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Search Results: 1 - 10 of 50714 matches for " Y. Sumi "
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Ultrasonic lateral modulation imaging, speckle reduction, and displacement vector measurements using simple single-beam scanning or plural crossed-beam scanning with new spectra frequency division processing methods
Sumi C, Ishii Y
Reports in Medical Imaging , 2012, DOI: http://dx.doi.org/10.2147/RMI.S33622
Abstract: rasonic lateral modulation imaging, speckle reduction, and displacement vector measurements using simple single-beam scanning or plural crossed-beam scanning with new spectra frequency division processing methods Original Research (1820) Total Article Views Authors: Sumi C, Ishii Y Published Date October 2012 Volume 2012:5 Pages 57 - 101 DOI: http://dx.doi.org/10.2147/RMI.S33622 Received: 05 May 2012 Accepted: 06 July 2012 Published: 09 October 2012 Chikayoshi Sumi, Yousuke Ishii Department of Information and Communication Sciences, Faculty of Science and Technology, Sophia University, Tokyo, Japan Abstract: The development of effective ultrasonic tissue displacement measurement methods increases the number of possible applications for various tissue displacement and strain measurements. These applications include measurements of spontaneous motions/deformations generated by heart motion; pulsations from phenomena such as blood flow (intracardiac, intravascular, and carotid); heart, blood vessel, and liver motion; and motion from artificial sources such as motions/deformations generated by applying static compression/stretching forces, vibration or acoustic radiation forces (breast and liver). For arbitrary orthogonal coordinate systems obtained using arbitrary transducer types (eg, linear, convex, sector, arc, or radial array types, or single aperture types with a mechanical scan), several lateral modulation (LM) methods (eg, scanning with plural crossed or steered beams over a region of interest) have been developed that can be used with new echo imaging methods for tissue displacement/deformation measurements. Specifically, by using such beamforming methods, in addition to highly accurate displacement vector and lateral displacement measurements, LM echo imaging with a high lateral carrier frequency and a high lateral resolution has been developed. Another new beamforming method, referred to as “a steering angle (ASTA) method,” ie, scanning with a defined steering angle, is also described. In addition to conventional non-steered-beam scanning (ie, a version of ASTA) and conventional steered-beam scanning with a variable steering angle (eg, sector, arc, radial scan), a simple, single-beam scanning method also permits the use of LM, which yields an accurate displacement vector measurement with fewer calculations than the original LM methods. This is accomplished by using a previously developed spectra frequency division method (SFDM). However, the lateral carrier frequency and the measurement accuracy acquired by using such a single-beam scanning method are lower than those achieved with the original LM scanning methods and should be increased (ie, by using a quasi-LM method). In this report, the effectiveness of the use of the new SFDMs is verified with experiments on agar phantoms, in which conventional non-steered, focused single-beam transmission/reception scanning is performed together with high-speed non-steered single plane-wave transmiss
Ultrasonic lateral modulation imaging, speckle reduction, and displacement vector measurements using simple single-beam scanning or plural crossed-beam scanning with new spectra frequency division processing methods
Sumi C,Ishii Y
Reports in Medical Imaging , 2012,
Abstract: Chikayoshi Sumi, Yousuke IshiiDepartment of Information and Communication Sciences, Faculty of Science and Technology, Sophia University, Tokyo, Japan: The development of effective ultrasonic tissue displacement measurement methods increases the number of possible applications for various tissue displacement and strain measurements. These applications include measurements of spontaneous motions/deformations generated by heart motion; pulsations from phenomena such as blood flow (intracardiac, intravascular, and carotid); heart, blood vessel, and liver motion; and motion from artificial sources such as motions/deformations generated by applying static compression/stretching forces, vibration or acoustic radiation forces (breast and liver). For arbitrary orthogonal coordinate systems obtained using arbitrary transducer types (eg, linear, convex, sector, arc, or radial array types, or single aperture types with a mechanical scan), several lateral modulation (LM) methods (eg, scanning with plural crossed or steered beams over a region of interest) have been developed that can be used with new echo imaging methods for tissue displacement/deformation measurements. Specifically, by