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

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