Degradation of Image Quality by Sound Velocity Fluctuations and Its Dependence on the Aperture Size

Hassler, Donald M.; Härer, Wolfgang; Temme, G.; Schmidt, Evanthia Kalpazidou; Wegener, P; Krammer, P.

doi:10.1109/ultsym.1987.199097

Cited by 6 publications

(2 citation statements)

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“…[1][2][3][4][5][6] Image degradation is more severe at higher frequencies and with larger apertures. [7][8][9] Delay-and-sum beamforming (DAS) is the standard beamforming technique used in commercial scanners and is somewhat robust to weak aberrations, but its performance is greatly diminished by stronger aberrations. [10][11][12] Phase aberration is typically modeled as either a near-field phase screen (NFPS) or as a distributed aberrator.…”

Section: Introductionmentioning

confidence: 99%

A Locally Adaptive Phase Aberration Correction (LAPAC) Method for Synthetic Aperture Sequences

et al. 2018

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Phase aberration is a phenomenon caused by heterogeneity of the speed of sound in tissue, in which the actual speed of sound of the tissue is different than the assumed speed of sound used for beamforming. It reduces the quality and resolution of ultrasonic images and impairs clinical diagnostic capabilities. Although phase aberration correction (PAC) methods can reduce these detrimental effects, most practical implementations of PAC methods are based on the near field phase screen model, which have limited ability to represent the true aberration induced by inhomogeneous tissue. Accordingly, we propose a locally adaptive phase aberration correction (LAPAC) method that is applied through the use of synthetic aperture. The method is tested using full-wave simulations of models of human abdominal wall, experiments with tissue aberrators, and in vivo carotid images. LAPAC is compared with conventional phase aberration correction (cPAC) where aberration profiles are computed at a preselected depth and applied to the beamformer's time delays. For all experiments, LAPAC shows an average of 1 to 2 dB higher contrast than cPAC, and enhancements of 3 to 7 dB with respect to the uncorrected cases. We conclude that LAPAC may be a viable option to enhance ultrasound image quality images even in the presence of clinically relevant aberrating conditions.

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Section: Introductionmentioning

confidence: 99%

A Locally Adaptive Phase Aberration Correction (LAPAC) Method for Synthetic Aperture Sequences

et al. 2018

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“…Several groups [1,2] have attempted to measure the magnitude and shape of phase aberrations caused by velocity inhomogeneities. Most of these studies were limited to in vitro measurements or indirect methods of in vivo measurements.…”

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Phase aberration measurement and correction in medical ultrasound

Trahey

Images of the Twenty-First Century. Proceedings of the Annual International Engineering in Medicine and Biology Society

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We have constructed an apparatus to measurement time-of-flight profiles in living tissues and, in addition, an experimental phased array imaging system capable of correcting unknown phase errors induced by inhomogeneities in the acoustic velocities in tissue. We present the results of in vivo measurements of phase error profiles in abdominal, breast and transcranial imaging applications. We also demonstrate the success of the phase correction system in restoring the quality of images degraded by these errors.BACKGROUND

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1989

Ultrasonic Measurements for Process Control

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Degradation of Image Quality by Sound Velocity Fluctuations and Its Dependence on the Aperture Size

Cited by 6 publications

References 1 publication

A Locally Adaptive Phase Aberration Correction (LAPAC) Method for Synthetic Aperture Sequences

A Locally Adaptive Phase Aberration Correction (LAPAC) Method for Synthetic Aperture Sequences

Phase aberration measurement and correction in medical ultrasound

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