Powers, Jeff; Kremkau, Frederick

2011-08-01

325

AMUM LECTURE: Therapeutic ultrasound  

NASA Astrophysics Data System (ADS)

The use of ultrasound in medicine is now quite commonplace, especially with the recent introduction of small, portable and relatively inexpensive, hand-held diagnostic imaging devices. Moreover, ultrasound has expanded beyond the imaging realm, with methods and applications extending to novel therapeutic and surgical uses. These applications broadly include: tissue ablation, acoustocautery, lipoplasty, site-specific and ultrasound mediated drug activity, extracorporeal lithotripsy, and the enhancement of natural physiological functions such as wound healing and tissue regeneration. A particularly attractive aspect of this technology is that diagnostic and therapeutic systems can be combined to produce totally non-invasive, imageguided therapy. This general lecture will review a number of these exciting new applications of ultrasound and address some of the basic scientific questions and future challenges in developing these methods and technologies for general use in our society. We shall particularly emphasize the use of High Intensity Focused Ultrasound (HIFU) in the treatment of benign and malignant tumors as well as the introduction of acoustic hemostasis, especially in organs which are difficult to treat using conventional medical and surgical techniques.

Crum, Lawrence A.

2004-01-01

326

A New Sensitive Chromogenic Substrate Assay of Tissue Factor Pathway Inhibitor Type 1  

Microsoft Academic Search

The present assay is a modification of our previously published two-stage chromogenic substrate assay of tissue factor pathway inhibitor type-1 (TFPI) activity [1]. In the first stage, the reaction mixture was made with factor VIIa (FVIIa) molecules in excess of tissue factor (TF) binding sites and contained diluted plasma, recombinant FVIIa (10 nM), recombinant TF (1\\/400 vol\\/vol), bovine factor Xa

Bjørn Bendz; Trine O Andersen; Per Morten Sandset

2000-01-01

327

What is ultrasound?  

PubMed

This paper is based on material presented at the start of a Health Protection Agency meeting on ultrasound and infrasound. In answering the question 'what is ultrasound?', it shows that the simple description of a wave which transports mechanical energy through the local vibration of particles at frequencies of 20 kHz or more, with no net transport of the particles themselves, can in every respect be misleading or even incorrect. To explain the complexities responsible for this, the description of ultrasound is first built up from the fundamental properties of these local particle vibrations. This progresses through an exposition of the characteristics of linear waves, in order to explain the propensity for, and properties of, the nonlinear propagation which occurs in many practical ultrasonic fields. Given the Health Protection environment which framed the original presentation, explanation and examples are given of how these complexities affect issues of practical importance. These issues include the measurement and description of fields and exposures, and the ability of ultrasound to affect tissue (through microstreaming, streaming, cavitation, heating, etc.). It is noted that there are two very distinct regimes, in terms of wave characteristics and potential for bioeffect. The first concerns the use of ultrasound in liquids/solids, for measurement or material processing. For biomedical applications (where these two processes are termed diagnosis and therapy, respectively), the issue of hazard has been studied in depth, although this has not been done to such a degree for industrial uses of ultrasound in liquids/solids (sonar, non-destructive testing, ultrasonic processing etc.). However, in the second regime, that of the use of ultrasound in air, although the waves in question tend to be of much lower intensities than those used in liquids/solids, there is a greater mismatch between the extent to which hazard has been studied, and the growth in commercial applications for airborne ultrasound. PMID:17045633

Leighton, Timothy G

2007-01-01

328

Different modes of herpes simplex virus type 1 spread in brain and skin tissues.  

PubMed

Herpes simplex virus type 1 (HSV-1) initially infects the skin and subsequently spreads to the nervous system. To investigate and compare HSV-1 mode of propagation in the two clinically relevant tissues, we have established ex vivo infection models, using native tissues of mouse and human skin, as well as mouse brain, maintained in organ cultures. HSV-1, which is naturally restricted to the human, infects and spreads in the mouse and human skin tissues in a similar fashion, thus validating the mouse model. The spread of HSV-1 in the skin was concentric to form typical plaques of limited size, predominantly of cytopathic cells. By contrast, HSV-1 spread in the brain tissue was directed along specific neuronal networks with no apparent cytopathic effect. Two additional differences were noted following infection of the skin and brain tissues. First, only a negligible amount of extracellular progeny virus was produced of the infected brain tissues, while substantial quantity of infectious progeny virus was released to the media of the infected skin. Second, antibodies against HSV-1, added following the infection, effectively restricted viral spread in the skin but have no effect on viral spread in the brain tissue. Taken together, these results reveal that HSV-1 spread within the brain tissue mostly by direct transfer from cell to cell, while in the skin the progeny extracellular virus predominates, thus facilitating the infection to new individuals. PMID:24408306

Tsalenchuck, Yael; Tzur, Tomer; Steiner, Israel; Panet, Amos

2014-02-01

329

Tracked ultrasound elastography (TRUE)  

NASA Astrophysics Data System (ADS)

Medical ultrasound research has experienced a renaissance in the past decade leading to innovations in flow mapping, elasticity and thermal imaging, measurement of optical properties, beamforming, and image enhancement. In this thesis, we focus on ultrasound elastography, an emerging imaging modality with great potential to become a part of several ultrasound diagnostic applications. Elastography images the stiffness of soft tissue by applying a mechanical stimulus and estimating the disturbance created by this stimulus. In freehand elastography, soft tissue is palpated by hand using the ultrasound transducer. The elastography image is generated by comparing the pre- and post-compression images to form a displacement map which is then differentiated to produce the final strain map. To achieve the best result in freehand elastography, the sonographer must compress and decompress the tissue uniformly in a specific direction with adequate compression. This can be a difficult task even for trained users. A small rotational or out-of-plane motion in the collected ultrasound frames can render them unusable for elastography. This has made freehand elastography highly qualitative and user-dependent. We tackle this issue by incorporating the extra information from a position sensor attached to the ultrasound transducer. Our aim is to show that the localization information of ultrasound images may be utilized to improve the quality and reliability of freehand elastography. For this purpose, we have developed a frame selection scheme that finds pairs of images with optimal compression and minimal lateral and out-of-plane displacement. Relying on the localization information, our algorithm merges multiple strain images computed from the selected frame pairs. This method is applicable to both 2D and 3D elastography. Our 3D elastography does not require for the transducer to be held still during the acquisition of each volume. Instead, the sonographer freely palpates the tissue similar to the 2D case while a series of volumes are being collected. For applications such as needle ablation therapy, it is also possible to palpate the tissue internally using the ablation needle. In this case, we have assessed the feasibility of incorporating the localization information about the tip of the needle in elastography. We have evaluated these methods using tissue mimicking phantom, animal, and patient experiments. Our results suggest that in challenging clinical conditions, the proposed methods are capable of producing high-quality strain images.

Foroughi, Pezhman

330

Interventional ultrasound  

SciTech Connect

This book discusses: Introduction to interventional ultrasound/handling of aspirated material/general principles of fine needle aspiration cytology/procedure and principles in ultrasonically guided puncture/puncture of focal liver lesions/intraoperative puncture of the liver guided by ultrasound/Interventional ultrasound in cancer therapy/Interventional echocardiography/Fine-needle aspiration biopsy: Are there any risks./Puncture of renal mass lesions/Intrauterine needle diagnosis/Percutaneous nephrolithotomy.

Holm, H.H.; Kristensen, J.K.

1985-01-01

331

Immunohistological assessment of the synovial tissue in small joints in rheumatoid arthritis: validation of a minimally invasive ultrasound-guided synovial biopsy procedure  

PubMed Central

The aim of the present study was to perform an immunohistological assessment of the synovial tissue from involved small joints in rheumatoid arthritis (RA) and to explore the reliability of a mini-invasive ultrasound (US)-guided technique of small joint synovial biopsy for the histopathological assessment. Synovial tissue collected during arthrotomic surgery of small joints in nine patients served as the gold standard for the validation of the histological assessment. Small hand-joint synovial biopsies from an additional nine patients with erosive RA were obtained by a mini-invasive US-guided procedure, performed percutaneously by the portal and rigid forceps technique. Using digital image analysis, the area fractions of synovial macrophages (CD68 cells), T cells (CD3 cells) and B cells (CD20 cells) were measured in all high-power fields of every sample at different cutting levels. The representative sample was defined as the minimal number of high-power fields whose mean area fraction would reflect the overall mean area fraction within a percentage mean difference of 10%. For each patient, a range of three to five large samples for surgical biopsies and a range of 8–12 samples for US-guided biopsies were collected and analysed. In arthrotomic samples, the analysis of a randomly selected tissue area of 2.5 mm2 was representative of the overall value for CD68, CD3 and CD20 cells. US-guided samples allowed histological evaluation in 100% of cases, with a mean valid area of 18.56 mm2 (range 7.29–38.28 mm2). The analysis of a cumulative area of 2.5 mm2 from eight randomly selected sections (from different samples or from different cutting levels) allowed to reduce the percentage mean difference to less than 10% for CD68, CD3 and CD20 cells. In conclusion, US-guided synovial biopsy represents a reliable tool for the assessment of the histopathological features of RA patients with a mini-invasive approach.

