Nonlinear Pulse Compression in Pulse-Inversion Fundamental Imaging
Journal
Ultrasonic Imaging
Journal Volume
29
Journal Issue
2
Pages
73-86
Date Issued
2007-04
Date
2007-04
Author(s)
Abstract
Coded excitation can be applied in ultrasound contrast agent imaging to enhance the signal-to-noise ratio with minimal destruction of the microbubbles. Although the axial resolution is usually compromised by the requirement for a long coded transmit waveforms, this can be restored by using a compression filter to compress the received echo. However, nonlinear responses from microbubbles may cause difficulties in pulse compression and result in severe range side-lobe artifacts, particularly in pulse-inversion-based (PI) fundamental imaging. The efficacy of pulse compression in nonlinear contrast imaging was evaluated by investigating several factors relevant to PI fundamental generation using both in-vitro experiments and simulations. The results indicate that the acoustic pressure and the bubble size can alter the nonlinear characteristics of microbubbles and change the performance of the compression filter. When nonlinear responses from contrast agents are enhanced by using a higher acoustic pressure or when more microbubbles are near the resonance size of the transmit frequency, higher range side lobes are produced in both linear imaging and PI fundamental imaging. On the other hand, contrast detection in PI fundamental imaging significantly depends on the magnitude of the nonlinear responses of the bubbles and thus the resultant contrast-to-tissue ratio (CTR) still increases with acoustic pressure and the nonlinear resonance of microbubbles. It should be noted, however, that the CTR in PI fundamental imaging after compression is consistently lower than that before compression due to obvious side-lobe artifacts. Therefore, the use of coded excitation is not beneficial in PI fundamental contrast detection. Copyright 2007 by Dynamedia, Inc. All rights of reproduction in any form reserved.
Subjects
Coded excitation; Contrast imaging; Nonlinear imaging; Pulse compression; Pulse-inversion fundamental imaging
SDGs
Other Subjects
Pulse compression; Signal to noise ratio; Ultrasonic applications; Coded excitation; Contrast imaging; Contrast-to-tissue ratio; Nonlinear characteristics; Nonlinear imaging; Nonlinear pulse compression; Pulse-inversion fundamental imaging; Ultrasound contrast agent; Passive filters; contrast medium; acoustics; article; artifact; compression; evaluation; imaging system; nonlinear system; signal noise ratio; simulation; ultrasound; waveform
Publisher
Dynamedia Inc.
Type
journal article