Quinary excitation method for pulse compression ultrasound measurements

Cowell, David M. J.; Freear, Steven

doi:10.1016/j.ultras.2007.10.001

Cited by 44 publications

(37 citation statements)

References 14 publications

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“…Connected to the Ultrasound Array Research Platform II [12]- [15], a Verasonics L11-4 transducer (Verasonics, Inc., WA, USA) was triggered with a train of pulses to realize MB trapping and fast imaging. For trapping, central 64 elements were divided into two sub-groups symmetrically.…”

Section: A Acoustic Trapping and Fast Detection Of Contrast Agentsmentioning

confidence: 99%

Acoustic microbubble trapping in blood mimicking fluid

Nie¹,

Harput²,

McLaughlan³

et al. 2017

2017 IEEE International Ultrasonics Symposium (IUS)

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Section: A Acoustic Trapping and Fast Detection Of Contrast Agentsmentioning

confidence: 99%

Acoustic microbubble trapping in blood mimicking fluid

Nie¹,

Harput²,

McLaughlan³

et al. 2017

2017 IEEE International Ultrasonics Symposium (IUS)

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“…Diluted SonoVue R microbubble solution with a clinically relevant concentration was driven by a syringe pump (Aladdin AL-1000, World Precision Instruments) with a constant volume rate of 24 ml/minute. [14], [15] which is capable of providing arbitrary excitation schemes, and ultrafast PWI at 500 Hz was acquired by firing all the 128 elements of the linear transducer array with negative excitation pulse controlled by the Leeds UARP II.…”

Section: Materials and Experimentsmentioning

confidence: 99%

Velocity estimation error reduction in stenosis areas using a correlation correction method

Nie

Harput

Cowell

et al. 2016

2016 IEEE International Ultrasonics Symposium (IUS)

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Abstract-The advent of ultrafast ultrasound imaging proved beneficial for capturing transient flow patterns which was never readily achievable before. Velocity estimation methods based on 2D block-matching outperform Doppler based methods by offering higher frame rate with the cost of increased uncertainty in presence of out-of-plane motion as a result of turbulent flow.Local median filtering can partially address the estimation error reduction in stenosis areas at the risk of higher inaccuracy, since neighboring values may be also outliers. In this study, a correlation correction method is proposed, where the out-of-plane motion is eliminated by means of multiplying correlation maps from a same area but in two adjacent pairs of RF images.Experimental investigations were performed on a wall-less flow phantom, and proposed method achieved an error reduction of 66% in turbulent flow regions.

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“…This choice, provided by the additional levels, can be exploited to reduce the harmonic content of the signal as demonstrated by Tang and Clement [10]. An additional benefit of multi-level switched mode excitation is that it enables windowing of the excitation sequence in the time domain as described in (3) and discussed in more detail in [9].…”

Section: Switched Mode Excitationmentioning

confidence: 99%

“…LFM signals can be generated using multi-level switched excitation circuits as demonstrated previously [9]. Multi-level switched excitation circuits can improve coded excitation [9] and reduce harmonic content [10]. This paper discusses switched mode LFM signals for use in coded harmonic imaging with arrays; a particularly demanding application requiring excitation signals with low levels of harmonic distortion and the use of multiple channels.…”

Section: Introductionmentioning

confidence: 97%

See 1 more Smart Citation

Harmonic cancellation in switched mode Linear Frequency Modulated (LFM) excitation of ultrasound arrays

Cowell¹,

Smith²,

Freear³

2011

2011 IEEE International Ultrasonics Symposium

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Abstract-Switched excitation is a convenient alternative to high frequency linear power amplifiers for multi-channel array systems. Unfortunately, switched mode excitation signals often contain harmonics that are undesirable in applications such as coded harmonic imaging. Harmonics can be reduced in switched excitation with the addition of intermediary voltage levels and careful control of switching timing. This work discusses two, three, five and nine level switched mode excitations suitable for Linear Frequency Modulated (LFM) coded excitation. Simulations in MATLAB compare two LFM signals with a central frequency 0.5 MHz, duration of 100 µ µ µs and bandwidths of 25% and 100% to an ideal 'analogue' case. Simulated results shows harmonic cancellation in the switched mode signals. For the nine level case, all harmonics below the 11th are cancelled. Experimental measurements are also obtained using the UARP system loaded with a 0.5 MHz transducer. Experimental results show cancellation of harmonics to −40 dB below the fundamental, however an increase in the third harmonic is apparent when comparing nine levels to five levels. To further verify harmonic reduction, calculations of the Total Harmonic Distortion are provided for each switched mode excitation up to the ninth harmonic.

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Quinary excitation method for pulse compression ultrasound measurements

Cited by 44 publications

References 14 publications

Acoustic microbubble trapping in blood mimicking fluid

Acoustic microbubble trapping in blood mimicking fluid

Velocity estimation error reduction in stenosis areas using a correlation correction method

Harmonic cancellation in switched mode Linear Frequency Modulated (LFM) excitation of ultrasound arrays

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