Scire, Carlo Alberto; Epis, Oscar; Codullo, Veronica; Humby, Frances; Morbini, Patrizia; Manzo, Antonio; Caporali, Roberto; Pitzalis, Costantino; Montecucco, Carlomaurizio

2007-01-01

332

Pregnancy ultrasound  

MedlinePLUS

Pregnancy sonogram; Obstetric ultrasonography; Obstetric sonogram; Ultrasound - pregnancy ... In: Gabbe SG, Niebyl JR, Simpson JL, eds. Obstetrics: Normal and Problem Pregnancies . 5th ed. Philadelphia, Pa: ...

333

Modulation of ultrasound to produce multifrequency radiation force1  

PubMed Central

Dynamic radiation force has been used in several types of applications, and is performed by modulating ultrasound with different methods. By modulating ultrasound, energy can be transmitted to tissue, in this case a dynamic force to elicit a low frequency cyclic displacement to inspect the material properties of the tissue. In this paper, different types of modulation are explored including amplitude modulation (AM), double sideband suppressed carrier amplitude modulation AM, linear frequency modulation, and frequency-shift keying. Generalized theory is presented for computing the radiation force through the short-term time average of the energy density for these various types of modulation. Examples of modulation with different types of signals including sine waves, square waves, and triangle waves are shown. Using different modulating signals, multifrequency radiation force with different numbers of frequency components can be created, and can be used to characterize tissue mimicking materials and soft tissue. Results for characterization of gelatin phantoms using a method of vibrating an embedded sphere are presented. Different degrees of accuracy were achieved using different modulation techniques and modulating signals. Modulating ultrasound is a very flexible technique to produce radiation force with multiple frequency components that can be used for various applications.

Urban, Matthew W.; Fatemi, Mostafa; Greenleaf, James F.

2010-01-01

334

Cell-type-specific isolation of ribosome-associated mRNA from complex tissues  

PubMed Central

Gene profiling techniques allow the assay of transcripts from organs, tissues, and cells with an unprecedented level of coverage. However, most of these approaches are still limited by the fact that organs and tissues are composed of multiple cell types that are each unique in their patterns of gene expression. To identify the transcriptome from a single cell type in a complex tissue, investigators have relied upon physical methods to separate cell types or in situ hybridization and immunohistochemistry. Here, we describe a strategy to rapidly and efficiently isolate ribosome-associated mRNA transcripts from any cell type in vivo. We have created a mouse line, called RiboTag, which carries an Rpl22 allele with a floxed wild-type C-terminal exon followed by an identical C-terminal exon that has three copies of the hemagglutinin (HA) epitope inserted before the stop codon. When the RiboTag mouse is crossed to a cell-type-specific Cre recombinase-expressing mouse, Cre recombinase activates the expression of epitope-tagged ribosomal protein RPL22ha, which is incorporated into actively translating polyribosomes. Immunoprecipitation of polysomes with a monoclonal antibody against HA yields ribosome-associated mRNA transcripts from specific cell types. We demonstrate the application of this technique in brain using neuron-specific Cre recombinase-expressing mice and in testis using a Sertoli cell Cre recombinase-expressing mouse.

Sanz, Elisenda; Yang, Linghai; Su, Thomas; Morris, David R.; McKnight, G. Stanley; Amieux, Paul S.

2009-01-01

335

Renal ultrasound elastography.  

PubMed

Chronic kidney disease (CKD) incidence and prevalence are increasing in Western countries, due particularly to diabetes mellitus and hypertension-related nephropathies. CKD may lead to end-stage renal failure, with extensive morbidity, mortality and increasing health costs. Primary and secondary prevention requires a better knowledge of mechanisms underlying renal scarring, the development of specific therapies to slow down the progression of the disease and the development of non-invasive diagnostic tools to characterize the process. Ultrasound elastography is a new imaging technique under development that provides information about renal stiffness. Kidney elasticity measurements with ultrasound should be performed with a quantitative technique, such as Shearwave techniques. However kidney stiffness is not only related to fibrosis, as it also sensitive to mechanical and functional parameters such as anisotropy, vascularization, hydronephrosis and external pressure. This paper reviews the existing ultrasound elastography techniques. Elastography is a new tool under development for renal tissue characterization and needs further validation in clinical practice. PMID:23567180

Grenier, N; Gennisson, J-L; Cornelis, F; Le Bras, Y; Couzi, L

2013-05-01

336

Subcutaneous and Visceral Adipose Tissue Gene Expression of Serum Adipokines That Predict Type 2 Diabetes  

Microsoft Academic Search

Type 2 diabetes mellitus (T2D) is predicted by central obesity and circulating adipokines regulating inflammation. We hypothesized that visceral adipose tissue (VAT) in T2D expresses greater levels of proinflammatory molecules. Paired samples of subcutaneous (SAT) and VAT were excised at elective surgery (n = 16, 6 with T2D, n = 8 age- and gender- matched controls). Metabolic parameters were measured

Katherine Samaras; Natalia K. Botelho; Donald J. Chisholm; Reginald V. Lord

2010-01-01

337

Glycolipid Analysis of Different Tissues and Cerebrospinal Fluid in Type II Gaucher Disease  

Microsoft Academic Search

The lipid composition or the liver, spleen, brain, cerebellum and cerebrospinal fluid of a Gaucher disease type II patient who died at the age of 5 months was examined. The glycolipid analysis demonstrated a marked increase of total amounts not only in the peripheral tissues but also in the brain cerebellum and cerebrospinal fluid, with a prevalence of glucosylceramide. A

R. Gornati; B. Berra; G. Montorfano; C. Martini; G. Ciana; P. Ferrari; M. Romano; B. Bembi

2002-01-01

338

Degradation of human plasma and extracellular matrix fibronectin by tissue type plasminogen activator and urokinase.  

PubMed

Fibronectins and plasminogen activators, both tissue and urokinase types, are involved in the physiopathological degradation of the extracellular matrix. Previous reports indicate that fibronectin can be degraded by urokinase without plasminogen. Also, we have shown that tissue-type plasminogen activator can cleave fibronectin, without plasminogen, generating fragments of 30 and 220-250 kDa detectable by immunoblotting analysis. A comparison with urokinase-induced degradation indicates that the cleavage sites are the same for both plasminogen activators. One is close to the carboxyl-terminal, disrupting the fibronectin dimeric structure, and one is near the amino-terminal, generating a 30 kDa fragment. In solution, the activity of tissue-type plasminogen activator was prevalent on the amino-terminal site, while urokinase activity was prevalent on the carboxyl-terminal site. On fibronectin immobilized onto a gelatin coated surface, only the 30 kDa fragment was released when treated with both plasminogen activators. Plasminogen activators also were active on fibronectin assembled into the extracellular matrix of cultured fibroblasts. Urokinase caused the complete disappearance of extracellular matrix fibronectin, together with the release of the 30 and the 220-250 kDa fibronectin fragments, but left a flat morphology, while tissue-type plasminogen activator induced the release of the 30 kDa fragment associated with changes in cellular morphology. The plasminogen-independent fibronectin degradation exerted by tissue-type plasminogen activator and urokinase is 100 times lower than that exerted by plasmin. This may provide a mechanism for localized and limited degradation of fibronectin preventing the generalized proteolysis associated with plasminogen activation. PMID:8930138

Marchina, E; Barlati, S

1996-10-01

339

Ultrasound-enhanced delivery of targeted echogenic liposomes in a novel ex vivo mouse aorta model  

PubMed Central

The goal of this study was to determine whether targeted, Rhodamine-labeled echogenic liposomes (Rh-ELIP) containing nanobubbles could be delivered to the arterial wall, and whether 1 MHz continuous wave ultrasound would enhance this delivery profile. Aortae excised from apolipoprotein-E-deficient (n = 8) and wild-type (n = 8) mice were mounted in a pulsatile flow system through which Rh-ELIP were delivered in a stream of bovine serum albumin. Half the aortae from each group were treated with 1-MHz continuous wave ultrasound at 0.49 MPa peak-to-peak pressure, and half underwent sham exposure. Ultrasound parameters were chosen to promote stable cavitation and avoid inertial cavitation. A broadband hydrophone was used to monitor cavitation activity. After treatment, aortic sections were prepared for histology and analyzed by an individual blinded to treatment conditions. Delivery of Rh-ELIP to the vascular endothelium was observed, and subendothelial penetration of Rh-ELIP was present in five of five ultrasound-treated aortae and was absent in those not exposed to ultrasound. However, the degree of penetration in the ultrasound-exposed aortae was variable. There was no evidence of ultrasound-mediated tissue damage in any specimen. Ultrasound-enhanced delivery within the arterial wall was demonstrated in this novel model, which allows quantitative evaluation of therapeutic delivery.

Hitchcock, Kathryn E.; Caudell, Danielle N.; Sutton, Jonathan T.; Klegerman, Melvin E.; Vela, Deborah; Pyne-Geithman, Gail J.; Abruzzo, Todd; Cyr, Peppar E. P.; Geng, Yong-Jian; McPherson, David D.; Holland, Christy K.