using such beamforming methods, in addition to highly accurate displacement vector and lateral displacement measurements, LM echo imaging with a high lateral carrier frequency and a high lateral resolution has been developed. Another new beamforming method, referred to as “a steering angle (ASTA) method,” ie, scanning with a defined steering angle, is also described. In addition to conventional non-steered-beam scanning (ie, a version of ASTA) and conventional steered-beam scanning with a variable steering angle (eg, sector, arc, radial scan), a simple, single-beam scanning method also permits the use of LM, which yields an accurate displacement vector measurement with fewer calculations than the original LM methods. This is accomplished by using a previously developed spectra frequency division method (SFDM). However, the lateral carrier frequency and the measurement accuracy acquired by using such a single-beam scanning method are lower than those achieved with the original LM scanning methods and should be increased (ie, by using a quasi-LM method). In this report, the effectiveness of the use of the new SFDMs is verified with experiments on agar phantoms, in which conventional non-steered, focused single-beam transmission/reception scanning is performed together with high-speed non-steered single plane-wave transmission and non-steered, focused single-beam reception scanning usin
Consideration of generated beam angles increases the accuracy of ultrasonic displacement measurements
Sumi C, Takanashi Y, Ichimaru K
Reports in Medical Imaging , 2012, DOI: http://dx.doi.org/10.2147/RMI.S27307
Abstract: nsideration of generated beam angles increases the accuracy of ultrasonic displacement measurements Original Research (2469) Total Article Views Authors: Sumi C, Takanashi Y, Ichimaru K Published Date March 2012 Volume 2012:5 Pages 23 - 50 DOI: http://dx.doi.org/10.2147/RMI.S27307 Received: 13 October 2011 Accepted: 11 November 2011 Published: 09 March 2012 Chikayoshi Sumi, Yuuki Takanashi, Kento Ichimaru Department of Information and Communication Sciences, Faculty of Science and Technology, Sophia University, Tokyo, Japan Abstract: The development of practical ultrasonic (US) tissue displacement measurement methods increases the number of available and useful applications of displacement/strain measurements that can be made (eg, various blood flow measurements and measurements of tissue motion in organs such as the heart, liver, and so forth). Previously developed lateral modulation (LM) methods with a multidimensional autocorrelation method (MAM) or multidimensional Doppler method (MDM) and a steering angle method (ASTA) with lateral Doppler method produced accurate displacement vector and lateral displacement measurements, respectively. Such measurements cannot be obtained using only a conventional Doppler technique. Another new method has also been reported, using multiple crossed beams (MCBs) to obtain high-accuracy displacement vector measurements; that is, a displacement vector is synthesized using accurately measured axial displacements with previously developed multidimensional displacement measurement methods, including the one-dimensional autocorrelation method (1D AM) with a multidimensional moving average (MA), together with conventional rotation processing of global echo data or a coordinate system (ie, a global echo rotation referred to as r method) by the negative value of the steering angles used in beamforming. However, in real-world applications, directivities of transmission and reception apertures, scattering, reflection, and attenuation affect the direction and properties of US beams used for conventional axial displacement measurements employing beamforming methods such as a conventional nonsteered, steered, or secta beam, and they also affect ASTA and MCB methods. In this report, to improve accuracy in the measurements of an arbitrary directional displacement and a displacement vector using any beamforming methods, a spatial resolution in a beam angle (BA) is generated. For instance, for a two-dimensional (2D) Cartesian coordinate system, this is obtained by calculating the arctangent of the ratio of the axial and lateral instantaneous frequencies or the first moments of local spectra. On the basis of the 1D AM with a multidimensional MA, the local displacement in the beam direction is accurately measured by dividing the local instantaneous phase change by the instantaneous frequency calculated in the beam direction, and an arbitrary directional displacement can be measured (axial, lateral, radial, and so forth), which is
Beam steering and coordinate system rotation improves accuracy of ultrasonic measurements of tissue displacement vector and lateral displacement
Sumi C, Ichimaru K, Shinozuka Y
Reports in Medical Imaging , 2011, DOI: http://dx.doi.org/10.2147/RMI.S24568
