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The effect of amplitude modulation on subharmonic imaging with chirp excitation


, : The effect of amplitude modulation on subharmonic imaging with chirp excitation. IEEE Transactions on Ultrasonics, Ferroelectrics, and Frequency Control 60(12): 2532-2544

Subharmonic generation from ultrasound contrast agents depends on the spectral and temporal properties of the excitation signal. The subharmonic response can be improved by using wideband and long-duration signals. However, for sinusoidal tone-burst excitation, the effective bandwidth of the signal is inversely proportional to the signal duration. Linear frequency-modulated (LFM) and nonlinear frequency-modulated (NLFM) chirp excitations allow independent control over the signal bandwidth and duration; therefore, in this study LFM and NLFM signals were used for the insonation of microbubble populations. The amplitude modulation of the excitation waveform was achieved by applying different window functions. A customized window was designed for the NLFM chirp excitation by focusing on reducing the spectral leakage at the subharmonic frequency and increasing the subharmonic generation from microbubbles. Subharmonic scattering from a microbubble population was measured for various excitation signals and window functions. At a peak negative pressure of 600 kPa, the generated subharmonic energy by ultrasound contrast agents was 15.4 dB more for NLFM chirp excitation with 40% fractional bandwidth when compared with tone-burst excitation. For this reason, the NLFM chirp with a customized window was used as an excitation signal to perform subharmonic imaging in an ultrasound flow phantom. Results showed that the NLFM waveform with a customized window improved the subharmonic contrast by 4.35 ± 0.42 dB on average over a Hann-windowed LFM excitation.

US$19.90

PMID: 24297019

DOI: 10.1109/TUFFC.2013.2852


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Biswal, B.K.; Vijayan, M., 2001: Structure of human methaemoglobin: The variation of a theme. There has been considerable interest in the variability of the structure of the liganded haemoglobin after characterization of the R2 state in addition to the original relaxed R state. The structures of three crystallographically independent relax...

Dommergues, Y., 1968: CO2 evolution in soils. Its measurement and Interpretation. General review. Field and laboratory methods for measuring CO2 evolution in soils are reviewed and interpretation of results is discussed. The coefficient of mineralization of soil organic C is defined and its use in the biological characterization of soils is co...

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