2010-01-01

340

Multi-Tissue Computational Modeling Analyzes Pathophysiology of Type 2 Diabetes in MKR Mice  

PubMed Central

Computational models using metabolic reconstructions for in silico simulation of metabolic disorders such as type 2 diabetes mellitus (T2DM) can provide a better understanding of disease pathophysiology and avoid high experimentation costs. There is a limited amount of computational work, using metabolic reconstructions, performed in this field for the better understanding of T2DM. In this study, a new algorithm for generating tissue-specific metabolic models is presented, along with the resulting multi-confidence level (MCL) multi-tissue model. The effect of T2DM on liver, muscle, and fat in MKR mice was first studied by microarray analysis and subsequently the changes in gene expression of frank T2DM MKR mice versus healthy mice were applied to the multi-tissue model to test the effect. Using the first multi-tissue genome-scale model of all metabolic pathways in T2DM, we found out that branched-chain amino acids' degradation and fatty acids oxidation pathway is downregulated in T2DM MKR mice. Microarray data showed low expression of genes in MKR mice versus healthy mice in the degradation of branched-chain amino acids and fatty-acid oxidation pathways. In addition, the flux balance analysis using the MCL multi-tissue model showed that the degradation pathways of branched-chain amino acid and fatty acid oxidation were significantly downregulated in MKR mice versus healthy mice. Validation of the model was performed using data derived from the literature regarding T2DM. Microarray data was used in conjunction with the model to predict fluxes of various other metabolic pathways in the T2DM mouse model and alterations in a number of pathways were detected. The Type 2 Diabetes MCL multi-tissue model may explain the high level of branched-chain amino acids and free fatty acids in plasma of Type 2 Diabetic subjects from a metabolic fluxes perspective.

Kumar, Amit; Harrelson, Thomas; Lewis, Nathan E.; Gallagher, Emily J.; LeRoith, Derek; Shiloach, Joseph; Betenbaugh, Michael J.

2014-01-01

341

Reconstruction of viscoelastic tissue properties from MR elastography-type measurements  

NASA Astrophysics Data System (ADS)

This study is concerned with an optimization-based approach to the identification of "background" viscoelastic properties of soft tissues from magnetic resonance (MR) elastography-type measurements. In this approach, the triaxial tissue displacements, captured by the MR scanner over a suitable subdomain that is free of major heterogeneities, are split into (i) a boundary subset that is used to formulate the forward (Dirichlet) problem, and (ii) an internal subset, employed as "the data" for the inverse (material characterization) problem. For an elevated performance of the minimization scheme, material sensitivities of the featured cost functional are computed semi-analytically via a boundary-integral formulation, resulting in alternative "direct" and adjoint-field sensitivity formulas. The numerical results, obtained assuming input parameters that are relevant to MR elastography, indicate that the proposed approach may provide an effective means for comprehensive multi-frequency characterization of the "background" viscoelasticity of soft tissues.

Yuan, Huina; Guzina, Bojan B.

2010-07-01

342

Complex heterogeneous tissue constructs containing multiple cell types prepared by inkjet printing technology.  

PubMed

This study was designed to develop a versatile method for fabricating complex and heterogeneous three-dimensional (3D) tissue constructs using simultaneous ink-jetting of multiple cell types. Human amniotic fluid-derived stem cells (hAFSCs), canine smooth muscle cells (dSMCs), and bovine aortic endothelial cells (bECs), were separately mixed with ionic cross-linker calcium chloride (CaCl(2)), loaded into separate ink cartridges and printed using a modified thermal inkjet printer. The three cell types were delivered layer-by-layer to pre-determined locations in a sodium alginate-collagen composite located in a chamber under the printer. The reaction between CaCl(2) and sodium alginate resulted in a rapid formation of a solid composite gel and the printed cells were anchored in designated areas within the gel. The printing process was repeated for several cycles leading to a complex 3D multi-cell hybrid construct. The biological functions of the 3D printed constructs were evaluated in vitro and in vivo. Each of the printed cell types maintained their viability and normal proliferation rates, phenotypic expression, and physiological functions within the heterogeneous constructs. The bioprinted constructs were able to survive and mature into functional tissues with adequate vascularization in vivo. These findings demonstrate the feasibility of fabricating complex heterogeneous tissue constructs containing multiple cell types using inkjet printing technology. PMID:23063369

Xu, Tao; Zhao, Weixin; Zhu, Jian-Ming; Albanna, Mohammad Z; Yoo, James J; Atala, Anthony

2013-01-01

343

Tissue Mimicking Elastography Phantoms.  

National Technical Information Service (NTIS)

Tissue mimicking materials for elastography phantoms have elastic, ultrasound, and magnetic resonance characteristics that are characteristic of human soft tissues and well suited for the calibration and performance assessment of elastography imaging syst...

E. L. Madsen G. R. Frank

2005-01-01

344

Hot topics in biomedical ultrasound: ultrasound therapy and its integration with ultrasonic imaging  

NASA Astrophysics Data System (ADS)

Since the development of biomedical ultrasound imaging from sonar after WWII, there has been a clear divide between ultrasonic imaging and ultrasound therapy. While imaging techniques are designed to cause as little change as possible in the tissues through which ultrasound propagates, ultrasound therapy typically relies upon heating or acoustic cavitation to produce a desirable therapeutic effect. Concerns over the increasingly high acoustic outputs of diagnostic ultrasound scanners prompted the adoption of the Mechanical Index (MI) and Thermal Index (TI) in the early 1990s. Therapeutic applications of ultrasound, meanwhile, have evolved from deep tissue heating in sports medicine to include targeted drug delivery, tumor and plaque ablation, cauterization via high intensity focused ultrasound (HIFU), and accelerated dissolution of blood clots. The integration of ultrasonic imaging and therapy in one device is just beginning, but the promise of improved patient outcomes is balanced by regulatory and practical impediments.

Everbach, E. Carr

2005-09-01

345

Contourlet Transform for Texture Representation of Ultrasound Thyroid Images  

Microsoft Academic Search

\\u000a Texture representation of ultrasound (US) images is currently considered a major issue in medical image analysis. This paper\\u000a investigates the texture representation of thyroid tissue via features based on the Contourlet Transform (CT) using different\\u000a types of filter banks. A variety of statistical texture features based on CT coefficients, have been considered through a\\u000a selection schema. The Sequential Float Feature

Stamos Katsigiannis; Eystratios G. Keramidas; Dimitris Maroulis

2010-01-01

346

21 CFR 1271.85 - What donor testing is required for different types of cells and tissues?  

Code of Federal Regulations, 2013 CFR

...immunodeficiency virus, type 1; (2) Human immunodeficiency virus, type 2; (3) Hepatitis B virus; (4) Hepatitis C virus; and (5) Treponema pallidum . (b) Donors of viable, leukocyte-rich cells or tissue . In addition to...

2013-04-01

347

Peroxynitrite: A Key Molecule in Skin Tissue Response to Different Types of Stress  

Microsoft Academic Search

Skin, the largest tissue exposed to a variety of stresses demonstrates a common cellular biochemical response unrelated to\\u000a the type of the stress allegedly. In this chapter we will describe a phenomenon in which different insults, unrelated to oxidative\\u000a events to start with, resulted in an activation of common cellular biochemical pathways. These processes are similar to those\\u000a evoked following

Meital Portugal; Ron Kohen

348

Wild-type Measles Virus in Brain Tissue of Children with Subacute Sclerosing Panencephalitis, Argentina  

PubMed Central

We studied eight children who had measles at 6 to 10 months of age during the 1998 Argentine measles outbreak and in whom subacute sclerosing panencephalitis developed 4 years later. We report the genetic characterization of brain tissue–associated measles virus samples from three patients. Phylogenetic relationships clustered these viruses with the wild-type D6 genotype isolated during the 1998 outbreak. The children received measles vaccine; however, vaccinal strains were not found.

Barrero, Paola Roxana; Grippo, Jorge; Viegas, Mariana

2003-01-01

349

Subretinal administration of tissue-type plasminogen activator to speed the drainage of subretinal hemorrhage  

Microsoft Academic Search

• Background: Bleeding into the subretinal space in the vicinity of the macula is associated with age-related macular degeneration\\u000a or retinal arterial macroaneurysm. The prognosis for restoration of vision is poor in the presence of blood clots.?• Methods:\\u000a Using a simple device composed of three disposable syringes we injected tissue-type plasminogen activator (tPA) into the subretinal\\u000a space during conventional vitrectomy

Shizuya Saika; Akifumi Yamanaka; Akio Yamanaka; Ayako Minamide; Keisyu Kin; Kumi Shirai; Sai-ichi Tanaka; Yoshiji Kawashima; Tadashi Katoh; Yuka Okada; Kiyomi Ohkawa; Yoshitaka Ohnishi

1998-01-01

350

Decreased type V collagen expression in human decidual tissues of spontaneous abortion during early pregnancy.  