Abstract: eam steering and coordinate system rotation improves accuracy of ultrasonic measurements of tissue displacement vector and lateral displacement Original Research (2320) Total Article Views Authors: Sumi C, Ichimaru K, Shinozuka Y Published Date November 2011 Volume 2011:4 Pages 47 - 66 DOI: http://dx.doi.org/10.2147/RMI.S24568 Chikayoshi Sumi1,2, Kento Ichimaru2, Yusuke Shinozuka2 1Department of Information and Communication Science, 2Department of Electrical and Electronics Engineering, Faculty of Science and Technology, Sophia University, Kioi-cho, Chiyoda-ku, Tokyo, Japan Abstract: With the proper use of beam steering and apodization, a higher resolution lateral echo image is obtained than with conventional imaging. This is achieved by superimposing crossed, steered beams, which is referred to as “lateral modulation” (LM). This type of beamforming achieves almost the same accuracy in lateral displacement measurements as in axial displacement measurements, ie, displacement vector measurements. The steering angle (ASTA) can also be used instead of LM, which uses only beams with a steering angle. In this report, the accuracy of the displacement vectors and lateral displacement measurements for LM and ASTA were evaluated using simulations and agar phantom experiments. The parameters used were direction of a displacement vector, steering angles, and rotation angle for the coordinate system. Changes in the steering angle and rotation angle of the coordinate system permit control of frequencies in the respective directions of the coordinate axes. As shown, when performing a simple ASTA for displacement vector measurement, a spectra frequency division should be performed using a previously developed multidimensional autocorrelation or Doppler method instead of block-matching methods. In this version of ASTA, the combination of nonsteering and rotation of the coordinate system is also effective, because the lateral bandwidth does not decrease. In such a case, transmission of a laterally wide wave will also be effective, particularly for three-dimensional measurement/imaging using a two-dimensional array transducer. ASTA can also be used for accurate lateral displacement measurements. Although a proper beam steering and/or a proper coordinate rotation improves the measurement accuracy achieved with LM and ASTA, all measurement accuracies obtained with ASTA are lower than with LM.
Erratum
Sumi C, Ichimaru K, Shinozuka Y
Reports in Medical Imaging , 2011, DOI: http://dx.doi.org/10.2147/RMI.S28366
Abstract: Erratum Erratum (2540) Total Article Views Authors: Sumi C, Ichimaru K, Shinozuka Y Published Date November 2011 Volume 2011:4 Pages 67 - 68 DOI: http://dx.doi.org/10.2147/RMI.S28366 Sumi C, Ichimaru K, Shinozuka Y Beam steering and coordinate system rotation improves accuracy of ultrasonic measurements of tissue displacement vector and lateral displacement Reports in Medical Imaging 2011:4 47-66. Original article Post to: Cannotea Citeulike Del.icio.us Facebook LinkedIn Twitter Other articles by Dr Chikayoshi Sumi Beam steering and coordinate system rotation improves accuracy of ultrasonic measurements of tissue displacement vector and lateral displacement Consideration of generated beam angles increases the accuracy of ultrasonic displacement measurements Ultrasonic agar phantom experiment for comparison of the measurement accuracy of tissue elasticity obtained by displacement vector measurement using lateral modulation with multidimensional autocorrelation and Doppler methods and corresponding one-dimensional methods Ultrasonic lateral modulation imaging, speckle reduction, and displacement vector measurements using simple single-beam scanning or plural crossed-beam scanning with new spectra frequency division processing methods Readers of this article also read: Effective ultrasonic virtual sources which can be positioned independently of physical aperture focus positions Hydrocele of the canal of Nuck: ultrasound and MRI findings Advances in the diagnostic imaging of pheochromocytomas Ultrasonic agar phantom experiment for comparison of the measurement accuracy of tissue elasticity obtained by displacement vector measurement using lateral modulation with multidimensional autocorrelation and Doppler methods and corresponding one-dimensional methods Beam steering and coordinate system rotation improves accuracy of ultrasonic measurements of tissue displacement vector and lateral displacement Ultrasonic lateral modulation imaging, speckle reduction, and displacement vector measurements using simple single-beam scanning or plural crossed-beam scanning with new spectra frequency division processing methods Topical azithromycin or ofloxacin for endophthalmitis A characteristic optic disc appearance associated with myopia in subjects with Graves' ophthalmopathy and in subjects with primary open-angle glaucoma Navigated macular laser decreases retreatment rate for diabetic macular edema: a comparison with conventional macular laser Imaging of cervicothoracic junction trauma
