Coherent plane-wave compounding for very high frame rate ultrasonography and transient elastography

• Published in: IEEE transactions on ultrasonics, ferroelectrics, and frequency control Vol. 56; no. 3; pp. 489 - 506
• Main Authors: Montaldo, G., Tanter, M., Bercoff, J., Benech, N., Fink, M.
• Format: Journal Article
• Language: English
• Published: New York, NY IEEE 01.03.2009; Institute of Electrical and Electronics Engineers; The Institute of Electrical and Electronics Engineers, Inc. (IEEE)
• Subjects: Acoustic signal processing; Acoustics; Algorithms; Array signal processing; Beamforming; Biological and medical sciences; Biological tissues; Cardiovascular system; Coherence; Data acquisition; Data visualization; Digital cameras; Elasticity; Elasticity Imaging Techniques; Exact sciences and technology; Female; Frames; Fundamental areas of phenomenology (including applications); Humans; Image contrast; Image Enhancement - methods; Image quality; Image resolution; Imaging; Investigative techniques, diagnostic techniques (general aspects); Mathematical models; Medical sciences; Miscellaneous. Technology; Models, Statistical; Models, Theoretical; Physics; Signal Processing, Computer-Assisted; Transduction; acoustical devices for the generation and reproduction of sound; Ultrasonic imaging; Ultrasonic investigative techniques; Ultrasonography; Ultrasonography, Mammary; Viscosity; Averaging method; B scan; Ultrasound imaging; Noise reduction; Elastic wave; Modeling; Beam forming; Tissue; Acoustic antenna; Model test; Acoustic image; Elastography; Ultrasound; Human; Transient response; Experimental study; Real time; Color image; Wave transmission; Echography; Plane wave; Medical imagery; S wave; Hemodynamics; Signal to noise ratio
• ISSN: 0885-3010; 1525-8955; 1525-8955
• DOI: 10.1109/TUFFC.2009.1067

The emergence of ultrafast frame rates in ultrasonic imaging has been recently made possible by the development of new imaging modalities such as transient elastography. Data acquisition rates reaching more than thousands of images per second enable the real-time visualization of shear mechanical waves propagating in biological tissues, which convey information about local viscoelastic properties of tissues. The first proposed approach for reaching such ultrafast frame rates consists of transmitting plane waves into the medium. However, because the beamforming process is then restricted to the receive mode, the echographic images obtained in the ultrafast mode suffer from a low quality in terms of resolution and contrast and affect the robustness of the transient elastography mode. It is here proposed to improve the beamforming process by using a coherent recombination of compounded plane-wave transmissions to recover high-quality echographic images without degrading the high frame rate capabilities. A theoretical model is derived for the comparison between the proposed method and the conventional B-mode imaging in terms of contrast, signal-to-noise ratio, and resolution. Our model predicts that a significantly smaller number of insonifications, 10 times lower, is sufficient to reach an image quality comparable to conventional B-mode. Theoretical predictions are confirmed by in vitro experiments performed in tissue-mimicking phantoms. Such results raise the appeal of coherent compounds for use with standard imaging modes such as B-mode or color flow. Moreover, in the context of transient elastography, ultrafast frame rates can be preserved while increasing the image quality compared with flat insonifications. Improvements on the transient elastography mode are presented and discussed.