PubMed Central

AIM: To provide some insight into the aetiology of spontaneous abortion, the contents of type V collagen was investigated in human decidual tissues in spontaneous abortion and normal pregnancy. METHODS: Collagens were extracted from decidual tissues in spontaneous abortion (n = 19) and normal pregnancy (n = 25). The different types of collagen alpha chains were separated by sodium dodecyl sulphate-polyacrylamide gel electrophoresis (SDS-PAGE), stained with Coomassie brilliant blue, and measured by densitometry. The relative amounts of the alpha 1 (III) and alpha 1 (V) chains were calculated by dividing the band intensities of the alpha 1 (III) and alpha 1 (V) chains by that of the alpha 1 (I) chain. RESULTS: The ratio of the alpha 1 (V) chain to that of the alpha 1 (I) chain in decidual tissues in spontaneous abortion was significantly lower than that found in normal pregnancy (p < 0.05). CONCLUSIONS: These results suggest that type V collagen might play an important role in the maintenance of pregnancy and that decreased expression of this collagen could be associated with spontaneous abortion. Images

Iwahashi, M; Nakano, R

1998-01-01

351

Ultrasound in analytical chemistry.  

PubMed

Ultrasound is a type of energy which can help analytical chemists in almost all their laboratory tasks, from cleaning to detection. A generic view of the different steps which can be assisted by ultrasound is given here. These steps include preliminary operations usually not considered in most analytical methods (e.g. cleaning, degassing, and atomization), sample preparation being the main area of application. In sample preparation ultrasound is used to assist solid-sample treatment (e.g. digestion, leaching, slurry formation) and liquid-sample preparation (e.g. liquid-liquid extraction, emulsification, homogenization) or to promote heterogeneous sample treatment (e.g. filtration, aggregation, dissolution of solids, crystallization, precipitation, defoaming, degassing). Detection techniques based on use of ultrasonic radiation, the principles on which they are based, responses, and the quantities measured are also discussed. PMID:17103146

Priego Capote, F; Luque de Castro, M D

2007-01-01

352

Combined ultrasound, optoacoustic, and elasticity imaging  

NASA Astrophysics Data System (ADS)

Combination of three complementary imaging technologies - ultrasound imaging, elastography, and optoacoustic imaging - is suggested for detection and diagnostics of tissue pathology including cancer. The fusion of these ultrasound-based techniques results in a novel imaging system capable of simultaneous imaging of the anatomy (ultrasound imaging), cancer-induced angiogenesis (optoacoustic imaging) and changes in mechanical properties (elasticity imaging) of tissue to uniquely identify and differentiate pathology at various stages. To evaluate our approach, analytical and numerical studies were performed using heterogeneous phantoms where ultrasonic, optical and viscoelastic properties of the materials were chosen to closely mimic soft tissue. The results of this study suggest that combined ultrasound-based imaging is possible and can provide more accurate, reliable and earlier detection and diagnosis of tissue pathology. In addition, monitoring of cancer treatment and guidance of tissue biopsy are possible with a combined imaging system.

Emelianov, Stanislav Y.; Aglyamov, Salavat R.; Shah, J.; Sethuraman, S.; Scott, W. G.; Schmitt, R.; Motamedi, Massoud; Karpiouk, A.; Oraevsky, Alexander A.

2004-07-01

353

An optimized ultrasound-assisted extraction and simultaneous quantification of 26 characteristic components with four structure types in functional foods from ginkgo seeds.  

PubMed

An optimized method of ultrasound-assisted extraction followed by ultra-high-performance liquid chromatography coupled with triple-quadrupole tandem mass spectrometry (UAE-UHPLC-TQ/MS(2)) was proposed for the simultaneous extraction and determination of 26 characteristic components covering four structure types (flavonoids, terpene lactones, ginkgolic acids and phenylpropanols) in ginkgo seeds (GSs). The UAE parameters (ultrasound power, time and solvent-to-material ratio) were optimized using a response surface methodology. This is the first report of the simultaneous analysis of 26 compounds in Ginkgo biloba using UHPLC-TQ/MS(2); this analysis afforded good linearity, precision, repeatability and accuracy. UAE-UHPLC-TQ/MS(2) was successfully applied to ginkgo seed samples, and the analysis showed that GSs are rich in terpene lactones and could be selected as a healthy food resource. The results suggest that UAE-UHPLC-TQ/MS(2) might be able to be utilized as a tool for the quality assessment of samples from GSs or other related products using flavonoids, terpene lactones, ginkgolic acids and phenylpropanols as markers. PMID:24731329

Zhou, Guisheng; Yao, Xin; Tang, Yuping; Qian, Dawei; Su, Shulan; Zhang, Li; Jin, Chun; Qin, Yong; Duan, Jin-ao

2014-09-01

354

Characterization of Human Papillomavirus Type 154 and Tissue Tropism of Gammapapillomaviruses  

PubMed Central

The novel human papillomavirus type 154 (HPV154) was characterized from a wart on the crena ani of a three-year-old boy. It was previously designated as the putative HPV type FADI3 by sequencing of a subgenomic FAP amplicon. We obtained the complete genome by combined methods including rolling circle amplification (RCA), genome walking through an adapted method for detection of integrated papillomavirus sequences by ligation-mediated PCR (DIPS-PCR), long-range PCR, and finally by cloning of four overlapping amplicons. Phylogenetically, the HPV154 genome clustered together with members of the proposed species Gammapapillomavirus 11, and demonstrated the highest identity in L1 to HPV136 (68.6%). The HPV154 was detected in 3% (2/62) of forehead skin swabs from healthy children. In addition, the different detection sites of 62 gammapapillomaviruses were summarized in order to analyze their tissue tropism. Several of these HPV types have been detected from multiple sources such as skin, oral, nasal, and genital sites, suggesting that the gammapapillomaviruses are generalists with a broader tissue tropism than previously appreciated. The study expands current knowledge concerning genetic diversity and tropism among HPV types in the rapidly growing gammapapillomavirus genus.

Ure, Agustin Enrique; Forslund, Ola

2014-01-01

355

Ultrasound Imaging and Its Modeling  

NASA Astrophysics Data System (ADS)

Modern medical ultrasound scanners are used to image nearly all soft tissue structures in the body. The anatomy can be studied from gray-scale B-mode images, where the reflectivity and scattering strength of the tissues are displayed. The imaging is performed in real time with 20 to 100 images per second. The technique is widely used, since it does not use ionizing radiation and is safe and painless for the patient. This chapter gives a short introduction to modern ultrasound imaging using array transducers. It includes a description of the different imaging methods, the beam-forming strategies used, and the resulting fields and their modeling.

Jensen, Jorgen A.

356

Tissue reaction to three different types of tissue glues in an experimental aorta dissection model: a quantitative approach.  

PubMed

Tissue glues are used during surgical treatment of acute aorta dissection although some glues release toxic products and thus alter the histological structure of the vessel wall. The aim of our study was to use a porcine experimental model of infrarenal aorta dissection to compare histological changes of the vessel wall 1, 6 and 12 months after application of BioGlue, Gelatin-resorcin-formaldehyde (GRF) glue and Tissucol. For quantification, stereological methods were used. All types of glue caused stenosis, GRF most and Tissucol least severely. With increasing postoperative survival time, stenosis was again reduced. Elastine length density decreased with increasing survival time in Control as well as in all Experimental groups. The immunohistochemical phenotype of vascular smooth muscle cells was similar in Tissucol and Control samples. In GRF samples, actin, desmin and vimentin expression changed most severely. Similarly, number and distribution of vasa vasorum in the aortic wall was altered most severely in GRF samples. They tended to return to normal with increasing postoperative survival time, but at a slow rate in the GRF samples. It can be concluded that GRF causes the most severe histopathological changes within the treated aorta, which could be a reason for late failures of dissection surgery. However, glue handling and adhesive properties have to be taken into account, too, when certain glue is chosen for surgical intervention. Increased inflammation and vascularisation might even stabilise the aortic wall. Long-term experimental studies would be helpful to assess healing processes after initial disorganisation of the aortic wall structure. PMID:19902233

Witter, Kirsti; Tonar, Zbynek; Matejka, Vít Martin; Martinca, Tomás; Jonák, Michael; Rokosný, Slavomír; Pirk, Jan

2010-02-01

357

Transmission of Therapeutic Ultrasound by Wound Dressings  

Microsoft Academic Search

Ultrasound has been used for the treatment of a variety of cutaneous wounds, particularly venous ulcers. Many of the published studies involved application of ultrasound to the surrounding tissue rather than directly over the wound. Insonating the wound itself may enhance the healing process, but the lack of data regarding the trans- mission characteristics of dressings has limited the use

Leon Poltawski; Tim Watson

358

The role of ultrasound operation mode for safely interfering in the heart rate  

Microsoft Academic Search

Dia gnostic ultrasound applies low intensity acoustic waves to noninvasively investigate biological tissues. Higher intensities can alter tissue characteristics, and this is of interest for therapeutic ultrasound, when the occurrence of bioeffects is - to a certain extent - desirable for tissue healing. Relative to cardiology, diagnostic ultrasound is well established, whereas there is an unexplored potential for therapeutic applications.

E. Belassiano; R. Miller; E. Hartman; W. D. OaBrien; F. Buiochi; E. T. Costa

2011-01-01

359

[Marginal zone B-cell lymphoma of mucosa-associated lymphoid tissue type (MALT lymphoma)].  