Beam steering and coordinate system rotation improves accuracy of ultrasonic measurements of tissue displacement vector and lateral displacement
Sumi C,Ichimaru K,Shinozuka Y
Reports in Medical Imaging , 2011,
Abstract: Chikayoshi Sumi1,2, Kento Ichimaru2, Yusuke Shinozuka21Department of Information and Communication Science, 2Department of Electrical and Electronics Engineering, Faculty of Science and Technology, Sophia University, Kioi-cho, Chiyoda-ku, Tokyo, JapanAbstract: With the proper use of beam steering and apodization, a higher resolution lateral echo image is obtained than with conventional imaging. This is achieved by superimposing crossed, steered beams, which is referred to as “lateral modulation” (LM). This type of beamforming achieves almost the same accuracy in lateral displacement measurements as in axial displacement measurements, ie, displacement vector measurements. The steering angle (ASTA) can also be used instead of LM, which uses only beams with a steering angle. In this report, the accuracy of the displacement vectors and lateral displacement measurements for LM and ASTA were evaluated using simulations and agar phantom experiments. The parameters used were direction of a displacement vector, steering angles, and rotation angle for the coordinate system. Changes in the steering angle and rotation angle of the coordinate system permit control of frequencies in the respective directions of the coordinate axes. As shown, when performing a simple ASTA for displacement vector measurement, a spectra frequency division should be performed using a previously developed multidimensional autocorrelation or Doppler method instead of block-matching methods. In this version of ASTA, the combination of nonsteering and rotation of the coordinate system is also effective, because the lateral bandwidth does not decrease. In such a case, transmission of a laterally wide wave will also be effective, particularly for three-dimensional measurement/imaging using a two-dimensional array transducer. ASTA can also be used for accurate lateral displacement measurements. Although a proper beam steering and/or a proper coordinate rotation improves the measurement accuracy achieved with LM and ASTA, all measurement accuracies obtained with ASTA are lower than with LM.Keywords: lateral modulation, single steering angle, coordinate system rotation, spectra frequency division
Consideration of generated beam angles increases the accuracy of ultrasonic displacement measurements
Sumi C,Takanashi Y,Ichimaru K
Reports in Medical Imaging , 2012,
Abstract: Chikayoshi Sumi, Yuuki Takanashi, Kento IchimaruDepartment of Information and Communication Sciences, Faculty of Science and Technology, Sophia University, Tokyo, Japan: The development of practical ultrasonic (US) tissue displacement measurement methods increases the number of available and useful applications of displacement/strain measurements that can be made (eg, various blood flow measurements and measurements of tissue motion in organs such as the heart, liver, and so forth). Previously developed lateral modulation (LM) methods with a multidimensional autocorrelation method (MAM) or multidimensional Doppler method (MDM) and a steering angle method (ASTA) with lateral Doppler method produced accurate displacement vector and lateral displacement measurements, respectively. Such measurements cannot be obtained using only a conventional Doppler technique. Another new method has also been reported, using multiple crossed beams (MCBs) to obtain high-accuracy displacement vector measurements; that is, a displacement vector is synthesized using accurately measured axial displacements with previously developed multidimensional displacement measurement methods, including the one-dimensional autocorrelation method (1D AM) with a multidimensional moving average (MA), together with conventional rotation processing of global echo data or a coordinate system (ie, a global echo rotation referred to as r method) by the negative value of the steering angles used in beamforming. However, in real-world applications, directivities of transmission and reception apertures, scattering, reflection, and attenuation affect the direction and properties of US beams used for conventional axial displacement measurements employing beamforming methods such as a conventional nonsteered, steered, or secta beam, and they also affect ASTA and MCB methods. In this report, to improve accuracy in the measurements of an arbitrary directional displacement and a displacement vector using any beamforming methods, a spatial resolution in a beam angle (BA) is generated. For instance, for a two-dimensional (2D) Cartesian coordinate system, this is obtained by calculating the arctangent of the ratio of the axial and lateral instantaneous frequencies or the first moments of local spectra. On the basis of the 1D AM with a multidimensional MA, the local displacement in the beam direction is accurately measured by dividing the local instantaneous phase change by the instantaneous frequency calculated in the beam direction, and an arbitrary directional displacement can be measured (axial, lateral, r
