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

Jensen, Jørgen Arendt; Hoyos, Carlos Armando Villagómez; Stuart, Matthias Bo; Ewertsen, Caroline; Nielsen, Michael Bachmann

doi:10.1109/ultsym.2016.7728662

Cited by 5 publications

(4 citation statements)

References 13 publications

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“…This has been employed in the new TO estimator to estimate the mean lateral oscillation frequency and thereby reduce the bias for the different measurement angles. The approach can also be combined with a full directional beamforming along the flow direction to improve on the bias [41], [42].…”

Section: Discussionmentioning

confidence: 99%

Real-Time 2-D Phased Array Vector Flow Imaging

Holbek

Hansen

Fogh

et al. 2018

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

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Echocardiography examination of the blood flow is currently either restricted to 1-D techniques in real-time or experimental offline 2-D methods. This paper presents an implementation of transverse oscillation for real-time 2-D vector flow imaging (VFI) on a commercial BK Ultrasound scanner. A large field-of-view (FOV) sequence for studying flow dynamics at 11 frames per second (fps) and a sequence for studying peak systolic velocities (PSVs) with a narrow FOV at 36 fps were validated. The VFI sequences were validated in a flow rig with continuous laminar parabolic flow and in a pulsating flow pump system before being tested in vivo, where measurements were obtained on two healthy volunteers. Mean PSV from 11 cycles was 155 cms with a precision of ±9.0% for the pulsating flow pump. In vivo, PSV estimated in the ascending aorta was 135 cms ± 16.9% for eight cardiac cycles. Furthermore, in vivo flow dynamics of the left ventricle and in the ascending aorta were visualized. In conclusion, angle independent 2-D VFI on a phased array has been implemented in real time, and it is capable of providing quantitative and qualitative flow evaluations of both the complex and fully transverse flow.

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Section: Discussionmentioning

confidence: 99%

Real-Time 2-D Phased Array Vector Flow Imaging

Holbek

Hansen

Fogh

et al. 2018

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: 88%

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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“…Vector flow imaging (VFI) is a relatively novel and still unexploited method, which is based on different technologies, 15–17 allowing the collection of speed and direction data of all the blood cells moving in the sampled volume, regardless of the insonation angle. Smart Flow (SF) is a VFI tool, available on the Carestream Touch Prime Ultrasound System, based upon transverse oscillation principle.…”

Section: Introductionmentioning

confidence: 99%

Smart Flow for the evaluation of the hemodialysis arteriovenous fistula

et al. 2020

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Background: Smart Flow is an innovative tool available on the Carestream Touch Prime Ultrasound machines, which provides automated blood flow measurement and shows the vectors that form the blood flow in the vessel. We compared the use of Smart Flow with traditional Duplex Doppler Ultrasound to evaluate blood flow of arteriovenous fistulas in prevalent hemodialysis patients. Methods: A total of 31 chronic patients on hemodialysis were enrolled. Blood flow was measured on the brachial artery with Smart Flow and duplex Doppler ultrasound. In a subset of 26 patients, a video of the juxta-anastomotic efferent vein was recorded and analyzed to calculate an index of flow turbulence. Results: We enrolled 21 males and 10 females aged 68.52 ± 11.64 years at the time of evaluation with an average arteriovenous fistulas vintage of 50.23 ± 47.42 months and followed them up for 18.03 ± 5.18 months. Smart Flow and Duplex Doppler Ultrasound blood flow measurements positively correlated (p < 0.0001) in the same patient but Smart Flow gave higher blood flow values (995.0 vs 730.3 mL/min, p < 0.0001), and the Duplex Doppler Ultrasound blood flow standard deviation was similar to Smart Flow (125.4 vs 114.4 mL/min, p < 0.0001). The time needed to evaluate arteriovenous fistulas with Smart Flow was significantly shorter than Duplex Doppler Ultrasound (67.58 ± 19.89 vs 146.3 ± 26.35 s, p < 0.0001). No correlation was found between blood flow turbulence and the subsequent access failure. Conclusion: Smart Flow is reliable, reproducible, and faster than traditional duplex ultrasound. However, the additional information given by the Smart Flow technique does not seem to add any further benefits in terms of prediction of the access failure.

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

Cited by 5 publications

References 13 publications

Real-Time 2-D Phased Array Vector Flow Imaging

Real-Time 2-D Phased Array Vector Flow Imaging

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

Smart Flow for the evaluation of the hemodialysis arteriovenous fistula

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