PubMed

Extranodal marginal zone B-cell lymphoma of mucosa-associated lymphoid tissue type (MALT lymphoma) is a B-cell tumor thought to originate from B-lymphocytes that are normally present in the marginal zone of lymphoid follicles of the lymphoid tissue. About 50% of MALT lymphoma occurs in gastrointestinal tract. The majority of patients present with localized disease and indolent clinical progression. In localized gastric MALT lymphoma with Helicobacter pylori (HP) infection, HP eradication is recommended as first line therapy. In those without HP infection and localized non-gastric MALT lymphoma, involved field radiation therapy(IFRT) is recommended as first line therapy. Patients in advanced stage and salvage setting are managed according to the recommendations for advanced follicular lymphoma. The long-term survival rate of MALT lymphoma patients is 80-90%. PMID:24724410

Takahashi, Tsutomu; Suzumiya, Junji

2014-03-01

360

Intravascular ultrasound and photoacoustic imaging.  

PubMed

There is a need for an imaging technique that can reliably identify and characterize the vulnerability of atherosclerotic plaques. Catheter-based intravascular ultrasound (IVUS) is one of the imaging tools of the clinical evaluation of atherosclerosis. However, histopathological information obtained with IVUS imaging is limited. We present and discuss the applicability of a combined intravascular photoacoustic (IVPA) and intravascular ultrasound (IVUS) imaging approach to assess both vessel structure and tissue composition thus identifying rupture-prone atherosclerotic plaques. Photoacoustic (or optoacoustic and, generally, thermoacoustic) imaging relies on the absorption of electromagnetic energy, such as light, and the subsequent emission of an acoustic wave. Therefore, the amplitude and temporal characteristics of the photoacoustic signal is primarily determined by optical absorption properties of different types of tissues and can be used to differentiate the lipid, fibrous and fibro-cellular components of an inflammatory lesion. Simultaneous IVUS and IVPA imaging studies were conducted using 40 MHz clinical IVUS imaging catheter interfaced with a pulsed laser system. The performance of the IVPA/IVUS imaging was assessed using phantoms with point targets and vessel-mimicking phantoms. To detect the lipids in the plaque, ex-vivo IVPA imaging studies of a normal and an atherosclerotic rabbit aorta were performed at a 532 nm wavelength. To assess plaque composition, multi-wavelength (680-950 nm) spectroscopic IVPA imaging studies were carried out. Finally, molecular and cellular IVPA imaging was demonstrated using plasmonic nanoparticles. Overall, our studies suggest that plaque detection and characterization can be improved using the combined IVPA/IVUS imaging. PMID:19162578

Emelianov, Stanislav; Wang, Bo; Su, Jimmy; Karpiouk, Andrei; Yantsen, Evgeniya; Sokolov, Konstantin; Amirian, James; Smalling, Richard; Sethuraman, Shriram

2008-01-01

361

Mast cells orchestrate type 2 immunity to helminths through regulation of tissue-derived cytokines  

PubMed Central

Mast cells (MCs) are potent inflammatory cells that are distributed throughout mucosal barrier tissues and respond rapidly to pathogenic stimuli. During helminth infections, MCs play an important role as late-stage effectors. However, it is currently unknown whether MCs contribute to the early innate events that determine the priming of adaptive immunity. MC-deficient mouse strains and mice treated with the MC stabilizing agent cromolyn sodium had dramatically reduced Th2 priming and type 2 cytokine production and harbored increased parasite burdens following infection with gastrointestinal helminths (Heligmosomoides polygyrus bakeri and Trichuris muris). In addition, early production of the tissue-derived cytokines IL-25, IL-33, and thymic stromal lymphopoietin (TSLP) was significantly diminished in MC-deficient mice and resulted in decreased numbers of infection-elicited IL-25–dependent (Lin?CD45?)CD34+Sca-1+ progenitors, which produced type 2 cytokines and could be differentiated into mast cells ex vivo. Finally, repair of MC deficiency increased production of IL-25, IL-33, and TSLP, restored progenitor cell numbers and Th2 priming, and reduced parasite burden. Our data reveal an innate IgE-independent role for MCs in orchestrating type 2 immune responses via the regulation of IL-25, IL-33, and TSLP.

Hepworth, Matthew R.; Danilowicz-Luebert, Emilia; Rausch, Sebastian; Metz, Martin; Klotz, Christian; Maurer, Marcus; Hartmann, Susanne

2012-01-01

362

Simulation of ultrasound backscatter images from fish  

NASA Astrophysics Data System (ADS)

The objective of this work is to investigate ultrasound (US) backscatter in the MHz range from fish to develop a realistic and reliable simulation model. The long term objective of the work is to develop the needed signal processing for fish species differentiation using US. In in-vitro experiments, a cod (Gadus morhua) was scanned with both a BK Medical ProFocus 2202 ultrasound scanner and a Toshiba Aquilion ONE computed tomography (CT) scanner. The US images of the fish were compared with US images created using the ultrasound simulation program Field II. The center frequency of the transducer is 10 MHz and the Full Width at Half Maximum (FWHM) at the focus point is 0.54 mm in the lateral direction. The transducer model in Field II was calibrated using a wire phantom to validate the simulated point spread function. The inputs to the simulation were the CT image data of the fish converted to simulated scatter maps. The positions of the point scatterers were assumed to be uniformly distributed. The scatter amplitudes were generated with a new method based on the segmented CT data in Hounsfield Units and backscatter data for the different types of tissues from the literature. The simulated US images reproduce most of the important characteristics of the measured US image.

Pham, An Hoai; Stage, Bjarne; Hemmsen, Martin Christian; Lundgren, Bo; Pedersen, Mads Møller; Pedersen, Tina Bock; Jensen, Jørgen Arendt

2011-03-01

363

Soft tissue sarcomas and central nervous system tumors in children with neurofibromatosis type 1  

Microsoft Academic Search

Objects  We aim to evaluate the characteristics of pediatric patients with neurofibromatosis type 1 (NF1) who developed soft tissue\\u000a sarcomas (STSs) and central nervous system (CNS) tumors that have been followed up in our center.\\u000a \\u000a \\u000a \\u000a \\u000a Materials and methods  Medical records of children with NF1 were retrospectively analyzed.\\u000a \\u000a \\u000a \\u000a Results  There were 78 patients who met at least two diagnostic criteria for NF1. The median

Emre Cecen; Dilek Ince; Kamer Mutafoglu Uysal; Erdener Ozer; Riza Cetingoz; Ali Aykan Ozguven; Handan Cakmakci; Faik Sarialioglu; Nur Olgun

364

Study of factors affecting the magnitude and nature of ultrasound exposure with in vitro set-ups.  

PubMed

Therapeutic ultrasound is a clinically applied method to improve fracture healing and holds great potential as a manipulator of biologic material relevant to tissue engineering approaches. Unfortunately, the cell stimulating property of ultrasound is not known, which inhibits the optimal use of this technique. Additionally, many in vitro studies in this field use ultrasound configurations that are vulnerable to errors during calibration and use. These errors arise from the structural simplicity and incomplete characterization of these configurations. In this study, pulse-echo ultrasound, laser Doppler vibrometry and Schlieren imaging were applied to noninvasively characterize common in vitro experimental configurations. Fine wire thermocouple measurements were conducted to characterize any possible temperature rise during the ultrasound exposures. The results quantified the frequency dependent sound transmission through culture wells and the standing wave effect within the cell volume. These effects can cause uncertainty of up to 700% in the actual ultrasound exposure experienced by the cell. A temperature rise of 2.7°C was measured from an ultrasound configuration commonly used in vitro ultrasound studies. Furthermore, wave mode conversion in culture wells was observed, emphasizing the complexity of these sonications. Similar type Lamb waves have been observed in bone in vivo. Thus, Lamb waves may be a mechanism for stimulating the cells. PMID:22425382

Leskinen, Jarkko J; Hynynen, Kullervo

2012-05-01

365

In Vitro Effects of Low-Intensity Pulsed Ultrasound Stimulation on the Osteogenic Differentiation of Human Alveolar Bone-Derived Mesenchymal Stem Cells for Tooth Tissue Engineering  

PubMed Central

Ultrasound stimulation produces significant multifunctional effects that are directly relevant to alveolar bone formation, which is necessary for periodontal healing and regeneration. We focused to find out effects of specific duty cycles and the percentage of time that ultrasound is being generated over one on/off pulse period, under ultrasound stimulation. Low-intensity pulsed ultrasound ((LIPUS) 1?MHz) with duty cycles of 20% and 50% was used in this study, and human alveolar bone-derived mesenchymal stem cells (hABMSCs) were treated with an intensity of 50?mW/cm2 and exposure time of 10?min/day. hABMSCs exposed at duty cycles of 20% and 50% had similar cell viability (O.D.), which was higher (*P < 0.05) than that of control cells. The alkaline phosphatase (ALP) was significantly enhanced at 1 week with LIPUS treatment in osteogenic cultures as compared to control. Gene expressions showed significantly higher expression levels of CD29, CD44, COL1, and OCN in the hABMSCs under LIPUS treatment when compared to control after two weeks of treatment. The effects were partially controlled by LIPUS treatment, indicating that modulation of osteogenesis in hABMSCs was related to the specific stimulation. Furthermore, mineralized nodule formation was markedly increased after LIPUS treatment than that seen in untreated cells. Through simple staining methods such as Alizarin red and von Kossa staining, calcium deposits generated their highest levels at about 3?weeks. These results suggest that LIPUS could enhance the cell viability and osteogenic differentiation of hABMSCs, and could be part of effective treatment methods for clinical applications.

