Effect of self-demodulation on the subharmonic response of contrast agent microbubbles
Artikel i vetenskaplig tidskrift, 2012

Subharmonic (SH) emission from the ultrasound contrast agent (UCA) is of interest since it is produced only by the UCA and not by tissue, opposite to harmonic imaging modes where both tissue and microbubble show harmonics. In this work, the use of the self-demodulation (S-D) signal as a means of microbubble excitation at the SH frequency to enhance the SH emission of UCA is studied. The S-D wave is a low-frequency signal produced by the weak nonlinear propagation of an ultrasound wave. It is proportional to the second time derivative of the squared envelope of the transmitted signal. A diluted population of BR14 UCA (Bracco Research SA, Geneva, Switzerland) was insonified by a 10 MHz transducer focused at 76 mm firing bursts with different envelopes, durations and peak pressure amplitudes. The center frequency of the S-D signal changes from low frequencies (around 0.5 MHz) toward the transmitted frequency (10 MHz) by modifying the envelope function from Gaussian to rectangular. For 6 and 20 transmitted cycles, the SH response is enhanced up to 25 and 22 dB, respectively, when using a rectangular envelope instead of a Gaussian one. The experimental results are confirmed by the numerical simulation. The effects of the excitation duration and pressure amplitude are also studied. This study shows that a suitable design of the envelope of the transmit excitation to generate a S-D signal at the SH frequency can enhance the SH emission of UCA, and the SH imaging is feasible at high frequencies with a shorter transmit burst (six-cycle) and low acoustic pressure (similar to 100 KPa).

oscillations

ang ph

high-frequency ultrasound

encapsulated microbubbles

radial modulation

approximation

1995

excitation technique

generation

bubbles

driving pulse

intravascular

ieee transactions on ultrasonics ferroelectrics and frequency control

ultrasound

Författare

Verya Daeichin

Chalmers, Signaler och system

T. Faez

Erasmus Universiteit Rotterdam

G. Renaud

Erasmus Universiteit Rotterdam

J.G. Bosch

Erasmus Universiteit Rotterdam

A.F.W. Van Der Steen

Interuniversity Cardiology Institute of the Netherlands ICIN - KNAW

Erasmus Universiteit Rotterdam

N. De Jong

Erasmus Universiteit Rotterdam

Interuniversity Cardiology Institute of the Netherlands ICIN - KNAW

Physics in Medicine and Biology

0031-9155 (ISSN)

Vol. 57 12 3675-3691

Ämneskategorier

Medicinteknik

DOI

10.1088/0031-9155/57/12/3675

Mer information

Senast uppdaterat

2020-12-01