An elasticity microscope. Part I: Methods

Cohn, N.A.; Emelianov, Stanislav; Lubinski, M.A.; O’Donnell, Matthew

doi:10.1109/58.656634

Cited by 83 publications

(48 citation statements)

References 39 publications

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“…The beam width is in turn dependent on the central frequency and f-number of the focused ultrasonic transducer. [10][11][12] For the 25 MHz transducer used in our experiments, the spatial resolution within the sensor plane was approximately 120 m. Resolution on the order of few micrometers can be obtained using low f-number, high frequency ultrasound transducers.…”

Section: Discussionmentioning

confidence: 99%

Photoacoustic technique to measure beam profile of pulsed laser systems

Mallidi

Emelianov

2009

Review of Scientific Instruments

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The beam profiles of pulsed lasers are currently measured using either complementary metal oxide semiconductor ͑CMOS͒ or charge coupled device ͑CCD͒ cameras. Despite providing high-resolution beam profiles, these devices cannot work with high power lasers. If additional optical attenuators are used, beam distortions may occur. In this paper we demonstrate a high-resolution photoacoustic technique capable of measuring the beam profile of pulsed lasers. The beam profiles of a pulsed neodymium-doped yttrium aluminium garnet ͑Nd:YAG͒ laser and a pulsed optical parametric oscillator ͑OPO͒ laser system were measured using a polydimethylsiloxane film and a single element high-frequency ultrasonic transducer. The advantages and limitations of the developed photoacoustic technique are discussed.

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Section: Discussionmentioning

confidence: 99%

Photoacoustic technique to measure beam profile of pulsed laser systems

Mallidi

Emelianov

2009

Review of Scientific Instruments

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“…1,9,10 Briefly, AlloDerm and EVPOME samples were immersed in deionized water and imaged with a singleelement fixed-focus transducer, producing ultrasonic B-scans. The transducer has an approximate frequency of 50 MHz, and the element is 3 mm in diameter and focused to a depth of 4.1 mm, giving an f/number of *1.4.…”

Section: Fig 2 (A-d) Sam 2d B-scans Between the Unseeded Allodermmentioning

confidence: 99%

“…The advantages of using SAM over conventional optical and electron microscopy include being able to image cells and tissues without doing any preparations that could potentially kill or alter these tissues; this provides a more accurate representation of the tissues' properties. 1,2,20 We used SAM and an in-house-built mechanical compressor to examine the morphology and nonlinear elastic properties, specifically Ogden nonlinear elastic stress-strain models, respectively, of the commercially available acellular cadaveric dermis, AlloDerm Ò (LifeCell Corp.) and an in-housedesigned ex vivo produced oral mucosa equivalent (EVPOME).…”

mentioning

confidence: 99%

Characterizing Morphology and Nonlinear Elastic Properties of Normal and Thermally Stressed Engineered Oral Mucosal Tissues Using Scanning Acoustic Microscopy

Winterroth

Hollman

Kuo

et al. 2013

Tissue Engineering Part C: Methods

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This study examines the use of high-resolution ultrasound to monitor changes in the morphology and nonlinear elastic properties of engineered oral mucosal tissues under normal and thermally stressed culture conditions. Nonlinear elastic properties were determined by first developing strain maps from acoustic ultrasound, followed by fitting of nonlinear stress-strain data to a 1-term Ogden model. Testing examined a clinically developed ex vivo produced oral mucosa equivalent (EVPOME). As seeded cells proliferate on an EVPOME surface, they produce a keratinized protective upper layer that fills in and smoothens out surface irregularities. These transformations can also alter the nonlinear stress/strain parameters as EVPOME cells differentiate. This EVPOME behavior is similar to those of natural oral mucosal tissues and in contrast to an unseeded scaffold. If ultrasonic monitoring could be developed, then tissue cultivation could be adjusted in-process to account for biological variations in their development of the stratified cellular layer. In addition to ultrasonic testing, an inhouse-built compression system capable of accurate measurements on small (*1.0-1.5 cm 2 ) tissue samples is presented. Results showed a near 2.5-fold difference in the stiffness properties between the unstressed EVPOME and the noncell-seeded acellular scaffold (AlloDerm Ò ). There were also 4 · greater differences in root mean square values of the thickness in the unseeded AlloDerm compared to the mature unstressed EVPOME; this is a strong indicator for quantifying surface roughness.

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“…A discretized version of this receive signal, denoted as f(k), can be written as (1) where N r is the grid size determined by the range interval size and the sampling rate, n(k) is the noise signal, g i (k − j) is the system impulse response created by a unit strength scatterer located on the ith image line at the jth range grid position, and s i (j) is the actual scatterer strength at that location. 2 , · · ·, g i , N r ] and g i, j be the vector version of g i (k − j). Then (1) can be rewritten as (2) where f, s and n are the vector versions of f(k), s(k), n(k), and n(k), respectively.…”

Section: A System Modelmentioning

confidence: 99%

“…2 , · · ·, g i , N r ] and g i, j be the vector version of g i (k − j). Then (1) can be rewritten as (2) where f, s and n are the vector versions of f(k), s(k), n(k), and n(k), respectively. The imaging operator G, defined as (3) is a (typically, underdetermined) matrix operator consisting of N φ linear convolution matrices.…”

Section: A System Modelmentioning

confidence: 99%

Filter-based coded-excitation system for high-speed ultrasonic imaging

Shen

Ebbini

1998

IEEE Trans. Med. Imaging

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We have recently presented a new algorithm for high-speed parallel processing of ultrasound pulse-echo data for real-time three-dimensional (3-D) imaging. The approach utilizes a discretized linear model of the echo data received from the region of interest (ROI) using a conventional beam former. The transmitter array elements are fed with binary codes designed to produce distinct impulse responses from different directions in ROI. Image reconstruction in ROI is achieved with a regularized pseudoinverse operator derived from the linear receive signal model. The reconstruction operator can be implemented using a transversal filter bank with every filter in the bank designed to extract echoes from a specific direction in the ROI. The number of filters in the bank determines the number of image lines acquired simultaneously. In this paper, we present images of a cyst phantom reconstructed based on our formulation. A number of issues of practical significance in image reconstruction are addressed. Specifically, an augmented model is introduced to account for imperfect blocking of echoes from outside the ROI. We have also introduced a column-weighting algorithm for minimizing the number of filter coefficients. In addition, a detailed illustration of a full image reconstruction using subimage acquisition and compounding is given. Experimental results have shown that the new approach is valid for phased-array pulse-echo imaging of speckle-generating phantoms typically used in characterizing medical imaging systems. Such coded-excitation-based image reconstruction from specklegenerating phantoms, to the best of our knowledge, have not been reported previously.

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An elasticity microscope. Part I: Methods

Cited by 83 publications

References 39 publications

Photoacoustic technique to measure beam profile of pulsed laser systems

Photoacoustic technique to measure beam profile of pulsed laser systems

Characterizing Morphology and Nonlinear Elastic Properties of Normal and Thermally Stressed Engineered Oral Mucosal Tissues Using Scanning Acoustic Microscopy

Filter-based coded-excitation system for high-speed ultrasonic imaging

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