Lim, KiTaek; Kim, Jangho; Choung, Pill-Hoon; Chung, Jong Hoon

2013-01-01

366

Phase-inversion tissue harmonic imaging compared to fundamental B-mode ultrasound in the evaluation of the pathology of large and small bowel.  

PubMed

Our purpose was to compare phase-inversion harmonic imaging (PIHI) with conventional B-mode ultrasound (US) regarding image quality in the evaluation of bowel pathology. Forty-one patients prospectively underwent intestinal ultrasound scans with US and PIHI in randomly chosen order. Crucial technical parameters were standardized. Bowel morphology as well as perienteric pathology and complications were documented. In 24 cases, the ultrasound results were compared to those of other imaging modalities. Three radiologists evaluated (1) overall image quality, (2) lesion conspicuity and diagnostic confidence, and (3) detection of free fluid on hardcopy films. The ratings for image quality were compared using the two-sample paired t test for means and Bowker's test for symmetry (p=0.05). Compared to US, PIHI provided significantly better overall image quality, lesion conspicuity and diagnostic confidence, as well as better detection of free fluid (p< 0.05). Bowel wall pathology, detected by both modalities, showed good correlation to additional imaging modalities. In 12 patients (29.3%), a gain of crucial diagnostic information was observed with PIHI when compared to US. PIHI significantly enhances sonography of the intestine by offering better overall image quality, better visualization of bowel pathology and associated changes. Additionally, PIHI adds crucial diagnostic information in several patients. PMID:15818478

Schmidt, T; Hohl, C; Haage, P; Honnef, D; Mahnken, A H; Krombach, G; Piroth, W; Günther, R W

2005-09-01

367

A new type of magnification system in free microvascular tissue transfer: Varioscope M5.  

PubMed

Free microvascular tissue transfers have become today a key instrument for the surgical treatment of wide loss of tissue. These procedures can provide definitive treatment in a single operation but they are expensive and require specialized practitioners. The operating microscope traditionally has provided this requirement; our study is focusing on the prospect of using a new visual system-Varioscope M5-in the reconstructive microsurgery field. Varioscope M5 (Life Optics, Vienna, Austria) has been employed in 21 microvascular anastomoses, where different free flaps were used in head and neck reconstruction. The necessity to operate in a different department, not provided with an operating microscope, brought along the idea of exploring an alternative procedure to classical visualization systems. Specific advantages such as reduced cost, freedom of movement, autofocus, minimal upkeep, a variable range of magnification from 2x to 9x are some of the reasons that convinced the authors to use this new type of magnification system. Increasing interest in microsurgery magnification highlights the need for further technical development in that field. We consider Varioscope M5 a future mean of anastomotic magnification in most free-tissue transfers with specific characteristics that combine the microscope and loupe philosophies. PMID:17705280

Chiummariello, Stefano; Fioramonti, Paolo; Menichini, Giulio; Scuderi, Nicolò; Alfano, Carmine

2007-01-01

368

Cell lines of novel type derived from a diabetic secrete tissue-reactive human monoclonal antibodies.  

PubMed

Human monoclonal antibodies have been produced from lymphocytes of an acute-onset insulin-dependent diabetic patient. Peripheral blood lymphocytes were hybridized with a fusion partner HMY-1320. Initial screening of human immunoglobulin secretion was made by a nitrocellulose dot blot assay. Ten stable cell lines of novel type, secreting human immunoglobulin, were obtained. These cell lines have been maintained in continuous culture over 6 months and cryopreserved in liquid nitrogen for 14 months. Human monoclonal antibodies of IgG and IgM class have been produced and are secreted at a rate of 150-650 ng/ml/10(6) cells/day. Monoclonal antibodies were tested for histological staining against a variety of endocrine and non-endocrine tissues. One monoclonal antibody, LT1E12, demonstrates a staining pattern in human, rat, and mouse tissues, similar to that of mitochondrial antibodies. Another antibody, LT3C4, demonstrates weak staining of smooth muscle in rat and mouse kidney sections. Neither specificities were detected in the diabetic patient's serum. The variety of immune tissue specificities obtained in this study demonstrates the potential value of human monoclonal antibodies as probes to analyze the complexity of autoimmunity in diabetes mellitus. PMID:1873494

De Silva, M G; Ebsworth, N M; Dodwell, L C; Moyle, S P; Swana, G T; Tan, K S

1991-01-01

369

Ultrasound-targeted microbubble destruction enhances gene transduction of adeno-associated virus in a less-permissive cell type, NIH/3T3  

PubMed Central

Adeno-associated virus (AAV) is a common vector utilized in gene therapy. The NIH/3T3 cell line, which is a potential induced pluripotent stem (iPS) cell type, was identified to be a less-permissive cell type to AAV due to its defective endosomal processing. Ultrasound-targeted microbubble destruction (UTMD) enhanced the gene transduction of AAV in permissive cells. However, there are no data concerning UTMD enhancement in less-permissive cells, and the exact mechanism of UTMD enhancement in cellular uptake is unclear. Greater knowledge concerning the rate-limiting steps in NIH/3T3 cells would aid in the elucidation of the mechanism of UTMD enhancement in the gene transduction of AAV. In the present study, UTMD enhanced the gene transduction of AAV in NIH/3T3 cells, suggesting that UTMD-enhanced AAV-mediated gene transduction may be beneficial for gene therapy in iPS cells. The dose dependence of UTMD enhancement indicated that mechanisms other than sonoporation were involved in the cellular uptake of AAV. However, UTMD did not greatly increase the gene transduction of AAV in NIH/3T3 cells. Additionally, the similar degree of enhancement in the two cell types resulted in no correlation between UTMD and endosomal processing. Future studies on UTMD-mediated AAV transduction in other non- or less-permissive cell types may aid in elucidating the exact mechanism of UTMD enhancement in cellular uptake.

JIN, LIFANG; LI, FAN; WANG, HUIPING; LI, YUNHUA; WEI, FANG; DU, LIANFANG

2013-01-01

370

Implementation of vibro-acoustography on a clinical ultrasound system  

Microsoft Academic Search

Vibro-acoustography is an ultrasound-based im- aging modality that uses two ultrasound beams of slightly dif- ferent frequencies to produce images based on the acoustic response caused by harmonic ultrasound radiation force exci- tation at the difference frequency between the two ultrasound frequencies. Vibro-acoustography has demonstrated feasibility and usefulness in imaging of breast and prostate tissue. How- ever, previous studies have

Matthew W. Urban; Carl Chalek; Randall Kinnick; Thomas Kinter; Bruno Haider; James Greenleaf; Kai Thomenius; Mostafa Fatemi

2011-01-01

371

Endobronchial Ultrasound  

Microsoft Academic Search

Complex technical problems interfered with the application of thoracic ultrasound (US) for studies and clinical research. Moreover, in contrast to radiologists, cardiologists, gastroenterologists, internists, obstetricians, gynecologists and others, pulmonologists were not trained in the basics of US images. However, endoscopic US methods were developed in the last 20 years and these methods also provided important results for pulmonologists. As soon

Franco Falcone; Flavio Fois; Daniele Grosso

2003-01-01

372

Ultrasound characterization of the infertile male testis with rf power spectrum analysis  

NASA Astrophysics Data System (ADS)

Objective: To investigate and diagnose testicular pathology in patients with testicular dysfunction using the technique of ultrasound power spectrum analysis. Methods: Testicular ultrasound studies with power spectrum tissue characterization analysis were performed on men with testicular abnormalities as well as normal controls. Semen analysis, biopsy data, microscopic intra-operative findings and data pertaining to testicular function were collected for each surgically evaluated subject. Ultrasound data were analyzed for power spectrum characteristics of microscopic scatterer size and concentration within discrete areas of testicular tissue. Results: Patients with varicoceles and greater than 2x106 sperm/ml on semen analysis had larger average scatterer size (107.7 micrometers ) and lower scatterer concentration (-15.02 dB) than non-obstructed, azoospermic patients with varicoceles (92.4 micrometers and -11.41 dB, respectively). Subjects with obstructed azoospermia had slightly larger average tissue scatterer size (108.1 micrometers ) and lower concentration (-15.73 dB) while normal control data revealed intermediate values of size (102.3 micrometers ) and concentration (-13.1 dB) of scatterers. Spectral data from pure testicular seminoma lesions had the lowest average scatterer size (82.3 micrometers ) with low relative concentration (-14.7 dB). Summary: Ultrasound tissue characterization based on RF spectrum analysis may distinguish different types of testicular pathology including obstructed and non-obstructed azoospermia and tissue changes due to varicocele and tumor.

