New developments in vector velocity imaging using the transverse oscillation approach

Jensen, Jørgen Arendt; Pihl, Michael Johannes; Olesen, Jacob Bjerring; Hansen, P.; Hansen, Kristoffer Lindskov; Nielsen, Michael Bachmann

doi:10.1117/12.2013701

Cited by 4 publications

(6 citation statements)

References 30 publications

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“…recent progress in clinical application of velocity estimation stems from commercial scanners capable of estimating 2-d velocity vectors in the scan plane. one of the implemented methods is the transverse oscillation (To) approach [7], and the commercial implementation of this approach has been Fda approved for clinical use [8].…”

mentioning

confidence: 99%

A transverse oscillation approach for estimation of three-dimensional velocity vectors, Part I: concept and simulation study

Pihl

Jensen

2014

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

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Abstract-A method for 3-D velocity vector estimation using transverse oscillations is presented. The method employs a 2-D transducer and decouples the velocity estimation into three orthogonal components, which are estimated simultaneously and from the same data. The validity of the method is investigated by conducting simulations emulating a 32 × 32 matrix transducer. The results are evaluated using two performance metrics related to precision and accuracy. The study includes several parameters including 49 flow directions, the SNR, steering angle, and apodization types. The 49 flow directions cover the positive octant of the unit sphere. In terms of accuracy, the median bias is −2%. The precision of v x and v y depends on the flow angle β and ranges from 5% to 31% relative to the peak velocity magnitude of 1 m/s. For comparison, the range is 0.4 to 2% for v z . The parameter study also reveals, that the velocity estimation breaks down with an SNR between −6 and −3 dB. In terms of computational load, the estimation of the three velocity components requires 0.75 billion floating point operations per second (0.75 Gflops) for a realistic setup. This is well within the capability of modern scanners.

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mentioning

confidence: 99%

A transverse oscillation approach for estimation of three-dimensional velocity vectors, Part I: concept and simulation study

Pihl

Jensen

2014

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

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“…Figures 1 and 2 illustrate the achieved performance of the proposed estimator as compared to the 2nd-order and the 4th-order methods, where the cross-correlation of (7) and (8), and the product of the auto-correlations of (7) and (8), respectively, are used to form the velocity estimate (see [7,15,20] for details on these algorithms). As is clear from the figures, the 2nd-order method suffers from strong spectral artefacts whereas the 4th-order method has problems with yielding broad spectral lines.…”

Section: Numerical Resultsmentioning

confidence: 99%

“…This is done by forming an estimate of the correlation, the power spectral density, or fourth order moment of the sampled signal along the transversal dimension. The method has been extensively evaluated using both simulated flow data and with in vivo data [11][12][13][14], and was recently approved by the US FDA [15]. In this work, exploiting the transversal oscillation (TO) technique, we further these works by proposing a novel data-adaptive spectral estimation technique allowing for improved velocity estimates as compared to earlier methods.…”

Section: Introductionmentioning

confidence: 99%

Data adaptive estimation of transversal blood flow velocities

Pirnia

Jakobsson

Gudmundson

et al. 2014

2014 IEEE International Conference on Acoustics, Speech and Signal Processing (ICASSP)

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The examination of blood flow inside the body may yield important information about vascular anomalies, such as possible indications of, for example, stenosis. Current medical ultrasound systems suffer from only allowing for measuring the blood flow velocity along the direction of irradiation, posing natural difficulties due to the complex behaviour of blood flow, and due to the natural orientation of most blood vessels. Recently, a transversal modulation scheme was introduced to induce also an oscillation along the transversal direction, thereby allowing for the measurement of also the transversal blood flow. In this paper, we propose a novel data-adaptive blood flow estimator exploiting this modulation scheme. Using realistic Field II simulations, the proposed estimator is shown to achieve a notable performance improvement as compared to current state-of-the-art techniques.

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“…While blood velocities can be fairly high, relative lateral motion remains fairly small as it is estimated between SQ signals sampled at a pulse repetition frequency in the order of kHz [6]. On the other hand, if tracking is based on beamformed PWTO images, the frame rate is substantially lower.…”

Section: Beamforming Strategiesmentioning

confidence: 99%

“…[4]. This technique has been applied in the context of tissue imaging [5] and blood flow imaging [6], with the majority of work tailored to 2D linear arrays. More recently, the TO technique has been extended to phased-array [7] and convex array geometries [8] for blood flow imaging.…”

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 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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New developments in vector velocity imaging using the transverse oscillation approach

Cited by 4 publications

References 30 publications

A transverse oscillation approach for estimation of three-dimensional velocity vectors, Part I: concept and simulation study

A transverse oscillation approach for estimation of three-dimensional velocity vectors, Part I: concept and simulation study

Data adaptive estimation of transversal blood flow velocities

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

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