Erratum
Sumi C,Ichimaru K,Shinozuka Y
Reports in Medical Imaging , 2011,
Abstract: Sumi C, Ichimaru K, Shinozuka YBeam steering and coordinate system rotation improves accuracy of ultrasonic measurements of tissue displacement vector and lateral displacementReports in Medical Imaging 2011:4 47-66.Original article
Constraining the Location of Microlensing Objects towards the LMC through Parallax Measurement in EAGLE Observations
T. Sumi,Y. Kan-ya
Physics , 2002, DOI: 10.1046/j.1365-8711.2002.05981.x
Abstract: We investigate the possibility of determining whether microlensing objects towards the Large Magellanic Cloud (LMC) are in a Galactic thick disc, or are in a Galactic halo, by using parallax measurements with an Earth-radius scale baseline. Our method makes use of EAGLE (Extremely Amplified Gravitational LEnsing) events which are microlensing events with an invisible faint source. We show that the rate of EAGLE events is as high as that of normal microlensing events, even if they are caused by dark stars in the Galactic thick disc. We explore the possibility of measuring the parallax effect in EAGLE events towards the LMC by using the {\it Hubble Space Telescope} (HST) or the {\it Very Large Telescope} (VLT). We find that EAGLE events enlarge the opportunity of parallax measurements by $4 \sim 10$ times relative to that in normal microlensing events. We show that the parallax effect can be measured in $\sim75%$ (from the HST) and $\sim 60%$ (from the VLT) of all EAGLE events if most lenses are stars in the Galactic thick or thin disc, while $\sim 20%$ (from the HST) and $\sim 10%$ (from the VLT) can be measured if most lenses are halo MACHOs. In combination with the finite source size effect observations, we can strongly constrain the location of lenses.
Determination of Lateral Modulation Apodization Functions Using a Regularized, Weighted Least Squares Estimation
Chikayoshi Sumi
International Journal of Biomedical Imaging , 2010, DOI: 10.1155/2010/635294
Abstract: Recently, work in this group has focused on the lateral cosine modulation method (LCM) which can be used for next-generation ultrasound (US) echo imaging and tissue displacement vector/strain tensor measurements (blood, soft tissues, etc.). For instance, in US echo imaging, a high lateral spatial resolution as well as a high axial spatial resolution can be obtained, and in tissue displacement vector measurements, accurate measurements of lateral tissue displacements as well as of axial tissue displacements can be realized. For an optimal determination of an apodization function for the LCM method, the regularized, weighted minimum-norm least squares (WMNLSs) estimation method is presented in this study. For designed Gaussian-type point spread functions (PSFs) with lateral modulation as an example, the regularized WMNLS estimation in simulations yields better approximations of the designed PSFs having wider lateral bandwidths than a Fraunhofer approximation and a singular-value decomposition (SVD). The usefulness of the regularized WMNLS estimation for the determination of apodization functions is demonstrated. 1. Introduction A beamformer and a transducer are used in applications such as medical ultrasound (US) imaging, blood flow measurement, tissue displacement/strain measurements, and sonar measurements. For these applications, US beamforming parameters such as US frequency, US bandwidth, pulse shape, effective aperture size, and the apodization function are chosen or selected, and appropriate values are set. In addition, US transducer parameters such as the size and materials used for the US array elements are also chosen. In choosing such settings, the US properties of the target are also considered (e.g., attenuation and scattering). Thus, all of the above parameters must be appropriately chosen and set when considering a system that involves the US properties of the target. In general, such parameters are chosen using the knowledge and experience of an engineer. Recently, a cosine modulation (LCM) method [1–3] was described that was used for US echo imaging [3, 4] and tissue displacement vector measurements (blood, soft tissues, etc.) [3, 5] using the multidimensional autocorrelation method (MAM) [1], the multidimensional Doppler method (MDM) [1], and the multidimensional cross-spectrum phase gradient method (MCSPGM) [6]. Specifically, for instance, in US echo imaging, a high lateral spatial resolution as well as a high axial spatial resolution can be obtained, and in tissue displacement vector measurements, accurate measurements of lateral as
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