Coleman, Jonathan A.; Silverman, Ronald H.; Rondeau, Mark; Coleman, D. J.; Schlegel, Peter

2002-04-01

373

Metabolically Favorable Remodeling of Human Adipose Tissue by Human Adenovirus Type 36  

PubMed Central

OBJECTIVE—Experimental infection of rats with human adenovirus type 36 (Ad-36) promotes adipogenesis and improves insulin sensitivity in a manner reminiscent of the pharmacologic effect of thiozolinediones. To exploit the potential of the viral proteins as a therapeutic target for treating insulin resistance, this study investigated the ability of Ad-36 to induce metabolically favorable changes in human adipose tissue. RESEARCH DESIGN AND METHODS—We determined whether Ad-36 increases glucose uptake in human adipose tissue explants. Cell-signaling pathways targeted by Ad-36 to increase glucose uptake were determined in the explants and human adipose–derived stem cells. Ad-2, a nonadipogenic human adenovirus, was used as a negative control. As a proof of concept, nondiabetic and diabetic subjects were screened for the presence of Ad-36 antibodies to ascertain if natural Ad-36 infection predicted improved glycemic control. RESULTS—Ad-36 increased glucose uptake by adipose tissue explants obtained from nondiabetic and diabetic subjects. Without insulin stimulation, Ad-36 upregulated expressions of several proadipogenic genes, adiponectin, and fatty acid synthase and reduced the expression of inflammatory cytokine macrophage chemoattractant protein-1 in a phosphotidylinositol 3-kinase (PI3K)-dependent manner. In turn, the activation of PI3K by Ad-36 was independent of insulin receptor signaling but dependent on Ras signaling recruited by Ad-36. Ad-2 was nonadipogenic and did not increase glucose uptake. Natural Ad-36 infection in nondiabetic and diabetic subjects was associated with significantly lower fasting glucose levels and A1C, respectively. CONCLUSIONS—Ad-36 proteins may provide novel therapeutic targets that remodel human adipose tissue to a more metabolically favorable profile.

Rogers, Pamela M.; Mashtalir, Nazar; Rathod, Miloni A.; Dubuisson, Olga; Wang, Zhong; Dasuri, Kumar; Babin, Scott; Gupta, Alok; Markward, Nathan; Cefalu, William T.; Dhurandhar, Nikhil V.

2008-01-01

374

Effect of resonance frequency, power input, and saturation gas type on the oxidation efficiency of an ultrasound horn.  

PubMed

The sonochemical oxidation efficiency (?(ox)) of a commercial titanium alloy ultrasound horn has been measured using potassium iodide as a dosimeter at its main resonance frequency (20 kHz) and two higher resonance frequencies (41 and 62 kHz). Narrow power and frequency ranges have been chosen to minimise secondary effects such as changing bubble stability, and time available for radical diffusion from the bubble to the liquid. The oxidation efficiency, ?(ox), is proportional to the frequency and to the power transmitted to the liquid (275 mL) in the applied power range (1-6 W) under argon. Luminol radical visualisation measurements show that the radical generation rate increases and a redistribution of radical producing zones is achieved at increasing frequency. Argon, helium, air, nitrogen, oxygen, and carbon dioxide have been used as saturation gases in potassium iodide oxidation experiments. The highest ?(ox) has been observed at 5 W under air at 62 kHz. The presence of carbon dioxide in air gives enhanced nucleation at 41 and 62 kHz and has a strong influence on ?(ox). This is supported by the luminol images, the measured dependence of ?(ox) on input power, and bubble images recorded under carbon dioxide. The results give insight into the interplay between saturation gas and frequency, nucleation, and their effect on ?(ox). PMID:20573535

Rooze, Joost; Rebrov, Evgeny V; Schouten, Jaap C; Keurentjes, Jos T F

2011-01-01

375

Bacillus anthracis oedema toxin as a cause of tissue necrosis and cell type-specific cytotoxicity.  

PubMed

Oedema factor (OF) and protective antigen (PA) are secreted by Bacillus anthracis, and their binary combination yields oedema toxin (OT). Following PA-mediated delivery to the cytosol, OF functions as an adenylate cyclase generating high levels of cAMP. To assess OT as a possible cause of tissue damage and cell death, a novel approach was developed, which utilized a developing zebrafish embryo model to study toxin activity. Zebrafish embryos incubated with OT exhibited marked necrosis of the liver, cranium and gastrointestinal tract, as well as reduced swim bladder inflation. The OT-treated embryos survived after all stages of development but succumbed to the toxin within 7 days. Additional analysis of specific cell lines, including macrophage and non-macrophage, showed OT-induced cell death is cell type-specific. There was no discernible correlation between levels of OF-generated cAMP and cell death. Depending on the type of cell analysed, cell death could be detected in low levels of cAMP, and, conversely, cell survival was observed in one cell line in which high levels of cAMP were found following treatment with OT. Collectively, these data suggest OT is cytotoxic in a cell-dependent manner and may contribute to disease through direct cell killing leading to tissue necrosis. PMID:16008581

Voth, Daniel E; Hamm, Elaine E; Nguyen, Lan G; Tucker, Amy E; Salles, Isabelle I; Ortiz-Leduc, William; Ballard, Jimmy D

2005-08-01

376

Ultrasound Intensity and Treatment Time Fuzzy Logic Control System for Low Cost Effective Ultrasound Therapy Devices  

Microsoft Academic Search

Therapeutic ultrasound is an emerging field with many medical applications. High intensity focused ultrasound provides the\\u000a ability to localize the deposition of acoustic energy within the body, which can cause tissue necrosis and hemostasis. The\\u000a ultrasound applied in therapy is usually ranged from 1MHz to 1000MHz. Even the least vibration of 1MHz would be as keen as\\u000a a sharp knife

Ahmet Yardimci; O. Celik

2004-01-01

377

Ultrasound to assess bone quality.  

PubMed

Bone quality is determined by a variety of compositional, micro- and ultrastructural properties of the mineralized tissue matrix. In contrast to X-ray-based methods, the interaction of acoustic waves with bone tissue carries information about elastic and structural properties of the tissue. Quantitative ultrasound (QUS) methods represent powerful alternatives to ionizing x-ray based assessment of fracture risk. New in vivo applicable methods permit measurements of fracture-relevant properties, [eg, cortical thickness and stiffness at fragile anatomic regions (eg, the distal radius and the proximal femur)]. Experimentally, resonance ultrasound spectroscopy and acoustic microscopy can be used to assess the mesoscale stiffness tensor and elastic maps of the tissue matrix at microscale resolution, respectively. QUS methods, thus, currently represent the most promising approach for noninvasive assessment of components of fragility beyond bone mass and bone microstructure providing prospects for improved assessment of fracture risk. PMID:24652476

Raum, Kay; Grimal, Quentin; Varga, Peter; Barkmann, Reinhard; Glüer, Claus C; Laugier, Pascal

2014-06-01

378

Individual-specific muscle maximum force estimation using ultrasound for ankle joint torque prediction using an EMG-driven Hill-type model.  

PubMed

EMG-driven models can be used to estimate muscle force in biomechanical systems. Collected and processed EMG readings are used as the input of a dynamic system, which is integrated numerically. This approach requires the definition of a reasonably large set of parameters. Some of these vary widely among subjects, and slight inaccuracies in such parameters can lead to large model output errors. One of these parameters is the maximum voluntary contraction force (F(om)). This paper proposes an approach to find F(om) by estimating muscle physiological cross-sectional area (PCSA) using ultrasound (US), which is multiplied by a realistic value of maximum muscle specific tension. Ultrasound is used to measure muscle thickness, which allows for the determination of muscle volume through regression equations. Soleus, gastrocnemius medialis and gastrocnemius lateralis PCSAs are estimated using published volume proportions among leg muscles, which also requires measurements of muscle fiber length and pennation angle by US. F(om) obtained by this approach and from data widely cited in the literature was used to comparatively test a Hill-type EMG-driven model of the ankle joint. The model uses 3 EMGs (Soleus, gastrocnemius medialis and gastrocnemius lateralis) as inputs with joint torque as the output. The EMG signals were obtained in a series of experiments carried out with 8 adult male subjects, who performed an isometric contraction protocol consisting of 10s step contractions at 20% and 60% of the maximum voluntary contraction level. Isometric torque was simultaneously collected using a dynamometer. A statistically significant reduction in the root mean square error was observed when US-obtained F(om) was used, as compared to F(om) from the literature. PMID:20541763

de Oliveira, Liliam Fernandes; Menegaldo, Luciano Luporini

2010-10-19

379

Low-frequency quantitative ultrasound imaging of cell death in vivo  

SciTech Connect

Purpose: Currently, no clinical imaging modality is used routinely to assess tumor response to cancer therapies within hours to days of the delivery of treatment. Here, the authors demonstrate the efficacy of ultrasound at a clinically relevant frequency to quantitatively detect changes in tumors in response to cancer therapies using preclinical mouse models.Methods: Conventional low-frequency and corresponding high-frequency ultrasound (ranging from 4 to 28 MHz) were used along with quantitative spectroscopic and signal envelope statistical analyses on data obtained from xenograft tumors treated with chemotherapy, x-ray radiation, as well as a novel vascular targeting microbubble therapy.Results: Ultrasound-based spectroscopic biomarkers indicated significant changes in cell-death associated parameters in responsive tumors. Specifically changes in the midband fit, spectral slope, and 0-MHz intercept biomarkers were investigated for different types of treatment and demonstrated cell-death related changes. The midband fit and 0-MHz intercept biomarker derived from low-frequency data demonstrated increases ranging approximately from 0 to 6 dBr and 0 to 8 dBr, respectively, depending on treatments administrated. These data paralleled results observed for high-frequency ultrasound data. Statistical analysis of ultrasound signal envelope was performed as an alternative method to obtain histogram-based biomarkers and provided confirmatory results. Histological analysis of tumor specimens indicated up to 61% cell death present in the tumors depending on treatments administered, consistent with quantitative ultrasound findings indicating cell death. Ultrasound-based spectroscopic biomarkers demonstrated a good correlation with histological morphological findings indicative of cell death (r{sup 2}= 0.71, 0.82; p < 0.001).Conclusions: In summary, the results provide preclinical evidence, for the first time, that quantitative ultrasound used at a clinically relevant frequency, in addition to high-frequency ultrasound, can detect tissue changes associated with cell death in vivo in response to cancer treatments.

