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Renal Elasticity Quantification by Acoustic Radiation Force Impulse Applied to the Evaluation of Kidney Diseases : A Review

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      Most cited references 29

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      On the feasibility of remote palpation using acoustic radiation force.

      A method of acoustic remote palpation, capable of imaging local variations in the mechanical properties of tissue, is under investigation. In this method, focused ultrasound is used to apply localized (on the order of 2 mm3) radiation force within tissue. and the resulting tissue displacements are mapped using ultrasonic correlation based methods. The tissue displacements are inversely proportional to the stiffness of the tissue, and thus a stiffer region of tissue exhibits smaller displacements than a more compliant region. In this paper, the feasibility of remote palpation is demonstrated experimentally using breast tissue phantoms with spherical lesion inclusions, and in vitro liver samples. A single diagnostic transducer and modified ultrasonic imaging system are used to perform remote palpation. The displacement images are directly correlated to local variations in tissue stiffness with higher contrast than the corresponding B-mode images. Relationships between acoustic beam parameters, lesion characteristics and radiation force induced tissue displacement patterns are investigated and discussed. The results show promise for the clinical implementation of remote palpation.
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        Acoustic Radiation Force Impulse (ARFI) Imaging: a Review.

        Acoustic radiation force based elasticity imaging methods are under investigation by many groups. These methods differ from traditional ultrasonic elasticity imaging methods in that they do not require compression of the transducer, and are thus expected to be less operator dependent. Methods have been developed that utilize impulsive (i.e. < 1 ms), harmonic (pulsed), and steady state radiation force excitations. The work discussed herein utilizes impulsive methods, for which two imaging approaches have been pursued: 1) monitoring the tissue response within the radiation force region of excitation (ROE) and generating images of relative differences in tissue stiffness (Acoustic Radiation Force Impulse (ARFI) imaging); and 2) monitoring the speed of shear wave propagation away from the ROE to quantify tissue stiffness (Shear Wave Elasticity Imaging (SWEI)). For these methods, a single ultrasound transducer on a commercial ultrasound system can be used to both generate acoustic radiation force in tissue, and to monitor the tissue displacement response. The response of tissue to this transient excitation is complicated and depends upon tissue geometry, radiation force field geometry, and tissue mechanical and acoustic properties. Higher shear wave speeds and smaller displacements are associated with stiffer tissues, and slower shear wave speeds and larger displacements occur with more compliant tissues. ARFI images have spatial resolution comparable to that of B-mode, often with greater contrast, providing matched, adjunctive information. SWEI images provide quantitative information about the tissue stiffness, typically with lower spatial resolution. A review these methods and examples of clinical applications are presented herein.
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          Acoustic Radiation Force Impulse (ARFI) technique in ultrasound with Virtual Touch tissue quantification of the upper abdomen.

          Virtual Touch tissue quantification is an implementation of ultrasound (US) Acoustic Radiation Force Impulse (ARFI) imaging that provides numerical measurements (wave-velocity values) of tissue stiffness. The aim of this study was to define the normal values of shear-wave speed for the healthy liver, gallbladder, pancreas, spleen and kidneys. Thirty-five young healthy volunteers underwent Virtual Touch tissue quantification after having signed an informed consent form. All upper abdominal organs were examined by two independent operators. A phantom fluid model was also evaluated. All mean wave-velocity values were analysed and compared. Results. One hundred and forty measurements of liver, pancreas, spleen and kidneys, and 70 measurements of the gallbladder lumen were performed. Twenty measurements on the phantom were also performed. Comparing all measurements separately made by each operator in different parts of the organs, no statistically significant differences were observed. A "XXXX/0" value was always obtained from all measurements performed on the gallbladder lumen and on the phantom fluid model. Liver, pancreas, spleen and kidney mean values were 1.59 m/s, 1.40 m/s, 2.44 m/s and 2.24 m/s, respectively. Virtual Touch tissue quantification is a new, promising implementation of the US ARFI technique, which provides numerical measurements of tissue stiffness. The mean shear-wave speed is lower in the pancreatic parenchyma than in the liver and kidney, whereas the spleen is characterised by the highest mean value. In simple fluids such as water, the value identified by the system with "XXXX" or 0, is always measured.
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            Author and article information

            Journal
            Journal of Investigative Medicine
            Journal of Investigative Medicine
            Ovid Technologies (Wolters Kluwer Health)
            1081-5589
            2015
            April 2015
            : 63
            : 4
            : 605-612
            10.1097/JIM.0000000000000186
            © 2015

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