High frame rate vector velocity estimation using plane waves and transverse oscillation

Jensen, Jørgen Arendt; Stuart, Matthias Bo

doi:10.1109/ultsym.2015.0423

Cited by 8 publications

(4 citation statements)

References 12 publications

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“…1b, the receive-only PWTO approach used in this paper is incompatible with this scheme. Instead, the TOs could be introduced after a coherent summing scheme by filtering in the frequency domain [15][16][17]. However, this technique has only been described in the context of linear arrays, and further research is required to extent it to a sector scan as there may not be enough overlap between neighboring PWs to warrant the TO filtering approach.…”

Section: Resultsmentioning

confidence: 99%

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Evaluation of the Transverse Oscillation Technique for Cardiac Phased Array Imaging: A Theoretical Study

Heyde

Bottenus

D'hooge

et al. 2017

IEEE Trans. Ultrason., Ferroelect., Freq. Contr.

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The transverse oscillation (TO) technique can improve the estimation of tissue motion perpendicular to the ultrasound beam direction. TOs can be introduced using plane wave (PW) insonification and bi-lobed Gaussian apodisation (BA) on receive (abbreviated as PWTO). Furthermore, the TO frequency can be doubled after a heterodyning demodulation process is performed (abbreviated as PWTO*). This study is concerned with identifying the limitations of the PWTO technique in the specific context of myocardial deformation imaging with phased arrays and investigating the conditions in which it remains advantageous over traditional focused (FOC) beamforming. For this purpose, several tissue phantoms were simulated using Field II, undergoing a wide range of displacement magnitudes and modes (lateral, axial and rotational motion). The Cramer-Rao lower bound (CRLB) was used to optimize TO beamforming parameters and theoretically predict the fundamental tracking performance limits associated with the FOC, PWTO and PWTO* beamforming scenarios. This framework was extended to also predict performance for BA functions which are windowed by the physical aperture of the transducer, leading to higher lateral oscillations. It was found that windowed BA functions resulted in lower jitter errors compared to tradional BA functions. PWTO* outperformed FOC at all investigated SNR levels but only up to a certain displacement, with the advantage rapidly decreasing when SNR increased. These results suggest that PWTO* improves lateral tracking performance, but only when inter-frame displacements remain relatively low. The study concludes by translating these findings to a clinical environment by suggesting optimal scanner settings.

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Section: Resultsmentioning

confidence: 99%

“…As an alternative, TOs can also be generated after the beamforming process, i.e. synthetically without the use of dedicated beamformers, either by performing signal manipulations in the frequency domain [12][13][14] or by image filtering in the frequency domain [15][16][17]. …”

Section: Introductionmentioning

confidence: 99%

Evaluation of the Transverse Oscillation Technique for Cardiac Phased Array Imaging: A Theoretical Study

Heyde

Bottenus

D'hooge

et al. 2017

IEEE Trans. Ultrason., Ferroelect., Freq. Contr.

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“…The objectives are to obtain velocity estimates with an improved performance compared to TO and to have a beamforming load, which is between TO and conventional NCF DB. The concept and first measurements were presented in preliminary versions of the method as published in conference proceedings [25], [26]. This paper expands the theory, and a parameter study of simulated parabolic flow in straight vessel phantoms is performed to reveal the ideal performance of the estimator.…”

Section: Introductionmentioning

confidence: 87%

Fast Plane Wave 2-D Vector Flow Imaging Using Transverse Oscillation and Directional Beamforming

Jensen

Hoyos

Stuart

et al. 2017

IEEE Trans. Ultrason., Ferroelect., Freq. Contr.

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Several techniques can estimate the 2-D velocity vector in ultrasound. Directional beamforming (DB) estimates blood flow velocities with a higher precision and accuracy than transverse oscillation (TO), but at the cost of a high beamforming load when estimating the flow angle. In this paper, it is proposed to use TO to estimate an initial flow angle, which is then refined in a DB step. Velocity magnitude is estimated along the flow direction using cross correlation. It is shown that the suggested TO-DB method can improve the performance of velocity estimates compared with TO, and with a beamforming load, which is 4.6 times larger than for TO and seven times smaller than for conventional DB. Steered plane wave transmissions are employed for high frame rate imaging, and parabolic flow with a peak velocity of 0.5 m/s is simulated in straight vessels at beam-to-flow angles from 45° to 90°. The TO-DB method estimates the angle with a bias and standard deviation (SD) less than 2°, and the SD of the velocity magnitude is less than 2%. When using only TO, the SD of the angle ranges from 2° to 17° and for the velocity magnitude up to 7%. Bias of the velocity magnitude is within 2% for TO and slightly larger but within 4% for TO-DB. The same trends are observed in measurements although with a slightly larger bias. Simulations of realistic flow in a carotid bifurcation model provide visualization of complex flow, and the spread of velocity magnitude estimates is 7.1 cm/s for TO-DB, while it is 11.8 cm/s using only TO. However, velocities for TO-DB are underestimated at peak systole as indicated by a regression value of 0.97 for TO and 0.85 for TO-DB. An in vivo scanning of the carotid bifurcation is used for vector velocity estimations using TO and TO-DB. The SD of the velocity profile over a cardiac cycle is 4.2% for TO and 3.2% for TO-DB.

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“…The latter approach is used here, where a Gaussian filter is applied on the Fourier transformed HRIs to only select Fourier components around a desired lateral oscillation frequency [8], [9]. The directional information of the flow is preserved by applying the Hilbert transform on the TO image for each of the lines in the lateral direction.…”

Section: A Transverse Oscillationmentioning

confidence: 99%

In vivo high frame rate vector flow imaging using plane waves and directional beamforming

Jensen

Hoyos

Stuart

et al. 2016

2016 IEEE International Ultrasonics Symposium (IUS)

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Abstract-Directional beamforming (DB) estimates blood flow velocities accurately when the flow angle is known. However, for automatically finding the flow angle a computationally expensive approach is used. This work presents a method for estimating the flow angle using a combination of inexpensive transverse oscillation (TO) estimators and only 3 directional beamformed lines. The suggested DB vector flow estimator is employed with steered plane wave transmissions for high frame rate imaging. Two distinct plane wave sequences are used: a short sequence (3 angles) for fast flow and an interleaved long sequence (21 angles) for both slow flow and B-mode. Parabolic flow with a peak velocity of 0.5 m/s is measured at beam-to-flow angles of 60• and 90• . The DB method estimates the angle with a bias and standard deviation (STD) less than 2• , and the STD of the velocity magnitude is 2.5 %. This is 7 -8.5 % when using TO. The long sequence has a higher sensitivity, and when used for estimation of slow flow with a peak velocity of 0.04 m/s, the SD is 2.5 % and bias is 0.1 %. This is a factor of 4 better than if the short sequence is used. The carotid bifurcation was scanned on a healthy volunteer, and the short sequence was used with TO and DB to estimate velocity vectors. The STD of the velocity profile over a cardiac cycle was 6.1 % for TO and 4.9 % for DB.

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High frame rate vector velocity estimation using plane waves and transverse oscillation

Cited by 8 publications

References 12 publications

Evaluation of the Transverse Oscillation Technique for Cardiac Phased Array Imaging: A Theoretical Study

Evaluation of the Transverse Oscillation Technique for Cardiac Phased Array Imaging: A Theoretical Study

Fast Plane Wave 2-D Vector Flow Imaging Using Transverse Oscillation and Directional Beamforming

In vivo high frame rate vector flow imaging using plane waves and directional beamforming

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