Sadeghi-Naini, Ali; Falou, Omar; Czarnota, Gregory J. [Imaging Research – Physical Science, Sunnybrook Research Institute, Sunnybrook Health Sciences Centre, Toronto, Ontario M4N 3M5 (Canada) [Imaging Research – Physical Science, Sunnybrook Research Institute, Sunnybrook Health Sciences Centre, Toronto, Ontario M4N 3M5 (Canada); Department of Radiation Oncology, Odette Cancer Centre, Sunnybrook Health Sciences Centre, Toronto, Ontario M4N 3M5 (Canada); Department of Medical Biophysics, Faculty of Medicine, University of Toronto, Toronto, Ontario M4N 3M5 (Canada); Department of Radiation Oncology, Faculty of Medicine, University of Toronto, Toronto, Ontario M4N 3M5 (Canada); Papanicolau, Naum; Tadayyon, Hadi [Imaging Research – Physical Science, Sunnybrook Research Institute, Sunnybrook Health Sciences Centre, Toronto, Ontario M4N 3M5, Canada and Department of Medical Biophysics, Faculty of Medicine, University of Toronto, Toronto, Ontario M4N 3M5 (Canada)] [Imaging Research – Physical Science, Sunnybrook Research Institute, Sunnybrook Health Sciences Centre, Toronto, Ontario M4N 3M5, Canada and Department of Medical Biophysics, Faculty of Medicine, University of Toronto, Toronto, Ontario M4N 3M5 (Canada); Lee, Justin [Department of Radiation Oncology, Odette Cancer Centre, Sunnybrook Health Sciences Centre, Toronto, Ontario M4N 3M5, Canada and Department of Radiation Oncology, Faculty of Medicine, University of Toronto, Toronto, Ontario M4N 3M5 (Canada)] [Department of Radiation Oncology, Odette Cancer Centre, Sunnybrook Health Sciences Centre, Toronto, Ontario M4N 3M5, Canada and Department of Radiation Oncology, Faculty of Medicine, University of Toronto, Toronto, Ontario M4N 3M5 (Canada); Zubovits, Judit [Department of Pathology, Sunnybrook Health Sciences Centre, Toronto, Ontario M4N 3M5 (Canada)] [Department of Pathology, Sunnybrook Health Sciences Centre, Toronto, Ontario M4N 3M5 (Canada); Sadeghian, Alireza [Department of Computer Science, Ryerson University, Toronto, Ontario M5B 2K3 (Canada)] [Department of Computer Science, Ryerson University, Toronto, Ontario M5B 2K3 (Canada); Karshafian, Raffi [Department of Physics, Ryerson University, Toronto, Ontario M5B 2K3 (Canada)] [Department of Physics, Ryerson University, Toronto, Ontario M5B 2K3 (Canada); Al-Mahrouki, Azza; Giles, Anoja [Imaging Research – Physical Science, Sunnybrook Research Institute, Sunnybrook Health Sciences Centre, Toronto, Ontario M4N 3M5, Canada and Department of Radiation Oncology, Odette Cancer Centre, Sunnybrook Health Sciences Centre, Toronto, Ontario M4N 3M5 (Canada)] [Imaging Research – Physical Science, Sunnybrook Research Institute, Sunnybrook Health Sciences Centre, Toronto, Ontario M4N 3M5, Canada and Department of Radiation Oncology, Odette Cancer Centre, Sunnybrook Health Sciences Centre, Toronto, Ontario M4N 3M5 (Canada); Kolios, Michael C. [Department of Medical Biophysics, Faculty of Medicine, University of Toronto, Toronto, Ontario M4N 3M5, Canada and Department of Physics, Ryerson University, Toronto, Ontario M5B 2K3 (Canada)] [Department of Medical Biophysics, Faculty of Medicine, University of Toronto, Toronto, Ontario M4N 3M5, Canada and Department of Physics, Ryerson University, Toronto, Ontario M5B 2K3 (Canada)

2013-08-15

380

IL-1 antagonism reduces hyperglycemia and tissue inflammation in the type 2 diabetic GK rat  

PubMed Central

Recent studies suggest an inflammatory process, characterized by local cytokine/chemokine production and immune cell infiltration, regulates islet dysfunction and insulin resistance in type 2 diabetes. However, the factor initiating this inflammatory response is not known. Here, we characterized tissue inflammation in the type 2 diabetic GK rat with a focus on the pancreatic islet and investigated a role for IL-1. GK rat islets, previously characterized by increased macrophage infiltration, displayed increased expression of several inflammatory markers including IL-1?. In the periphery, increased expression of IL-1? was observed primarily in the liver. Specific blockade of IL-1 activity by the IL-1 receptor antagonist (IL-1Ra) reduced the release of inflammatory cytokines/chemokines from GK islets in vitro and from mouse islets exposed to metabolic stress. Islets from mice deficient in IL-1? or MyD88 challenged with glucose and palmitate in vitro also produced significantly less IL-6 and chemokines. In vivo, treatment of GK rats with IL-1Ra decreased hyperglycemia, reduced the proinsulin/insulin ratio, and improved insulin sensitivity. In addition, islet-derived proinflammatory cytokines/chemokines (IL-1?, IL-6, TNF?, KC, MCP-1, and MIP-1?) and islet CD68+, MHC II+, and CD53+ immune cell infiltration were reduced by IL-1Ra treatment. Treated GK rats also exhibited fewer markers of inflammation in the liver. We conclude that elevated islet IL-1? activity in the GK rat promotes cytokine and chemokine expression, leading to the recruitment of innate immune cells. Rather than being directly cytotoxic, IL-1? may drive tissue inflammation that impacts on both ? cell functional mass and insulin sensitivity in type 2 diabetes.

Ehses, J. A.; Lacraz, G.; Giroix, M.-H.; Schmidlin, F.; Coulaud, J.; Kassis, N.; Irminger, J.-C.; Kergoat, M.; Portha, B.; Homo-Delarche, F.; Donath, M. Y.

2009-01-01

381

Cell-type-specific expression pattern of ceramide synthase 2 protein in mouse tissues.  

PubMed

Ceramide synthase 2 (CerS2) catalyzes the synthesis of dihydroceramides from dihydrosphingosine and very long fatty acyl (C22-C24)-CoAs. CerS2-deficient (gene trap) mice were reported to exhibit myelin and behavioral abnormalities, associated with the expression of CerS2 in oligodendrocytes and neurons based on expression of lacZ reporter cDNA instead of the cers2 gene in these mice. In order to clarify the cell-type-specific expression of CerS2 protein, we have raised antibodies that specifically recognize the glycosylated and non-glycosylated CerS2 protein in wild-type but not in CerS2-deficient mouse tissues. In early postnatal, juvenile and adult mouse brain, the new antibodies detect CerS2 protein only in oligodendrocytes but not in neurons, suggesting that the gene trap vector in CerS2-deficient mice led to ectopic expression of the lacZ reporter gene in neurons. In liver, the CerS2 protein is expressed in hepatocytes but not in Ito cells or Kupffer cells. We conclude that the behavioral abnormalities observed in CerS2-deficient mice originate primarily in oligodendrocytes and not in neurons. The identification of specific cell types in which CerS2 protein is expressed is prerequisite to further mechanistic characterization of phenotypic abnormalities exhibited by CerS2-deficient mice. The amount of CerS2 protein detected in different tissues by immunoblot analyses does not strictly correspond to the activity of the CerS2 enzyme. Disproportional results are likely due to post-translational regulation of the CerS2 protein. PMID:23591958

Kremser, Christiane; Klemm, Anna-Lena; van Uelft, Martina; Imgrund, Silke; Ginkel, Christina; Hartmann, Dieter; Willecke, Klaus

2013-11-01

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Cryopreservation and in vitro culture of primary cell types from lung tissue of a stranded pygmy sperm whale (Kogia breviceps)?  

PubMed Central

Current models for in vitro studies of tissue function and physiology, including responses to hypoxia or environmental toxins, are limited and rely heavily on standar